Risk factors for inguinal hernia among adults in the US population.

The authors examined risk factors for incident inguinal hernia among US adults (5,316 men and 8,136 women) participating in the First National Health and Nutrition Examination Survey (1971-1975) who were followed through 1992-1993 for a hospital (International Classification of Diseases, Ninth Revision, Clinical Modification, code 550) or physician diagnosis of inguinal hernia. Ninety-six percent of the baseline cohort was recontacted, with a median follow-up of 18.2 years (range, 0.02-22.1 years). Because the cumulative incidence of inguinal hernia was higher among men (13.9%) than among women (2.1%), more detailed analyses were conducted in men. Among men in multivariate analysis, a higher incidence (p < 0.05) of inguinal hernia was associated with an age of 40-59 years (hazard ratio (HR) = 2.2, 95% confidence interval (CI): 1.7, 2.8), an age of 60-74 years (HR = 2.8, 95% CI: 2.2, 3.6), and hiatal hernia (HR = 1.8, 95% CI: 1.2, 2.7), while Black race (HR = 0.58, 95% CI: 0.42, 0.79), being overweight (HR = 0.79, 95% CI: 0.66, 0.95), and obesity (HR = 0.51, 95% CI: 0.36, 0.71) were associated with a lower incidence. Among women, older age, rural residence, greater height, chronic cough, and umbilical hernia were associated with inguinal hernia. In the United States, inguinal hernias are common among men, especially with aging. The lower risk among heavier men was unexpected and bears further study.