Medicare Claim-Based National Institutes of Health Stroke Scale to Predict 30-Day Mortality and Hospital Readmission

Moderating Effects of Informal Care on the Relationship Between ADL Limitations and Adverse Outcomes in Stroke Survivors

BACKGROUND

Stroke survivors with limitations in activities of daily living (ADL) have a greater risk of experiencing falls, hospitalizations, or physical function decline. We examined how informal caregiving received in hours per week by stroke survivors moderated the relationship between ADL limitations and adverse outcomes.

METHODS

In this retrospective cohort, community-dwelling participants were extracted from the National Health and Aging Trends Study (2011-2020; n=277) and included if they had at least 1 formal or informal caregiver and reported an incident stroke in the prior year. Participants reported the amount of informal caregiving received in the month prior (low [<5.8], moderate [5.8-27.1], and high [27.2-350.4] hours per week) and their number of ADL limitations (ranging from 0 to 7). Participants were surveyed 1 year later to determine the number of adverse outcomes (ie, falls, hospitalizations, and physical function decline) experienced over the year. Poisson regression coefficients were converted to average marginal effects and estimated the moderating effects of informal caregiving hours per week on the relationship between ADL limitations and adverse outcomes.

RESULTS

Stroke survivors were 69.7% White, 54.5% female, with an average age of 80.5 (SD, 7.6) years and 1.2 adverse outcomes at 2 years after the incident stroke. The relationships between informal caregiving hours and adverse outcomes and between ADL limitations and adverse outcomes were positive. The interaction between informal caregiving hours per week and ADL limitations indicated that those who received the lowest amount of informal caregiving had a rate of 0.12 more adverse outcomes per ADL (average marginal effect, 0.12 [95% CI, 0.005-0.23]; P=0.041) than those who received the highest amounts.

CONCLUSIONS

Informal caregiving hours moderated the relationship between ADL limitations and adverse outcomes in this sample of community-based stroke survivors. Higher amounts relative to lower amounts of informal caregiving hours per week may be protective by decreasing the rate of adverse outcomes per ADL limitation.

National Institutes of Health Stroke Scale Reporting in Medicare Claims Data: Reporting in the First 3 Years

BACKGROUND

Since 2016, hospitals have been able to document International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes for the National Institutes of Health Stroke Scale (NIHSS). As of 2023, the Centers for Medicare & Medicaid Services uses NIHSS as a risk adjustment variable. We assessed associations between patient- and hospital-level variables and contemporary NIHSS reporting.

METHODS

We performed a retrospective cross-sectional analysis of 2019 acute ischemic stroke admissions using deidentified, national 100% inpatient Medicare Fee-For-Service data sets. We identified index acute ischemic stroke admissions using the ICD-10-CM code I63.x and abstracted demographic information, medical comorbidities, hospital characteristics, and NIHSS. We linked Medicare and Mount Sinai Health System (New York, NY) registry data from 2016 to 2019. We calculated NIHSS documentation at the patient and hospital levels, predictors of documentation, change over time, and concordance with local data.

RESULTS

There were 231 383 index acute ischemic stroke admissions in 2019. NIHSS was documented in 44.4% of admissions and by 66.5% of hospitals. Hospitals that documented ≥1 NIHSS were more commonly teaching hospitals (39.0% versus 5.5%; standardized mean difference score, 0.88), stroke certified (37.2% versus 8.0%; standardized mean difference score, 0.75), higher volume (mean, 80.8 [SD, 92.6] versus 6.33 [SD, 14.1]; standardized mean difference score, 1.12), and had intensive care unit availability (84.9% versus 23.2%; standardized mean difference score, 1.57). Adjusted odds of documentation were lower for patients with inpatient mortality (odds ratio, 0.64 [95% CI, 0.61-0.68]; P<0.0001), in nonmetropolitan areas (odds ratio, 0.49 [95% CI, 0.40-0.61]; P<0.0001), and male sex (odds ratio, 0.95 [95% CI, 0.93-0.97]; P<0.0001). NIHSS was documented for 52.9% of Medicare cases versus 93.1% of registry cases, and 74.7% of Medicare NIHSS scores equaled registry admission NIHSS.

CONCLUSIONS

Missing ICD-10-CM NIHSS data remain widespread 3 years after the introduction of the ICD-10-CM NIHSS code, and there are systematic differences in reporting at the patient and hospital levels. These findings support continued assessment of NIHSS reporting and caution in its application to risk adjustment models.

The effect of post-acute rehabilitation setting on 90-day mobility after stroke: A difference-in-difference analysis

Background

After discharged from the hospital for acute stroke, individuals typically receive rehabilitation in one of three settings: inpatient rehabilitation facilities (IRFs), skilled nursing facilities (SNFs), or home with community services (i.e., home health or outpatient clinics). The initial setting of post-acute care (i.e., discharge location) is related to mortality and hospital readmission; however, the impact of this setting on the change in functional mobility at 90-days after discharge is still poorly understood. The purpose of this work was to examine the impact of discharge location on the change in functional mobility between hospital discharge and 90-days post-discharge.

