Evaluation of a simple tool to assess the results of Ponseti treatment for use by clubfoot therapists: a diagnostic accuracy study

BACKGROUND: We aimed to develop and evaluate a tool for clubfoot therapists in low resource settings to assess the results of Ponseti treatment of congenital talipes equinovarus, or clubfoot, in children of walking age. METHOD: A literature review and a Delphi process based on the opinions of 35 Ponseti trainers in Africa were used to develop the Assessing Clubfoot Treatment (ACT) tool and score. We followed up children with clubfoot from a cohort treated between 2011 and 2013, in 2017. A full clinical assessment was conducted to decide if treatment was successful or if further treatment was required. The ACT score was then calculated for each child. Inter-observer variation for the ACT tool was assessed. Sensitivity, specificity, positive and negative predictive values were calculated for the ACT score compared to full clinical assessment (gold standard). Predictors of a successful outcome were explored. RESULTS: The follow up rate was 31.2% (68 children). The ACT tool consisted of 4 questions; each scored from 0 to 3, giving a total from 0 to 12 where 12 is the ideal result. The 4 questions included one physical assessment and three parent reported outcome measures. It took 5 min to administer and had excellent inter-observer agreement. An ACT score of 8 or less demonstrated 79% sensitivity and 100% specificity in identifying children that required further intervention, with a positive predictive value of 100% and negative predictive value of 90%. Children who completed two or more years of bracing were four times more likely to achieve an ACT score of 9 or more compared to those who did not (OR: 4.08, 95% CI: 1.31–12.65, p = 0.02). CONCLUSIONS: The ACT tool is simple to administer, had excellent observer agreement, and good sensitivity and specificity in identifying children who need further intervention. The score can be used to identify those children who definitely need referral and further treatment (score 8 or less) and those with a definite successful outcome (score 11 or more), however further discrimination is needed to decide how to manage children with a borderline ACT score of 9 or 10. LEVEL OF EVIDENCE: Level II, Diagnostic Study. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13047-019-0323-4) contains supplementary material, which is available to authorized users.