The value of physical performance tests for predicting therapy outcome in patients with subacute low back pain: a prospective cohort study

Abstract

Considering the enormous costs of intensive multidisciplinary treatment, predictive tests for therapy outcome are needed to evaluate patients' performance potential and increase cost effectiveness. Somatic parameters are commonly used to evaluate health status and serve as an additional means of forecasting the prognosis, yet little is known of their validity. In this study, we investigated the prognostic value of somatic parameters regarding the outcome of multidisciplinary treatment in patients with subacute low back pain. The study was designed as a prospective cohort study of 162 patients. Somatic parameters were assessed with three physical performance tests (Villiger test, Oesch test, Biering-Sørensen test) before treatment (T0), after 3 weeks' inpatient therapy (T1) and at 6-month follow-up (T2). Psychometric characteristics of subjective pain perception (VAS), a pain disability index (PDI) and a physical capability index (FFbH-R) were recorded. Correlation coefficients between the physical performance test scores and psychometric characteristics were calculated. To predict therapy outcome, discriminant analyses were performed. A control group (n = 30) was evaluated at similar time points without receiving any therapy. Our results demonstrate good discrimination between patients and controls by means of the investigated performance tests and exhibit a significant negative correlation with the psychometric data. Lower outcome values at study entry correlated with higher pain intensity and disability after multidisciplinary treatment. However, the statistical magnitude of correlation was relatively low and further discriminant analysis did not reveal any predictive value. Consequently the physical performance tests do not have a prognostic value regarding therapy outcome.