The German simpler modified fried frailty scale: translation, cross-cultural adaptation and clinical validation

The Simpler Modified Fried Frailty Scale (SFS) was developed for the rapid evaluation of physical frailty in older adults. The aim of this study was to translate, culturally adapt and validate the German version of the SFS using the Fried Frailty Phenotype (FFP) as a reference. The methodological implementation was carried out in two phases: First, the German version was translated from the original English version according to established standards, culturally adapted and tested for comprehensibility in a small sample. Interrater reliability and test-retest reliability were assessed in 20 older patients. This was followed by clinical validation in a sample of 100 geriatric participants (mean age 82 ± 6.5 years; 66% women). The German SFS proved to be understandable and reliable. Internal consistency was moderate with a Cronbach’s alpha of 0.692. Agreement with the FFP was substantial (Cohen’s kappa = 0.80; p < 0.001). All five individual items showed significant positive correlations with the total score and with the corresponding FFP domains. In regression analyses, the total SFS score was significantly associated with frailty status (OR = 2.954; 95% CI: 1.877–4.649; p < 0.001), with unintentional weight loss, fatigue and physical inactivity showing particularly high discriminatory power. A cut-off value of ≥ 3 points showed a sensitivity of 91.67%, a specificity of 88.46%, a positive predictive value of 88.00% and a negative predictive value of 92.00%. The likelihood ratios (LR) were LR⁺ = 7.97 and LR⁻ = 0.09. The ROC analysis yielded an area under the curve (AUC) of 0.817 (95% CI: 0.734–0.899), confirming the good diagnostic accuracy of the scale. Overall, the German SFS proved to be a practical, reliable and valid instrument for identifying frailty in older people and is suitable for use in research and everyday clinical practice.