National study of cause-specific mortality in rheumatoid arthritis, juvenile chronic arthritis, and other rheumatic conditions: a 20 year followup study

Abstract

Objective: To quantify risks for cause-specific mortality among hospitalized patients with rheumatoid arthritis (RA), juvenile chronic arthritis (JCA), and 4 other rheumatic conditions in a nationwide, population based cohort over a 20 year period.

Methods: All subjects were identified from Scottish hospital inpatient records from 1981 to 2000 and were followed up by computer linkage to the national registry of deaths. Expected mortality was calculated from national mortality rates and was related to the observed incidence by the standardized mortality ratio (SMR) and the corresponding 95% confidence interval (95% CI).

Results: Overall mortality was elevated in each of the 6 rheumatic conditions examined, most notably in JCA (males: SMR 3.4, 95% CI 2.0,5.5; females: SMR 5.1, 95% CI 3.2,7.8). Among patients with RA, there was an increased risk for death in all International Classification of Disease chapters other than those relating to mental disorders. Specific causes of death with an increased risk for subjects with RA included lung cancer [males: 1.4 (1.2,1.5); females: 1.6 (1.5,1.8)], hematopoietic malignancies [M: 1.8 (1.4,2.3); F: 2.0 (1.7,2.3)], coronary artery disease (CAD) [M: 1.6 (1.5,1.7); F: 1.95 (1.9,2.0)], respiratory infections [M: 1.9 (1.7,2.2); F: 2.4 (2.3,2.6)], chronic obstructive pulmonary disease [M: 1.8 (1.6,2.0); F: 2.1 (1.9,2.3)], and renal failure [M: 3.1 (2.5,3.9); F: 3.5 (3.0,4.0)]. Conversely, RA subjects were less likely to die from gastrointestinal tract malignancies [M: 0.82 (0.7,1.0); F: 0.8 (0.7,0.9)].

Conclusion: Population studies for primary data collection are required to extend our knowledge about the underlying mechanisms of early mortality in patients with rheumatic conditions.