Heterogeneity in functional status among moderately frail older adults: improving predictive performance using a modified approach of subgrouping the Clinical Frailty Scale

Purpose Moderately frail individuals [Clinical Frailty Scale (CFS) 6] demonstrate heterogeneity in basic activities of daily living (bADL). We aimed to establish whether functional dependency in moderate frailty predicts poorer outcomes and examined the utility of subgrouping the CFS in predicting mortality and institutionalisation. Methods We prospectively studied 201 hospitalised frail patients (89.5 +/- 4.7 years, female 70.1%). We examined Katz Index (KI) against adverse outcomes in CFS6 (n = 106). We then compared predictive performances of a modified CFS version 1 (mCFS-1; category 6A: CFS6 and KI >= 2; 6B: CFS6 and KI <= 1) and modified CFS version 2 (mCFS-2; category 6A: CFS6 and KI >= 2; 6B1: CFS6, KI <= 1 and feeding independent; 6B2: CFS6, KI <= 1 and feeding dependent) against the CFS. Multivariate analysis was used to compare each tool against mortality and institutionalisation. Receiver operator characteristic analysis was performed to determine area under curve and optimal cut-points for each tool. Results KI <= 1 in CFS6 was associated with higher 12-month mortality (39.3% vs. 15.6%, p = 0.01); amongst KI items, feeding dependent predicted 12-month mortality (p < 0.05). Using mCFS-1, category 6A did not increase 12-month mortality compared with category 5 (OR 1.83, 95% CI 0.52-6.47), unlike category 6B (OR 6.33, 95% CI 2.07-19.33). mCFS-2 produced higher mortality in category 6B1 (OR 5.19, 95% CI 1.30-20.69) and 6B2 (OR 6.92, 95% CI 2.14-22.35). Similar observations were seen for institutionalisation. Optimal cut-point for 12-month mortality was category 6 for CFS, and 6B and 6B1 for mCFS-1 and mCFS-2, respectively. Conclusion This study corroborates the heterogeneity of functional status in moderately frail individuals and validates the use of a modified approach to subgrouping the CFS6 via bADL functional status for improved predictive performance. Key summary pointsAims To establish if dependency in basic activities of daily living (bADL) amongst moderately frail older adults predict poorer health outcomes including mortality and institutionalisation. We also examined the utility of subgrouping category 6 of the Clinical Frailty Scale (CFS) by level of functional dependency to improve predictive performance. Findings We observed a wider range in functional dependency among CFS 6 patients when compared to other frail categories. Incorporating CFS 6 subcategories based on bADL functional status increased predictive performance for longitudinal adverse outcomes compared with the original CFS scoring. Message This study corroborates the heterogeneity of bADL functional status in CFS 6 individuals and validates the use of a modified approach to subgrouping the CFS via bADL dependency for improved predictive performance.

Automated summary

This study investigates the heterogeneity of functional dependency in moderately frail individuals and the utility of subgrouping the Clinical Frailty Scale (CFS) 6 based on basic activities of daily living (bADL). The findings suggest that categorizing CFS 6 based on bADL status can improve predictive performance for mortality and institutionalization outcomes.