Positive predictive values in clinical screening for developmental dysplasia of the hip

Abstract

Aim: To establish the positive predictive value (PPV) of clinical hip examinations performed by referrers in the Danish screening programme for Developmental Dysplasia of the Hip (DDH) utilising three definitions of true positive DDH diagnosis.

Methods: We retrospectively identified 290 children (169 female) referred during a 4-year period to the orthopaedic outpatient clinic at our institution with a positive clinical hip examination. Positive predictive value was calculated for clinical hip examinations across three definitions of a true positive clinical hip examination for all referrers and subgroups consisting of general practitioners, midwives and paediatricians. The PPV for clinical hip examinations was calculated for paediatric orthopaedic surgeons using one of the three definitions.

Results: Positive predictive value of clinical hip examinations for all referrers were 5.4%, 3.6% and 1.8% with the definition of a true positive DDH diagnosis defined as clinical instability found by orthopaedic surgeon, ultrasound classification ≥Graf IIc or both definitions combined, respectively. Positive predictive value of clinical hip examinations performed by orthopaedic surgeons was 33.3% with a true positive clinical examination defined as an ultrasound classification ≥Graf IIc.

Conclusion: We conclude that the positive predictive value of clinical hip examinations made by referrers in the Danish screening programme for DDH is low.

Keywords: developmental dysplasia of the hip; paediatric orthopaedics; predictive values; screening.