Bivariate descriptive analysis - Complete cases
Abdelaziz Ibn abdelouahab
2025-07-15
Descriptive statistics by MS
Table showing summary statistics for the entire sample and by migration status, with sex sub-stratification. Country of birth and country of citizenship were included as dichotomic variables. Categorical variables are expressed as counts (%). Normally distributed continuous variables (age) are expressed as mean (SD), and non-normally distributed continuous variables (preoperative length of stay, surgery duration and HDI for both country of birth and country of citizenship) are expressed as median (Q1 - Q3). Outcome-related variables are not included (SSI, SSI type and follow-up time).
| Total (Both) | Total by Sex | Migrants (Both) | Migrants by Sex | Non-migrants (Both) | Non-migrants by Sex | |||
|---|---|---|---|---|---|---|---|---|---|
Variable | N = 5,7991 | Male | Female | N = 4901 | Male | Female | N = 5,3091 | Male | Female |
Age | |||||||||
Min - Max | 16 - 95.0 | 18 - 95.0 | 16 - 95.0 | 20 - 94.0 | 21 - 94.0 | 20 - 85.0 | 16 - 95.0 | 18 - 95.0 | 16 - 95.0 |
Mean (SD) | 66 (12.5) | 65 (12.2) | 68 (12.6) | 59 (13.3) | 58 (12.6) | 60 (14.1) | 67 (12.2) | 66 (12.0) | 68 (12.2) |
Sex | |||||||||
Male | 3,056 (52.7%) | 254 (51.8%) | 2,802 (52.8%) | ||||||
Female | 2,743 (47.3%) | 236 (48.2%) | 2,507 (47.2%) | ||||||
Year of surgery | |||||||||
2007 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
2008 | 95 (1.6%) | 50 (1.6%) | 45 (1.6%) | 2 (0.4%) | 1 (0.4%) | 1 (0.4%) | 93 (1.8%) | 49 (1.7%) | 44 (1.8%) |
2009 | 245 (4.2%) | 111 (3.6%) | 134 (4.9%) | 8 (1.6%) | 5 (2.0%) | 3 (1.3%) | 237 (4.5%) | 106 (3.8%) | 131 (5.2%) |
2010 | 290 (5.0%) | 138 (4.5%) | 152 (5.5%) | 14 (2.9%) | 6 (2.4%) | 8 (3.4%) | 276 (5.2%) | 132 (4.7%) | 144 (5.7%) |
2011 | 348 (6.0%) | 180 (5.9%) | 168 (6.1%) | 14 (2.9%) | 7 (2.8%) | 7 (3.0%) | 334 (6.3%) | 173 (6.2%) | 161 (6.4%) |
2012 | 369 (6.4%) | 185 (6.1%) | 184 (6.7%) | 29 (5.9%) | 10 (3.9%) | 19 (8.1%) | 340 (6.4%) | 175 (6.2%) | 165 (6.6%) |
2013 | 379 (6.5%) | 197 (6.4%) | 182 (6.6%) | 23 (4.7%) | 12 (4.7%) | 11 (4.7%) | 356 (6.7%) | 185 (6.6%) | 171 (6.8%) |
2014 | 295 (5.1%) | 138 (4.5%) | 157 (5.7%) | 11 (2.2%) | 9 (3.5%) | 2 (0.8%) | 284 (5.3%) | 129 (4.6%) | 155 (6.2%) |
2015 | 208 (3.6%) | 103 (3.4%) | 105 (3.8%) | 15 (3.1%) | 6 (2.4%) | 9 (3.8%) | 193 (3.6%) | 97 (3.5%) | 96 (3.8%) |
2016 | 297 (5.1%) | 128 (4.2%) | 169 (6.2%) | 20 (4.1%) | 10 (3.9%) | 10 (4.2%) | 277 (5.2%) | 118 (4.2%) | 159 (6.3%) |
2017 | 298 (5.1%) | 133 (4.4%) | 165 (6.0%) | 19 (3.9%) | 6 (2.4%) | 13 (5.5%) | 279 (5.3%) | 127 (4.5%) | 152 (6.1%) |
2018 | 160 (2.8%) | 93 (3.0%) | 67 (2.4%) | 8 (1.6%) | 6 (2.4%) | 2 (0.8%) | 152 (2.9%) | 87 (3.1%) | 65 (2.6%) |
2019 | 395 (6.8%) | 179 (5.9%) | 216 (7.9%) | 30 (6.1%) | 11 (4.3%) | 19 (8.1%) | 365 (6.9%) | 168 (6.0%) | 197 (7.9%) |
2020 | 361 (6.2%) | 181 (5.9%) | 180 (6.6%) | 21 (4.3%) | 9 (3.5%) | 12 (5.1%) | 340 (6.4%) | 172 (6.1%) | 168 (6.7%) |
2021 | 283 (4.9%) | 140 (4.6%) | 143 (5.2%) | 27 (5.5%) | 10 (3.9%) | 17 (7.2%) | 256 (4.8%) | 130 (4.6%) | 126 (5.0%) |
2022 | 175 (3.0%) | 98 (3.2%) | 77 (2.8%) | 20 (4.1%) | 10 (3.9%) | 10 (4.2%) | 155 (2.9%) | 88 (3.1%) | 67 (2.7%) |
2023 | 829 (14.3%) | 520 (17.0%) | 309 (11.3%) | 108 (22.0%) | 60 (23.6%) | 48 (20.3%) | 721 (13.6%) | 460 (16.4%) | 261 (10.4%) |
2024 | 772 (13.3%) | 482 (15.8%) | 290 (10.6%) | 121 (24.7%) | 76 (29.9%) | 45 (19.1%) | 651 (12.3%) | 406 (14.5%) | 245 (9.8%) |
Surgical procedure (study classification) | |||||||||
THA | 1,191 (20.5%) | 604 (19.8%) | 587 (21.4%) | 101 (20.6%) | 43 (16.9%) | 58 (24.6%) | 1,090 (20.5%) | 561 (20.0%) | 529 (21.1%) |
TKA | 1,305 (22.5%) | 406 (13.3%) | 899 (32.8%) | 83 (16.9%) | 26 (10.2%) | 57 (24.2%) | 1,222 (23.0%) | 380 (13.6%) | 842 (33.6%) |
Valve replacement | 329 (5.7%) | 182 (6.0%) | 147 (5.4%) | 37 (7.6%) | 18 (7.1%) | 19 (8.1%) | 292 (5.5%) | 164 (5.9%) | 128 (5.1%) |
CABG + valve | 74 (1.3%) | 53 (1.7%) | 21 (0.8%) | 3 (0.6%) | 2 (0.8%) | 1 (0.4%) | 71 (1.3%) | 51 (1.8%) | 20 (0.8%) |
Colon or rectal resection | 2,069 (35.7%) | 1,118 (36.6%) | 951 (34.7%) | 158 (32.2%) | 81 (31.9%) | 77 (32.6%) | 1,911 (36.0%) | 1,037 (37.0%) | 874 (34.9%) |
CABG | 831 (14.3%) | 693 (22.7%) | 138 (5.0%) | 108 (22.0%) | 84 (33.1%) | 24 (10.2%) | 723 (13.6%) | 609 (21.7%) | 114 (4.5%) |
Preoperative length of stay (days) | |||||||||
Min - Max | 0 - 59.0 | 0 - 59.0 | 0 - 51.0 | 0 - 26.0 | 0 - 20.0 | 0 - 26.0 | 0 - 59.0 | 0 - 59.0 | 0 - 51.0 |
