Predictors for future activity limitation in women with chronic low back pain consulting primary care: a 2-year prospective longitudinal cohort study

OBJECTIVES To assess if body function, activity, participation, health-related quality of life and lifestyle behavioural factors can predict activity limitation in women with chronic low back pain (CLBP) in primary healthcare (PHC) 2 years later. DESIGN A 2-year prospective longitudinal cohort study within PHC. SETTINGS PHC in southwestern Sweden. PARTICIPANTS The cohort comprised 130 women with CLBP attending PHC at baseline 2004-2005 and were reassessed after 2 years. MEASURES The dependent outcome variable was self-reported activity limitation (Roland Morris disability questionnaire (RMDQ)) at 2-year follow-up. Independent predictors at baseline were age, body mass index, smoking, alcohol consumption, sleep quantity and quality, leisure time physical activity, a questionnaire of clinical manifestation of stress (Stress and Crises Inventory (SCI-93)), pain localisation, pain intensity, fatigue, anxiety, depression, RMDQ, work status, private social support, health-related quality of life and measures of physical performance specified as 6 min walk test (6MWT) and hand grip strength. Relation between baseline predictors and variation in later self-reported activity limitation (RMDQ) was analysed using multivariate linear regression. RESULTS Ninety-five per cent (n=123/130) were followed up after 2 years. The participants were middle-aged (mean 45 (SD 10) years), mostly educated >9 years (88%; 108/123), mainly living with another adult (76%; 93/122) and born in Sweden (90%; 111/123). Seventy-nine per cent (97/123) were categorised as having work ability at baseline. The final prognostic model including 6MWT, SCI-93 and RMDQ at baseline explained 54% of the variance in self-reported activity limitation (RMDQ) at the 2-year follow-up. CONCLUSIONS Lower physical performance, more severe clinical stress symptoms and more severe activity limitation predicted activity limitation after 2 years in women with CLBP within PHC. The results can give guidance for interventional trials aiming to improve physical capacity and decrease stress. The impact of the interaction between prognostic factors and interventions on activity limitation needs further investigation.