Predicting walking in osteoarthritis: a series of n-of-1 studies with individually-tailored interventions

Abstract

Background. This study compares a biomedical, a psychological, and an integrated model of activity and activity limitations to predict walking within individuals with osteoarthritis. The effectiveness of a walking intervention is also tested. Methods. Diary methods were used to assess impairment (pain, pain-on-movement, joint stiffness), cognitions (intention, self-efficacy, perceived controllability) and walking (pedometer stepcount) in four individuals with osteoarthritis twice-daily over 12 weeks. An AB intervention design was used with an individually-tailored walking intervention delivered at six weeks. Simulation modelling analysis tested cross-correlations and differences between baseline and intervention phase means. Multiple regression analyses examined the predictive ability of models. Findings. Cognitions were better, more consistent within-individual predictors of walking than impairment. The intervention did not increase walking in any participant. The integrated and psychological models, which recognise a role for cognitions in predicting behaviour, accounted for substantially more variance in walking than the biomedical model. Discussion. Despite lack of evidence for the intervention, data suggest that interventions in osteoarthritis that address cognitions are likely to be more effective than those that address impairment only. Further within-individual investigation is warranted.