Median (Q1 - Q3) | 1 (0.0 - 1) | 1 (0.0 - 1) | 1 (0.0 - 1) | 1 (0.0 - 1) | 1 (0.0 - 1) | 1 (0.0 - 1) | 1 (0.0 - 1) | 1 (0.0 - 1) | 1 (0.0 - 1) |
ASA classification | |||||||||
I | 455 (7.8%) | 200 (6.5%) | 255 (9.3%) | 48 (9.8%) | 16 (6.3%) | 32 (13.6%) | 407 (7.7%) | 184 (6.6%) | 223 (8.9%) |
II | 3,211 (55.4%) | 1,447 (47.3%) | 1,764 (64.3%) | 252 (51.4%) | 112 (44.1%) | 140 (59.3%) | 2,959 (55.7%) | 1,335 (47.6%) | 1,624 (64.8%) |
III | 1,557 (26.8%) | 961 (31.4%) | 596 (21.7%) | 111 (22.7%) | 67 (26.4%) | 44 (18.6%) | 1,446 (27.2%) | 894 (31.9%) | 552 (22.0%) |
IV | 572 (9.9%) | 444 (14.5%) | 128 (4.7%) | 79 (16.1%) | 59 (23.2%) | 20 (8.5%) | 493 (9.3%) | 385 (13.7%) | 108 (4.3%) |
V | 4 (0.1%) | 4 (0.1%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 4 (0.1%) | 4 (0.1%) | 0 (0.0%) |
Degree of urgency | |||||||||
Elective | 5,675 (97.9%) | 2,975 (97.3%) | 2,700 (98.4%) | 474 (96.7%) | 245 (96.5%) | 229 (97.0%) | 5,201 (98.0%) | 2,730 (97.4%) | 2,471 (98.6%) |
Urgent | 6 (0.1%) | 1 (0.0%) | 5 (0.2%) | 2 (0.4%) | 1 (0.4%) | 1 (0.4%) | 4 (0.1%) | 0 (0.0%) | 4 (0.2%) |
Semi-elective | 118 (2.0%) | 80 (2.6%) | 38 (1.4%) | 14 (2.9%) | 8 (3.1%) | 6 (2.5%) | 104 (2.0%) | 72 (2.6%) | 32 (1.3%) |
Wound class | |||||||||
Clean | 3,733 (64.4%) | 1,937 (63.4%) | 1,796 (65.5%) | 333 (68.0%) | 174 (68.5%) | 159 (67.4%) | 3,400 (64.0%) | 1,763 (62.9%) | 1,637 (65.3%) |
Clean-contaminated | 1,744 (30.1%) | 949 (31.1%) | 795 (29.0%) | 138 (28.2%) | 72 (28.3%) | 66 (28.0%) | 1,606 (30.3%) | 877 (31.3%) | 729 (29.1%) |
Contaminated | 317 (5.5%) | 165 (5.4%) | 152 (5.5%) | 19 (3.9%) | 8 (3.1%) | 11 (4.7%) | 298 (5.6%) | 157 (5.6%) | 141 (5.6%) |
Infected | 5 (0.1%) | 5 (0.2%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 5 (0.1%) | 5 (0.2%) | 0 (0.0%) |
Antibiotic prophylaxis | |||||||||
Adequate | 5,433 (93.7%) | 2,843 (93.0%) | 2,590 (94.4%) | 439 (89.6%) | 230 (90.6%) | 209 (88.6%) | 4,994 (94.1%) | 2,613 (93.3%) | 2,381 (95.0%) |
Inadequate | 366 (6.3%) | 213 (7.0%) | 153 (5.6%) | 51 (10.4%) | 24 (9.4%) | 27 (11.4%) | 315 (5.9%) | 189 (6.7%) | 126 (5.0%) |
Minimally invasive surgery | 1,827 (31.5%) | 983 (32.2%) | 844 (30.8%) | 142 (29.0%) | 69 (27.2%) | 73 (30.9%) | 1,685 (31.7%) | 914 (32.6%) | 771 (30.8%) |
Surgery duration (minutes) | |||||||||
Min - Max | 4 - 1,685.0 | 4 - 689.0 | 10 - 1,685.0 | 22 - 531.0 | 35 - 460.0 | 22 - 531.0 | 4 - 1,685.0 | 4 - 689.0 | 10 - 1,685.0 |
Median (Q1 - Q3) | 120 (90.0 - 186) | 140 (99.0 - 218) | 105 (83.0 - 150) | 135 (99.0 - 215) | 155 (110.0 - 246) | 120 (90.0 - 181) | 120 (90.0 - 183) | 140 (98.0 - 215) | 105 (81.0 - 147) |
Country of birth (Dicotomic) | |||||||||
Non-Spain | 487 (8.4%) | 253 (8.3%) | 234 (8.5%) | 487 (99.4%) | 253 (99.6%) | 234 (99.2%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Spain | 5,312 (91.6%) | 2,803 (91.7%) | 2,509 (91.5%) | 3 (0.6%) | 1 (0.4%) | 2 (0.8%) | 5,309 (100.0%) | 2,802 (100.0%) | 2,507 (100.0%) |
Country of birth - World Region | |||||||||
East Asia & Pacific | 28 (0.5%) | 15 (0.5%) | 13 (0.5%) | 28 (5.7%) | 15 (5.9%) | 13 (5.5%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Europe & Central Asia | 5,432 (93.7%) | 2,869 (93.9%) | 2,563 (93.4%) | 123 (25.1%) | 67 (26.4%) | 56 (23.7%) | 5,309 (100.0%) | 2,802 (100.0%) | 2,507 (100.0%) |
Latin America & Caribbean | 246 (4.2%) | 109 (3.6%) | 137 (5.0%) | 246 (50.2%) | 109 (42.9%) | 137 (58.1%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Middle East & North Africa | 52 (0.9%) | 35 (1.1%) | 17 (0.6%) | 52 (10.6%) | 35 (13.8%) | 17 (7.2%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
North America | 5 (0.1%) | 3 (0.1%) | 2 (0.1%) | 5 (1.0%) | 3 (1.2%) | 2 (0.8%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
South Asia | 27 (0.5%) | 19 (0.6%) | 8 (0.3%) | 27 (5.5%) | 19 (7.5%) | 8 (3.4%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Sub-Saharan Africa | 9 (0.2%) | 6 (0.2%) | 3 (0.1%) | 9 (1.8%) | 6 (2.4%) | 3 (1.3%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Country of birth - Human Development Index | |||||||||
Min - Max | 0.5 - 1.0 | 0.5 - 1.0 | 0.5 - 1.0 | 0.5 - 1.0 | 0.5 - 1.0 | 0.5 - 1.0 | 0.9 - 0.9 | 0.9 - 0.9 | 0.9 - 0.9 |
Median (Q1 - Q3) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | 0.8 (0.7 - 0.8) | 0.8 (0.7 - 0.8) | 0.8 (0.7 - 0.8) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) |
Country of birth - Human Development Index category | |||||||||
