Optimising the use of SARC-F for the identification of muscle weakness by considering alternative cut-points: findings from the Newcastle SarcScreen project.

Purpose: We assessed the impact of applying different SARC-F cut-points for the identification of muscle weakness in an older clinical population.

Methods: We included 159 men and 311 women aged 56-98 years who had completed the SARC-F questionnaire and had their maximum grip strength measured at an Older People's Medicine Day Unit. We applied cut-points of ≥ 4, 3 and 2 to SARC-F and tested agreement with muscle weakness (grip strength < 27kg men, < 16kg women) in analyses stratified by sex and obesity status.

Results: Prevalence of muscle weakness was 86.8% and 82.6% in men and women, respectively. Sensitivity of the SARC-F increased at lower cut-points (e.g. 81% for ≥ 4 vs 97% for ≥ 2 in women). There was typically greater sensitivity among women than men and among those classified as obese vs non-obese.

Conclusions: These findings suggest that different cut-points may be required to optimise the utility of SARC-F for identifying muscle weakness in different patient sub-groups.