Younger boys have a higher risk of inguinal hernia after ventriculo-peritoneal shunt: a 13-year nationwide cohort study.

Background: Few studies associate ventriculo-peritoneal shunt (VPS) in children with higher incidence of inguinal hernia (IH). These institutional-based data have small numbers and provided little information about the effects of age and sex. This study aims to examine the incidences and risk factors of IH in children with hydrocephalus treated with VPS.

Study Design: Using a 13-year nationwide database, a cohort of 1,568 children younger than 5 years of age who received VPS were followed up for IH. Of these, 194 received IH repair. Kaplan-Meier analysis and Cox regression were conducted.

Results: Overall incidence of IH after VPS in children younger than 5 years old was 22.9 per 1,000 person-years. The average follow-up time was 5.41 years, and the mean time interval between VPS and IH repair was 1.14 years. Age-specific incidences were 45.0, 21.3, 18.5, and 4.1 per 1000 person-years for neonates, infants, toddlers, and preschool children, respectively. Compared with preschool children, neonates, infants, and toddlers, were more likely to have IH (crude hazard ratio = 9.8, 5.3, and 4.4; p < 0.001, p = 0.001, and p = 0.006, respectively). Sex and age were significantly different in children with and without IH (both, p < 0.001). Differences of cumulative incidence rates in the 4 age groups were significant in both male and female patients (p < 0.001 and p = 0.023, respectively).

Conclusions: The patient's age on VPS surgery significantly affects the likelihood of subsequent IH development. IH is more likely to develop in neonates after VPS than in infants, toddlers, and preschool-aged children. This age-related effect is more prominent in boys than in girls.