High | 184 (3.2%) | 79 (2.6%) | 105 (3.8%) | 184 (37.6%) | 79 (31.1%) | 105 (44.5%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Low | 19 (0.3%) | 14 (0.5%) | 5 (0.2%) | 19 (3.9%) | 14 (5.5%) | 5 (2.1%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Medium | 109 (1.9%) | 59 (1.9%) | 50 (1.8%) | 109 (22.2%) | 59 (23.2%) | 50 (21.2%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Very High | 5,487 (94.6%) | 2,904 (95.0%) | 2,583 (94.2%) | 178 (36.3%) | 102 (40.2%) | 76 (32.2%) | 5,309 (100.0%) | 2,802 (100.0%) | 2,507 (100.0%) |
Country of citizenship (Dicotomic) | |||||||||
Non-Spain | 234 (4.0%) | 141 (4.6%) | 93 (3.4%) | 234 (47.8%) | 141 (55.5%) | 93 (39.4%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Spain | 5,565 (96.0%) | 2,915 (95.4%) | 2,650 (96.6%) | 256 (52.2%) | 113 (44.5%) | 143 (60.6%) | 5,309 (100.0%) | 2,802 (100.0%) | 2,507 (100.0%) |
Country of citizenship - World Region | |||||||||
East Asia & Pacific | 14 (0.2%) | 7 (0.2%) | 7 (0.3%) | 14 (2.9%) | 7 (2.8%) | 7 (3.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Europe & Central Asia | 5,667 (97.7%) | 2,980 (97.5%) | 2,687 (98.0%) | 358 (73.1%) | 178 (70.1%) | 180 (76.3%) | 5,309 (100.0%) | 2,802 (100.0%) | 2,507 (100.0%) |
Latin America & Caribbean | 64 (1.1%) | 32 (1.0%) | 32 (1.2%) | 64 (13.1%) | 32 (12.6%) | 32 (13.6%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Middle East & North Africa | 26 (0.4%) | 17 (0.6%) | 9 (0.3%) | 26 (5.3%) | 17 (6.7%) | 9 (3.8%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
North America | 4 (0.1%) | 3 (0.1%) | 1 (0.0%) | 4 (0.8%) | 3 (1.2%) | 1 (0.4%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
South Asia | 19 (0.3%) | 13 (0.4%) | 6 (0.2%) | 19 (3.9%) | 13 (5.1%) | 6 (2.5%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Sub-Saharan Africa | 5 (0.1%) | 4 (0.1%) | 1 (0.0%) | 5 (1.0%) | 4 (1.6%) | 1 (0.4%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Country of citizenship - Human Development Index | |||||||||
Min - Max | 0.5 - 0.9 | 0.5 - 0.9 | 0.5 - 0.9 | 0.5 - 0.9 | 0.5 - 0.9 | 0.5 - 0.9 | 0.9 - 0.9 | 0.9 - 0.9 | 0.9 - 0.9 |
Median (Q1 - Q3) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | 0.9 (0.8 - 0.9) | 0.9 (0.8 - 0.9) | 0.9 (0.8 - 0.9) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) |
Country of citizenship - Human Development Index category | |||||||||
High | 64 (1.1%) | 31 (1.0%) | 33 (1.2%) | 64 (13.1%) | 31 (12.2%) | 33 (14.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Low | 14 (0.2%) | 10 (0.3%) | 4 (0.1%) | 14 (2.9%) | 10 (3.9%) | 4 (1.7%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Medium | 48 (0.8%) | 28 (0.9%) | 20 (0.7%) | 48 (9.8%) | 28 (11.0%) | 20 (8.5%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Very High | 5,673 (97.8%) | 2,987 (97.7%) | 2,686 (97.9%) | 364 (74.3%) | 185 (72.8%) | 179 (75.8%) | 5,309 (100.0%) | 2,802 (100.0%) | 2,507 (100.0%) |
RCA document | |||||||||
DNI | 5,568 (96.0%) | 2,916 (95.4%) | 2,652 (96.7%) | 259 (52.9%) | 114 (44.9%) | 145 (61.4%) | 5,309 (100.0%) | 2,802 (100.0%) | 2,507 (100.0%) |
NIE | 209 (3.6%) | 130 (4.3%) | 79 (2.9%) | 209 (42.7%) | 130 (51.2%) | 79 (33.5%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Passeport | 22 (0.4%) | 10 (0.3%) | 12 (0.4%) | 22 (4.5%) | 10 (3.9%) | 12 (5.1%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
Yearly income category | |||||||||
< 18.000 euros | 3,252 (56.1%) | 1,550 (50.7%) | 1,702 (62.0%) | 387 (79.0%) | 194 (76.4%) | 193 (81.8%) | 2,865 (54.0%) | 1,356 (48.4%) | 1,509 (60.2%) |
18.000 - 100.000 euros | 2,475 (42.7%) | 1,460 (47.8%) | 1,015 (37.0%) | 97 (19.8%) | 56 (22.0%) | 41 (17.4%) | 2,378 (44.8%) | 1,404 (50.1%) | 974 (38.9%) |
> 100.000 euros | 72 (1.2%) | 46 (1.5%) | 26 (0.9%) | 6 (1.2%) | 4 (1.6%) | 2 (0.8%) | 66 (1.2%) | 42 (1.5%) | 24 (1.0%) |
Health insurance at the time of surgery | 5,792 (99.9%) | 3,052 (99.9%) | 2,740 (99.9%) | 487 (99.4%) | 253 (99.6%) | 234 (99.2%) | 5,305 (99.9%) | 2,799 (99.9%) | 2,506 (100.0%) |
1n (%) | |||||||||
Age: migrant patients were younger than non-migrant patients
Sex distribution was similar between groups, with only a slight over representation of women in the migrants groups compared to the non-migrants group
Surgical year: overall, the number of surgical interventions increased gradually from 2008 to 2013. From 2014 to 2018, the number of included surgeries varied from year to year. During the 2019-20122 period, the number of included surgeries decreased gradually. In the last two years (2023 and 2024), the number of included surgeries increased sharply. The proportion of migrant patients increased gradually, with a sharp increase in the last two years. The following bar plot shows the number of surgeries performed in each year, stratified by migration status.
