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Impact of certified stroke care: A nationwide analysis of the
potential to improve outcomes (PASCH)
Authors
Evers J1, Schneider M1, Schmitt J2, Günster C3, Barlinn J4, Neumann-Haefelin5, Karagiannidis
C6, Bschor T7, Geraedts M1
Affiliations
1Institute for Health Services Research and Clinical Epidemiology, Philipps-Universität
Marburg, Marburg, Germany
2Center for Evidence-Based Healthcare, University Hospital and Faculty of Medicine Carl
Gustav Carus, Dresden, Germany
3AOK Research Institute, Berlin, Germany
4Department of Neurology, University Hospital Carl Gustav Carus Dresden, Technische
Universität Dresden, Germany
5Department of Neurology, Klinikum Fulda, Fulda, Germany
6Department of Pneumology and Critical Care Medicine, ARDS and ECMO Centre, Cologne-
Merheim Hospital, Kliniken der Stadt Köln gGmbH, Witten/Herdecke University Hospital,
Cologne, Germany
7Government commission for modern and needs-based hospital care, c/o Federal Ministry of
Health, Berlin, and Department of Psychiatry and Psychotherapy, University Hospital of
Dresden, Dresden, Germany
Corresponding Author
Geraedts M: Institute for Health Services Research and Clinical Epidemiology, Philipps-
Universität Marburg, Marburg, Germany; E-Mail: geraedts@uni-marburg.de
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Abstract
Background: Despite Germany's extensive healthcare resources and high hospital density,
challenges persist in optimizing healthcare quality and safety. The Government Commission
for Modern and Needs-Based Hospital Care emphasizes the need for concentrated and
specialized healthcare services to enhance treatment outcomes and patient safety.
Preliminary analyses suggest that quality assurance measures, especially when integrated into
the care at certified stroke centers, may lead to significantly lower mortality risks following
strokes. However, comprehensive nationwide more recent data and consideration of multiple
confounders have been lacking. The planned study aims to fill this gap by assessing the
potential benefits of exclusive treatment in certified stroke centers across Germany, thereby
providing a detailed exploration of the impact of specialized stroke care on patient outcomes,
including survival rates, stroke recurrence, long-term care level increase, and rehospitalization
rates.
Methods and Analysis: This retrospective cohort study will use claims data of Germany’s
largest statutory health care insurer (“AOK”) to analyze acute stroke outcomes over intervals
up to one year, focusing on survival rates, long-term care level increase, stroke recurrence, and
rehospitalization. Data span is set from 2021 to 2022, targeting AOK-insured individuals aged
20 years or older hospitalized for acute stroke, differentiating between primary and secondary
study groups based on treatment history and treatment intention. Facilities are classified into
(certified) Stroke Units and hospitals without Stroke Unit, with subcategories reflecting the
level of stroke care specialization. The analysis will consider confounders like age, gender,
comorbidity, patient transfers, and palliative care intention. Statistical methods will
encompass descriptive analyses, univariate estimations of mortality and secondary outcomes,
and multivariable logistic regression adjusting for confounders to evaluate the impact of
hospital specialization on patient outcomes, aiming to understand how certification and
specialization influence stroke care quality in Germany.
Ethics
This dataset does not identify institutions or patients. According to §15 of the Professional
Code for Physicians in Germany, a vote of an ethics committee is not required for this study.
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Introduction
The German healthcare system, despite its substantial investment in healthcare and a high
density of hospitals, faces challenges in ensuring and enhancing the quality and safety of
healthcare [1]. The Government Commission for Modern and Needs-Based Hospital Care has
highlighted the importance of concentrating and specializing healthcare services to
significantly improve treatment outcomes and patient safety, as demonstrated in a recent
‘analysis of potential’ [2]. This analysis underscores that quality assurance measures are linked
to a lower mortality risk with a more pronounced effect observed when care is centralized in
institutions with specialized qualifications.
A specific focus of this analysis on the survival rates of stroke patients revealed that those
treated in certified stroke centers had higher survival rates [3]. However, this study
acknowledges several limitations related to potential confounders and was criticized for using
outdated data. In light of these findings, the subsequent study aims to extend the analysis by
incorporating multiple confounders and leveraging nationwide data to offer a comprehensive
and more recent assessment of the potential benefits associated with certified stroke care.
Stroke represents a notable conflict between specialized diagnosis and treatment on the one
hand and timely acute therapies on the other hand. Thus, it can serve as a model for
implementing a stepped care approach, as outlined in recent healthcare reform plans. Recent
studies have highlighted the significance of hospital specialization in the treatment and
outcomes of stroke patients. A study conducted in the USA on acute ischemic stroke patient
characteristics, care quality, and outcomes in 2019 emphasized the importance of targeted
quality improvement efforts and resource allocation in improving care and outcomes in acute
ischemic stroke (AIS) [4]. Similarly, cost-effectiveness and enhanced patient outcomes
associated with stroke units in Australian teaching hospitals have been confirmed, indicating
that specialized care not only improves treatment outcomes but also reduces hospital length
of stay, thereby achieving cost-effectiveness [5].
