EFFECTS OF OBESITY CLASS ON CLINICAL OUTCOMES CONSEQUENT TO AN 18-MONTH BEHAVIORAL DIET AND EXERCISE INTERVENTION IN ADULTS WITH KNEE OSTEOARTHRITIS

Abstract

Background: Among adults with knee osteoarthritis (OA), those living with class III obesity present with worse baseline pain, function, quality of life, mental health and self-efficacy, and have often been underrepresented in clinical trials. Purpose: To compare the responses of adults with knee OA and class III obesity to an 18-month behavioral diet and exercise intervention to participants with overweight/class I and II obesity. Methods: Descriptive statistics summarized the data. To determine if there was a possible differential effect by obesity subgroups due to the intervention, we used the generalized linear model. Tests were two-sided, p=0.05 and conducted in SAS v9.4. Results: People living with class III obesity responded similarly to overweight/class I and II obesity for changes in pain (WOMAC, ICOAP), function (WOMAC, 6-minute walk test, SPPB), quality of life (SF-36, SWL), mental health (CES-D, PSS, PANAS) and self-efficacy (WEL, gait, duration) at follow-up (p0.12). They achieved the MCID for waist circumference, 6-minute walking distance, physical health composite subscore of the SF-36 (PCS) and walking efficacy for duration, while people with overweight/class I-II obesity only achieved the MCID for the 6-minute walking distance. For WOMAC knee function, the MCII was achieved within both obesity classes in the D+E group at follow-up. Conclusions: These results reinforce the inclusion of people living with class III obesity in clinical trials, ensuring equitable representation and adherence to principles of justice in research.