Chronic fatigue syndrome and fibromyalgia in Canada: prevalence and associations with six health status indicators Abstract: Introduction: Few studies have considered the factors independently associated with chronic fatigue syndrome (CFS) and/or fibromyalgia (FM) or considered the impact of these conditions on health status using population-based data. Methods: We used data from the nationally representative 2010 Canadian Community Health Survey (n= 59 101) to describe self-reported health professional-diagnosed CFS and/or FM, and their associations with 6 health status indicators. Results: In 2010, diagnosed CFS and FM are reported by 1.4% (95% confidence interval [CI]: 1.3%–1.6%) and 1.5% (1.4%–1.7%), respectively, of the Canadian household population aged 12 years and over, with comorbid CFS and FM affecting 0.3% (0.3%– 0.4%) of that population. Prevalent CFS and/or FM were more common among women, adults aged 40 years and over, those with lowest income, and those with certain risk factors for chronic disease (i.e. obesity, physical inactivity and smoking). After controlling for differences between the groups, people with CFS and/or FM reported poorer health status than those with neither condition on 5 indicators of health status, but not on the measure of fair/poor mental health. Having both CFS and FM and having multiple comorbid conditions was associated with poorer health status. Conclusion: Co-occurrence of CFS and FM and having other chronic conditions were strongly related to poorer health status and accounted for much of the differences in health status. Understanding factors contributing to improved quality of life in people with CFS and/or FM, particularly in those with both conditions and other comorbidities, may be an important area for future research http://www.phac-aspc.gc.ca/publicat/hpcdp-pspmc/35-1/assets/pdf/35-1_E_v3_SD.pdf Also available in french: http://www.phac-aspc.gc.ca/publicat/hpcdp-pspmc/35-1/assets/pdf/35-1_F_v3_SD.pdf This is a peer-reviewed paper.