Health Services Research and Policy
Original Article
Updated Trends, Disparities, and Clinical Impact of Neuroimaging Utilization in Ischemic Stroke in the Medicare Population: 2012 to 2019

https://doi.org/10.1016/j.jacr.2022.03.008Get rights and content

Abstract

Objective

The purpose of this study was to update trends, investigate sociodemographic disparities, and evaluate the impact on mortality of stroke neuroimaging across the United States from 2012 to 2019.

Methods

Retrospective cohort study using CMS Medicare 5% Research Identifiable Files, representing consecutive ischemic stroke emergency department or hospitalized patients aged ≥65 years. A total of 85,547 stroke episodes with demographic and clinical information were analyzed using Cochran-Mantel-Haenszel tests and logistic regression. Outcome measures were neuroimaging (CT angiography [CTA], CT perfusion [CTP], MRI, MR angiography [MRA]) utilization, acute treatment (endovascular thrombectomy [EVT] and intravenous thrombolysis [IVT]), and mortality while in the hospital and at 30 days and 1 year post discharge.

Results

Significantly increasing utilization trends for CTA (250%), CTP (428%) and MRI (18%), and a decreasing trend for MRA (−33%) were observed from 2012 to 2019 (P < .0001). Controlling for covariates in the logistic regression models, CTA and CTP were significantly associated with higher EVT and IVT utilization. Although CTA, MRI, and MRA were associated with lower mortality, CTP was associated with higher mortality post discharge. Less neuroimaging was performed in rural patients; older patients (≥80 years) had lower utilization of CTA, MRI, and MRA; female patients had lower rates of CTA; and Black patients had lower utilization of CTA and CTP.

Conclusions

CTA and CTP utilization increased in the Medicare ischemic stroke population from 2012 to 2019 and both were associated with greater EVT and IVT use. However, disparities exist in neuroimaging utilization across all demographic groups, and further understanding of the root causes of these disparities will be crucial to achieving equity in stroke care.

Introduction

In the past decade, the United States population experienced demographic changes impacting stroke care, such as growth in the elderly population and continued increase in the prevalence of obesity and diabetes mellitus, which are stroke risk factors. At the same time, advances in stroke care made lifesaving medical and endovascular treatments available to more patients than in the previous decade. Every year, approximately 795,000 patients suffer a stroke in the United States, with ischemic stroke accounting for 87% of these [1]. Stroke risk increases with age, doubling every 10 years after 55 [1]. Approximately three-quarters of all strokes occur in persons aged ≥65 years, which corresponds to the Medicare population [2].

Intravenous thrombolysis (IVT) with recombinant tissue-type plasminogen activator and endovascular thrombectomy (EVT) are the only early treatments for ischemic stroke endorsed by the American Heart Association [3]. Several studies have shown favorable clinical outcomes with IVT [4, 5, 6] and EVT [7,8], using the results of advanced imaging. CT and MRI, including angiography and perfusion studies, provide valuable information to select patients beyond the previously limited therapeutic time windows for ischemic stroke treatment. In the United States, overall use of IVT and EVT in stroke cases increased from 7.0% in 2008 to 19.1% in 2018 [9]. Concomitantly, the utilization of CT and MRI increased markedly in patients with ischemic stroke [10,11]. From 2006 to 2010, CT angiography (CTA) increased by 142% and CT perfusion (CTP) grew by 6,429% [10]. Additionally, MRI use increased by 235% from 1999 to 2008 [11]. Published trends in nationwide neuroimaging and treatment utilization, particularly relating to other components of stroke care, do not exist beyond 2012 [10,12]. Furthermore, the literature does not address socioeconomic disparities in stroke imaging [10,12].

Understanding recent trends and socioeconomic disparities in neuroimaging utilization among patients with ischemic stroke, and how imaging relates to clinical treatment decisions and outcomes, is critically important for clinicians and health care policymakers as we strive to ensure optimal and equitable access to high-quality stroke care across an increasingly diverse and aging population. We hypothesized that advanced neuroimaging (CTA, CTP, MRI, MR angiography [MRA]) utilization in patients with ischemic stroke has continued to increase in the United States from 2012 to 2019. Furthermore, we hypothesized that (1) these trends were associated with increased acute treatment utilization and improved clinical outcomes and (2) sociodemographic disparities associated with ischemic stroke imaging utilization exist. We focused our analyses on the Medicare population given the much higher incidence of stroke compared with commercially insured patients [13].

