Seasonal effects in rheumatoid arthritis: when is disease activity lowest?

This study investigated disease activity in patients with rheumatoid arthritis (RA) by season. They found that disease activity was lowest in fall and highest in spring.

Rheumatoid arthritis (RA) is a condition affecting the joints of the body. In RA, there is an excess of inflammation. This leads to painful swelling in the joints. This can lead to disability and reduced quality of life. RA is a long-term condition and disease activity may vary. Some studies suggest that weather may affect disease activity (DA). Factors that may affect DA include temperature, humidity, sunshine, and atmospheric pressure. 

It is difficult to test if these factors affect DA. One way of understanding if these factors may affect DA is to look at the seasonal difference. It has been suggested that DA is higher in winter. In winter, temperatures are usually lower and there is reduced sunlight. No studies have investigated if there is a difference in the joints affected each season. 

This study included 12,839 patients with RA. The medical records of these patients were analyzed. Patients were grouped depending on when DA was measured. This included spring, summer, fall and winter. DA scores were compared between the groups. 

Average DA scores were highest in spring and lowest in fall. DA was significantly higher in spring compared to winter.  In the fall, patients were more likely to be in remission from RA (no symptoms). Patients were more likely to have high DA in spring. Moderate DA was common in winter. DA in the upper and lower limbs was highest in spring and lowest in fall. DA in large joints (such as the hip) was similar throughout all seasons. 

The authors concluded that disease activity was lowest in fall and highest in spring.

This study only analyzed data from one doctor’s appointment. The long-term pattern of DA has not been assessed. There are a number of factors unaccounted for and more investigation is needed. 

If you have any concerns regarding RA, please consult with your doctor.