How does multimorbidity impact quality of life, disease activity and health assessment in patients with new-onset rheumatoid arthritis?
Rheumatoid arthritis (RA) is a chronic autoimmune disease most commonly associated with inflammation of the synovial membrane, which can cause pain, joint damage, and result in loss of function, disability and a reduced quality of life (QoL). Despite high levels of comorbidity and multimorbidity (≥2 long-term conditions (LTCs)) seen in people with RA, little is known about how presence of multimorbidity impacts health outcomes in people living with RA over time. This study aims to longitudinally assess the overall effect of the presence of multimorbidity in people with RA in relation to commonly used QoL, disease activity and health assessment metrics.
We identified 572 RA participants from the Scottish Early Rheumatoid Arthritis (SERA) inception cohort and collected data at baseline, month 6 and month 12. Participants comorbidities were counted and categorised into the groups: RA only, RA +1 LTC and RA ≥2 LTCs. Mixed effects models (adjusted for age and sex) were used to investigate the association between the number of comorbidities and disease activity (DAS28-ESR), QoL (EQ-5D), function (HAQ-DI), and anxiety and depression status (HADS), with effects determined using estimated marginal means.
In the dataset 251 (43.9%) participants had no additional comorbidities, 174 (30.4%) one and 147 (25.7%) two or more. There were significant differences between the RA ≥2 LTC and RA only groups at each visit for DAS28-ESR and HAQ-DI scores. At baseline for DAS28-ESR the mean difference was 0.47 (95% CI 0.12-0.83) and at month 12 0.45 (95% CI 0.09-0.81). For HAQ-DI the difference was 0.37 (95% CI 0.17-0.56) at baseline and 0.27 (95% CI 0.07-0.47) at month 12. For EQ-5D and HAD depression scores any significant differences present between LTC groups at baseline were not present at month 12. There were no significant differences in anxiety between LTC groups at any visit. Across all LTC groups, there was a significant improvement in all measures at month 6 and month 12 relative to baseline.
These findings suggest that multimorbidity should be taken into account in the management of patients with RA. While it has been demonstrated that in all LTC groups disease activity, QoL, function, anxiety, and depression can all be significantly improved, it may not be possible for patients with two or more additional LTCs to achieve the same level of improvement as patients with only RA for DAS28-ESR and HAQ-DI scores. This could have implications for the treat-to-target strategy recommended for the management of RA, where the goal is for the patient to reach a disease activity level of remission or low activity, and raises the prospect of personalised treatment goals that take into consideration multimorbidity.