Section snippets

Study Population and Data Collection

We performed a retrospective study to assess trends in the utilization of advanced neuroimaging in ischemic stroke care using the Medicare 5% Research Identifiable Files (RIF; 2012-2019). The RIF data contain individual level fee-for-service administrative claims data for a 5% nationally representative sample of Medicare beneficiaries across all places of service (ie, emergency departments, inpatient and outpatient facilities, skilled nursing and hospice facilities, and home health agencies).

Results

During the 2012 to 2019 study period, there were 85,547 stroke episodes in patients aged 65 years and older. Sociodemographic and clinical characteristics of patients with stroke episodes during this period are shown in Table 1. CTA was performed in 29.7%, CTP in 4.2%, MRI in 68.6%, and MRA in 26.8% of stroke episodes. From 2012 to 2019, we observed significant increasing trends in utilization of CTA (from 15.7% to 54.9%, P < .0001), CTP (from 2.2% to 11.4%, P < .0001), and MRI (from 62.1% to

Discussion

Using Medicare claims data from 2012 to 2019, we identified a marked increase in advanced neuroimaging utilization of CTA (250%) and CTP (428%) in patients with ischemic stroke similar to, and a continuation of, the upward trends reported from 2006 to 2010 [10]. It is likely that these utilization trends are a consequence of several landmark clinical trials, starting in 2015, which showed the significant benefit of EVT [19, 20, 21, 22, 23, 24] and led to the American Heart Association [3] and

Take-Home Points

  • From 2012 to 2019, we found significantly increased use of CTA, CTP, and MRI for patients with ischemic stroke based on Medicare claims data. Over the same period, MRA use was on the decline.

  • Overall, neuroimaging was performed less often among rural, older (≥80 years), Black, and female patients.

  • CTA and CTP uptrends were significantly associated with increased IVT and EVT utilization, which decreased the risk of mortality.

Acknowledgments

This work was supported by the National Institute of Neurological Disorders and Stroke (NINDS) of the National Institutes of Health, under award R56NS114275, and a research partnership between Siemens Healthineers and The Feinstein Institutes for Medical Research, Northwell Health. Funding support was received from the Harvey L. Neiman Health Policy Institute through a research partnership.

References (46)

  • K. Psychogios et al.

    Advanced neuroimaging preceding intravenous thrombolysis in acute ischemic stroke patients is safe and effective

    J Clin Med

    (2021)
  • J.S. McDonald et al.

    Pretreatment advanced imaging in patients with stroke treated with IV thrombolysis: evaluation of a multihospital data base

    AJNR Am J Neuroradiol

    (2014)
  • G. Thomalla et al.

    MRI-guided thrombolysis for stroke with unknown time of onset

    N Engl J Med

    (2018)
  • R.G. Nogueira et al.

    Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct

    N Engl J Med

    (2018)
  • G.W. Albers et al.

    Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging

    N Engl J Med

    (2018)
  • G. Asaithambi et al.

    Current trends in the acute treatment of ischemic stroke: analysis from the Paul Coverdell National Acute Stroke Program

    J Neurointerv Surg

    (2020)
  • A. Vagal et al.

    Increasing use of computed tomographic perfusion and computed tomographic angiograms in acute ischemic stroke from 2006 to 2010

    Stroke

    (2014)
  • J.F. Burke et al.

    Wide variation and rising utilization of stroke magnetic resonance imaging: data from 11 states

    Ann Neurol

    (2012)
  • V.T. Ng et al.

    Temporal trends in the use of investigations after stroke or transient ischemic attack

    Med Care

    (2016)
  • T.E. Madsen et al.

    Temporal trends in stroke incidence over time by sex and age in the GCNKSS [published correction appears in Stroke 2020 Jul;51:e141]

    Stroke

    (2020)
  • S.E. Andrade et al.

    A systematic review of validated methods for identifying cerebrovascular accident or transient ischemic attack using administrative data

    Pharmacoepidemiol Drug Saf

    (2012)
  • B19013 median household income in the past 12 months (in 2018 inflation-adjusted dollars). 2018 American Community Survey 5-year estimates

  • O. Adeoye et al.

    Geographic access to acute stroke care in the United States

    Stroke

    (2014)
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    Dr Wang and Dr Katz have received grants from Siemens Healthineers and NINDS during the conduct of the study. Dr Boltyenkov has received grants from Siemens Healthineers and NINDS during the conduct of the study and grants, personal fees, and nonfinancial support from Siemens Healthineers outside the submitted work. Dr Sanelli has received research grants from Siemens Healthineers and NINDS during the conduct of the study and research grants from the Harvey L. Neiman Health Policy Institute outside the submitted work. The other authors state that they have no conflict of interest related to the material discussed in this article. The authors are non-partner/non-partnership track/employees.

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