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 2007-2013, the prevalence of hypospadias was 100.8 per 10,000 live male births.
Reports Defects Births Prevalence (95% CI)
Total 461 411.5 40838 100.8 (91.4, 110.9)
Notes: 95% CI = 95% Confidence Interval

Trend

Prevalence per 10,000 births of hypospadias during 2007-2013 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 5855.0 92.3 (70.3, 119.7) 92.6
2008-2010 63.3 56.6 5913.0 95.8 (73.5, 123.6) 96.3
2009-2011 67.7 60.3 5893.0 102.5 (79.2, 131.1) 100.2
2010-2012 67.3 60.0 5808.7 103.3 (79.8, 132.3) 104.3
2011-2013 70.7 62.9 5807.3 108.3 (84.3, 138.0) 108.5
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 a significant increase in the number of live births with hypospadias during 2007-2013. See p-value estimate
Estimate Std. Error t value Pr(>|t|)
0.03968 0.00449 8.83974 0.00305

Regional Distribution

Distribution of hypospadias in Alaska by Public Health Region of maternal residence at the time of birth. For a description of regional breakdowns please click here. Data suppressed for # of reports < 6.
Reports Defects Births Prevalence (95% CI)
Anchorage 225 199.7 16800 118.9 (103.1, 136.1)
Gulf Coast 32 28.5 2517 113 (77.2, 160.8)
Interior 80 71.5 7442 96.1 (75.7, 120.3)
Mat-Su 56 49.9 4692 106.3 (79.1, 138.1)
Northern 17 15.7 2887 54.2 (31.7, 85.7)
Southeast 13 12.1 2538 47.6 (27.3, 82.6)
Southwest 38 34.1 3962 86.1 (61.5, 119.9)
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)
Sex
  <2500 63 55.1 2237 246.1 (189.1, 320.0)
  2500+ 396 354.7 38534 92.0 (82.8, 102.0)
Birth weight (grams)
  12-19 36 32.2 3486 92.5 (65.2, 129.6)
  20-24 135 120.3 11480 104.8 (87.5, 125.0)
  25-29 139 124.0 12202 101.7 (85.3, 121.2)
  30-34 99 88.3 8674 101.8 (82.4, 125.0)
  35-39 43 38.4 3912 98.2 (70.9, 133.3)
  40+ 9 8.1 1071 75.9 (38.4, 147.2)
Maternal age
  Alaska Native/American Indian 80 72.6 10346 70.1 (55.3, 87.6)
  Asian/Pacific Islander 34 30.6 3708 82.5 (56.8, 115.5)
  Black 19 17.0 1658 102.2 (59.7, 156.7)
  White 319 283.5 24660 115.0 (102.2, 128.9)
Maternal race
  <12 41 36.7 3824 95.9 (68.1, 130.3)
  12 162 145.0 15386 94.2 (79.5, 110.2)
  12+ 241 214.7 20252 106.0 (92.5, 120.8)
Maternal education (years)
  Married 294 262.3 25698 102.1 (90.3, 115.1)
  Unmarried 166 148.3 15055 98.5 (83.7, 115.5)
Marital status
  Reported smoking 54 48.6 5951 81.7 (60.9, 106.9)
  Reported not smoking 404 360.1 34508 104.4 (94.1, 115.7)
Maternal smoking use
  Medicaid 235 209.8 20976 100.0 (87.0, 114.1)
  non-Medicaid 226 201.7 19840 101.6 (88.3, 116.3)
Medicaid (mother or child)
  None 28 24.9 2149 115.8 (75.3, 166.2)
  Present 433 386.6 38689 99.9 (90.3, 110.2)
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]

Contact

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

Updated: November 28, 2017
Code source: R:\ABDR\Analysis_New\ABDR_CASECONF\cond_reports\Published_reports\Hypospadias.Rmd