Comparison of mortality trends among rheumatoid arthritis subjects

Oct 29 2007

An autoimmune inflammatory disease that takes a progressive toll on the heart, kidney and liver as well as the joints, rheumatoid arthritis (RA) is associated with a high risk of early death.

This sobering fact is well known. Less is known about whether longevity has improved for RA patients over the past few decades of remarkable improvements in longevity in the general population. Are earlier diagnosis, breakthrough drugs, and more aggressive antirheumatic treatment regimens paying off in terms of survival"

For answers to this vital question, researchers at the Mayo Clinic conducted a sweeping comparison of mortality trends among RA subjects with those in the general population. Their unsettling results, presented in the November 2007 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis), underscore the urgent need to find strategies that will work to reduce the excess mortality consistently associated with RA.

Drawn from the comprehensive medical records of all residents of Olmsted County, Minnesota, 822 RA subjects were identified. The subjects included all residents of Rochester, Minnesota, first diagnosed with RA between January 1, 1955, and January 1, 1995, as well as all Olmsted County residents diagnosed with RA between January 1, 1995, and January 1, 2000. The subjects were 71.5 percent women, with a mean age of 57.6 years at RA incidence. All were followed up through their entire medical records until death or January 1, 2007. The median time of follow-up was 11.7 years, during which 445 of the RA subjects died.

Researchers compared the survival rates of patients diagnosed with RA in 5 time periods: 1955-1964, 1965-1974, 1975-1984, 1985-1994, and 1995-2000 using Cox regression models, adjusting for age and sex. In the 5 time periods, there was no significant difference in survival rates for RA subjects—which also means no significant gains in longevity.

To confirm their findings, researchers calculated and compared mortality rates using person-year methods. Based on the National Center for Health Statistics life tables for the Minnesota white population, researchers also determined the number of expected deaths for people of similar age and sex in the general population. Between 1965 and 2005, the mortality rates for female and male RA subjects were relatively constant at 2.4 and 2.5 per 100 person-years, respectively. In contrast, the expected mortality rate decreased substantially for both female and male subjects from the general population over the same time period. Mortality in women in the Minnesota general population declined from 1.0 per 100 person-years in 1965 to 0.2 per 100 person-years in 2000. Similarly, mortality in men decreased from 1.2 per 100 person-years in 1965 to 0.3 per 100 person-years in 2000.

“We found no evidence indicating that RA subjects experienced improvements in survival over the last 4-5 decades” states the study's leading author, Dr. Sherine Gabriel. “In fact, RA subjects 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 subjects and the general population throughout time.”

While the study's findings focused almost exclusively on white individuals in one geographic area, they raise general concerns about current intervention strategies for RA. “Although the reasons for the widening mortality gap are unclear,” Dr. Gabriel notes, “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.” She stresses the urgent need for research aimed at fully understanding this alarming trend and finding solutions that will close the mortality gap for more people with RA.

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