Daily Symptom Fluctuations and Functional Impact in Fibromyalgia

Fibromyalgia symptoms do not always remain at the same level. Pain and fatigue may increase or decrease between days and may also change between morning and evening. Clinical assessments usually focus on the average severity of these symptoms. However, patients with similar average pain or fatigue levels may have different levels of difficulty in daily life. This study will therefore examine whether symptom fluctuation provides additional information about functional impact beyond average symptom severity.

Adults diagnosed with fibromyalgia according to the 2016 American College of Rheumatology criteria will be included. At the initial visit, demographic and clinical information will be recorded. Functional impact will be assessed using the Fibromyalgia Impact Questionnaire. Anxiety and depression symptoms will be assessed using the Hospital Anxiety and Depression Scale, and symptoms related to central sensitization will be assessed using the Central Sensitization Inventory.

After the initial visit, participants will record pain and fatigue levels every morning and evening for seven days using 0-10 numerical rating scales. They will also record their sleep quality each morning and their perceived control over symptoms once daily. These records will be used to calculate average pain and fatigue levels, daily fluctuations in these symptoms, maximum symptom levels, and the degree to which pain and fatigue change together within each participant.

The main analysis will examine the relationship between pain and fatigue fluctuations and functional impact. It will also evaluate whether symptom fluctuation is related to functional impact after considering average pain and fatigue levels, age, sex, and disease duration. Additional analyses will examine the relationships of pain-fatigue synchrony, sleep quality, maximum symptom levels, and perceived symptom control with functional impact. The study is observational and is not designed to determine cause-and-effect relationships.

Inclusion criteria

• Diagnosis of fibromyalgia according to the 2016 American College of Rheumatology criteria
• Age between 18 and 65 years
• Ability to understand and complete the daily symptom records
• Ability and willingness to provide written informed consent

Exclusion criteria

• Active inflammatory rheumatic disease
• Major neurological disease
• Major change in fibromyalgia treatment within the previous three months
• Pregnancy, postpartum period, or breastfeeding
• Cognitive impairment or inability to provide informed consent
• Completion of less than 70% of the required daily symptom records
• Major change in fibromyalgia treatment during the seven-day monitoring period