Validation of the International Classification of Diseases, Tenth Revision Code for the National Institutes of Health Stroke Scale Score
Circulation: Cardiovascular Quality and Outcomes, Ahead of Print.
Background:Administrative data can be useful for stroke research but have historically lacked data on stroke severity. Hospitals increasingly report the National Institutes of Health Stroke Scale (NIHSS) score using anInternational Classification of Diseases,Tenth Revision(ICD-10) diagnosis code, but this code’s validity remains unclear.Methods:We examined the concordance ofICD-10NIHSS scores versus NIHSS scores recorded in CAESAR (Cornell Acute Stroke Academic Registry). We included all patients with acute ischemic stroke from October 1, 2015, when US hospitals transitioned toICD-10, through 2018, the latest year in our registry. The NIHSS score (range, 0–42) recorded in our registry served as the reference gold standard.ICD-10NIHSS scores were derived from hospital discharge diagnosis code R29.7xx, with the latter 2 digits representing the NIHSS score. Multiple logistic regression was used to explore factors associated with availability ofICD-10NIHSS scores. We used ANOVA to examine the proportion of variation (R2) in the true (registry) NIHSS score that was explained by theICD-10NIHSS score.Results:Among 1357 patients, 395 (29.1%) had anICD-10NIHSS score recorded. This proportion increased from 0% in 2015 to 46.5% in 2018. In a logistic regression model, only higher registry NIHSS score (odds ratio per point, 1.05 [95% CI, 1.03–1.07]) and cardioembolic stroke (odds ratio, 1.4 [95% CI, 1.0–2.0]) were associated with availability of theICD-10NIHSS score. In an ANOVA model, theICD-10NIHSS score explained almost all the variation in the registry NIHSS score (R2=0.88). Fewer than 10% of patients had a large discordance (≥4 points) between theirICD-10and registry NIHSS scores.Conclusions:When present,ICD-10codes representing NIHSS scores had excellent agreement with NIHSS scores recorded in our stroke registry. However,ICD-10NIHSS scores were often missing, especially in less severe strokes, limiting the reliability of these codes for risk adjustment.
Source link