Associations of Healthy Lifestyles with All-Cause Mortality Among Individuals with Osteoarthritis: Results from UK Biobank and US NHANES

OBJECTIVETo investigate the association of both individual and combined healthy lifestyle factors with the risk of all-cause mortality among patients with osteoarthritis (OA). DESIGNProspective population-based cohort study. SETTINGUK biobank and US National Health and Nutrition Examination Survey (US NHANES, 2007-2018) PARTICIPANTS104, 142 UK participants with OA aged 39-72 years and 3, 472 US participants with OA aged 20-80 years. EXPOSURESIndividual healthy lifestyle factors and a combined healthy lifestyle score were constructed from body mass index (BMI) and self-reported information on diet, sleep duration, physical activity, sedentary time, social connection, smoking and alcohol drinking. MAIN OUTCOME MEASURESAll-cause mortality was the primary outcome in both studies. Secondary outcomes included cause-specific mortalities (cardiovascular, cancer, digestive and respiratory). Hazard ratios were adjusted for age, sex, economic situation, race, education and employment (UK biobank only). RESULTSUK Biobank documented 9,914 deaths during a median follow-up of 12.7 years, and US NHANES documented 463 deaths during a mean follow-up of 6.01 years. For all-cause mortality using restricted cubic spline graph (RCS) models, sleep duration had a U-shaped (with a nadir at 7 hours/day), moderate physical activity (MPA) had an L-shaped (with a turning point at 550 minutes/week), while BMI, vigorous physical activity (VPA) and sedentary time had J-shaped (with turning points at 28 kg/m2, 240 minutes/week and 5 hours/day, respectively) associations in the UK biobank. Similar results were observed in US NHANES. In multivariable Cox models, each healthy lifestyle factor was significantly associated with all-cause mortality (hazard ratio [HRs] range 0.49 to 0.84 for UK biobank, and 0.26 to 0.73 for US NHANES), and HRs (95% CI) for associations with combined healthy lifestyle score (scoring 6-8 vs. 0-2) were 0.38 (0.35, 0.41) in UK biobank and healthy lifestyle score (scoring 5-7 vs. 0-1) were 0.20 (0.13, 0.31) in US NHANES for all-cause mortality. The results for cause-specific mortality were largely similar and consistent across two cohorts. CONCLUSIONSThe nonlinear relationships suggested patients with OA had the lowest risk of all-cause mortality when BMI was 28 kg/m2, sleep was 7 hours/day, VPA was 240 minutes/week, sedentary time was less than 5 hours/day, MPA was more than 550 minutes/week. The newly constructed healthy lifestyle score for OA population was associated with a significantly lower risk of all-cause mortality. WHAT IS ALREADY KNOWN ON THIS TOPICHealthy lifestyles are thought to reduce the risk of multiple causes of mortality in the general population. People with osteoarthritis (OA) are at higher risk of mortality than the general population. However, evidence of associations between combined healthy lifestyle and risks of all-cause and cause-specific mortality among OA patients are lacking. Whether and what kind of healthy lifestyles in patients with OA could offset the risk of mortality are unknown. WHAT THIS STUDY ADDSBy using two nationwide cohort studies in UK and US, a comprehensive healthy lifestyle pattern that integrates 8 or 7 lifestyle factors was established among OA individuals for the first time. People who had the highest combined healthy lifestyle score were significantly associated with 62% to 80% lower risk of all-cause mortality compared with those who had the lowest score in both the UK and US OA populations.