Predictive factors for post-poliomyelitis syndrome.

Post-poliomyelitis syndrome (PPS) is generally defined as a clinical syndrome of new weakness, fatigue, and pain in individuals who have previously recovered from acute paralytic poliomyelitis. The purpose of this study was to identify, through a case-control study design, factors that predict subsequent PPS in patients with prior paralytic poliomyelitis. Among patients attending a university-affiliated hospital post-polio clinic, "cases" were patients with new weakness and fatigue, and "controls" were patients without these complaints. A chart review of 353 patients identified 127 cases and 39 controls. Logistic regression modeling was used to calculate adjusted and unadjusted odds ratios. In univariate analyses, significant risk factors for PPS were a greater age at time of presentation to clinic (p = 0.01), a longer time since acute polio (p = 0.01), and more weakness at acute polio (p = 0.02). Other significant associated, but not necessarily causal factors were a recent weight gain (p = 0.005), muscle pain (p = 0.01) particularly that associated with exercise (p = 0.005), and joint pain (p = 0.04). Multivariate analyses revealed that a model containing age at presentation to clinic, severity of weakness at acute polio, muscle pain with exercise, recent weight gain, and joint pain best distinguished cases from controls. Age at acute polio, degree of recovery after polio, weakness at best point after polio, physical activity, and sex were not contributing factors. These findings suggest that the degree of initial motor unit involvement as measured by weakness at acute polio, and possibly the aging process and overuse are important in predicting PPS.