Furthermore, the impact of establishing a Stroke Care Unit (SCU) in a community hospital was
found to increase the survival of stroke patients and the proportion of patients discharged
home to live independently [6]. The finding underlines that the benefits of SCUs reported in
larger tertiary centers extend to smaller community hospitals with more limited resources. The
concept of stepped Stroke Unit care has been implemented in Germany for over twenty years
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and is facilitated through scaled certification and network development. Additionally,
variations in home-time post-discharge in older ischemic stroke survivors have been observed
to vary by hospital annual stroke volume, case-mix severity and region, indicating the influence
of hospital specialization on patient outcomes [7].
A recent meta-analysis showed endovascular thrombectomy to be of benefit to most patients
with acute ischemic stroke caused by occlusion of the proximal anterior circulation,
irrespective of patient characteristics or geographical location, so the authors called for
implications on structuring systems of care to provide timely treatment to patients with acute
ischemic stroke due to large vessel occlusion [8]
These studies collectively underscore the importance of hospital specialization and quality
assurance in stroke care. They provide a compelling rationale for the hypothesis that stroke
patients have better outcomes when treated in specialized hospitals, taking into account that
positive effects of evidence-based therapies like intravenous thrombolysis and endovascular
therapy are time-sensitive and require prompt patients’ work-up.
Given this background, the present study aims to determine the potential benefits if all stroke
patients were exclusively treated in certified clinics, focusing on how certification, integration
in a stroke-network and capabilities of hospitals specialized in stroke care impact patient
survival rates, recurrence of stroke, changes in long-term care needs, and rehospitalization
rates. This research seeks to contribute to the understanding of the role of hospital
specialization in improving stroke care outcomes in Germany.
Methods and Analysis
The study is designed as a retrospective cohort study based on routine data. Primary outcomes
are the survival rates over 10, 30, 90, 180, and 365 days after hospital admission. Secondary
outcomes are the increase in long-term care level within 1 year, stroke recurrence within 1
year and the rehospitalization due to any cause within a year.
Our study will be based on claims data from Germany’s largest statutory health care insurance
company, the AOK [9], stored at and provided by their research institute “Wissenschaftliches
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Institut der AOK, WIdO” [10]. We will examine acute stroke events from 2021 and 2022, with
a historical look back until 2011 to consider recurrences. Participants include AOK-insured
individuals over 19 years of age (21.9 Mill. = 32.2% of Germany’s population >19 y.) who were
hospitalized for an acute stroke. For data analysis, we will form different populations, including
a primary study group, comprising patients who experienced an acute event and were treated
in a single clinic, with no known stroke in the preceding 10 years and excluding those with a
palliative care procedure code, and various secondary study groups, such as patients treated
in multiple clinics due to transfers, and those with or without palliative care, including patients
with recurrences.
The relevant discharge diagnoses will be, as classified by the International Classification of
Diseases (ICD), subarachnoid hemorrhage (I60), intracerebral hemorrhage (I61), cerebral
infarction (I63), stroke, not specified as hemorrhage or infarction (I64) and transient cerebral
ischemic attacks and related syndromes (G45, excluding G45.4) for events occurring in 2021 or
2022.
This study examines the degree of specialization of the treating facilities, categorized based on
their certification status in 2021 and 2022. These, as well as status of telemedicine network
integration, will be provided by the German Stroke Society (Deutsche Schlaganfall Gesellschaft,
DSG). The DSG is a professional organization in Germany dedicated to the research,
prevention, and treatment of stroke. The DSG plays a crucial role in setting standards for stroke
care, promoting clinical research in the field of stroke medicine, and providing education and
guidelines for healthcare professionals [11]. The DSG develops certification criteria and
standards and promotes certification through independent certification companies [12].
The study classifies hospitals into various categories, including hospitals with DSG certification
(such as supra-regional Stroke Units, regional Stroke Units with or without thrombectomy
capability, and telemedicine networked Stroke Units) and hospitals without DSG certification
(including those part of a telemedicine network and those who are not, with further
subdivisions based on the mention of a – not certified - “Stroke Unit” in the hospitals’ quality
report and considering the numbers of stroke cases treated and specialized stroke procedures
performed). The full categorization will be as follows:
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A) Hospitals with Stroke Unit certification:
1. Supra-Regional Stroke Units (SRSU): These are clinics certified as supra-regional Stroke
Units, indicating the top level of specialization in stroke care.
2. Regional Stroke Units with DSG Certification (RSU): These clinics are further
subdivided based on their capabilities:
a. Regional Stroke Units with Thrombectomy Capability (RSU-T): These units are
equipped to perform thrombectomy, a critical procedure in stroke care.
b. Regional Stroke Units without Thrombectomy Capability (RSU-NT): These units,
while specialized, do not have thrombectomy facilities.
3. Telemedicine Networked Stroke Units (TNSU): Hospitals in this category are certified
as part of a telemedicine network, facilitating remote stroke care and consultations.
