Rheumatoid arthritis: fitness is more important than inflammation management

It is well-known that RA patients have a higher mortality risk, but many physicians and patients may be less aware of the benefits of physical fitness in RA.

What was the study investigating?

The researchers used data from the Trøndelag Health Study, a population-based open cohort study in Norway.
223 people with RA were included, with almost 32,000 subjects serving as a control group.
The median observation time for all participants was 11.2 years.
The overall mortality during this period was determined by linkage with the Norwegian cause of death register.
Various mediators were included in the study, with a focus on inflammation and cardiorespiratory fitness.

Why do RA patients have an higher mortality rate?

The aim of treating rheumatoid arthritis is to control inflammation as effectively as possible. In fact, the medications available today are often successful in preventing permanent joint damage. And yet the mortality rate for rheumatoid arthritis patients remains high.

This is partly due to co-morbidities such as cardiovascular diseases, which many RA patients also suffer from. At the same time, environmental factors and lifestyle can influence the course of RA. The question was therefore, to what extent modifiable risk factors such as physical inactivity contribute to increased mortality and, conversely, whether better cardiorespiratory fitness (CRF) can reduce the risk.

For their ambitious study, the researchers used several models in which they included different variables for the association of rheumatoid arthritis with overall mortality:

Model A examined the association between RA and all-cause mortality, adjusting for sex and age.
Model B included further adjustments for diabetes, BMI, smoking, and hypertension, all known mortality risk factors in patients with RA.
Model C added inflammatory events (CRP ≥ 3 mg/L) as a mediator.
Model D included CRF (calculated using formulas based on body mass index, physical activity and resting heart rate, among others) as a second mediator.

What are the effects of inflammation and fitness?

As expected, the overall mortality of people with RA was increased compared to the control group, regardless of other influencing factors. Both elevated CRP and low fitness also contributed to the risk. Their contribution to the overall effect was significant in each case (p<0.001). The astonishing thing is that the indirect effect on mortality mediated by CRF was three times as high as the indirect effect of inflammation (standardised coefficient 0.006 versus 0.002).

For the authors, the results suggest that mortality in patients with RA remains elevated even with optimal control of inflammation if they are physically inactive. They therefore advocate interdisciplinary treatment teams that offer patients suitable training programmes - similar to cardiac rehabilitation. Patients in turn need to be sensitised to the importance of an active lifestyle for their prognosis, as many are not aware of this connection.

Conclusion for medical practice

Regardless of the disease itself, external factors contribute to an increased mortality risk in patients with rheumatoid arthritis. Cardiovascular fitness has a significant influence, topping even the effect of inflammation. This is reason enough to motivate those affected to take more exercise. It also reduces pain and fatigue and has a positive effect on cognition and mood - all without side effects.

Source

Videm V et al. Relative importance of inflammation and cardiorespiratory fitness for all-cause mortality risk in persons with rheumatoid arthritis: the population-based Trøndelag Health Study. RMD Open 2023; 9: e003194. doi:10.1136/rmdopen-2023-003194