P238 RA and multimorbidity in UK Biobank: association with all-cause mortality and major adverse cardiac events
Authors: Nicholl Barbara , McQueenie Ross , Jani Bhautesh , Macdonald Sara , McCowan Colin , Canning Jordan , Mair Frances , Siebert Stefan 
Published: April 2020

Abstract

Background
Multimorbidity, the presence of ≥ 2 long-term conditions (LTCs) is common in people with rheumatoid arthritis (RA). However, most research in RA has focused on cardiovascular disease and depression as co-occurring morbidities, rather than multiple LTCs or a wide range of conditions. This study hypothesised that risk of all-cause mortality and major adverse cardiac events (MACE) would be greater in those with RA and ≥2 LTCs than those with RA only. Further, we explored which individual LTCs were associated with increased risk of mortality and MACE.

Methods
Data from UK Biobank, a cohort of over 500,000 adults aged 37-73 years across England, Scotland and Wales was analysed. RA and 42 other LTCs of interest were self-reported by participants in a questionnaire and nurse-led interview. Information on sociodemographic (age, gender, socioeconomic status) and lifestyle factors (smoking status, BMI, alcohol frequency, physical activity) were also gathered. Rheumatoid factor levels were also determined. MACE and mortality were classified using linked hospitalisations and mortality register data (median follow up time 9 years). Data were analysed using age-adjusted Cox’s proportional hazard modelling to calculate risk of all-cause mortality or MACE, adjusted for variables listed above. Predictor variable: no RA no LTCs (reference group), only RA, RA + 1-3LTCs, RA + ≥4LTCs. Finally, the relationship between comorbidity with individual LTCs (of the 42 studied) and both health outcomes was considered.

Results
5,658 (1.1%) of participants in UK Biobank self-reported RA (69.8% female, mean age 59 years). 74.7% of participants reported at least one LTC in addition to RA (1-3 LTCs 64.3%, ≥4 LTCs 10.4%), compared to 63.8% of participants without RA. 7.7% (N = 437) of participants with RA died and 5.9% (n = 331) had MACE events during the follow-up period. There was a dose response relationship in RA between LTC category and all-cause mortality and MACE risk. Only RA: mortality HR 1.42, 95% CI 1.08, 1.87, MACE HR 1.61 95% CI 1.20, 2.18; RA + 1-3LTCs: mortality HR 1.99 95% CI 1.74, 2.27, MACE HR 1.89, 95% CI 1.61, 2.20; RA + ≥4LTCs: mortality HR 3.34, 95% CI 2.64, 4.22; MACE HR 3.45, 95% CI 2.66, 4.49) compared to those with no RA no LTCs (results presented from fully adjusted models). Of the 42 individual LTCs considered, comorbid osteoporosis was the most concerning; participants with both RA and osteoporosis had a two-fold increased risk of all-cause mortality (HR 2.20, 95% CI 1.55, 3.12) and three-fold increased risk of MACE outcomes (HR 3.17, 95% CI 2.17, 4.64) compared to those with neither condition.

Conclusion
Participants with RA and multimorbidity or comorbidity, particularly osteoporosis, are at increased risk of adverse health outcomes. These results have important clinical relevance for the monitoring and optimal management of RA across the healthcare system.

Disclosures
B. Nicholl None. R. McQueenie None. B. Jani None. S. Macdonald None. C. McCowan None. J. Canning None. F. Mair None. S. Siebert None.