Surgical procedure: compared to non-migrants, the proportion of TKA, CABG + valve and colon or rectal resection surgeries were lower among migrants, while valve replacement and CABG surgeries were higher. THA were distributed equally in both groups.
Preoperative length of stay: similar across sub-groups
ASA classification: compared to non-migrants, the proportion of patients with ASA score I or IV was slightly higher among migrants, while those with ASA score II or III was slightly lower. The proportions of male and female patients in each ASA score were similar in both groups.
Degree of urgency: compared to the group of non-migrants, the proportion of patients with elective surgery was lower and the proportion of patients with semi-elective surgeries was higher among migrants.
Wound class: compared to the group of non-migrants, the proportion of patients with clean wound was higher and the proportion of patients with clean-contaminated and contaminated wounds was lower among migrants.
Antibiotic prophylaxis: compared to the group of non-migrants, the proportion of patients with inadequate prohylaxis was higher among migrants.
Minimally invasive surgery: the proportion of patients with minimally invasive surgery was lower in the group of migrants.
Surgery duration: the duration was higher among the group of migrants and in males.
Country of birth: among the group of migrants, approximately 50% in Latin America & Carribean (this proportion was higher in females), 25% were born in Europe & Central Asia, and approximately 10% in Middle East and North Africa. Almost every patient classified as migrant was born outside of Spain. The median HDI of the country of birth was lower among migrants compared to non-migrants. All patients in the non-migrant group were born in Spain, which is among countries with very-high HDI, while among migrants, approximately one third were born in a country with very-high HDI, another third were born in a country with high HDI, and 1/5 in a country with medium HDI.
Country of citizenship: Among the group of migrants, almost half patients had a Spanish citizenship, while the other half had a different citizenship. More than 70% of migrant patients had a citizenship from a country in Europe & Central Asia, and more than 10% from a country in Latin America & Carribean. The median HDI of the country of birth was slightly lower among migrants compared to non-migrants. All patients in the non-migrant group had a Spanish citizenship, which is among countries with very-high HDI, while among migrants, approximately 75% had a citizenship of a country with very-high HDI, the rest of patients holding citizenship from countries with lower HDI categories.
Document: All patients in the non-migrant group had a DNI, while approximately half patients in the migrant group had a DNI and more than 40% had NIE.
Income: Compared to non-migrants, among whom the proportion of patients with a yearly income lower than 18.000 euros was more than 50%, the proportion of patients with a similar income category was higher among the groups of migrants, reaching more than 75%.
Health Insurance: The proportion of patients with a health insurance was very high overall and in both migration groups, although slightly lower among the group pf migrants.
Crude incidence of SSI
Cumulative incidence
Both sexes: overall and by MS
The crude cumulative incidence in the group migrants is lower compared to the group of non-migrants. The CIR is lower than 1. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 31 459 490 6.33 (4.34 to 8.86)
## Exposed - 440 4869 5309 8.29 (7.56 to 9.06)
## Total 471 5328 5799 8.12 (7.43 to 8.86)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.76 (0.54, 1.09)
## Inc odds ratio 0.75 (0.51, 1.09)
## Attrib risk in the exposed * -1.96 (-4.24, 0.32)
## Attrib fraction in the exposed (%) -31.00 (-86.32, 7.89)
## Attrib risk in the population * -0.17 (-1.19, 0.86)
## Attrib fraction in the population (%) -2.04 (-4.44, 0.30)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 2.312 Pr>chi2 = 0.128
## Fisher exact test that OR = 1: Pr>chi2 = 0.142
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsFemales: overall and by MS
Among females, the crude cumulative incidence of SSI was lower among migrant compared to non-migrants. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 16 220 236 6.78 (3.92 to 10.78)
## Exposed - 184 2323 2507 7.34 (6.35 to 8.43)
## Total 200 2543 2743 7.29 (6.35 to 8.33)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.92 (0.56, 1.51)
## Inc odds ratio 0.92 (0.54, 1.56)
## Attrib risk in the exposed * -0.56 (-3.93, 2.81)
## Attrib fraction in the exposed (%) -8.26 (-77.26, 33.89)
## Attrib risk in the population * -0.05 (-1.46, 1.36)
## Attrib fraction in the population (%) -0.66 (-4.71, 3.23)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 0.100 Pr>chi2 = 0.752
## Fisher exact test that OR = 1: Pr>chi2 = 0.896
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsMales: overall and by MS
Among males, the crude cumulative incidence of SSI was lower among migrant compared to non-migrants. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 15 239 254 5.91 (3.34 to 9.55)
## Exposed - 256 2546 2802 9.14 (8.09 to 10.26)
## Total 271 2785 3056 8.87 (7.88 to 9.93)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.65 (0.39, 1.07)
## Inc odds ratio 0.62 (0.36, 1.07)
## Attrib risk in the exposed * -3.23 (-6.32, -0.14)
## Attrib fraction in the exposed (%) -54.71 (-156.24, 6.59)
## Attrib risk in the population * -0.27 (-1.74, 1.20)
## Attrib fraction in the population (%) -3.03 (-5.97, -0.17)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 3.008 Pr>chi2 = 0.083
## Fisher exact test that OR = 1: Pr>chi2 = 0.084
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsBoth sexes: overall and by MS - Surgical procedure strata
Colon resection
Considering only colon resection procedures, the crude cumulative incidence of SSI in the group of migrants is lower compared to the group of non-migrants. CIR is lower than one. Differences are statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 2 90 92 2.17 (0.26 to 7.63)
## Exposed - 115 1172 1287 8.94 (7.43 to 10.63)
## Total 117 1262 1379 8.48 (7.07 to 10.08)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.24 (0.06, 0.97)
## Inc odds ratio 0.23 (0.06, 0.93)
## Attrib risk in the exposed * -6.76 (-10.12, -3.40)
## Attrib fraction in the exposed (%) -311.03 (-1536.77, -3.22)
## Attrib risk in the population * -0.45 (-2.59, 1.69)
## Attrib fraction in the population (%) -5.32 (-8.07, -2.63)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 5.056 Pr>chi2 = 0.025
## Fisher exact test that OR = 1: Pr>chi2 = 0.019
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsRectal resection
Considering only rectal resection procedures, the crude cumulative incidence of SSI in the group of migrants is higher compared to the group of non-migrants. CIR is lower than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 13 53 66 19.70 (10.93 to 31.32)
