Bidirectional association between fibromyalgia and migraine among probands and unaffected non‐twin siblings: A nationwide population‐based study.

Objective: This study explored the bidirectional relationship between fibromyalgia and migraine among probands with either of the two disorders and their unaffected siblings. Background: Evidence suggests a bidirectional association between fibromyalgia and migraine in individuals and in twins. However, whether a bidirectional association between fibromyalgia and migraine also occurs among siblings remains unknown. Methods: Using the Taiwan National Health Insurance Research Database, we examined the data of 2677 probands with fibromyalgia, 2780 unaffected siblings, and 11,120 matched controls to assess the risk of migraine. In contrast, 1830 probands with migraine, 1936 unaffected siblings, and 7744 matched controls to assess the risk of fibromyalgia. Results: Logistic regression analyses demonstrated that patients with fibromyalgia (odds ratio [OR]: 3.69; 95% confidence interval [CI]: 2.87–4.74) and unaffected siblings (OR: 1.51; 95% CI: 1.08–2.10) were more likely to develop migraine than the controls during the follow‐up period. Moreover, patients with migraine and unaffected siblings had a 4.86‐fold (95% CI: 3.86–6.09) and 1.59‐fold (95% CI: 1.18–2.12) increased risk of fibromyalgia than the controls. Conclusion: The bidirectional association between fibromyalgia and migraine among probands and unaffected siblings suggests a familial coaggregation of these two conditions. Additional studies are required to investigate the genetic and environmental etiologies for this coaggregation. [ABSTRACT FROM AUTHOR]