The prevalence of co-morbidities and their impact on physical activity in people with inflammatory rheumatic diseases compared with the general population: results from the UK Biobank

Abstract

Objectives: To compare the prevalence and incidence of chronic co-morbidities in people with inflammatory rheumatic and musculoskeletal diseases (iRMDs), and to determine whether the prevalent co-morbidities are associated with physical activity levels in people with iRMDs and in those without iRMDs.

Methods: Participants were recruited to the UK Biobank; a population-based cohort. Data were collected about demographics, physical activity, iRMDs (RA, PsA, AS, SLE) and other chronic conditions, including angina, myocardial infarction, stroke, hypertension, pulmonary disease, diabetes and depression. The standardized prevalence of co-morbidities in people with iRMDs was calculated. Cox regression was used to determine the relationship between the presence of an iRMD and an incident co-morbidity. The relationship between the presence (versus absence) of a (co-)morbidity and physical activity level (low, moderate, high) in people with iRMDs and in those without was assessed using multinomial logistic regression.

Results: A total of 488 991 participants were included. The estimated prevalence of each co-morbidity was increased in participants with an iRMD, compared with in those without, particularly for stroke in participants with SLE (standardized morbidity ratio (95% CI), 4.9 (3.6, 6.6). Compared with people with no iRMD and no morbidity, the odds ratios (95% CI) for moderate physical activity were decreased for: no iRMD and morbidity, 0.87 (0.85, 0.89); iRMD and no co-morbidity, 0.71 (0.64, 0.80); and iRMD and co-morbidity, 0.58 (0.54, 0.63).

Conclusion: Having a (co-)morbidity is associated with reduced physical activity in the general population, and to a greater extent in participants with an iRMD. Optimal management of both iRMDs and co-morbidities may help to reduce their impact on physical activity.

Fig. 1

Standardized morbidity ratios for participants with a rheumatic/musculoskeletal disease Indirect age- and sex-standardized morbidity ratios for participants with a rheumatic/musculoskeletal disease. The referent group comprised participants with none of the rheumatic/musculoskeletal diseases being studied. MI: myocardial infarction.

Fig. 2

Hazard ratios for the development of co-morbidities after diagnosis of a rheumatic/musculoskeletal disease Hazard ratios calculated from a Cox proportional hazard model. Each participant with a rheumatic/musculoskeletal disease was age- and sex-matched to four participants with none of the rheumatic/musculoskeletal diseases being studied. Estimates based on less than 10 events are not presented. MI: myocardial infarction.

Fig. 3

Association between presence/absence of rheumatic/musculoskeletal disease, (co)morbidity and physical activity Results from multinomial logistic regression. Physical activity group (referent = low) is the dependent variable. Study group: no rheumatic/musculoskeletal disease and no morbidity (no RD-noM), no rheumatic/musculoskeletal disease and morbidity (no RD-M), rheumatic/musculoskeletal disease and no co-morbidity (RD-no M), and rheumatic/musculoskeletal disease and co-morbidity (RD-M) is the independent variable. Adjusted for age, sex, smoking, alcohol consumption, BMI and Townsend deprivation index.