The CPUP Hip Score predicts displacement of the hip in children with cerebral palsy

Abstract

Aims The Uppföljningsprogram för cerebral pares (CPUP) Hip Score distinguishes between children with cerebral palsy (CP) at different levels of risk for displacement of the hip. The score was constructed using data from Swedish children with CP, but has not been confirmed in any other population. The aim of this study was to determine the calibration and discriminatory accuracy of this score in children with CP in Scotland. Methods This was a total population-based study of children registered with the Cerebral Palsy Integrated Pathway Scotland. Displacement of the hip was defined as a migration percentage (MP) of > 40%. Inclusion criteria were children in Gross Motor Function Classification System (GMFCS) levels III to V. The calibration slope was estimated and Kaplan-Meier curves produced for five strata of CPUP scores to compare the observed with the predicted risk of displacement of the hip at five years. For discriminatory accuracy, the time-dependent area under the receiver operating characteristic curve (AUC) was estimated. In order to analyze differences in the performance of the score between cohorts, score weights, and subsequently the AUC, were re-estimated using the variables of the original score: the child’s age at the first examination, GMFCS level, head shaft angle, and MP of the worst hip in a logistic regression with imputation of outcomes for those with incomplete follow-up. Results The discriminatory accuracy of the score in the new population of 367 children was high (AUC 0.78 (95% confidence interval (CI) 0.71 to 0.86)). The calibration of the score was insufficient (slope 0.48 (95% CI 0.31 to 0.65)), and the absolute risks of displacement of the hip in this population were overestimated. The AUC increased with re-estimated weights (0.85 (95% CI 0.79 to 0.91)). Conclusion The CPUP Hip Score had a high ability to discriminate between children at different levels of risk for displacement of the hip. The score overestimated the absolute risks of displacement in this population, which may have resulted from differences in the way children were initially registered in the two programmes. The results are promising, but the score weights may need re-estimation before its clinical application in Scotland. Cite this article: Bone Joint J 2022;104-B(5):640–644.

Radiological assessment of hip disease in children with cerebral palsy: development of a core measurement set

“… 24 , 34 , 35 The CPUP hip score has been assessed in multiple populations, achieving a high discriminatory accuracy in evaluating risk of hip displacement. 24 , 36 Prospectively, the automatic calculation of core radiological measurements and hip displacement risk scores stand as an essential requirement for a fully-autonomous hip surveillance system; omitting head-shaft angle from the CMS could limit the potential application of such a system. 24 Moreover, the head-shaft angle percentage is already standardized within the protocol of prominent national hip surveillance programmes such as CPIPS, further highlighting its utility.…”

Hip reconstruction in cerebral palsy: Lessons from a single center and 137 hips

“…Adduction contracture was noted in the clinical setting for our patients; therefore, this information was extracted from clinical notes and categorized in line with the cerebral palsy integrated pathway (CPIP) preoperatively and at final follow-up (or before further intervention). 34 Poor abduction was classified as less than 30°, and satisfactory if 30° or more.…”