B) Hospitals without Stroke Unit certification, in a Telemedicine Network
4. Hospitals in a Telemedicine Network (Cooperation Hospitals, HTN): These hospitals,
although not DSG-certified, are part of a telemedicine network and are further
classified based on their self-reported capabilities:
a. Telemedicine Stroke Units with Quality Report Mention (TSU-QR): These hospitals
mention “Stroke Unit” in their quality reports.
b. Telemedicine Stroke Units without Quality Report Mention (TSU-NQR): These
hospitals do not mention “Stroke Unit” in their quality reports.
C) Hospitals without Stroke Unit certification, not in a Telemedicine Network: These are
categorized based on their quality report mentions:
a. Non-Telemedicine Stroke Units with Quality Report Mention (NTSU-QR):
Hospitals not in a telemedicine network but mentioning “Stroke Unit” in their
quality reports.
b. Hospitals without a Stroke Unit (OSU): Hospitals neither in a telemedicine network
nor mentioning “Stroke Unit” in their quality reports.
Confounders
We will consider several potential confounders to ensure the robustness of our findings. These
are age, categorized in less than 50 years and then in 10-year intervals up to over 99 years;
Gender as recorded as male or female; Comorbidity assessed using the Elixhauser Comorbidity
Conditions [13, 14], with categories less than 4, 4-6 and more than 6; Patient transfers during
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the acute event, noting whether transfers occurred within less than or more than 24 hours of
the acute event; Primary palliative care intention, identifying patients where a palliative care
procedure code was documented.
Stratification
In addition to the general comparison between facilities with and without a certified Stroke
Unit, this study will conduct stratified analyses to further dissect the data. These analyses will
focus on centers with and without mechanical thrombectomy capability to understand the
impact of this specific treatment option, and on the combination of treatments in TSU and
(S)RSU, evaluating the outcomes of combined treatment approaches and patient transfer time
and travel distances on patient outcomes. Additionally, the study plans to standardize severity
grades across hospitals to calculate how the performance of individual hospitals would
compare in similar cases.
Analytical Approach:
A multi-faceted analytical approach will be employed:
1) Descriptive analyses are conducted for different strata based on age and risk profile.
2) Univariate estimations are used to determine the empirical frequencies of mortality within
various time frames and the occurrence of secondary endpoints.
3) Multivariable adjusted estimations are applied to assess mortality risks and secondary
endpoints. This is achieved through logistic regression models, adjusting for confounders and
clustering within hospitals.
These models initially incorporate dichotomously scaled confounders, including age groups,
gender, and comorbidity (elixhauser comorbidity conditions), along with the dichotomously
scaled certification grade of the treating hospital. The first step involves calculating the relative
risks of various confounder combinations against the group with the lowest risk profile.
Subsequently, the overall risks from the model, combining confounders and certification
grade, are determined and adjusted by dividing by the relative risk of the confounders. This
method effectively estimates the risk associated with the certification grade of the treating
hospital, adjusted for the influence of confounders mentioned.
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Impact and dissemination
The comprehensive findings of our study on the effectiveness of certified stroke care in
Germany will evaluate the pivotal role of hospital specialization and certification in enhancing
patient outcomes post-stroke. By meticulously analyzing data from the AOK and categorizing
hospitals based on their certification status, our research will offer a nuanced understanding
of the impact specialized stroke care units have on survival rates, recurrence of stroke,
rehospitalization rates, and long-term care level changes after stroke. The study's implications
extend beyond the immediate healthcare outcomes, while highlighting the potential for
significant advancements in stroke outcomes by concentrating stroke patient care in
specialized and certified healthcare facilities.
Given the critical nature of these findings, we aim to disseminate the results widely through
publication in a peer-reviewed journal dedicated to healthcare quality and stroke care.
Additionally, we plan to present our research at relevant medical and healthcare policy
conferences to foster discussions on improving stroke care infrastructure and policy. The
publication and presentation of this study will not only contribute to academic discourse but
also inform clinical practices and healthcare policy, potentially guiding future efforts to
optimize stroke care delivery nationwide.
Authors contributions
JS: participation in study design development, critical revision of manuscript
JB: provision of data, critical revision of manuscript
TB: providing background information and references, critical revision of manuscript
CG: provision of data, participation in study design development, critical revision of manuscript
MG: study design development, participation in writing the manuscript
JE: participation in study design development, writing the manuscript
MS: participation in study design development, critical revision of manuscript
CK: providing background information, critical revision of manuscript
TN-H: providing background information, critical revision of manuscript
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Funding statement
The study received no research grant funding.
Competing interests’ statement.
JS and TB are members of the Government Commission for Modern and Needs-Based
Hospital Care that recommended centralization of stroke care. JB is speaker of the Telestroke
committee of the German Stroke Society.
The other authors declare that they have no competing interests related to this study. This
includes any financial, personal, or professional relationships that could be perceived to
influence the work presented in this document.
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