Mortality Risk for RA Smokers 50% Higher than Never Smokers

British researchers writing in the Oct. 6 issue of Arthritis Care & Researchconfirmed what many other studies have shown:  That active smoking is directly associated with an increased risk of all-cause mortality for rheumatoid arthritis patients. This study finds the risk is more than double as compared to patients who never smoked.

For patients with rheumatoid arthritis, the most common causes of premature mortality include cardiovascular disease, malignancy, infection and respiratory diseases. The patients face an approximately 1.5-fold increased risk of mortality as compared to the general population, which can possibly be attributed to a higher prevalence of smoking. Some studies have reported an increased risk of mortality of 47 percent per additional pack of cigarettes per day.

The new research is based on a review of electronic medical records of 5,677 patients (median age 61.4 years, 68% women). Forty percent of the patients were never smokers, 34 percent were former smokers and 26 percent were currently smokers at baseline.

As compared to patients who never smoked, current smokers were “at significantly increased risk of death from all-causes,” (hazard ratio 1.98, 95% CI), but in particular, mortality from circulatory disease and lung cancer. Mortality and all-cause mortality were 16.2% for never smokers, 22.4% for past smokers and 31.6% for current smokers. For each year in which they stopped smoking, their risk of all-cause mortality dropped. Risk of death fell sharply for each year former smokers were smoke free. Circulatory disease was the main cause of death in the cohort.

The authors point out that prior studies were inconsistent when associating smoking with mortality in those with rheumatoid arthritis and especially when linking smoking to specific causes.

Recognized limitations of the study include:  Limited follow-up time and study window, reliance on an algorithm to find patients with rheumatoid arthritis, possible misclassification of smoking exposure and underreporting by patients. Most of these factors would lead to underestimates of variable associations not overestimates. The researchers wrote that this is the first study to use a competing risk model to examine the relationship between smoking and cause-specific mortality in rheumatoid arthritis. And, by allowing smoking status to vary throughout follow-up, researchers were able to get a more accurate measurement.

The authors suggest that knowing the strong association between all-cause mortality in patients with rheumatoid arthritis and smoking, as well as the reduction in mortality seen in those who quit, may be useful in the development of smoking cessation programs.  

References:

Rebecca Joseph, Mohammad Movahedi, et a. “Smoking-Related Mortality in Patients With Early Rheumatoid Arthritis: A Retrospective Cohort Study Using the Clinical Practice Research Datalink,” Arthritis Care & Research, Oct. 6, 2016. DOI 10.1002/acr.22882