## Exposed - 109 515 624 17.47 (14.57 to 20.68)
## Total 122 568 690 17.68 (14.91 to 20.74)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 1.13 (0.67, 1.89)
## Inc odds ratio 1.16 (0.61, 2.20)
## Attrib risk in the exposed * 2.23 (-7.82, 12.28)
## Attrib fraction in the exposed (%) 11.32 (-48.59, 47.07)
## Attrib risk in the population * 0.21 (-3.91, 4.33)
## Attrib fraction in the population (%) 1.21 (-4.39, 6.50)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 0.204 Pr>chi2 = 0.652
## Fisher exact test that OR = 1: Pr>chi2 = 0.614
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsColon and/or rectal resection
Considering only colon and/or rectal resection surgeries, the crude cumulative incidence of SSI in the group of migrants is lower compared to the group of non-migrants. CIR is lower than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 15 143 158 9.49 (5.41 to 15.17)
## Exposed - 224 1687 1911 11.72 (10.31 to 13.25)
## Total 239 1830 2069 11.55 (10.21 to 13.01)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.81 (0.49, 1.33)
## Inc odds ratio 0.79 (0.46, 1.37)
## Attrib risk in the exposed * -2.23 (-7.02, 2.56)
## Attrib fraction in the exposed (%) -23.47 (-102.94, 24.88)
## Attrib risk in the population * -0.17 (-2.16, 1.82)
## Attrib fraction in the population (%) -1.47 (-4.70, 1.65)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 0.709 Pr>chi2 = 0.400
## Fisher exact test that OR = 1: Pr>chi2 = 0.516
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsOrthopedic interventions
TKA
Considering only TKA procedures, the crude cumulative incidence of SSI in the group of migrants is lower compared to the group of non-migrants. CIR is lower than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 3 80 83 3.61 (0.75 to 10.20)
## Exposed - 53 1169 1222 4.34 (3.27 to 5.63)
## Total 56 1249 1305 4.29 (3.26 to 5.54)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.83 (0.27, 2.61)
## Inc odds ratio 0.83 (0.25, 2.71)
## Attrib risk in the exposed * -0.72 (-4.90, 3.45)
## Attrib fraction in the exposed (%) -19.99 (-275.84, 61.69)
## Attrib risk in the population * -0.05 (-1.63, 1.54)
## Attrib fraction in the population (%) -1.07 (-7.45, 4.93)
## -------------------------------------------------------------------
## Yates corrected chi2 test that OR = 1: chi2(1) = 0.001 Pr>chi2 = 0.972
## Fisher exact test that OR = 1: Pr>chi2 = 1.000
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsTHA
Considering only THA procedures, the crude cumulative incidence of SSI in the group of migrants is lower compared to the group of non-migrants. CIR is lower than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 2 99 101 1.98 (0.24 to 6.97)
## Exposed - 47 1043 1090 4.31 (3.19 to 5.69)
## Total 49 1142 1191 4.11 (3.06 to 5.40)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.46 (0.11, 1.86)
## Inc odds ratio 0.45 (0.11, 1.87)
## Attrib risk in the exposed * -2.33 (-5.30, 0.64)
## Attrib fraction in the exposed (%) -117.75 (-783.31, 46.32)
## Attrib risk in the population * -0.20 (-1.85, 1.45)
## Attrib fraction in the population (%) -4.81 (-11.05, 1.09)
## -------------------------------------------------------------------
## Yates corrected chi2 test that OR = 1: chi2(1) = 0.751 Pr>chi2 = 0.386
## Fisher exact test that OR = 1: Pr>chi2 = 0.427
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsAll orthopedic procedures combined
Considering all orthopedic procedures procedures, the crude cumulative incidence of SSI in the group of migrants is lower compared to the group of non-migrants. CIR is lower than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 5 179 184 2.72 (0.89 to 6.23)
## Exposed - 100 2212 2312 4.33 (3.53 to 5.24)
## Total 105 2391 2496 4.21 (3.45 to 5.07)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.63 (0.26, 1.52)
## Inc odds ratio 0.62 (0.25, 1.54)
## Attrib risk in the exposed * -1.61 (-4.10, 0.88)
## Attrib fraction in the exposed (%) -59.17 (-285.87, 34.34)
## Attrib risk in the population * -0.12 (-1.26, 1.03)
## Attrib fraction in the population (%) -2.82 (-7.27, 1.45)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 1.093 Pr>chi2 = 0.296
## Fisher exact test that OR = 1: Pr>chi2 = 0.442
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsCardiac procedures
CABG
Considering only CABG procedures, the crude cumulative incidence of SSI in the group of migrants is lower compared to the group of non-migrants. CIR is lower than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 10 98 108 9.26 (4.53 to 16.37)
## Exposed - 90 633 723 12.45 (10.13 to 15.08)
## Total 100 731 831 12.03 (9.90 to 14.44)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.74 (0.40, 1.38)
## Inc odds ratio 0.72 (0.36, 1.43)
## Attrib risk in the exposed * -3.19 (-9.16, 2.78)
## Attrib fraction in the exposed (%) -34.44 (-150.23, 27.77)
## Attrib risk in the population * -0.41 (-3.68, 2.85)
## Attrib fraction in the population (%) -3.44 (-10.11, 2.82)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 0.903 Pr>chi2 = 0.342
## Fisher exact test that OR = 1: Pr>chi2 = 0.428
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsValve replacement
Considering only valve replacement procedures, there were no SSI events in the migrants group, therefore the crude cumulative incidence cannot be computed.
## Outcome + Outcome - Total Inc risk *
## Exposed + 0 37 37 0.00 (0.00 to 9.49)
## Exposed - 14 278 292 4.79 (2.65 to 7.91)
## Total 14 315 329 4.26 (2.35 to 7.04)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio NaN (NaN, NaN)
## Inc odds ratio NaN (NaN, NaN)
## Attrib risk in the exposed * -4.79 (-7.25, -2.34)
## Attrib fraction in the exposed (%) NaN (NaN, NaN)
## Attrib risk in the population * -0.54 (-3.82, 2.74)
## Attrib fraction in the population (%) -12.67 (-17.09, -8.42)
## -------------------------------------------------------------------
## Yates corrected chi2 test that OR = 1: chi2(1) = 0.863 Pr>chi2 = 0.353
## Fisher exact test that OR = 1: Pr>chi2 = 0.381
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsCABG + valve
Considering only CABG + valve replacement procedures, the crude cumulative incidence of SSI in the group of migrants is higher compared to the group of non-migrants. CIR is higher than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 1 2 3 33.33 (0.84 to 90.57)
## Exposed - 12 59 71 16.90 (9.05 to 27.66)
## Total 13 61 74 17.57 (9.70 to 28.17)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 1.97 (0.37, 10.60)
## Inc odds ratio 2.46 (0.21, 29.34)
## Attrib risk in the exposed * 16.43 (-37.62, 70.48)
## Attrib fraction in the exposed (%) 49.30 (-172.43, 90.56)
## Attrib risk in the population * 0.67 (-11.63, 12.96)
## Attrib fraction in the population (%) 3.79 (-10.22, 16.03)
## -------------------------------------------------------------------
## Yates corrected chi2 test that OR = 1: chi2(1) = 0.000 Pr>chi2 = 1.000
## Fisher exact test that OR = 1: Pr>chi2 = 0.445
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsAll cardiac procedures combined
Considering only cardiac procedures, the crude cumulative incidence of SSI in the group of migrants is lower compared to the group of non-migrants. CIR is lower than one. Differences are not statistically significant.
