High temperature also linked to exacerbations of Raynaud's phenomenon among systemic sclerosis patients: Study

Raynaud's phenomenon is an early and common symptom of systemic sclerosis, a chronic autoimmune disease of the skin and other organs. The symptom typically consists of episodes of reduced blood supply to extremities, such as fingers and toes, often in response to cold or stress. While cold is known to be a trigger for Raynaud's phenomenon, this large-scale study examined the full spectrum of ambient temperatures-warm temperatures included-on the severity of symptoms. Indeed, previous series had little to offer in terms of seasonal or temperature-related trends for Raynaud's phenomenon. In this study, using the cohort data of Scleroderma Patient-centered Intervention Network, a longer follow-up has been developed regarding how real-world fluctuations in temperature affect the severity of Raynaud's.

Participants included 2243 people with Raynaud's phenomenon secondary to systemic sclerosis who were enrolled between April 15, 2014, and August 1, 2023, from the SPIN cohort. For the same period, there were 20,233 Raynaud's phenomenon severity measurements gathered longitudinally through the self-report by participants using a 0-10 numerical rating scale of Raynaud's every three months. Weather data, including daily mean temperature and feels-like temperature (based on wind chill and humidity), came from routine weather stations near the participants' recruiting centers. The data were from the Iowa Environmental Mesonet and covered the week before each assessment. The authors flexibly modeled the nonlinear association of Raynaud's severity with the temperature using linear mixed models fitted with basis splines.

Key Results

• The study showed a linear decrease in the severity of Raynaud's phenomenon with a rising temperature until a threshold beyond which little additional change in severity occurs.

• The peak severity score of 6.8 points, 95% CI 5.6–8.1, occurred at –25°C.

• Over the range from –15°C to 5°C, there was only a 0.05 to 0.21 point decrease in severity score per 5°C rise in temperature.

• However, in the range between 5°C and 25°C, the scores declined 0.37 to 0.54 points for each 5°C rise in temperature.

• At 25°C, the predicted Raynaud's severity score was at its lowest, 2.6 points (95% CI 2.5–2.7), which is indicative of a significant decrease in symptoms for cases of mild temperatures.

• Above this temperature, the severity scores started to increase once again.

• By 35°C, scores had increased to 3.5 points, 95% CI 3.0–4.1, while at 40°C they have increased to 5.6 points, 95% CI 4.5–6.8.

• The feels-like temperatures gave similar results, underlining that the symptoms of Raynaud's are affected both for cold and for warm.

In conclusion, this large-scale study provides evidence that the severity of Raynaud's phenomenon is worst in both extremely cold and warm temperatures. The highest severity scores occurred at –25°C, whereas symptom severity also increased at temperatures above 25°C. The present study emphasizes the consideration of patterns of ambient temperature in the management of Raynaud's phenomenon and while designing clinical trials for interventions. Symptoms might be exacerbated by both cold and warm environments, and thus temperature regulation would have been an important aspect of patient care.

Reference:

Virgili-Gervais, G., Matthews, B., Nassar, E.-L., Carrier, M.-E., Kwakkenbos, L., Pauling, J. D., Bartlett, S. J., Gietzen, A., Gottesman, K., Guillot, G., Hudson, M., Hummers, L. K., Lawrie-Jones, A., Malcarne, V. L., Mayes, M. D., Richard, M., Sauvé, M., Wojeck, R. K., Mouthon, L., … Provencher, S. (2024). The association of outdoor temperature and self-reported Raynaud’s phenomenon severity among people with systemic sclerosis: a Scleroderma Patient-centered Intervention Network Cohort study. The Lancet. Rheumatology. https://doi.org/10.1016/s2665-9913(24)00189-9