Accelerometer-derived physical activity analysis of elderly osteoarthritis patients.

BACKGROUND: Because disability in Osteoarthritis (OA) may change physical activity (PA), which might affect the disease progression, it is important to measure a patient's daily PA to study the relationship between a patient's PA and disease progression. OBJECTIVE: The objective of the present study was to investigate the relationship between PA and patients with OA and people without OA using data from the Korea National Health and Nutrition Examination Survey (KNHANES). METHODS: Demographic study was conducted to obtain data of comorbidities of participants. PA was compared between the group with OA (OA group) and the group without OA (non-OA group). In addition, PAs of OA patients with comorbidities and those without comorbidities were compared. The cut-off of moderate to vigorous physical activity (MVPA) was obtained through a receiver operating characteristic (ROC) curve. RESULTS: In the demographic study, there were significantly more educated participants in the OA group (p < .001). Actigraph data showed a significant decrease in MVPA (p < .001) but a significant increase in light activity (p = .002) in the OA group. In addition, the OA group showed significantly lower light PA but significantly higher MVPA in ≥10 min bout length. OA patients with comorbidities showed higher MVPA than OA patients without comorbidities (p = .044). The cut-off point of MVPA was 7.071 min/day when ROC curve was conducted. CONCLUSIONS: The present study suggests that patients with OA and low activity need a certain level of physical activity and a cut-off point for MVPA is presented which accounts for comorbidities in OA patients.