Can an extended lifestyle score predict adverse outcomes in people with rheumatoid arthritis? Cross-sectional study of 5295 UK Biobank participants.

Problem

Traditional lifestyle risk factors, such as smoking, poor diet and physical inactivity, have been shown to contribute to adverse outcomes in people with rheumatoid arthritis (RA). Less is known about the added impact of emerging lifestyle risk factors, specifically short/long sleep duration and sedentary behaviour, in this population. We aimed to explore the associations, if any, between individual lifestyle risk factors and an extended lifestyle score and risk of all-cause mortality and major adverse cardiovascular events (MACE; myocardial infarction and stroke) in an RA population.

Approach

Cross-sectional study involving UK Biobank participants with self-reported RA. Lifestyle factors included: alcohol intake, diet, physical activity, sleep duration, smoking and television viewing time. Lifestyle factors were summed to create an extended lifestyle score ranging from 0-9, and participants categorised as more healthy (score 0-2), moderately healthy (score 3-5) and less healthy (score 6-9). Cox proportional hazards models were used to explore associations between individual lifestyle factors and lifestyle score categories and risk of all-cause mortality and MACE, adjusting for age, sex, socioeconomic status, body mass index, additional long-term condition count and other individual lifestyle factors (if applicable).

Findings

In UK Biobank, 5295 (1.05%) participants self-reported RA at baseline (mean age 59; 70% female) and had available lifestyle data. Over follow up, 594 deaths (median 11 years) and 328 MACE (median 8 years) were recorded. Smoking increased the adjusted risk of all-cause mortality (hazard ratio (HR) 1.94 [95% confidence interval (CI) 1.46-2.56]) and MACE (HR 1.83 [95% CI 1.24-2.70]), when compared to participants who have never smoked. Risk of MACE was increased in participants who reported short (<7 hours) or long (>9 hours) sleep durations (HR 1.38 [95% CI 1.02-1.87]), compared to participants who reported sleep durations between 7-9 hours per night. The adjusted HR for participants in the less healthy lifestyle category was 2.05 [95% CI 1.18-4.30] for all-cause mortality and 2.25 [95% CI 1.18-4.30] for MACE. For participants in the moderately healthy category, the adjusted HR was 1.27 [95% CI 1.08-1.50] for all-cause mortality and 1.42 [95% CI 1.13-1.78] for MACE.

Consequences

Participants with RA and moderately or less healthy lifestyles were at increased risk of all-cause mortality and MACE when compared to those with more healthy lifestyles, with a dose response association. This risk appears to be driven by smoking and short/long sleep duration (for MACE), thus emphasis on these individual lifestyle risk factors may be better than the use of an extended lifestyle score for risk stratification purposes. Further research in this area, particularly relating to sleep duration and quality, may help clinicians give more tailored lifestyle-related advice to individuals with RA, reducing morbidity and mortality burden in this population.