Arthritis Patients Don't Share in Life Expectancy Gains

ROCHESTER, Minn., Oct. 29 -- Life expectancy for patients with rheumatoid arthritis has not improved over the past four decades, despite the overall gains in the general population, researchers here have found.
A study comparing mortality rates in all residents of Rochester, Minn., diagnosed with RA from 1955 through 1995, and expanded to include all residents of Olmsted County diagnosed from 1995 through 2000, with national trends showed that the mortality gap between those with RA and those without has widened, said Sherine E. Gabriel, M.D., M.Sc., of the Mayo Clinic, and colleagues.
"We found no evidence indicating that RA patients experienced improvements in survival over the last four to five decades," the authors wrote in the November issue of Arthritis & Rheumatism.
"In fact, RA patients did not even experience the same improvements in survival as their peers without arthritis, resulting in a worsening of the relative mortality in more recent years, and a widening of the mortality gap between RA patients and the general population throughout time," they continued.
Although some recent studies of survival in RA patients have demonstrated improved longevity and have suggested that the improvement may be the result of earlier diagnosis and more aggressive therapies, at least some of the studies may be subject to survival bias, the authors noted. Because they examine survival not in newly diagnosed patients (incidence cohorts), but in prevalence cohorts, such studies exclude patients who die or leave the population shortly after the index diagnosis, the authors noted.
"This potential bias is particularly important in studies of RA, given the increased risk of cardiovascular events and mortality early in the course of RA," they wrote.
The authors examined inpatient and outpatient medical records for all incident cases of RA among residents of the city of Rochester, home of the Mayo Clinic, from 1955 through 1995, and for residents of Olmsted County from 1995 through the start of 2000.
They identified a total of 822 cases (71.5% female), with a mean age of 57.6 years at RA diagnosis. All patients were followed prospectively through their entire medical records until death or until Jan. 1, 2007.
The median follow-up was 11.7 years, during which 445 of the RA patients died. In Cox regression models adjusted for age and gender, the authors compared the survival rates of patients diagnosed from 1955-1964, 1965-1974, 1975-1984, 1985-1994, and 1995-2000.
They found that across all of the five time periods, there were no significant differences in survival rates for patients with RA. For women, the death rate was relatively consistent at 2.4 per 100 person-years across all time points; for men, the rate was 2.5 per 100 person-years.
In contrast, the mortality rate for white women in the general population in Minnesota declined from 1 per 100 person-years in 1965 to 0.2 per 100 in 2000. Among white men in the general population, the mortality went from 1.2 per 100 person-years in 1965 to 0.3 per 100 in 2000.
The difference between the observed mortality of the patients with RA and the mortality that would be expected based on population norms in more recent years suggest a widening of the mortality gap, rather than stasis, the authors wrote.
"Although the reasons for the widening mortality gap are unclear," Dr. Gabriel said, "cardiovascular deaths constitute at least half of the deaths in subjects with RA, and it is possible that the cardiovascular interventions that improved life expectancy in the general population may not have had the same beneficial effects in persons with RA."
Potential limitations, the authors noted, included the possibility of missing patients who did not seek medical attention for RA, and the use of a predominantly white cohort that may limit generalizability of the findings.
The study was funded in part by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Author conflicts of interest were not listed in the study. Primary source: Arthritis & RheumatismSource reference: Gonzalez A, et al "The Widening Mortality Gap Between Rheumatoid Arthritis Patients and the General Population" Arthritis & Rheumatism. 56; 11: 3583-3587.