In people with hip osteoarthritis (OA), the impact of obesity on health-related quality of life (HRQoL) remains unknown. Also whether cardiovascular conditions can modify the obesity–HRQoL relation has not been explored. We aimed to (1) study the cross-sectional relationship between body mass index (BMI) and HRQoL in symptomatic hip OA patients and determine whether cardiovascular comorbidity modifies this relationship and (2) examine the impact of BMI on the course of HRQoL over time.

We used data from the first 3 years of follow-up from the KHOALA study, which recruited patients from 2007 to 2009. HRQoL was assessed by the SF-36 and OAKHQOL questionnaires at baseline and during follow-up. We determined BMI and presence of cardiovascular disease by the Groll score. Associated factors at baseline and predictors of HRQoL over time were evaluated by multiple linear regression.

For 222 hip OA patients included, mean (SD) BMI was 26.9 (4.4) kg/m²; 37 (17.1%) had at least one cardiovascular comorbidity. Increased BMI but not presence of cardiovascular comorbidity was associated with poor HRQoL. Increased BMI affected mainly physical and social HRQoL dimensions (up to -1.0 points, 95% CI [−1.6;−0.4]; P=0.002). The BMI–HRQoL relationship was not modified by the presence of cardiovascular disease. BMI was not associated with the course of HRQoL.

In patients with hip OA, BMI had an independent weak negative impact on HRQoL that was not modified by cardiovascular comorbidities. Neither of these factors affected HRQoL change during a 3-year follow-up.