RESUMEN
BACKGROUND: The effectiveness of physiotherapy in patients with chronic low back pain is usually measured through changes in pain and disability domains. However, recent research has suggested that these two domains are not sufficient to capture all the physiotherapy benefits when patients' perspective is considered. OBJECTIVE: The aim of this study was to investigate the role of pain and disability changes in explaining the global perception of improvement in patients with chronic low back pain undergoing physiotherapy. DESIGN: Prospective cohort study. METHODS: The study was conducted on183 patients who were referred to physiotherapy treatment due to low back pain lasting more than 12 weeks. Sociodemographic and clinical characteristics were measured at baseline, together with pain intensity and disability. Eight (post-intervention) and twelve weeks later, global perception of improvement was measured together with pain and disability. The Pearson correlation coefficient and linear regression models were used for analyses. RESULTS: Of the 183 participants included, 144 completed the 12-weeks follow-up. Significant and moderate correlation was found between pain and disability changes and the global perception of improvement after intervention and at the 12-weeks follow-up. Pain and disability changes explained 20.7%-36.3% of the variance in the global perception of improvement. CONCLUSIONS: Pain and disability changes are related and contributed to explaining a partial proportion of variance in the global perception of improvement. The findings suggest that these domains are not sufficient to explain and measure all of the benefits of physiotherapy when patients' global perception of improvement is considered.