The influence of age at symptom onset and length of followup on mortality in patients with recent‐onset inflammatory polyarthritis

Objective To investigate the influence of age at symptom onset and length of followup on mortality in patients with recent‐onset inflammatory polyarthritis (IP), and to examine predictors of mortality in relation to disease duration. Methods From 1990 to 1994, patients with recent‐onset IP were registered with the Norfolk Arthritis Register (NOAR) and followed up prospectively. Standardized mortality ratios (SMRs) were calculated for all‐cause and cardiovascular disease (CVD) mortality and for those who were younger than age 55 years at disease onset and for the first 5 and 10 years of followup. Cox proportional hazards models were developed to assess predictors of early and later mortality. Results Of 1,098 patients, 224 (20%) had died by the end of 2004. All‐cause and CVD mortality were increased in rheumatoid factor (RF)–positive patients and in this subgroup, CVD mortality was increased at both early and later followup (SMR 5‐year followup 1.93 [95% confidence interval 1.08–3.19]; SMR 10‐year followup 2.00 [95% confidence interval 1.37–2.80]). CVD mortality was highest in seropositive patients <55 years of age at disease onset (SMR 5.58 [95% confidence interval 2.24–11.50]). In multivariate models, age at onset, male sex, RF positivity, Health Assessment Questionnaire score ≥1.5, and nodules were predictors of early and later mortality. Conclusion Patients with IP had higher rates of CVD mortality throughout the followup period studied, and this was highest in seropositive patients who were <55 years of age at symptom onset. This subgroup deserves particular attention in terms of disease and risk factor modification. Nodules were independent predictors of CVD mortality, suggesting that extraarticular/vascular inflammation identifies patients at particularly high CVD risk.