3.4.1 | Threshold effect and Heterogeneity test
Nine of 23 included studies(27–35), consisting of 3020 patients, evaluated the FRAIL scale. The calculation of the Spearman correlation coefficient (ρ = 0.450, P > 0.05) suggested the absence of a threshold effect. The heterogeneity of the included studies was tested using sensitivity and specificity as effect sizes. The results showed that I2 (sensitivity) was 93.98% (P < 0.01), and I2 (specificity) was 96.64% (P < 0.01). Five studies(29, 31, 34, 36–38), consisting of 686 patients, evaluated the PRISMA-7 scale. The calculation of the Spearman correlation coefficient (ρ = 0.667, P > 0.05) suggested the absence of a threshold effect. The heterogeneity of the included studies was tested using sensitivity and specificity as effect sizes. The results showed that I2 (sensitivity) was 0% (P = 0.69), and I2 (specificity) was 82.77% (P < 0.01). Five studies(29, 31, 36, 39, 40), consisting of 650, patients evaluated the GFI scale. The calculation of the Spearman correlation coefficient (ρ = 0.200, P > 0.05) suggested the absence of a threshold effect. The heterogeneity of the included studies was tested using sensitivity and specificity as effect sizes. The results showed that I2 (sensitivity) was 67.40% (P = 0.06), and I2 (specificity) was 73.62% (P = 0.16).
3.4.2 | Pooled effect size and SROC
A random-effects model was used to combine the effect sizes, since the significant heterogeneity among the studies. For the FRAIL scale, the combined sensitivity was 0.75, with a 95% confidence interval of 0.56–0.88, and the combined specificity was 0.85, with a 95% confidence interval of 0.77–0.91. For the PRISMA-7 scale, the combined sensitivity was 0.81, with a 95% confidence interval of 0.71–0.88, and the combined specificity was 0.78, with a 95% confidence interval of 0.69–0.85. For the GFI scale, the combined sensitivity was 0.72, with a 95% confidence interval of 0.62–0.80, and the combined specificity was 0.74, with a 95% confidence interval of 0.67–0.81. All forest plots are showed in Fig. 4.
The combined diagnostic odds ratio, positive likelihood ratio, negative likelihood ratio, and diagnostic score for FRAIL scale were 17.18(95%CI,7.30-40.42), 5.08(95%CI,3.30–7.81), 0.30(95%CI,0.16–0.55), 2.84(95%CI,1.00-3.70), respectively. The pooled diagnostic odds ratio, positive likelihood ratio, negative likelihood ratio, and diagnostic score for PRISMA-7 scale were 14.70(95%CI,8.24–26.24),3.66(95%CI,2.63–5.09), 0.25(95%CI,0.16–0.38), 2.69(95%CI,2.11–3.27), respectively. The combined diagnostic odds ratio, positive likelihood ratio, negative likelihood ratio, and diagnostic score for GFI scale were 7.37(95%CI,5.08–10.70), 2.80(95%CI,2.23–3.51), 0.38(95%CI,0.29-0.0.50), 2.00(95%CI,1.63–2.37), respectively. All forest plots are showed in Fig. 5 and Fig.S1-2.
Figures S3 present the summary receiver operating characteristic (SROC) curves for the diagnosis of frailty using the FRAIL scale, with a combined area under the curve (AUC) of 0.88 and a 95% confidence interval (CI) of 0.85–0.91. Figures S5(b) show the SROC curves for the diagnosis of frailty using the PRISMA-7 scale, with a combined AUC of 0.86 and a 95% CI of 0.82–0.88. Figure S5(c) displays the SROC curve for the diagnosis of frailty using the GFI scale, with a combined AUC of 0.79 and a 95% CI of 0.76–0.83. The pooled sensitivity, specificity, AUC and DOR were showed in Table 2.
Table 2
Pooled sensitivity, specificity, and AUC for FRAIL, PRISMA-7 and GFI
Tools | No. of studies | Sensitivity(95%CI) | Specificity (95%CI) | Area under SROCa curve | DORb (95%CI) |
FRAIL scale | 9 | 0.75 (0.56–0.88) | 0.85 (0.77–0.91) | 0.88 (0.85–0.91) | 17.18 (7.30-40.42) |
PRISMA-7 scale | 5 | 0.81 (0.71–0.88) | 0.78 (0.69–0.85) | 0.86 (0.82–0.88) | 14.70 (8.24–26.24) |
GFI scale | 5 | 0.72 (0.62–0.80) | 0.74 (0.67–0.81) | 0.79 (0.76–0.83) | 7.37 (5.08–10.70) |
a. SROC = Summary receiver operating characteristic; b. DOR = diagnostic odds ratio. |