Predicting the outcome of plantar heel pain in adults: a systematic review of prognostic factors

Background Plantar Heel Pain (PHP) is a common disorder with many treatment pathways and is not self-limiting, hence prognostic information concerning recovery or recalcitrance is needed to guide practice. In this systematic review, we investigate which prognostic factors are associated with favourable or unfavourable PHP outcomes. Methods MEDLINE, Web of Science, EMBASE, Scopus and PubMed electronic bibliographic databases were searched for studies evaluating baseline patient characteristics associated with outcomes in prospective longitudinal cohorts or after specific interventions. Cohort, clinical prediction rule derivation and single arms of randomised controlled trials were included. Risk of bias was evaluated with method-specific tools and evidence certainty with GRADE. Results The review included five studies which evaluated 98 variables in 811 participants. Prognostic factors could be categorised as demographics, pain, physical and activity-related. Three factors including sex and bilateral symptoms (HR: 0.49[0.30–0.80], 0.33[0.15–0.72], respectively) were associated with a poor outcome in a single cohort study. The remaining four studies reported twenty factors associated with a favourable outcome following shockwave therapy, anti-pronation taping and orthoses. Heel spur (AUC = 0.88[0.82–0.93]), ankle plantar-flexor strength (Likelihood ratio (LR): 2.17[1.20–3.95]) and response to taping (LR = 2.17[1.19–3.90]) were the strongest factors predicting medium-term improvement. Overall, the study quality was low. A gap map analysis revealed an absence of research that included psychosocial factors. Conclusions A limited number of biomedical factors predict favourable or unfavourable PHP outcomes. High quality, adequately powered, prospective studies are required to better understand PHP recovery and should evaluate the prognostic value of a wide range of variables, including psychosocial factors.