Prevalence of infantile hypertrophic pyloric stenosis in Texas, 1999-2002.

BACKGROUND

The cause of infantile hypertrophic pyloric stenosis (IHPS) is poorly understood. This descriptive study of IHPS focuses on the effect of maternal nativity, maternal Hispanic ethnicity, subtypes of maternal Asian ethnicity, and the timing of the infant's surgery, that is, pyloromyotomy.

METHODS

All cases of IHPS born in Texas from 1999 through 2002 were retrieved from the Texas Birth Defects Registry. Crude prevalence ratios and adjusted prevalence ratios (aPRs) were calculated using logistic regression.

RESULTS

IHPS occurred predominantly in boys (aPR 4.21; 95% CI: 3.81, 4.65) compared with girls. Compared with Whites, there was a lower prevalence among Blacks (aPR 0.36; 95% CI: 0.30, 0.43), foreign-born Hispanics (aPR 0.61; 95% CI: 0.54, 0.69), Chinese (aPR 0.11; 95% CI: 0.01, 0.78), Vietnamese (aPR 0.17; 95% CI: 0.06, 0.46), Asian Indians (aPR 0.33; 95% CI: 0.15, 0.75), and Filipinos (aPR 0.22; 95% CI: 0.05, 0.91). In aggregate, foreign born Asians had a decreased risk of IHPS (aPR 0.20; 95% CI: 0.11, 0.37) compared to Whites. We observed no decrease in the risk of IHPS among US-born Asians (in aggregate) or US-born Hispanics. The strength of these risk factors did not vary according to the timing of the pyloromyotomy.

CONCLUSIONS

This study confirmed previous findings that female infants and Black infants have a lower rate of IHPS. Large decreases in rates of IHPS were observed among foreign-born Hispanics and foreign-born Asians, but not among their US-born counterparts. These findings may be explained by differences in the frequency of behavioral risk factors for IHPS or differences in the frequency of ascertainment of mild cases of IHPS by ethnicity or nativity.