P1.049: Association Between Patient Weight and Subsequent Hernia after Inguinal Hernia Repair in Infants

Background: Inguinal hernia repair (IHR) is a common procedure during early infancy, but there are limited data regarding the impact of prematurity, body weight, and corrected gestational age on the incidence of subsequent inguinal hernia after primary repair. It was hypothesized that (1) body weight at time of IHR would be the best predictor of risk for subsequent inguinal hernia in this age group, and (2) infants less than 3kg at time of IHR would be disproportionately affected.

Methods: Records were retrospectively reviewed for all patients who underwent primary IHR at less than 6 months old between 1/1/2018 and 12/31/2019 at 10 children’s hospitals within an established regional clinical research consortium. Data on patient demographics, surgical approach for IHR (open versus laparoscopic), and incidence of subsequent inguinal hernia postoperatively were collected from the electronic health record. Categorical variables were compared using chi-squared analysis, and multivariable logistic regression was performed to identify independent predictors of subsequent inguinal hernia.

Results: There were 987 infants who met inclusion criteria. Median weight was 4.3 kg (IQR 3.39-5.23) and median corrected gestational age (CGA) was 45 weeks (IQR 42-48) at time of primary IHR, 618 infants (62.6%) had a history of prematurity, and 308 (31.2%) underwent laparoscopic IHR. Median time interval from primary IHR to data collection was 5.9 years (IQR 5.4-6.4). Subsequent inguinal hernia occurred in 30 patients (3.0 %), including 17 (1.7%) with recurrent ipsilateral hernias and 13 (1.3%) with metachronous contralateral hernias. A multivariable logistic regression analysis that controlled for CGA, history of prematurity, and surgical approach demonstrated that odds of subsequent hernia decreased by 42% with each additional kilogram of body weight at time of surgery (OR 0.58, 95% CI 0.35-0.98, p=0.04, Table 1). There was no significant association between likelihood of subsequent inguinal hernia and CGA, prematurity, or surgical approach. Incidence of subsequent inguinal hernia was 5.9% in infants < 3 kg and 2.6% in infants ≥ 3 kg (p=0.02, Figure 1). Relative rates of recurrent ipsilateral hernia (p=0.12) and metachronous contralateral hernia (p=0.14) did not vary significantly between weight groups. This study was not powered to measure the effect of surgical approach on rates of recurrent ipsilateral hernia or metachronous contralateral hernia within specific weight groups.

Conclusion: These findings suggest that body weight at time of primary IHR in infants is a better predictor of risk for subsequent inguinal hernia than CGA or history of prematurity. Patients weighing less than 3kg at surgery are significantly more likely to require a second inguinal hernia operation, regardless of surgical approach. These results can inform decision-making regarding timing of IHR in small infants.