Neonatal hip screening

Abstract

In her otherwise well-founded Rapid review, Deborah Eastwood1Eastwood DM Neonatal hip screening.Lancet. 2003; 361: 595-597Summary Full Text Full Text PDF PubMed Scopus (69) Google Scholar states that clinical screening for developmental dysplasia of the hip (DDH) has a specificity of almost 100%. However, M Boere-Boonekamp and colleagues2Boere-Boonekamp MM Kerkhoff TH Schuil PB Zielhuis GA Early detection of developmental dysplasia of the hip in The Netherlands: the validity of a standardized assessment protocol in infants.Am J Public Health. 1998; 88: 285-288Crossref PubMed Scopus (26) Google Scholar found that even specially trained clinical examiners in child clinics achieve a specificity of only 82%. The specificity of ultrasonography-based neonatal hip screening is in a comparable range. As Eastwood observes, a low specificity will lead to false-positive results and over-treatment. This problem is a cause for concern in a rare condition such as DDH, because the positive predictive value of the screening examination will be low. In other words, most newborn babies treated for DDH because of a positive screening result will not actually have the condition. These babies will unnecessarily be put at risk of the side-effects of treatment. In Germany, ultrasonography hip screening was promoted by professional associations in paediatrics, orthopaedics, and radiology, despite unfavourable international reviews3Hernandez RJ Cornell RG Hensinger RN Ultrasound diagnosis of neonatal congenital dislocation of the hip: a decision analysis assessment.J Bone Joint Surg Br. 1994; 76: 539-543PubMed Google Scholar and without any evidence of efficacy. In 1996, such screening became part of the routine neonatal examination at the 4–6 week health check, which is done locally by doctors in private practice. F Niethard and co-workers4Niethard FU Günther KP von Kries R Allhoff P Altenhofen L Klinisches und sonographisches Screening der Säuglingshüfte [Evaluation of Ultrasound Examination of Hip Screening].Deutsches Ärzteblatt. 2000; 97: 1593-1599Google Scholar found that primary screening has a low specificity with 23·7% repeat examinations and a treatment rate of 6·7%. This treatment rate is three times higher than the estimated DDH prevalence at birth (2%), and 30 times higher than the prevalence of clinically relevant DDH (0·2%).1Eastwood DM Neonatal hip screening.Lancet. 2003; 361: 595-597Summary Full Text Full Text PDF PubMed Scopus (69) Google Scholar Moreover, ultrasonography hip screening in Germany is not subject to systematic quality assurance. There is much variability in rates of follow-up investigations, and children screened by orthopaedic specialists have follow-up and treatment rates twice as high as those screened by paediatricians.4Niethard FU Günther KP von Kries R Allhoff P Altenhofen L Klinisches und sonographisches Screening der Säuglingshüfte [Evaluation of Ultrasound Examination of Hip Screening].Deutsches Ärzteblatt. 2000; 97: 1593-1599Google Scholar About 98% of newborn babies are expected to have normal hips, so the ability of the screening test to correctly identify the unaffected—ie, its specificity—is of utmost importance. Given the wide gap in quality between centres of excellence and clinical routine, independent quality-control measures need to be in place when a screening programme starts. In Germany, where such measures do not exist, the low specificity of ultrasonography has become the Achilles heel of neonatal hip screening. A potentially beneficial preventive activity is thus associated with over-diagnosis and over-treatment, inadvertently channelling many healthy babies into the curative care system.5Jahn A Screening—the Trojan horse in preventive medicine?.Trop Med Int Health. 2002; 7: 295-297Crossref PubMed Scopus (6) Google Scholar