Epidemiology of developmental dysplasia of the hip within the UK: refining the risk factors

PURPOSE The epidemiology and risk factors for developmental dysplasia of the hip (DDH) are still being refined. We investigated the local epidemiology of DDH in order to define incidence, identify risk factors, and refine our policy on selective ultrasound screening. METHODS With a cohort study design, data were prospectively recorded on all live births in our region from January 1998 to December 2008. We compared data on babies treated for DDH with data for all other children. Crude odds ratios (ORs) were calculated to identify potential risk factors. Logistic regression was then used to control for interactions between variables. RESULTS There were 182 children born with DDH (with a total of 245 dysplastic hips) and 37,051 without. The incidence was 4.9 per 1000 live births. Female sex (adjusted OR 7.2, 95% confidence interval [CI] 4.6-11.2), breech presentation (adjusted OR 24.3, 95% CI 13.1-44.9), positive family history (adjusted OR 15.9, 95% CI 11.0-22.9) and first or second pregnancy (adjusted OR 1.8, 95% CI 1.5-2.3) were confirmed as risk factors (p < 0.001). In addition, there was an increased risk with vaginal delivery (adjusted OR 2.7, 1.6-4.5, p < 0.001) and post-maturity (OR 1.7, 1.2-2.4, p < 0.002). CONCLUSIONS One in 200 children born within our region requires treatment for DDH. Using both established and novel risk factors, we can potentially calculate an individual child's risk. Our findings may contribute to the debate regarding selective versus universal ultrasound screening. LEVEL OF EVIDENCE Prognostic Study: Level 1.