Validation of a frailty phenotype screening questionnaire for rural Chinese older adults: a cross-sectional study.

BACKGROUND: Frailty represents a significant public health issue among older adults in rural China. While the Fried Frailty Phenotype (FFP) is one of the most widely used and well-validated tools for assessing physical frailty, its reliance on physical performance measures and specialized devices limits its feasibility for large-scale screening in such settings. Therefore, a simple and feasible screening instrument based on the FFP framework is needed. AIM: To validate the Chinese Frailty Phenotype Questionnaire (CFPQ) for rural Chinese older adults. METHODS: This cross-sectional study enrolled 1590 rural-dwelling adults (≥ 65 years) in northern China. The 5-item dichotomous questionnaire operationalized the criteria of the Fried Frailty Phenotype (FFP) endorsed by the Chinese Medical Association (CMA) and included five items: Fatigue, Resistance, Ambulation, Inactivity and Loss of weight. The psychometric evaluation assessed reliability (including internal consistency and test-retest stability), construct validity (including convergent and discriminant validity) and criterion validity. Criterion validity was evaluated through diagnostic accuracy (ROC analysis) and agreement with the criterion standard (kappa statistic). RESULTS: The CFPQ showed a test-retest intraclass correlation coefficient of 0.89. The internal consistency, measured using Kuder-Richardson formula 20, was 0.49. Construct validity was assessed by calculating correlation coefficients between CFPQ items and cross-sectional outcomes, which ranged from - 0.33 to 0.23. Convergent validity was supported by theoretically consistent correlations: Ambulation was negatively associated with gait speed (r = -0.33, p < 0.001); Resistance with the 30-second chair stand test (r = -0.23, p < 0.001); Fatigue with the EQ-5D Visual Analogue Scale (r = -0.20, p < 0.001), and Loss of weight with body mass index (r = -0.11, p < 0.001). Discriminant validity was evidenced by statistically distinct patterns of correlations across domains. Against the Fried Frailty Phenotype (FFP-CMA) criterion, the CFPQ achieved an area under the curve of 0.93 (95% CI: 0.92-0.95). A score of ≥ 3 was identified as the optimal cut-off, with a specificity of 97.3%, a negative predictive value of 98.9%, and a positive predictive value of 34.4%. The kappa statistic indicating agreement between the CFPQ and FFP-CMA was 0.41. CONCLUSION: The CFPQ demonstrates acceptable validity and reliability as a practical tool for frailty phenotype screening among rural-dwelling older adults in China. CLINICAL TRIAL NUMBER: Not applicable.