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Validation of a novel claims-based stroke severity index in patients with intracerebral hemorrhage
Ling-Chien Hung1, Sheng-Feng Sung1, Cheng-Yang Hsieh2
1Division of Neurology, Department of Internal Medicine, Ditmanson Medical Foundation Chiayi Christian Hospital, Chiayi City, Taiwan.
Insights
A new Stroke Severity Index (SSI) derived from administrative claims data effectively estimates stroke severity in intracerebral hemorrhage (ICH) patients. This validated index aids in outcome prediction using readily available claims information.
Area of Science:
- Neurology
- Health Informatics
- Epidemiology
Background:
- Stroke severity is crucial for predicting outcomes in intracerebral hemorrhage (ICH).
- Administrative claims data often lack detailed stroke severity information.
- A validated claims-based Stroke Severity Index (SSI) is needed for ICH research.
Purpose of the Study:
- To validate a claims-based Stroke Severity Index (SSI) for patients with intracerebral hemorrhage (ICH).
- To assess the concurrent and predictive validity of the SSI against established stroke scales.
- To determine the utility of the SSI in predicting mortality using administrative claims data.
Main Methods:
- Linked hospital-based stroke registries with a nationwide claims database for consecutive ICH patients.
- Assessed stroke severity using the National Institutes of Health Stroke Scale (NIHSS) and functional outcomes with the modified Rankin Scale (mRS) from registries.
- Calculated SSI from billing codes and evaluated its correlation with NIHSS and mRS for criterion-related validity.
Main Results:
- The SSI demonstrated significant concurrent validity, correlating strongly with the admission NIHSS (r=0.731).
- The SSI showed significant predictive validity, correlating with 3-month (r=0.696), 6-month (r=0.685), and 1-year (r=0.664) mRS scores.
- Mortality prediction models incorporating NIHSS performed best, followed by models with SSI, outperforming models without stroke severity data.
Conclusions:
- The Stroke Severity Index (SSI) serves as a valid proxy for the NIHSS in ICH studies.
- The SSI effectively adjusts for stroke severity when using administrative claims data for outcome research.
- This claims-based index enhances the utility of administrative data in ICH research.
Background:
Stroke severity is an important outcome predictor for intracerebral hemorrhage (ICH) but is typically unavailable in administrative claims data. We validated a claims-based stroke severity index (SSI) in patients with ICH in Taiwan.
Methods:
Consecutive ICH patients from hospital-based stroke registries were linked with a nationwide claims database. Stroke severity, assessed using the National Institutes of Health Stroke Scale (NIHSS), and functional outcomes, assessed using the modified Rankin Scale (mRS), were obtained from the registries. The SSI was calculated based on billing codes in each patient's claims. We assessed two types of criterion-related validity (concurrent validity and predictive validity) by correlating the SSI with the NIHSS and the mRS. Logistic regression models with or without stroke severity as a continuous covariate were fitted to predict mortality at 3, 6, and 12 months.
Results:
The concurrent validity of the SSI was established by its significant correlation with the admission NIHSS (r = 0.731; 95% confidence interval [CI], 0.705-0.755), and the predictive validity was verified by its significant correlations with the 3-month (r = 0.696; 95% CI, 0.665-0.724), 6-month (r = 0.685; 95% CI, 0.653-0.715) and 1-year (r = 0.664; 95% CI, 0.622-0.702) mRS. Mortality models with NIHSS had the highest area under the receiver operating characteristic curve, followed by models with SSI and models without any marker of stroke severity.
Conclusions:
The SSI appears to be a valid proxy for the NIHSS and an effective adjustment for stroke severity in studies of ICH outcome with administrative claims data.
