Risk of secondary sarcopenia in Europeans with fibromyalgia according to the EWGSOP2 guidelines: systematic review and meta-analysis.

All data were cross-sectional, so the review shows an association, not that fibromyalgia causes sarcopenia. Most included studies did not account for potential confounders such as physical activity, sedentary time, BMI, and depression. Physical activity was measured with a validated instrument in only one study. Muscle quantity came from only five studies, all using bioelectrical impedance analysis, which can overestimate muscle mass in people with higher BMI. No study used the five-chair stand test, so lower-limb strength risk was not assessed. Grip strength was measured in many different ways and units, and four studies could not be converted for the cut-off analysis. Most studies were in Spain (15 studies), and 97% of participants were women, so it may not apply to other regions or men. This was a review of observational studies, not a treatment trial, so it cannot show that exercise reduces sarcopenia risk.

Authors declared no conflicts of interest. The work was funded by Universidad Católica de Murcia, grant number PMAFI-07/19.

Do not read the nine times higher risk as proof that fibromyalgia causes confirmed sarcopenia. The association is cross-sectional, the increased risk was for probable sarcopenia based on low grip strength only, and no higher risk of low muscle quantity was found.