## Outcome + Outcome - Total Inc risk *
## Exposed + 11 137 148 7.43 (3.77 to 12.91)
## Exposed - 116 970 1086 10.68 (8.91 to 12.67)
## Total 127 1107 1234 10.29 (8.65 to 12.12)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc risk ratio 0.70 (0.38, 1.26)
## Inc odds ratio 0.67 (0.35, 1.28)
## Attrib risk in the exposed * -3.25 (-7.86, 1.36)
## Attrib fraction in the exposed (%) -43.71 (-160.30, 20.65)
## Attrib risk in the population * -0.39 (-2.89, 2.11)
## Attrib fraction in the population (%) -3.79 (-9.30, 1.45)
## -------------------------------------------------------------------
## Uncorrected chi2 test that OR = 1: chi2(1) = 1.489 Pr>chi2 = 0.222
## Fisher exact test that OR = 1: Pr>chi2 = 0.251
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 100 population unitsIncidence rate
Both sexes: overall and by MS
The crude incidence rate in the group migrants is lower compared to the group of non-migrants. The IRR is lower than 1. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 31 33297 0.93 (0.63 to 1.32)
## Exposed - 440 344265 1.28 (1.16 to 1.40)
## Total 471 377562 1.25 (1.14 to 1.37)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.73 (0.49, 1.05)
## Attrib rate in the exposed * -0.35 (-0.70, 0.00)
## Attrib fraction in the exposed (%) -37.28 (-104.52, 4.68)
## Attrib rate in the population * -0.03 (-0.19, 0.13)
## Attrib fraction in the population (%) -2.45 (-2.77, -2.12)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskFemales: overall and by MS
Among females, the crude incidence rate in the group migrants is lower compared to the group of non-migrants. The IRR is lower than 1. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 16 15998 1.00 (0.57 to 1.62)
## Exposed - 184 165799 1.11 (0.96 to 1.28)
## Total 200 181797 1.10 (0.95 to 1.26)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.90 (0.50, 1.50)
## Attrib rate in the exposed * -0.11 (-0.63, 0.41)
## Attrib fraction in the exposed (%) -10.96 (-98.23, 33.47)
## Attrib rate in the population * -0.01 (-0.23, 0.21)
## Attrib fraction in the population (%) -0.88 (-1.47, -0.24)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskMales: overall and by MS
Among males, the crude incidence rate in the group migrants is lower compared to the group of non-migrants. The IRR is lower than 1. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 15 17299 0.87 (0.49 to 1.43)
## Exposed - 256 178466 1.43 (1.26 to 1.62)
## Total 271 195765 1.38 (1.22 to 1.56)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.60 (0.33, 1.02)
## Attrib rate in the exposed * -0.57 (-1.04, -0.09)
## Attrib fraction in the exposed (%) -65.43 (-199.93, 1.57)
## Attrib rate in the population * -0.05 (-0.29, 0.19)
## Attrib fraction in the population (%) -3.62 (-3.98, -3.24)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskBoth sexes: overall and by MS - Surgical procedure strata
Colon resection
Considering only colon resection procedures, the crude incidence rate of SSI in the group of migrants is lower compared to the group of non-migrants. IRR is lower than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 2 2706 0.74 (0.09 to 2.67)
## Exposed - 115 36248 3.17 (2.62 to 3.81)
## Total 117 38954 3.00 (2.48 to 3.60)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.23 (0.03, 0.86)
## Attrib rate in the exposed * -2.43 (-3.61, -1.26)
## Attrib fraction in the exposed (%) -329.25 (-3486.93, -16.16)
## Attrib rate in the population * -0.17 (-0.96, 0.63)
## Attrib fraction in the population (%) -5.63 (-5.79, -5.45)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskRectal resection
Considering only rectal resection procedures, the crude incidence rate of SSI in the group of migrants is higher compared to the group of non-migrants. IRR is higher than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 13 1763 7.37 (3.93 to 12.61)
## Exposed - 109 16549 6.59 (5.41 to 7.95)
## Total 122 18312 6.66 (5.53 to 7.95)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 1.12 (0.58, 2.00)
## Attrib rate in the exposed * 0.79 (-3.41, 4.98)
## Attrib fraction in the exposed (%) 10.68 (-73.12, 49.89)
## Attrib rate in the population * 0.08 (-1.63, 1.79)
## Attrib fraction in the population (%) 1.14 (0.12, 2.25)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskColon and/or rectal resection
Considering only colon and/or rectal resection surgeries, the crude IR of SSI in the group of migrants is lower compared to the group of non-migrants. IRR is lower than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 15 4469 3.36 (1.88 to 5.54)
## Exposed - 224 52797 4.24 (3.71 to 4.84)
## Total 239 57266 4.17 (3.66 to 4.74)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.79 (0.44, 1.33)
## Attrib rate in the exposed * -0.89 (-2.67, 0.90)
## Attrib fraction in the exposed (%) -26.40 (-129.64, 24.99)
## Attrib rate in the population * -0.07 (-0.84, 0.70)
## Attrib fraction in the population (%) -1.66 (-2.08, -1.20)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskOrthopedic interventions
TKA
Considering only TKA procedures, the IR of SSI in the group of migrants is lower compared to the group of non-migrants. IRR is lower than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 3 7301 4.11 (0.85 to 12.01)
## Exposed - 53 106725 4.97 (3.72 to 6.50)
## Total 56 114026 4.91 (3.71 to 6.38)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.83 (0.17, 2.55)
## Attrib rate in the exposed * -0.86 (-5.70, 3.98)
## Attrib fraction in the exposed (%) -20.86 (-504.67, 60.83)
## Attrib rate in the population * -0.05 (-1.91, 1.80)
## Attrib fraction in the population (%) -1.12 (-1.85, -0.27)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 10000 units of population time at riskTHA
Considering only THA procedures, the IR of SSI in the group of migrants is lower compared to the group of non-migrants. IRR is lower than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 2 8973 2.23 (0.27 to 8.05)
## Exposed - 47 95101 4.94 (3.63 to 6.57)
## Total 49 104074 4.71 (3.48 to 6.22)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.45 (0.05, 1.72)
## Attrib rate in the exposed * -2.71 (-6.11, 0.68)
## Attrib fraction in the exposed (%) -121.73 (-1784.49, 41.94)
## Attrib rate in the population * -0.23 (-2.17, 1.70)
## Attrib fraction in the population (%) -4.97 (-5.58, -4.25)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 10000 units of population time at riskAll orthopedic procedures combined
Considering all orthopedic procedures combined, the crude IR of SSI in the group of migrants is lower compared to the group of non-migrants. IRR is lower than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 5 16274 3.07 (1.00 to 7.17)
## Exposed - 100 201826 4.95 (4.03 to 6.03)
## Total 105 218100 4.81 (3.94 to 5.83)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.62 (0.20, 1.50)
## Attrib rate in the exposed * -1.88 (-4.75, 0.98)
## Attrib fraction in the exposed (%) -61.27 (-407.49, 33.15)
## Attrib rate in the population * -0.14 (-1.48, 1.20)
## Attrib fraction in the population (%) -2.92 (-3.40, -2.38)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 10000 units of population time at riskCardiac procedures
CABG
Considering only CABG procedures, the crude IR of SSI in the group of migrants is lower compared to the group of non-migrants. IRR is lower than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 10 9079 1.10 (0.53 to 2.03)
## Exposed - 90 58931 1.53 (1.23 to 1.88)
## Total 100 68010 1.47 (1.20 to 1.79)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.72 (0.33, 1.39)
## Attrib rate in the exposed * -0.43 (-1.18, 0.33)
## Attrib fraction in the exposed (%) -38.66 (-198.98, 27.98)
## Attrib rate in the population * -0.06 (-0.48, 0.37)
## Attrib fraction in the population (%) -3.87 (-4.97, -2.65)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskValve replacement
Considering only valve replacement procedures, there were no SSI events in the migrants group, therefore the IR cannot be computed.
