Osteoarthritis and risk of mortality in the USA: a population-based cohort study

Background Osteoarthritis (OA) is the most common joint disease, but its association with mortality is unclear. Methods We analysed data on adult participants in the 1988–94 and 1999–2010 National Health and Nutrition Examination Surveys, followed for mortality through 2011. OA was defined by self-report, and in a subset of participants 60 years or older with knee X-rays, radiographic knee OA (RKOA) was defined as Kellgren–Lawrence score ≥2. Cox proportional hazards were used to determine the mortality hazard ratio (HR) associated with self-reported OA and RKOA, adjusting for covariates. Results The sample included 51 938 participants followed for a median 8.9 years; 2589 of them had knee X-rays and were followed for a median of 13.6 years. Self-reported OA and RKOA prevalences were 6.6% and 40.6%, respectively. Self-reported OA was not associated with mortality. RKOA was associated with an increased risk of mortality from cardiovascular diseases (CVD) {HR 1.43 [95% confidence interval (CI): 1.32, 1.64]}, diabetes [HR 2.04 (1.87, 2.23)] and renal diseases [HR 1.14 (1.04, 1.25)], but with a reduced risk of cancer mortality [HR 0.88 (0.80, 0.96)]. Participants with early RKOA onset (diagnosed before age 40) had a higher risk of mortality from all causes [HR 1.53 (1.43, 1.65)] and from diabetes [HR 7.18 (5.45, 9.45)]. Obese participants with RKOA were at increased risk of mortality from CVD [HR 1.89 (1.56, 2.29)] and from diabetes [HR: 3.42 (3.01, 3.88)]. Conclusions Self-reported OA was not associated with mortality. RKOA was associated with higher CVD, diabetes and renal mortality, especially in people with early onset of the disease or with obesity.