Objectives To quantify the effect of secondary screening for hip dislocations.
Design Retrospective analysis of hospital files from participants in a prospectively collected nationwide registry.
Setting Child healthcare centres and orthopaedic departments in Sweden.
Participants Of 126 children with hip dislocation diagnosed later than 14 days age in the 2000–2009 birth cohort, 101 had complete data and were included in the study.
Interventions The entire birth cohort was subject to clinical screening for hip instability at 6–8 weeks, 6 months and 10–12 months age. Children diagnosed through this screening were compared with children presenting due to symptoms, which was used as a surrogate variable representing a situation without secondary screening.
Main outcome measures Age at diagnosis and disease severity of late presenting hip dislocations.
Results Children diagnosed through secondary screening were 11 months younger (median: 47 weeks) compared with those presenting with symptoms (p<0.001). Children diagnosed through secondary screening had 11% risk of having a high (severe) dislocation, compared with 38% for those diagnosed due to symptoms; absolute risk reduction 27% (95% CI: 9.7% to 45%), relative risk 0.28 (95% CI: 0.11 to 0.70). Children presenting due to symptoms had OR 5.1 (95% CI: 1.7 to 15) of having a high dislocation, and OR 11 (95% CI: 4.1 to 31) of presenting at age 1 year or older, compared with the secondary screening group. The secondary screening was able to identify half of the children (55%, 95% CI: 45% to 66%) not diagnosed through primary screening.
Conclusions Secondary screening at child healthcare centres may have substantially lowered the age at diagnosis in half of all children with late presenting hip dislocation not diagnosed through primary screening, with the risk of having a high dislocation decreased almost to one-quarter in such cases.
- health services research
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Contributors DW conceived and designed the study. HD and DW acquired the data. All authors analysed and interpreted the pooled data. DW drafted the manuscript. All authors critically revised the manuscript for important intellectual content. DW carried out the statistical analysis of the pooled data. DW is the guarantor.
Funding This study was supported by a grant from the Greta and Johan Kock Foundation.
Disclaimer The funding organisation had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript or decision to submit the manuscript for publication. The authors are independent from the funder. The authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Competing interests None declared.
Patient and public involvement statement This research was done without patient involvement. Patients were not invited to comment on the study design and were not consulted to develop patient relevant outcomes or interpret the results. Patients were not invited to contribute to the writing or editing of this document for readability or accuracy. The patients were aged from 25 days to 4.5 years at inclusion, and 8–18 years at the end of study.
Patient consent for publication Not required.
Ethics approval The study was performed in accordance with the WMA Declaration of Helsinki. Approval was obtained from the regional ethical review board at Lund University (LU 578-99 and LU 2014/736). Verbal informed consent was given by the subjects’ parents on entering the registry.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request to the corresponding author, DW.
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