Reply to Estimated Glomerular Filtration Rate and Muscle Mass in Older Patients: Diagnostic Accuracy of Creatinine-Based Equations and Implications in Practice

We thank doctors Dharmarayan and Yoo for their comments on our article.1 In line with the literature and our results, they found a substantial lack of consistency among the results of different formulas estimating renal function by investigating a sample including a large proportion of frail older people.2 We believe that this could partly depend on the age-composition of different samples generating such equations, which in turn may reflect differently the age-related decay of skeletal muscle mass.