Osteoarthritis-related walking disability and cardiovascular disease risk

Abstract

Purpose: While osteoarthritis (OA)-related morbidity is well known, the association between OA and increased cardiovascular disease (CVD) risk is not fully elucidated. Arterial stiffness is a validated marker of cardiovascular risk and a predictor of mortality. However, evidence suggests physical exercise reduces arterial stiffness, indicating that arterial stiffness can be modified. Moreover, it seems clear that OA disability increases the risk of CVD beyond what can be explained by common risk factors like ageing and obesity. Hence, the objectives in this study were to compare walking ability in a population-based OA cohort with age- and gender-matched peers from the general population, and to explore the associations between walking ability and CVD risk measured as arterial stiffness in the OA cohort. Methods: This cross-sectional study included participants (40-80 years) who self-reported OA (n = 500) in a population-based study and matched peers from the general population (n = 370). Both groups performed the 6 min walk distance-test (6 MWD) according to the American Thoracic Society statement guidelines. Further, participants who self-reported OA completed comprehensive clinical examinations and were classified according to the American College of Rheumatology criteria by a medical doctor. In addition, data on demographic (age, gender, body mass index, smoking habits, education level) and clinical characteristics (non-steroidal anti-inflammatory drugs, Numeric Rating Scale of Joint pain) were collected. Arterial stiffness determined by carotid-femoral Pulse Wave Velocity was measured using a non-invasive gold standard method. Pulse Wave Velocity and resting heart rate were assessed using the Sphygomocor apparatus (Atcor, Australia). Brachial blood pressure was measured after 5 min rest, using the OMRON M7 (Kyoto, Japan). Group difference in 6 MWD was calculated with t-test, and the association between 6 MWD and CVD risk (arterial stiffness) in the OA cohort was explored in multivariate regression models. Results: The mean (SD) age of the OA-participants was 63.2 (8.8) years, 28% were men. More than 2/3 (68.4%) were classified with overweight or obesity, and one in four of the participants reported using non-steroidal anti-inflammatory drugs on a daily basis. Most participants (78%) described joint pain of five or lower on the Numeric Rating Scale. In total, 347 participants (69.4%) were classified with OA in one or more joint(s) according to the American College of Rheumatology criteria. Mean (SD) arterial stiffness (Pulse Wave Velocity) in the OA- group was 8.82 (2.06) m/s, ranging from 4.65 to 18.30 m/s. Compared to the general population, OA participants achieved a significantly shorter 6 MWD (551.4 m vs. 615.3 m, P < 0.001). In age stratified analyses, the largest mean difference in 6 MWD was observed in the youngest age group (40–49 years) (594.9 m vs. 685.3 m, P < 0.001) (Figure 1). These differences attenuated gradually with increasing age. In the OA group, the 6 MWD was significantly associated to arterial stiffness (Pulse Wave Velocity) in adjusted analysis (P = 0.001); 100 m longer walking distance corresponded to 0.3 m/s reduction in arterial stiffness. Conclusions: Already from the age of forty, people with OA have significantly shorter walking distance compared to age matched peers, underlining the importance of early clinical approach to OA. Further, in the OA-group, the 6 MWD was significantly associated with arterial stiffness, suggesting that walking disability is important for the CVD risk profile in OA.