- The mortality gap between patients with rheumatoid arthritis and the general population is limited to those with rheumatoid factor (RF)-positive rheumatoid arthritis, results of a study published in the June issue of the Journal of Rheumatology indicate.
"We previously demonstrated a widening in the mortality gap between subjects with rheumatoid arthritis (RA) and the general population," Dr. Hilal Maradit Kremers, of the Mayo Clinic, Rochester, Minnesota, and colleagues write. In the present study, the researchers examined the influence of RF positivity on overall mortality trends and cause-specific mortality.
They followed a population-based cohort of 603 RA patients (73% female) longitudinally until death or January 1, 2006. A total of 398 patients died during a mean follow-up of 16 years.
The team reports that 260 of the patients who died were RF positive, for an age-adjusted overall mortality rate of 4.94 per 100 person-years. Overall mortality for these RF+ RA patients was significantly higher than that in the general population (standardized mortality ratio, SMR = 1.81).
The other 138 subjects who died were RF negative, for an age-adjusted overall mortality rate of 3.18 per 100 person-years. The SMR of this group was 0.99.
Cause-specific mortality was higher than expected for circulatory diseases (SMR 1.50) and for respiratory diseases (SMR 3.49) among RF+ RA subjects. No significant differences were found between observed and expected cause-specific mortality among RF- RA subjects.
"Reductions in major cardiovascular risk factors and evidence-based medical therapies for primary and secondary prevention of heart disease were the major contributors of improvements in cardiovascular mortality in the general population," Dr. Kremers pointed out. "Given these trends in the general population, there are at least two potential explanations for lack of improvements in mortality in RF+ RA patients."
First, "RA patients may not have received the same level of primary and secondary prevention interventions as their non-arthritic peers," Dr. Kremers said.
"The second potential explanation is failure of the primary and secondary preventive interventions to provide the same level of beneficial effects in RF+ RA patients as in the general population," Dr. Kremers concluded. "This would also imply that different biological pathways for cardiovascular disease in RF+ patients may require different approaches to prevention and treatment."
J Rheumatol 2008;35:1009-1014.