The prevalence and associations of unexplained chronic fatigue in Brazilian primary care

Background: Unexplained chronic fatigue (UCF) and chronic fatigue syndrome (CFS) have been reported to be associated with female gender, older age, lower socioeconomic status and psychiatric disorders by previous studies, mostly conducted in Western developed countries. To date, there have been very few studies of UCF/CFS in Brazil. Aim: We examined the prevalence and associations of UCF in Brazilian primary care. The main question was whether the profile of risk factors for UCF in Brazil is similar to that reported in Western developed countries. Methods: A cross-sectional survey was conducted at two general practices in So Paulo. 304 consecutive attenders, aged 18-45 years, completed questionnaires on fatigue, psychological distress and sociodemographic characteristics. Those with substantial fatigue lasting 6 months or more were interviewed to ascertain the presence of CFS and psychiatric disorders. Patients suffering from substantial fatigue for 6 months or more with no medical explanation and no psychiatric exclusion diagnoses for CFS were classified as cases of UCF. Results: The prevalence of UCF and CFS was respectively 10.9% and 1.3%. Psychological distress was significantly correlated with fatigue. Older age, female gender and higher education level were independent risk factors for UCF. Conclusion: The prevalence of UCF and CFS in Brazilian primary care was comparable to that reported by the previous studies in Western affluent countries. However, while age and gender followed the previously observed pattern of association, an opposite pattern was found regarding education. Possible reasons for this unusual finding were discussed