## Outcome + Time at risk Inc rate *
## Exposed + 0 3249 0.00 (0.00 to 1.14)
## Exposed - 14 25111 0.56 (0.30 to 0.94)
## Total 14 28360 0.49 (0.27 to 0.83)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio NaN (NaN, NaN)
## Attrib rate in the exposed * -0.56 (-0.85, -0.27)
## Attrib fraction in the exposed (%) NaN (NaN, NaN)
## Attrib rate in the population * -0.06 (-0.45, 0.33)
## Attrib fraction in the population (%) -12.94 (-12.94, -12.94)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskCABG + valve
Considering only CABG + valve replacement procedures, the IR of SSI in the group of migrants is higher compared to the group of non-migrants. IRR is higher than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 1 226 4.42 (0.11 to 24.65)
## Exposed - 12 5600 2.14 (1.11 to 3.74)
## Total 13 5826 2.23 (1.19 to 3.82)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 2.06 (0.05, 13.96)
## Attrib rate in the exposed * 2.28 (-6.47, 11.04)
## Attrib fraction in the exposed (%) 51.57 (-1970.21, 92.83)
## Attrib rate in the population * 0.09 (-1.63, 1.80)
## Attrib fraction in the population (%) 3.97 (1.90, 6.81)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskAll cardiac procedures combined
Considering all cardiac procedures combined, the crude IR of SSI in the group of migrants is lower compared to the group of non-migrants. IR is lower than one. Differences are not statistically significant.
## Outcome + Time at risk Inc rate *
## Exposed + 11 12554 0.88 (0.44 to 1.57)
## Exposed - 116 89642 1.29 (1.07 to 1.55)
## Total 127 102196 1.24 (1.04 to 1.48)
##
## Point estimates and 95% CIs:
## -------------------------------------------------------------------
## Inc rate ratio 0.68 (0.33, 1.26)
## Attrib rate in the exposed * -0.42 (-0.99, 0.15)
## Attrib fraction in the exposed (%) -47.68 (-204.05, 20.45)
## Attrib rate in the population * -0.05 (-0.37, 0.27)
## Attrib fraction in the population (%) -4.13 (-4.97, -3.21)
## -------------------------------------------------------------------
## Wald confidence limits
## CI: confidence interval
## * Outcomes per 1000 units of population time at riskBivariate analysis - SSI
We perform a bivariate analysis to identify variables associated with SSI.
Appropriate tests are performed:
Continous variables:
Age (surage): t-test
Preoperative length of stay (preoplos): U Mann Withney test
Surgery duration (duration): U Mann Withney test
HDI (country of birth, whole sample - CoB_hdi): U Mann Withney test
HDI (country of citizenship, whole sample - CoC_hdi): U Mann Withney test
Categorical variables:
Sex (sex): Chi-square test
Surgery year (suryear): too many levels. Categorized as suryear_cat
Surgery year categories (suryear_cat): chi-squared test
Surgical procedure (surtype_2): chi-squared test
Degree of urgency (urg): Fisher’s exact test with Monte Carlo simulation
ASA classification (asa): Fisher’s exact test with Monte Carlo simulation
Antibiotic prophylaxis (atbprof): chi-squared test
Wound classification (wound): Fisher’s exact test with Monte Carlo simulation
Minimally invasive surgery (misurg): chi-squared test
Migration status (MS): chi-squared
Country of birth (CoB): categorized as dicotomic
Country of birth, dicotomic (CoB_dic): chi-squared test
Country of legal citizenship (CoC): categorized as dicotomic
Country of citizenship, dicotomic (CoC_dic): chi-squared test
Country of birth - World Region (CoB_WR): Fisher’s exact test with Monte Carlo simulation
Country of legal citizenship - World region (CoC_WR): Fisher’s exact test with Monte Carlo simulation
Country of birth - HDI category (CoB_hdicat): chi-squared test
Country of legal citizenship - HDI category (CoC_hdicat): Fisher’s exact test with Monte Carlo simulation
Document type (doc): Fisher’s exact test with Monte Carlo simulation
Health insurance (insurance): Fisher’s exact test
| Variable |
SSI
|
p-value2 | |
|---|---|---|---|
| No N = 5,3281 |
Yes N = 4711 |
||
| Age | 0.007 | ||
| Min - Max | 16 - 95.0 | 26 - 89.0 | |
| Mean (SD) | 66 (12.5) | 65 (12.6) | |
| Sex | 0.032 | ||
| Male | 2,785 (52.3%) | 271 (57.5%) | |
| Female | 2,543 (47.7%) | 200 (42.5%) | |
| Migration Status | 459 (8.6%) | 31 (6.6%) | 0.152 |
| Surgery Year categories | <0.001 | ||
| 2007-2014 | 1,904 (35.7%) | 117 (24.8%) | |
| 2015-2019 | 1,225 (23.0%) | 133 (28.2%) | |
| 2020-2024 | 2,199 (41.3%) | 221 (46.9%) | |
| Surgical procedure (study classification) | <0.001 | ||
| THA | 1,142 (21.4%) | 49 (10.4%) | |
| TKA | 1,249 (23.4%) | 56 (11.9%) | |
| Valve replacement | 315 (5.9%) | 14 (3.0%) | |
| CABG + valve | 61 (1.1%) | 13 (2.8%) | |
| Colon or rectal resection | 1,830 (34.3%) | 239 (50.7%) | |
| CABG | 731 (13.7%) | 100 (21.2%) | |
| Preoperative length of stay (days) | <0.001 | ||
| Min - Max | 0 - 59.0 | 0 - 52.0 | |
