medwireNews: Patients with rheumatoid arthritis (RA) have an increased risk for death that can be attributed in part to low cardiorespiratory fitness (CRF), researchers report.
“Because [estimated] CRF is modifiable, results from this study are particularly interesting as increasing [physical activity] that leads to improved CRF may translate to reduced mortality rates in patients with RA,” say Vibeke Videm (Norwegian University of Science and Technology, Trondheim) and fellow investigators.
Reporting in RMD Open, they add: “[I]ncreasing fitness may be an important tool for reduction of preterm mortality, counteracting the increased age-related decline in [estimated] CRF described in RA.
“In addition to early medical treatment, encouragement and information about suitable [physical activity] and exercise training, in particular at high intensity, should therefore be an obligatory part of RA treatment strategies from the time of diagnosis.”
Using data from the second (1995–1997) and third (2006–2008) waves of the Trøndelag Health Study (HUNT2/3) in Norway, the investigators found that the 348 patients with RA had a significantly higher mortality rate after a median follow-up of 19.3 years than the 60,938 controls, at 36.5% versus 21.2%.
Overall, patients with RA had a 28% excess relative risk for mortality, compared with controls, after adjusting for other risk factors, including hypertension, BMI, smoking, and cholesterol levels.
The researchers note that significantly more patients with RA had an estimated CRF below the median for their age and sex than did controls (74.0 vs 49.0%), which they found was “strongly associated with mortality in both groups.”
In mediation analysis, the indirect and direct contributions of having an estimated CRF below the age- and sex-specific median accounted for a total of 23% of the excess mortality risk. Meanwhile, just 5% of the excess mortality risk was attributed to RA itself.
Low CRF was therefore “an important mediator of the increased mortality found in patients with RA,” emphasize Videm and fellow investigators.
In a sensitivity analysis where the effects of prior cardiovascular disease were accounted for, a similar result was seen, whereby patients with RA had an excess mortality risk of 27% relative to controls, of which 21% was attributed to having an estimated CRF below the sex- and age-specific median.
The study authors therefore say: “In addition to optimal medical treatment, focus on improvement and follow-up of CRF should be an integral part of standard treatment of RA already from the time of diagnosis.”
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