Background

Hypospadias is a male birth defect in which the opening of the urethra, the tube that allows urine to drain from the bladder and exit the body, is not located on the tip of the penis. Instead the urethra opening is located somewhere along the underside of the penis. The type of hypospadias depends on the location of the opening of the urethra, which can fall into one of three locations: subcoronal (near the head of the penis); midshaft (on the shaft of penis); or penoscrotal (where the penis and scrotum meet). In some cases, boys with hypospadias will have a curved penis, difficulties urinating while standing up, and problems with sexual intercourse. Most cases can be treated with surgery to correct the defect. [1,2]

Recently, CDC reported on risk factors that may contribute to having a baby with hypospadias. The risk factors included, advanced maternal age coupled with obesity, fertility treatments, and certain hormones. [3,4,5]

Epidemiology

Alaska Birth Defects Registry (ABDR) registers birth defects as reported from health care providers using International Classification of Disease (ICD) billing codes. The use of these ICD codes can lead to misclassification of diagnosed conditions. Prior to this report, all prevalence estimates were based on the number of unique children reported to ABDR with an ICD code representing a specified condition regardless of case confirmation status.

The estimates in this report were derived by conducting medical record review and case confirmation of a random sample of cases of the condition reported to ABDR. The confirmation probability from the sample was used to develop informed estimates of the actual diagnosed defect prevalence. See Defect prevalence calculation.

For explanations of table columns see Column descriptions.

Prevalence

Hypospadias occurs in about 50 out of every 10,000 live male births in the United States.[6]

In Alaska, during 2007-2015, the prevalence of hypospadias was 99.1 per 10,000 live male births.
Reports Defects Births Prevalence (95% CI)
Total 583 520.7 52516 99.1 (90.9, 107.9)
Notes: 95% CI = 95% Confidence Interval

Trend

Prevalence per 10,000 births of hypospadias during 2007-2015 by three-year moving averages, with 95% confidence interval band and Poisson estimated fitted line.
Reports Defects Births Prevalence (95% CI) Predicted Prevalence†
2007-2009 60.3 54.0 5853.7 92.3 (70.3, 119.7) 96.0
2008-2010 63.3 56.6 5912.3 95.8 (73.6, 123.6) 97.5
2009-2011 67.7 60.3 5891.7 102.5 (79.3, 131.1) 99.0
2010-2012 67.3 60.0 5808.0 103.3 (79.8, 132.3) 100.5
2011-2013 71.0 63.2 5812.0 108.6 (84.8, 138.6) 102.1
2012-2014 65.0 58.0 5819.3 99.7 (76.8, 128.1) 103.6
2013-2015 66.7 59.5 5843.7 101.8 (78.5, 130.2) 105.2
Notes: Each row is based on three-year moving averages; Prevalence reported per 10,000 live births; 95% CI=95% Confidence Interval

† Estimated rate based on Poisson model
The p-value test for trend detected no significant increase or decrease in the number of live births with hypospadias during 2007-2015. See p-value estimate
Estimate Std. Error t value Pr(>|t|)
0.01523 0.00873 1.74520 0.14139

Regional Distribution

Distribution of hypospadias in Alaska by Public Health Region of maternal residence at the time of birth. A description of regional breakdowns can be found here. Data suppressed for # of reports < 6.
Reports Defects Births Prevalence (95% CI)
Anchorage 278 247.0 21484 115 (101.5, 130.2)
Gulf Coast 39 34.7 3259 106.6 (74.8, 145.8)
Interior 108 96.4 9619 100.2 (81.8, 121.9)
Mat-Su 69 61.6 6249 98.6 (76.1, 125.4)
Northern 19 17.6 3642 48.5 (29.3, 74.7)
Southeast 18 16.6 3211 51.8 (30.8, 80.9)
Southwest 52 46.6 5052 92.2 (68.4, 121.5)
Notes:Prevalence reported per 10,000 live births; Data suppressed for # of reports < 6; 95% CI = 95% Confidence Interval

Demographics

Some subgroups may be more at risk for having a baby boy with hypospadias. This section provides the descriptive epidemiology of specified maternal, birth, and child characteristics identified from the birth certificate.