| Median (Q1 - Q3) | 1 (0.0 - 1) | 1 (1.0 - 1) | |
| ASA classification | <0.001 | ||
| I | 438 (8.2%) | 17 (3.6%) | |
| II | 2,971 (55.8%) | 240 (51.0%) | |
| III | 1,416 (26.6%) | 141 (29.9%) | |
| IV | 499 (9.4%) | 73 (15.5%) | |
| V | 4 (0.1%) | 0 (0.0%) | |
| Degree of urgency | 0.156 | ||
| Elective | 5,219 (98.0%) | 456 (96.8%) | |
| Urgent | 5 (0.1%) | 1 (0.2%) | |
| Semi-elective | 104 (2.0%) | 14 (3.0%) | |
| Wound class | <0.001 | ||
| Clean | 3,500 (65.7%) | 233 (49.5%) | |
| Clean-contaminated | 1,544 (29.0%) | 200 (42.5%) | |
| Contaminated | 280 (5.3%) | 37 (7.9%) | |
| Infected | 4 (0.1%) | 1 (0.2%) | |
| Antibiotic prophylaxis | 0.301 | ||
| Adequate | 4,986 (93.6%) | 447 (94.9%) | |
| Inadequate | 342 (6.4%) | 24 (5.1%) | |
| Minimally invasive surgery | 1,649 (30.9%) | 178 (37.8%) | 0.003 |
| Surgery duration (minutes) | <0.001 | ||
| Min - Max | 4 - 943.0 | 14 - 1,685.0 | |
| Median (Q1 - Q3) | 120 (90.0 - 180) | 164 (110.0 - 235) | |
| Country of birth (Dicotomic) | 0.117 | ||
| Non-Spain | 457 (8.6%) | 30 (6.4%) | |
| Spain | 4,871 (91.4%) | 441 (93.6%) | |
| Country of birth - World Region | 0.692 | ||
| East Asia & Pacific | 26 (0.5%) | 2 (0.4%) | |
| Europe & Central Asia | 4,985 (93.6%) | 447 (94.9%) | |
| Latin America & Caribbean | 228 (4.3%) | 18 (3.8%) | |
| Middle East & North Africa | 51 (1.0%) | 1 (0.2%) | |
| North America | 5 (0.1%) | 0 (0.0%) | |
| South Asia | 25 (0.5%) | 2 (0.4%) | |
| Sub-Saharan Africa | 8 (0.2%) | 1 (0.2%) | |
| Country of birth - Human Development Index | 0.265 | ||
| Min - Max | 0.5 - 1.0 | 0.6 - 0.9 | |
| Median (Q1 - Q3) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | |
| Country of birth - Human Development Index category | 0.576 | ||
| High | 171 (3.2%) | 13 (2.8%) | |
| Low | 19 (0.4%) | 0 (0.0%) | |
| Medium | 100 (1.9%) | 9 (1.9%) | |
| Very High | 5,038 (94.6%) | 449 (95.3%) | |
| Country of citizenship (Dicotomic) | 0.715 | ||
| Non-Spain | 213 (4.0%) | 21 (4.5%) | |
| Spain | 5,115 (96.0%) | 450 (95.5%) | |
| Country of citizenship - World Region | 0.697 | ||
| East Asia & Pacific | 12 (0.2%) | 2 (0.4%) | |
| Europe & Central Asia | 5,208 (97.7%) | 459 (97.5%) | |
| Latin America & Caribbean | 58 (1.1%) | 6 (1.3%) | |
| Middle East & North Africa | 24 (0.5%) | 2 (0.4%) | |
| North America | 4 (0.1%) | 0 (0.0%) | |
| South Asia | 18 (0.3%) | 1 (0.2%) | |
| Sub-Saharan Africa | 4 (0.1%) | 1 (0.2%) | |
| Country of citizenship - Human Development Index | 0.702 | ||
| Min - Max | 0.5 - 0.9 | 0.6 - 0.9 | |
| Median (Q1 - Q3) | 0.9 (0.9 - 0.9) | 0.9 (0.9 - 0.9) | |
| Country of citizenship - Human Development Index category | 0.468 | ||
| High | 58 (1.1%) | 6 (1.3%) | |
| Low | 14 (0.3%) | 0 (0.0%) | |
| Medium | 42 (0.8%) | 6 (1.3%) | |
| Very High | 5,214 (97.9%) | 459 (97.5%) | |
| RCA document | 0.673 | ||
| DNI | 5,118 (96.1%) | 450 (95.5%) | |
| NIE | 189 (3.5%) | 20 (4.2%) | |
| Passeport | 21 (0.4%) | 1 (0.2%) | |
| Yearly income category | 0.676 | ||
| < 18.000 euros | 2,997 (56.3%) | 255 (54.1%) | |
| 18.000 - 100.000 euros | 2,265 (42.5%) | 210 (44.6%) | |
| > 100.000 euros | 66 (1.2%) | 6 (1.3%) | |
| Health insurance at the time of surgery | 5,321 (99.9%) | 471 (100.0%) | >0.999 |
| 1 n (%) | |||
| 2 Welch Two Sample t-test; Pearson’s Chi-squared test; Wilcoxon rank sum test; Fisher’s exact test | |||
Variables statistically associated to SSI (p<0.05):
Age: mean age was higher among non-infected patients
Sex: the proportion of males was higher among infected patients
Surgery year: the proportion of patients intervened in the 2015-2019 and 2019-2024 periods was higher among the infected compared to the non-infected group.
Surgical procedure: among patients that had an infection, the proportion of patients that had colorectal resection, CABG and CABG + valve was higher, compared to patients with no infection, while the proportion of patients that had orthopedic surgeries or valve replacement was lower.
Preoperative length of stay: higher among the infected group
ASA classification: among patients that had an infection, the proportion of patients that had an ASA classification I or II was lower, while the proportion of patients that had an ASA classification III or IV was higher.
Wound class: among patients that had an infection, the proportion of patients that had a clean wound was lower, while the proportion of patients that had a clean-contaminated or contaminated wound was higher.
Minimally invasive surgery: the proportion of patients that underwent a minimally invasive surgery was higher among the infected group
Surgery duration: The median duration of the surgical procedure was higher among the infected group.
Additionally, variables with a p-value lower than 0.20:
Migration status
Degree of urgency
Country of birth (dicotomic)