Mortality trends in rheumatoid arthritis: the role of rheumatoid factor.
OBJECTIVE
We previously demonstrated a widening in the mortality gap between subjects with rheumatoid arthritis (RA) and the general population. We examined the contribution of rheumatoid factor (RF) positivity on overall mortality trends and cause-specific mortality.


METHODS
A population-based RA incidence cohort (1955-1995, and aged >or= 18 yrs) was followed longitudinally until death or January 1, 2006. The underlying cause of death as coded from national mortality statistics and grouped according to ICD-9/10 chapters was used to define cause-specific mortality. Expected cause-specific mortality rates were estimated by applying the age-, sex-, and calendar-year-specific mortality rates from the general population to the RA cohort. Poisson regression was used to model the observed overall and cause-specific mortality rates according to RF status, accounting for age, sex, disease duration, and calendar year.


RESULTS
A cohort of 603 subjects (73% female; mean age 58 yrs) with RA was followed for a mean of 16 years, during which 398 died. Estimated survival at 30 years after RA incidence was 26.0% in RF+ RA subjects compared to 36.0% expected (p < 0.001), while in RF- RA subjects, estimated survival was 29.1% compared to 28.3% expected (p = 0.9). The difference between the observed and the expected mortality in the RF+ RA subjects increased over time, resulting in a widening of the mortality gap, while among RF- RA subjects, observed mortality was very similar to the expected mortality over the entire time period. Among RF+ RA subjects, cause-specific mortality was higher than expected for cardiovascular [relative risk (RR) 1.50; 95% confidence interval (CI) 1.22, 1.83] and respiratory diseases [RR 3.49; 95% CI 2.51, 4.72]. Among RF- RA subjects, no significant differences were found between observed and expected cause-specific mortality.


CONCLUSIONS
The widening in the mortality gap between RA subjects and the general population is confined to RF+ RA subjects and largely driven by cardiovascular and respiratory deaths.
Gonzalez
Angel
A
Department of Internal Medicine, Caritas St. Elizabeth's Medical Center, Boston, Massachusetts, USA.
Icen
Murat
M
Kremers
Hilal Maradit
HM
Crowson
Cynthia S
CS
Davis
John M
JM
Therneau
Terry M
TM
Roger
Veronique L
VL
Gabriel
Sherine E
SE
D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000401:mortality*; D002318:Cardiovascular Diseases / Q000150:complications / Q000401:mortality; D002423:Cause of Death / Q000639:trends; D015331:Cohort Studies; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008171:Lung Diseases / Q000150:complications / Q000401:mortality; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D012217:Rheumatoid Factor / Q000009:adverse effects*; D012720:Severity of Illness Index; D044465:White People
D012217:Rheumatoid Factor