Can the weather affect disease activity in rheumatoid arthritis?

This study examined how the weather can affect disease activity in patients with rheumatoid arthritis. The authors concluded that increased exposure to sunshine and lower humidity can decrease disease activity in patients with rheumatoid arthritis.

In rheumatoid arthritis (RA), the immune system attacks the healthy joints, causing inflammation, swelling, and pain. Increased levels of joint pain and stiffness are often reported during cold and wet weather. A number of studies have found an effect of weather on on joint pain and disease activity in RA patients. However, evidence to this effect is still mixed.

133 patients with active RA were included in this study. All patients were undergoing anti-TNF therapy such as etanercept (Enbrel) or adalimumab (Humira), for at least 6 months. Disease activity was measured at the beginning of the study and at four follow up visits over a period of 2 years. Weather conditions were measured at each visit.

Disease activity was measured on a scale. A score greater than 5.1 implies active disease, less than 3.2 implies low disease activity, and less than 2.6 implies remission. The average disease activity score in all patients at the start of the study was 3.54.

Increasing exposure to sunshine by 1 hour per day was associated with a significant decrease of 0.037 in disease activity score. Exposure to 13 hours of sunshine a day was associated with an average decrease of 0.52 in disease activity score.

Low humidity was associated with a significantly lower disease activity score. Every one percent increase in humidity was linked to an increase of 0.007 in disease activity score. 

Higher temperatures were associated with an average reduction in disease activity score of 0.011. However, this was not statistically significant.

The authors concluded that exposure to sunshine and lower levels of humidity are linked to a decrease in disease activity in patients with rheumatoid arthritis.

Weather conditions were only measured on the day of the assessments. The weather on the days before patient assessments may have affected disease activity. Results may also differ for patients who do not have stable, well-controlled disease.

Consult with your physician about possible ways to manage rheumatoid arthritis in cold and wet weather.