Developmental dysplasia of the hip (DDH), otherwise known as dislocated hips, refers to a spectrum of hip disease that affects approximately 2-3% of newborns. Hip dysplasia is the single largest cause of total hip replacement in young adults. Early diagnosis of DDH is crucial as a simple treatment (harnesses), has greater than 90% success rates when started within the first few months of life. The success rate of simple treatment falls significantly with increasing age, necessitating surgery. A screening programme for DDH exists in the UK whereby every newborn child has a routine examination of the hips after birth. An abnormal hip exam, or the presence of major risk factors requires a hip ultrasound scan (USS) at 6 weeks of age. Despite this screening programme cases are missed by screening, and diagnoses after six months of age are frequent. In Austria uniform USS screening is performed and there are negligible cases of missed/late presenting DDH. The Clinical Practice Research Datalink provides a unique opportunity to investigate the incidence of DDH in the UK, and in particular those diagnosed after the screening period. This data may inform the debate on hip screening in the UK.
The main objective of this study is to assess the incidence of DDH requiring intervention, as well as in those diagnosed outside of the timescale of the infant screening programme (>6 months gestation). Within CPRD GOLD, patients aged <8years old on the date of entry of a diagnostic code indicative for DDH, will be searched for, after 1st January 1990 and before 1st November 2015. HES will be used to validate this cohort, with the study population restricted to children who are eligible for linkage between CPRD GOLD and HES. Cases with diagnostic codes for neuromuscular disease will be excluded. Cases will also be internally validated. Descriptive analysis will be performed on data in 3 and 6 month bands. Poisson confidence intervals will be calculated and Poisson regression performed to examine trends using Stata 14.0.
Cases will be defined by an entry of a diagnostic code representing 'developmental dysplasia of the hip' within the individual's electronic patient record. The keywords searched were 'hip', 'dysplasia', 'dysplastic', 'dislocated' and 'DDH', 'CDH', 'Pavlik', 'open reduction' and 'closed reduction'. Risk factors (e.g. breech presentation and family history) are known to possibly predict a diagnosis of DDH. However, these patients are all seen in selected screening programmes. Therefore, late presenting cases are more likely to not have these risk factors. Late diagnosed DDH (>6 months) is much more difficult to treat, with higher rates of complications. As a result, it has an increased use of health resources.
Nicholas Clarke - Chief Investigator - University of Southampton
Charlotte Broadhurst - Corresponding Applicant - University of Southampton
Alexander Aarvold - Collaborator - Southampton University Hospitals
Daniel Perry - Collaborator - University of Warwick
Joanna Thomas - Collaborator - Southampton University Hospitals
Tjeerd van Staa - Collaborator - University of Manchester
HES Admitted Patient Care