Is Risk-Standardized In-Hospital Stroke Mortality an Adequate Proxy for Risk-Standardized 30-Day Stroke Mortality Data?

Linking the Paul Coverdell National Acute Stroke Program to commercial claims to establish a framework for real-world longitudinal stroke research

BACKGROUND

Non-interventional large-scale research on real-world patients who had a stroke requires the use of multiple data sources ensuring access to longitudinal data from large populations with clinically-detailed information. We sought to establish a framework for longitudinal research on patients hospitalised with stroke by linking information-rich, deidentified inpatient data from the Paul Coverdell National Acute Stroke Program (PCNASP) to commercial and Medicare Advantage longitudinal claims data.

METHODS

All stroke admissions in PCNASP between 2008 and 2015 were evaluated for linkage to longitudinal claims from a commercial insurer using an algorithm based on six available common data fields (patient age, gender, admission date, discharge date, discharge diagnosis and state) and a hospital match. We evaluated the linkage quality (via the percentage of unique records in the linked dataset) and the representativeness of the linked population. We also described medical history, stroke severity and patterns of medication use among the PCNASP-claims linked cohort.

RESULTS

The linkage produced uniqueness equal to 99.1%. We identified 5644 linked and 98 896 unlinked patients who had an ischaemic stroke hospitalisation in claims data. Linked patients were younger than unlinked (69.7 vs 72.5 years), but otherwise similar by medical history, prestroke medication use or lab values. Stroke severity was mild and most patients were discharged home. Prestroke and discharge use of antihypertensive and statins in the PCNASP were greater than their use as measured by filled prescriptions in claims.

CONCLUSIONS

High-quality linkage between the PCNASP and commercial claims data is feasible. This linkage identified differences between reported or recommended versus actual out-of-hospital medication utilisation, highlighting the importance of longitudinal data availability for research aimed to improve the care of patients who had a stroke.

Impact of Missing Stroke Severity Data on the Accuracy of Hospital Ischemic Stroke Mortality Profiling

BACKGROUND

The Centers for Medicare and Medicaid Services have proposed 30-day ischemic stroke risk-standardized mortality rates that include adjustment for stroke severity using the National Institute of Health Stroke Scale (NIHSS), which is often undocumented. We used simulations to quantify the effect of missing NIHSS data on the accuracy of hospital-level ischemic stroke risk-standardized mortality rate profiling for 100 hypothetical hospitals with different case volumes.

METHODS AND RESULTS

We generated simulated data sets of patients with NIHSS scores and other predictors of 30-day mortality based on empirical analysis of data from 7654 patients with ischemic stroke in the Michigan Stroke Registry. We assigned and rank-ordered a true (known) 30-day mortality rate to each hospital in the simulated data sets of N=100 hospitals with either low (100 patients with stroke), medium (300), or high (500) case volumes. We then estimated and rank-ordered 30-day risk-standardized mortality rates for the N=100 hospitals in each simulated data set using hierarchical logistic regression models. In each data set, we systematically varied the rate of missing NIHSS data and whether missing NIHSS data was independent (missing completely at random) or dependent (missing not at random) on the NIHSS score. With no missing NIHSS data, the Spearman correlation between the true hospital performance rank order assigned during data set generation and the estimated 30-day risk-standardized mortality rate rank order was 0.72, 0.88, and 0.91 in low, medium, and high volume hospitals, respectively. However, this fell to as low as 0.50, 0.71, and 0.79 as missing NIHSS data reached 70%.

CONCLUSIONS

Missing NIHSS data had substantial detrimental effects on the accuracy of profiling of ischemic stroke mortality, especially in lower volume hospitals. Even with complete NIHSS documentation, significant limitations in ischemic stroke mortality profiling remain.

Impact of Delayed Appropriate Antibiotic Therapy on Patient Outcomes by Antibiotic Resistance Status From Serious Gram-negative Bacterial Infections

BACKGROUND

To examine the clinical and economic burdens associated with delayed receipt of appropriate therapy among patients with Gram-negative bacteria (GNB) infections, stratified by antibiotic resistance status.

MATERIALS AND METHODS

Retrospective analysis using the Premier Hospital Database. Adult admissions (July 2011-September 2014) with evidence of complicated urinary tract infection, complicated intra-abdominal infection, hospital-associated pneumonia, or bloodstream infection, length of stay (LOS) ≥1 days and a positive GNB culture from a site consistent with infection type (culture draw date = index date) were identified and stratified by antibiotic susceptibility to index pathogens. Delayed appropriate therapy was defined as no receipt of antibiotic(s) with relevant microbiological activity on or within 2 days of index date. Inverse probability weighting and multivariate regression analyses were used to estimate the association between delayed appropriate therapy and outcomes. Generalized linear models were used to evaluate postindex duration of antibiotic therapy, LOS and total in-hospital costs. Logistic models were used to evaluate discharge destination and in-hospital mortality/discharge to hospice.

RESULTS

A total of 56,357 patients with GNB infections were identified (resistant, n = 6,055; susceptible, n = 50,302). Delayed appropriate therapy was received by 2,800 (46.2%) patients with resistant and 16,585 (33.0%) patients with susceptible infections. Using multivariate analysis, delayed appropriate therapy was associated with worse outcomes including ∼70% increase in LOS, ∼65% increase in total in-hospital costs and ∼20% increase in the risk of in-hospital mortality/discharge to hospice, regardless of susceptibility status.

CONCLUSIONS

Our results suggest that outcomes in patients with GNB infections, regardless of resistance status, significantly improve if timely appropriate therapy can be provided.