Abstract
Responses to physical activity interventions vary among adults with arthritis, and baseline functional limitations may affect increases in walking. To determine whether baseline physical function moderated changes in accelerometer-measured steps/day after a telephone-delivered Walk With Ease (WWE-T) intervention. This secondary analysis included 267 adults from a randomized trial of WWE-T versus wait-list control. Baseline function was assessed with the 30-Second Chair Stand Test and 6-Minute Walk Test and categorized as high or low using sample means. Steps/day were measured at baseline, 6 weeks, 6 months, and 12 months. Repeated-measures mixed-effects models tested time, physical function category, intervention group, and their three-way interaction, adjusting for age, sex, and body mass index. Participants had a mean age of 64.2 years (standard deviation 9.2); 92% were female, and mean body mass index was 34.2 kg/m² (standard deviation 7.7). The three-way interaction for chair stands was not significant (P = 0.27). Higher chair-stand performance was associated with more steps/day across follow-up (P = 0.0003). In the high-repetition WWE-T subgroup, steps/day increased at 6 weeks by 731 (95% confidence interval 281 to 1182) and at 6 months by 457 (72 to 843). The three-way interaction for walking endurance was not significant (P = 0.20), though higher walking endurance was associated with more steps/day (P < 0.0001). The presence of limitations with physical function did not moderate changes to steps/day following a telephone‑delivered physical activity intervention, though those without limitations had more steps/day.