Introduction: This study aims to describe the translation and adaptation of the European Portuguese Clinical Frailty Scale and assess its convergent validity and test-retest reliability.
Material and Methods: This validation study included a sample of elderly people admitted in two convalescence units from the National Network of Integrated Continuous Care in Northern Portugal and followed in two outpatient clinics of social solidarity institutions. Convergent validity of the scale was evaluated, against Tilburg Frailty Indicator. Test-retest reliability, sensitivity and specificity were assessed.
Results: Overall, 51 patients were included (mean age = 78 years old). The Clinical Frailty Scale identified 43.1% patients with frailty. Kappa values for test-retest reliability (non-frail/frail) was 1.00. The intraclass correlation coefficient for the 9-point total scale was 0.999. A correlation between Clinical Frailty Scale and Tilburg Frailty Indicator was also found (rs = 0.683; p < 0.001). The Cohen’s kappa coefficient was 0.423 in the agreement analysis between these scales. The results for sensitivity and specificity defined that 62.0% of patients were true positives and 81.8% true negatives. The scale accuracy determined by the receiver operating characteristics curve analysis was 0.782.
Discussion: This scale showed an excellent test-retest reliability. Robust results on convergent validity were also achieved, with a moderate correlation and agreement with the Tilburg Frailty Indicator, showing good sensitivity and accuracy, as well as high specificity.
Conclusion: This version has an excellent test-retest reliability and good convergent validity, and is both a reliable and valid test for application in clinical practice for assessing Portuguese elderly population admitted in convalescence units and outpatient clinics.

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