Objectives The study examines how environmental factors contribute to the onset of restricted mobility outside the home among older adults with osteoarthritis.

Methods This is a prospective cohort study of adults aged 50 years and older with osteoarthritis (n=1802). Logistic regression tested the association between the onset of restricted mobility outside the home and health, sociodemographic and perceived environmental barriers (hills and steep slopes, inaccessible public buildings, poor pavement condition, lack of access to public parks or sport facilities, heavy traffic or speeding cars and poor weather). The potential moderating role of environmental barriers on the association between health factors and onset was examined using interaction terms and stratified analysis.

Results Of 1802 participants, 13.5% (n=243) reported the onset of restricted mobility outside the home at 3-year follow-up. Walking disability, anxiety, depression, cognitive impairment and obesity and all environmental barriers were associated with onset after adjustment for confounders. Environmental barriers had an added contribution to the effect of the health conditions on onset of restricted mobility, which was attenuated when adjusted for confounders. The added contribution remained only for walking disability and the presence of hills and steep slopes; in the presence of both, the association with onset of restricted mobility was stronger (OR 7.66, 95% CI 4.64 to 12.64) than in the presence of walking disability (3.60, 2.43 to 5.32) or the presence of hills and steep slopes alone (4.55, 2.89 to 7.16).

Conclusion For older adults with osteoarthritis, environmental barriers are associated and add a contribution to that of morbidities and walking disability on the onset of restricted mobility outside the home. Awareness of environmental barriers is important when aiming to maintain mobility and activities outside the home despite health conditions in older adults.