Important Points to Consider During Practical Application and in the Validation Studies of SARC-F Tool to Screen Sarcopenia [Letter]

Dear editor

We have read the study of Zasadzka et al entitled “Polish Translation and Validation of the SARC-F Tool for the Assessment of Sarcopenia” with great interest.¹ In this paper, the authors reported their study on Polish validation of the SARC-F questionnaire and reported it as a reliable tool for the assessment of sarcopenia in older adults.

As authors noted, SARC-F has originally been developed in English. As it stands as one of the best tools to evaluate sarcopenia in every day practice, considering the variety of languages across Europe, the European Union Geriatric Medicine Society (EuGMS) special interest group on sarcopenia coordinated a study to promote the cross-cultural adaptation, validation and consequent use of SARC-F. We published a methodological report paper to explain the details of the final consensus methodology.² In accordance with this aim, we are glad to see that Polish validation of SARC-F tool has been reported by the authors. However, we see that there are some problematic points in the article which should be clarified to help readers.

First, the authors noted that completion of the SARC-F questionnaire constitutes the obligatory first step in the diagnostic process of sarcopenia according to the revised European consensus on the definition and diagnosis of sarcopenia published by the European Working Group on Sarcopenia in Older People2 (EWGSOP2).³ However, it is important to note that clinicians should not consider SARC-F as an “obligatory” step to diagnose sarcopenia. EWGSOP2 recommends use of the SARC-F questionnaire “as a way to elicit self-reports” from patients on signs that are characteristic of sarcopenia. In clinical practice, case finding should start when a patient reports symptoms or signs of sarcopenia. In such cases, further testing for sarcopenia is recommended and there is no need to use any screening questionnaire.⁴ Therefore, in clinical practice one should not feel be obliged to use SARC-F, except with screening purposes in high-risk populations.

Another point is about the cross-cultural adaptation of the first item of the SARC-F questionnaire. The first question aims to evaluate the strength of the responder and has been developed as “How much difficulty do you have in lifting and carrying 10 lb?” originally.⁵ In the methodological report paper, we suggested that in countries/languages which use SI unit (kilogram) for weight instead of the imperial unit (pound), 10 lb would be translated/adapted as 5 kg². From our understanding, it seems that the authors applied the weight as 4.5 kg in their language validation as it is written as 4.5 kg at Table 1. Use of weight as 5 kg would be much better in practice for comprehension by the responder as 5 kg size is widely used in everyday life. On the other hand, assessing the same question for the responder for 4.5 kg would be somewhat confusing and challenging. The validation of questionnaires across countries/languages should not be a word-to-word translation but rather should include cross-cultural adaptation issues.