Rheumatoid arthritis (RA) is a debilitating systemic autoimmune disorder characterised by inflammation and joint damage. It affects 0.6% -1.0% of the general population. In addition, RA is associated with comorbidities such as cancer, heart disease, hypothyroidism and associates with an increased risk of death despite advances in treatment. While the association between RA and comorbidities has been examined in cross-sectional and prospective studies, it is not known whether RA increases the risk of developing comorbidities or if the comorbidities precede the onset of RA, and are a risk factor for developing RA. Thus, the overall purpose of this study is to assess the chronological relationship between RA and comorbidities. We will study all patients newly diagnosed with RA in CPRD between 1997 and 2005, and an equal number of people without RA. We will then examine the data to find out if they had a higher risk of having comorbidities 10 year, and 1 year before developing RA, and 10 years after they develop RA.
Objectives: To compare the burden of comorbidity between incident cases of RA and matched controls before and after the diagnosis of RA. Methods: A combined retrospective case-control and prospective cohort study. Incident RA cases will be sampled from the CPRD, and age, gender, practice and index date matched with a control without RA. Comorbidities within 10 years prior to and following the diagnosis of RA will be analysed. Data from linkages is not required in this study. Data analysis: For retrospective analysis, the prevalence of a specific comorbidity will be calculated using the number of people ever diagnosed with a given comorbidity during the past 10-year period or 1-year period before the index date as the numerator and the number of patients with incident RA or matched controls as denominators. ORs and 95% CIs will be used to estimate the association. Conditional logistic regression will be used to adjust for covariates. For prospective analysis, Kaplan-Meier plots will be used to estimate the cumulative probability of each comorbidity and all-cause mortality in people with incident RA and those without. Hazard ratio (HR) and 95% CI will be calculated using a Cox proportional hazard model and adjusted for covariates.
[1] Charlson comorbidities and other comorbidities (before, at the time of and after diagnosis of Rheumatoid Arthritis):cardiac arrhythmias, valvular heart disease, hypertension, hyperlipidaemia, multiple sclerosis, urolithiais, anaemia, depression, psychosis, hypothyroidism, psoriasis, gout, osteoarthritis. The definitions of these conditions will be based on physician diagnoses recorded as Read codes. [2] Total Charlson score [3] Death
Abhishek Abhishek - Chief Investigator - University of Nottingham
Abhishek Abhishek - Corresponding Applicant - University of Nottingham
Chang-Fu Kuo - Collaborator - University of Nottingham
Christian Mallen - Collaborator - Keele University
Michael Doherty - Collaborator - University of Nottingham
TingTing Chung - Collaborator - University of Nottingham