Preclinical biomarker associations with both incident rheumatoid arthritis and its subsequent mortality: sex effects in a 41-year, community-based, case-control cohort study.

OBJECTIVES

To identify sex effects and preclinical serum biomarker associations with both incident rheumatoid arthritis (RA) and its subsequent mortality, using a 41-year, community-based, case-control cohort.

METHODS

After cohort entry in 1974, incident RA cases (n=54) had clinical onsets between 1977 and 1994. Cohort control (CN) subjects were individually matched on entry to cases (4 CN:1 RA, n=216). All subjects were followed for survival from 1995 through 2015. Ranks (1-5) of preclinical z-scores within each set of 1 RA and 4 matched CN were analysed for associations with incident RA and mortality. Survival was evaluated using Cox proportional hazards models.

RESULTS

Preclinical serum IgG RF z-score ranks associated with incident RA in 90 males (18 RA, 72 CN). Cigarette smoking, androstenedione, pregnenolone, and sIL-2Rα ranks associated with incident RA in 180 females (36 RA, 144 CN). Total percentile mortality was greater (p=0.003) in RA (70.4) vs. CN (49.9) and equivalently increased in female RA (69.4) vs. CN (49.3) and in male RA (72.2) vs. CN (43.1) subjects. Percentile respiratory-related CODs were greater (p=0.009) only in the female RA cases (16.7) vs. CN (3.5). Ranks of preclinical hsCRP (p=0.028) and sIL-2Rα (p=0.030) independently associated with 140 total deaths, as did sTNF-R1 (p=0.003) and hsCRP (p=0.005) with 50 CVD deaths. Latter biomarker association were significant in females. Therapy responses in 1995 significantly associated with subsequent mortality.

CONCLUSIONS

Sex effects were important in preclinical biomarker associations with incident RA, total and CVD mortality as well as occurrence of respiratory deaths.