Fibromyalgia Pain: Why the Seasonal Fluctuations?
meaning that many variables affect the disease, both internal and external. Some of the external factors are geography and temporal factors (such as Circadian rhythms and seasonality). Past studies have shown that overall health in patients with fibromyalgia is worse in the late fall to early spring, and better from late spring through the summer. However, a study in 2023 in Spain showed no variation in the severity of symptoms by season.
Study design and patients evaluated
To look at this further, a team of rheumatologists and other specialists from Italy investigated whether the severity of fibromyalgia symptoms varied by season. Their retrospective, cross-sectional analysis was published in Clinical Rheumatology.
The patients studied (n = 2614; 93.7% female and 6.3% male) were from the Italian Fibromyalgia Registry (from 2018 to 2021) and had been diagnosed with fibromyalgia according to the American College of Rheumatology criteria. Fibromyalgia severity was measured with the PolySymptomatic Distress Scale (PSD), the revised Fibromyalgia Impact Questionnaire (FIQR), and the modified Fibromyalgia Assessment Status (FASmod).
A patient-reported measure, the PSD is the sum of the Widespread Pain Index (WPI) (presence or absence of pain in specific parts of the body). The Symptom Severity Scale measures the severity of non-pain symptoms, ie, fatigue, memory issues, and unrefreshing sleep, in addition to whether there is abdominal pain, depression, or headache.
The patients were evaluated during different seasons initially (21.0% in autumn, 43.6% in winter, 22.4% in spring, and 12.9% in summer). There were statistically significant differences for the total cohort in both the WPI (P =.042) and the FASmod (P =.037). These were even more significant for the female subgroup (P =.016 and P =.018 for the WPI and FASmod, respectively).
Several caveats
There were several limitations to the study noted by the authors. First, sample sizes in the different seasons varied widely. Next, because most of the patients were female, the statistical power may have been affected. In addition, there may have been other factors besides seasonality, such as availability of appointments, waiting lists, and holidays, which may have led to selection bias.
Widespread pain fluctuated significantly from season to season among female patients with fibromyalgia and was more severe in autumn than in summer. Although non-pain symptoms have a large adverse effect on quality of life, they were not affected by seasonality.
The authors hypothesized that the observed differences between female and male patients might be “explained by the complex interplay of genetic, hormonal, and sociocultural mechanisms that differentiate males and females and render females more pain-sensitive.”
Past studies have also found seasonal variations in inflammatory markers (C-reactive protein and erythrocyte sedimentation rate), underscoring that inflammation may vary by the season.One of the clinical implications of the investigators’ findings is the importance of educating female patients about seasonal variation in fibromyalgia pain and letting them know that their widespread pain may worsen in the autumn. There is also a need, they said, to adjust fibromyalgia therapy seasonally to help prevent exacerbation in autumn.
