A review of the incidence and risk factors for fibromyalgia and chronic widespread pain in population-based studies.

This review identified prospective cohort studies in the general population, which showed incidence (23 papers) and risk factors (37 papers) for fibromyalgia and chronic widespread pain. Median incidence of physician diagnosed fibromyalgia in the general population was 4.3 per 1000 person-years (range = 0.33-18.8) but 14.0 (1.2-32.7) if medical illness was present. Median incidence of chronic widespread pain was 12.5 per 1000 person-years (7.2-81.6) but 67 per 1000 person years (14.8-124) for those with pre-existing pain. Risk factors included various childhood difficulties, female sex (except with pre-existing medical disorders), older/middle age, smoking, high body mass index, alcohol abstinence, and pre-existing medical disorders in adulthood. The strongest associations were with sleep disorders, headaches and other pains, depression, and illness behaviour. These data suggest strongly that there are many aetiological routes into fibromyalgia, and future research could be enhanced by studying the underlying mechanisms relating to these risk factors.