Methods

In this retrospective cohort study, we used the electronic health record to identify individuals admitted to Johns Hopkins Medicine with an acute stroke and who had measurements of mobility [Activity Measure for Post Acute Care Basic Mobility (AM-PAC BM)] at discharge from the acute hospital and 90-days post-discharge. Individuals were grouped by discharge location (IRF=190 [40%], SNF=103 [22%], Home with community services=182 [(38%]). We compared the change in mobility from time of discharge to 90-days post-discharge in each group using a difference-in-differences analysis and controlling for demographics, clinical characteristics, and social determinants of health.

Results

We included 475 individuals (age 64.4 [14.8] years; female: 248 [52.2%]). After adjusting for covariates, individuals who were discharged to an IRF had a significantly greater improvement in AM-PAC BM from time of discharge to 90-days post-discharge compared to individuals discharged to a SNF or home with community services (β=-3.5 (1.4), p=0.01 and β=-8.2 (1.3), p=<0.001, respectively).

Conclusions

These findings suggest that the initial post-acute rehabilitation setting impacts the magnitude of functional recovery at 90-days after discharge from the acute hospital. These findings support the need for high-intensity rehabilitation and for policies that facilitate the delivery of high-intensity rehabilitation after stroke.

Validation of the International Classification of Diseases, Tenth Revision Code for the National Institutes of Health Stroke Scale Score

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 an International Classification of Diseases, Tenth Revision (ICD-10) diagnosis code, but this code's validity remains unclear.

METHODS

We examined the concordance of ICD-10 NIHSS 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 to ICD-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-10 NIHSS 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 of ICD-10 NIHSS scores. We used ANOVA to examine the proportion of variation (R2) in the true (registry) NIHSS score that was explained by the ICD-10 NIHSS score.

RESULTS

Among 1357 patients, 395 (29.1%) had an ICD-10 NIHSS 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 the ICD-10 NIHSS score. In an ANOVA model, the ICD-10 NIHSS 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 their ICD-10 and registry NIHSS scores.

CONCLUSIONS

When present, ICD-10 codes representing NIHSS scores had excellent agreement with NIHSS scores recorded in our stroke registry. However, ICD-10 NIHSS scores were often missing, especially in less severe strokes, limiting the reliability of these codes for risk adjustment.

Association of Medicare-Medicaid Dual Eligibility and Race and Ethnicity With Ischemic Stroke Severity

IMPORTANCE

Black and Hispanic US residents are disproportionately affected by stroke incidence, and patients with dual eligibility for Medicare and Medicaid may be predisposed to more severe strokes. Little is known about differences in stroke severity for individuals with dual eligibility, Black individuals, and Hispanic individuals, but understanding hospital admission stroke severity is the first important step for focusing strategies to reduce disparities in stroke care and outcomes.

OBJECTIVE

To examine whether dual eligibility and race and ethnicity are associated with stroke severity in Medicare beneficiaries admitted to acute hospitals with ischemic stroke.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cross-sectional study was conducted using Medicare claims data for patients with ischemic stroke admitted to acute hospitals in the United States from October 1, 2016, to November 30, 2017. Data were analyzed from July 2021 and January 2022.

EXPOSURES

Dual enrollment for Medicare and Medicaid; race and ethnicity categorized as White, Black, Hispanic, and other.

MAIN OUTCOMES AND MEASURES

Claim-based National Institutes of Health Stroke Scale (NIHSS) categorized into minor (0-7), moderate (8-13), moderate to severe (14-21), and severe (22-42) stroke.

RESULTS

Our sample included 45 459 Medicare fee-for-service patients aged 66 and older (mean [SD] age, 80.2 [8.4]; 25 303 [55.7%] female; 7738 [17.0%] dual eligible; 4107 [9.0%] Black; 1719 [3.8%] Hispanic; 37 715 [83.0%] White). In the fully adjusted models, compared with White patients, Black patients (odds ratio [OR], 1.21; 95% CI, 1.06-1.39) and Hispanic patients (OR, 1.54; 95% CI, 1.29-1.85) were more likely to have a severe stroke. Using White patients without dual eligibility as a reference group, White patients with dual eligibility were more likely to have a severe stroke (OR, 1.75; 95% CI, 1.56-1.95). Similarly, Black patients with dual eligibility (OR, 2.15; 95% CI, 1.78-2.60) and Hispanic patients with dual eligibility (OR, 2.50; 95% CI, 1.98-3.16) were more likely to have a severe stroke.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, Medicare fee-for-service patients with ischemic stroke admitted to acute hospitals who were Black or Hispanic had a higher likelihood of worse stroke severity. Additionally, dual eligibility status had a compounding association with stroke severity regardless of race and ethnicity. An urgent effort is needed to decrease disparities in access to preventive and poststroke care for dual eligible and minority patients.