Abstract
The LACE index has been shown to predict hospital readmissions and death with variable accuracy. A LACE index ≥ 10 is considered as high risk in the existing literature. We aimed to derive age-specific LACE index thresholds in the prediction of mortality and frequent readmissions. Analysis of prospectively collected data of consecutive alive-discharge episodes between 01/04/2017 and 31/03/2019 to a single hospital was conducted. The derivation of LACE index thresholds for predicting all-cause mortality within 6 months of hospital discharge or frequent readmissions (≥ 2 times within 28 days) was examined by receiver operating characteristics (ROC) in 32270 patients (14878 men, 17392 women) aged 18-107 year (mean = 64.0 years, SD = 20.5). For all patients with a LACE index ≥ 10, the area under the curve (AUC) for predicting mortality was 80.5% (95% CI 79.7-81.3) and for frequent readmissions was 84.0% (83.0-85.1). Two-graph ROC plots showed that the LACE index threshold where sensitivity equates specificity was 9.5 (95% intermediate range = 5.6-13.5) for predicting mortality and 10.3 (95% intermediate range = 6.6-13.6) for frequent readmissions. These thresholds were lowest among youngest individuals and rose progressively with age for mortality prediction: 18-49 years = 5.0, 50-59 years = 6.5, 60-69 years = 8.0, 70-79 years = 9.8 and ≥ 80 years = 11.6, and similarly for frequent readmissions: 18-49 years = 5.1, 50-59 years = 7.5, 60-69 years = 9.1, 70-79 years = 10.6 and ≥ 80 years = 12.0. Positive and negative likelihood ratios (LRs) ranged 1.5-3.3 and 0.4-0.6 for predicting mortality, and 2.5-4.4 and 0.3-0.6 for frequent readmissions, respectively, with stronger evidence in younger than in older individuals (LRs further from unity). In conclusion, the LACE index predicts mortality and frequent readmissions at lower thresholds and stronger in younger than in older individuals. Age should be taken into account when using the LACE index for identifying patients at high risk.