Disease activity and its predictors in early inflammatory arthritis: findings from a national cohort

Abstract

Objectives: We set out to characterize patient factors that predict disease activity during the first year of treatment for early inflammatory arthritis (EIA).

Methods: We used an observational cohort study design, extracting data from a national clinical audit. All NHS organizations providing secondary rheumatology care in England and Wales were eligible to take part, with recruitment from 215/218 (99%) clinical commissioning groups (CCGs)/Health Boards. Participants were >16 years old and newly diagnosed with RA pattern EIA between May 2018 and May 2019. Demographic details collected at baseline included age, gender, ethnicity, work status and postcode, which was converted to an area level measure of socioeconomic position (SEP). Disease activity scores (DAS28) were collected at baseline, three and 12 months follow-up.

Results: A total of 7455 participants were included in analyses. Significant levels of CCG/Health board variation could not be robustly identified from mixed effects modelling. Gender and SEP were predictors of low disease activity at baseline, three and 12 months follow-up. Mapping of margins identified a gradient for SEP, whereby those with higher degrees of deprivation had higher disease activity. Black, Asian and Minority Ethnic patients had lower odds of remission at three months follow-up.

Conclusion: Patient factors (gender, SEP, ethnicity) predict disease activity. The rheumatology community should galvanise to improve access to services for all members of society. More data are required to characterize area level variation in disease activity.

Keywords: Rheumatoid arthritis; disease activity; early inflammatory arthritis; outcome measures; patient factors; socioeconomic factors.

Fig. 1

CCG/Health Board remission rates and mean DAS28 scores CCG/Health Board remission rates mapped at (a) baseline, (b) three months and (c) 12 months. Darker colours represent higher remission rates. CCG/Health Board mean DAS28 scores at (d) baseline, (e) three months and (f) 12 months. Darker colours represent higher disease activity. Khaki represents CCGs/Health Boards with <6 patients. CCG: clinical commissioning group; DAS28: disease activity score.

Fig. 2

Predicted margins of IMD at baseline, three-month and 12-month follow-up Plotted margins of IMD from the three logistic regression models, predicting remission at baseline (black line), three months (grey line) and 12 months (blue dashed line) with vertical lines representing 95% CIs. All three models indicate that the likelihood of remission increases as IMD decile increases, which corresponds to reducing deprivation.