The cost effectiveness of potential risk factors for developmental dysplasia of the hip within a national screening programme

Abstract

Early detection of developmental dysplasia of the hip (DDH) is associated with improved outcomes of conservative treatment. Therefore, we aimed to evaluate a novel screening programme that included both the primary risk factors of breech presentation and family history, and the secondary risk factors of oligohydramnios and foot deformities. A five-year prospective registry study investigating every live birth in the study's catchment area (n = 27,731), all of whom underwent screening for risk factors and examination at the newborn and six- to eight-week neonatal examination and review. DDH was diagnosed using ultrasonography and the Graf classification system, defined as grade IIb or above or rapidly regressing IIa disease (≥4^o at four weeks follow-up). Multivariate odds ratios were calculated to establish significant association, and risk differences were calculated to provide quantifiable risk increase with DDH, positive predictive value was used as a measure of predictive efficacy. The cost-effectiveness of using these risk factors to predict DDH was evaluated using NHS tariffs (January 2021). The prevalence of DDH that required treatment within our population was 5/1,000 live births. The rate of missed presentation of DDH was 0.43/1000 live births. Breech position, family history, oligohydramnios, and foot deformities demonstrated significant association with DDH (p < 0.0001). The presence of breech presentation increased the risk of DDH by 1.69% (95% confidence interval (CI) 0.93% to 2.45%), family history by 3.57% (95% CI 2.06% to 5.09%), foot deformities by 8.95% (95% CI 4.81% to 13.1%), and oligohydramnios nby 11.6% (95 % CI 3.0% to 19.0%). Primary risk factors family history and breech presentation demonstrated an estimated cost-per-case detection of £6,276 and £11,409, respectively. Oligohydramnios and foot deformities demonstrated a cost-per-case detected less than the cost of primary risk factors of £2,260 and £2,670, respectively. The inclusion of secondary risk factors within a national screening programme was clinically successful as they were more cost and resource-efficient predictors of DDH than primary risk factors, suggesting they should be considered in the national guidance.

Fig. 1

Table demonstrating the breakdown of different classification of screening programs for developmental dysplasia of the hip within the UK. CTCV, congenital talipes calcaneovalgus; CTEV, fixed congenital talipes equinovarus; NIPE, newborn and infant physical examination; RF, risk factors; USS, ultrasound.

Fig. 2

A flow chart demonstrating the inclusion/exclusion and relevant numbers of participants. ‘Normal’ hips were defined as: an initial scan demonstrating type I hips or IIa with no regression of disease and type I hips on first follow up ultrasound (n = 3,747), or no missed presentation of developmental dysplasia of the hip (DDH) after between 24 and 94 months of follow-up (n = 23,843). DDH hips were defined as dislocated hips (Graf type III/IV), instability (Graf type IId), or critical range dysplasia (which were those defined on ultrasound Graf type 2b and above and those with type 2a disease that progressed to true dysplasia (type ≥ 2b) or required treatment secondary to regression of alpha angle by ≥ 4° after four weeks of follow-up) (n= 141). Of the 141 cases of DDH, 129 were identified by ultrasound screening, and 12 were identified as missed cases after 24 to 96 months of follow-up.