Reports Defects Births Prevalence (95% CI)
Birth weight (grams)
  <2500 78 68.2 2851 239.2 (188.3, 302.4)
  2500+ 503 450.7 49589 90.9 (82.8, 99.5)
Maternal age
  12-19 43 38.5 4136 93.1 (67.0, 126.1)
  20-24 166 148.1 14460 102.4 (87.2, 120.2)
  25-29 176 157.2 15779 99.6 (85.1, 116.3)
  30-34 131 116.9 11619 100.6 (83.3, 119.7)
  35-39 55 49.2 5160 95.3 (71.9, 125.5)
  40+ 12 10.8 1347 80.3 (40.8, 136.5)
Maternal race
  Alaska Native/American Indian 106 96.0 13286 72.2 (58.5, 87.4)
  Asian/Pacific Islander 43 38.8 4931 78.6 (56.2, 105.8)
  Black 27 24.0 2142 112.1 (75.5, 166.7)
  White 396 352.2 31484 111.9 (100.7, 124.1)
Maternal education (years)
  <12 51 45.7 4944 92.4 (68.1, 121.8)
  12 205 183.2 18833 97.3 (84.1, 112.3)
  12+ 309 275.7 27135 101.6 (90.1, 114.1)
Marital status
  Married 375 334.7 33197 100.8 (90.4, 112.0)
  Unmarried 205 183.3 19104 96.0 (82.9, 110.7)
Maternal smoking use
  Reported smoking 76 68.1 7364 92.4 (72.9, 117.1)
  Reported not smoking 502 448.0 44350 101.0 (92.1, 110.8)
Medicaid (mother or child)
  Medicaid 291 260.0 26590 97.8 (86.6, 110.4)
  non-Medicaid 292 260.6 25870 100.8 (89.0, 113.5)
Father on birth certificate
  None 31 27.7 2794 99.1 (66.6, 140.6)
  Present 552 493.0 49722 99.2 (90.6, 108.1)
Notes: Prevalence reported per 10,000 live births; Data suppressed for # of reports < 6; 95% CI = 95% Confidence Interval

Technical notes

Column descriptions

# Reports: Unless otherwise noted, the number of unique reports of the defect received by ABDR during the specified birth year(s). Each report represents a unique child with the specified defect.

# Defects: The estimated true number of reports that are diagnosed defects based on medical record review and case confirmation.

# Births: The number of live male births among Alaskan residents that occurred in Alaska during the specified birth year(s).

Prevalence (95% CI): The estimated diagnosed prevalence of the condition and corresponding 95% Confidence Interval. (For information on how the defect prevalence was estimated see below).

Defect prevalence calculation

The estimated defect prevalence was calculated using a Bayesian approach based on the reported prevalence, PPV and 1-NPV (see formula below).

Through medical records review and case confirmation of a random sample of reported cases, the defect prevalence is calculated as:

\[PPV (Positive Predictive Value) = p(defect|report)\] \[NPV (Negative Predictive Value) = p(\overline{defect}|\overline{report})\]

\[p(defect) \approx [p(report)\cdot PPV]+[p(\overline{report})\cdot (1-NPV)]\]

Defect prevalence estimates are a more accurate estimation of the actual diagnosed prevalance of birth defects compared to the reported prevalance estimates in Alaska. ABDR obtains reports from medical providers using International Classification of Disease (ICD) codes that are extracted from individual systems which when aggregated may not reflect true diagnostics. Caution should be used when interpreting and comparing the reported prevalence estimates with national estimates.

See Data analysis methods for more information.

P-value estimate

To evaluate the trend over time and account for under/over-dispersion we constructed a quasi-Poisson regression model. This model assumes the variance is a linear function of the mean and models the estimated number of annual defects by year with a natural log (ln) offset of the annual births. P-values < 0.05 are considered significant, which indicates that the predicted slope is significantly different from a slope of zero.

Data suppression

For region and demographic data tables, values are suppressed based on the number of reports received during the observation period. Counts less than 6 are suppressed (as indicated by ‘-’ in the table). For regions or demographics with only one cell count suppressed a second is suppressed to eliminate the ability to back-calculate the estimate.

References

[1] Kraft KH, Shukla AR, Canning DA. Hypospadias. Urol Clin North Am 2010; 37(2):167-81.

[2] Centers for Disease Control and Prevention. Facts about Hypospadias, https://www.cdc.gov/ncbddd/birthdefects/hypospadias.html#ref; 2016 [accessed 023.07.2017]

[3] Carmichael SL, Shaw GM, Laurent C, Olney RS, Lammer EJ, and the National Birth Defects Prevention Study. Maternal reproductive and demographic characteristics as risk factors for hypospadias. Paediatr Perinat Epidemiol. 2007; 21: 210-218.

[4] Reefhuis J, Honein MA, Schieve LA, Correa A, Hobbs CA, Rasmussen SA, and the National Birth Defects Prevention Study. Assisted reproductive technology and major structural birth defects in the United States. Human Rep. 2009; 24:360-366

[5] Carmichael SL, Shaw GM, Laurent C, Croughan MS, Olney RS, Lammer EJ. Maternal progestin intake and risk of hypospadias. Arch Pediatr Adolesc Med. 2005;159: 957-962

[6] Centers for Disease Control and Prevention, Birth Defects Data and Statistics, https://www.cdc.gov/ncbddd/birthdefects/data.html; 2016 [accessed 02.23.2017]

Suggested Citation

State of Alaska Department of Health and Social Services, Division of Public Health, Section of Women’s, Children’s, and Family Health. Alaska Birth Defects Registry Condition Report: Hypospadias, Alaska, 2007-2015. Updated January 1, 2020. Available at: http://rpubs.com/AK_ABDR/Hypospadias07_15.

Contact

Alaska Birth Defects Registry (ABDR)
3601 C Street, Suite 358
Anchorage, AK 99503
(907) 269-3400 phone
(907) 754-3529 fax

Updated: January 1, 2020
Code source: R:\ABDR\Analysis_New\ABDR_CASECONF\cond_reports\Published_reports\Hypospadias.Rmd