Are older adults with symptomatic knee osteoarthritis less active than the general population?

The aim of this study was to compare objectively-measured physical activity (PA) in older adults with symptomatic knee osteoarthritis (SxOA) with similarly aged adults without osteoarthritis (OA) or knee symptoms from the general population.

The authors included people age 50-85 years with SxOA from the Osteoarthritis Initiative (OAI, n=491), and people age 50-85 years from the general population from the National Health and Nutrition Examination Survey (NHANES, n=449). A uniaxial accelerometer was worn for >10 hours/day for >4 days in the NHANES in 2003-2004 (Actigraph 7124) and in the OAI in 2008-2010 (Actigraph GT1M). We calculated time spent in moderate-vigorous PA (MVPA in minutes/day) and described differences in MVPA and demographic variables between the samples. The team conducted matched-pairs sensitivity analyses to further evaluate the role of potential confounders.

Both cohorts had similarly low levels of PA in age and sex specific strata. Time in MVPA ranged from a median of 1 to 22 minutes/day in people with SxOA, and from 1 to 24 minutes/day in the general population without OA or knee pain. These results were similar in sensitivity analyses. Time spent in MVPA was similarly low in those with SxOA as in older adults without knee pain or OA.