Introduction
The German National Care Guideline on chronic Coronary Artery Disease (NVL-cKHK) and
the European Guidelines on myocardial revascularization recommend the establishment
of interprofessional decision-making structures and processes for myocardial revascularization
by heart teams, consisting of cardiologists and cardiac surgeons, to improve the quality
of care.[1 ]
[2 ]
[3 ] For the treatment of significant coronary artery disease (CAD), beside optimal medical
therapy, percutaneous coronary intervention (PCI), and coronary artery bypass grafting
(CABG) are available with the therapeutic goals to reduce cardiovascular morbidity
and mortality and to improve disease-related quality of life. In Germany, PCI is by
far the most frequently used revascularization therapy (ratio of PCI:CABG = 10:1).[4 ]
[5 ] However, there are scarce data on the appropriateness of revascularization procedures
in Germany.[6 ]
[7 ]
According to the NVL-cKHK, various patients characteristics, concomitant diseases,
and coronary anatomy should be taken into account for the right decision for a revascularization
procedure.[1 ] These include cardiac related features (left ventricular ejection fraction, left
main stenosis, single- or multivessel disease, chronic coronary artery occlusion,
and peculiarities of calcifications) and noncardiac patient characteristics (age,
renal function, diabetes mellitus, and other concomitant diseases such as lung diseases).
This results in numerous patient subgroups for which specific recommendations for
the preferred revascularization procedure exist.[2 ]
To the best of our knowledge, the German REVASK study is one of the first scientific
investigations in the field of myocardial revascularization that combines primary
prospective data analysis, including the patients' view with secondary retrospective
routine data.
Material/Methodology/Study Design
The observational study is based on statutory health insurance (SHI) providers data
of BARMER, Techniker Kasse (TK), and a data pool of several craft guild and company
health insurance funds from the Institute for Applied Health Care Research (InGef;
6 million SHI patients). In addition to these secondary analyses of health care provider
claims the REVASK study will prospectively evaluate primary data from service providers
and patients focused on the adherence to current scientific guidelines ([Fig. 2 ]).
Fig. 2 REVASK study design—overview.
Patients' inclusion criteria are chronic coronary artery disease in the sense of a
two- or three-vessel resp. left main disease, isolated CABG or PCI, and statutory
health insurance at prespecified German health insurance companies (BARMER or TK).
The study consists of four modules presented here ([Fig. 3 ]).
Fig. 3 REVASK study design—details. cCAD, chronic coronary artery disease; CRF, case report
form; HCP, health care provider; M, module. ALKK, Arbeitsgemeinschaft leitende kardiologische
Krankenhausärzte.
Module I: Care Situation Analyses Based on Routine SHI Data
Routine data from BARMER, TK, and InGef, as well as registry data from the DGK and
DGTHG, will serve as the basis for the analyses that include insured patients with
CAD who underwent a myocardial revascularization procedure.
The aim of the first module ([Fig. 4 ]) is a descriptive, population-based analysis of PCI and CABG rates in chronic CAD
in Germany. In detail, this will focus on annual numbers of CABG or PCI in different
supply sectors, care situations, regional variations in Germany, and patient contacts
with medical specialists for Cardiac Surgery and Cardiology. Furthermore, a routine
data investigation will be performed to evaluate to which extent specific patient
subgroups underwent a guideline-recommended CABG procedure, especially against the
background that the influential Syntax score (SyS)[8 ] is not available from routine data. Finally, a network analysis will illustrate
typical treatment procedures starting from the initial diagnosis to the first invasive
myocardial revascularization. Various methods of machine learning, such as gradient
boosting and stability selection, are used to identify these pathways.
Fig. 4 REVASK data flow/management modules I–III. CRF, case report form; DGTHG, German Society
for Thoracic and Cardiovascular Surgery; PHFR, data collection center of the University
of Education Freiburg; ZKS, Centre for Clinical Studies, University of Cologne.
Data Processing Module I
Data of insured persons with documented CAD who underwent myocardial revascularization
therapy are examined. Selected German physicians' fee schedule items (GOP) and German
operation and procedure codes (OPS; adaption of the International Classification of
Procedures in Medicine [ICPM]) serve as inclusion criteria ([Table 1 ]). Further relevant variables include data on the insured population, out- and inpatient
treatment, outpatient medical care, prescription data, and incapacity to work data
including sick benefits. The analyses are based on the guidelines and recommendations
formulated for the performance of secondary data analyses (Good Practice Secondary
Data Analysis).[9 ]
[10 ]
[11 ] First the routine SHI data from the health insurance funds are transmitted to the
Confidence Centre (Centre for Clinical Studies, University of Cologne; ZKS) for pseudonymization.
Then the data pool is forwarded to primary medical care (PMV) research group at university
cologne (PMV) for specific insured database import and preparation for different analyses
(SQL Server Management Studio, SAS Enterprise Guide, and R-Studio). In a separate
step, the aggregated result sets of InGef are pooled with those of TK and BARMER by
PMV.
Table 1
Selected German physicians fee schedule items (GOP)/German operation and procedure
code (OPS)
GOP
34292
Zuschlag zu der Gebührenordnungsposition 34291
bei Durchführung einer interventionellen Maßnahme (z. B. PTCA, Stent)
OPS
5–360
Desobliteration (Endarteriektomie) der Koronararterien
5–361
Anlegen eines aortokoronaren Bypass
5–362
Anlegen eines aortokoronaren Bypass durch minimalinvasive Technik
5–363
Andere Revaskularisation des Herzens
5–369.3
Rekonstruktion des Koronarostiums
8–837
Perkutan-transluminale Gefäßintervention an Herz und Koronargefäßen
Module II: Decision-Making Processes: Perspective of Health Care Providers
The aim of the second module ([Fig. 4 ]) is to gain an in-depth and broad insight into the decision structures and processes
for myocardial revascularization with a focus on heart team structures[12 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ] and the application of the SyS (guideline recommendation IB) in everyday clinical
practice.[8 ] This module covers two phases: phase I with a qualitative in-depth analysis of a
selected sample of health care institutions. Thereby actual insights on decision paths
care (pre-, intra-, and postprocedural) for PCI or CABG at the health care providers
are obtained. In phase II, a large nationwide quantitative survey of institutions,
providing myocardial revascularization procedures, will be performed.
For phase I, high-volume providers from different treatment settings are recruited
as follows: outpatient cardiology practices with or without connection to a hospital
(settings 1 and 2), hospitals with a cardiology but no cardiac surgery department
(setting 3), and hospitals with cardiology and cardiac surgery departments (setting
4). The data collection in the first phase covers the following three:
A preparatory written survey concerning medical staff, technical equipment, and the
workflow such as interdisciplinary cooperation and communication pathways within the
team and with the patients.
An on-site audit (1–2 days) with qualitative guideline-based expert interview with
relevant and knowledgeable staff members, preferably members of the heart team.
A web-based case report form (CRF) survey of 25 resp. 75 patients from each institution
consisting of patient characteristics, concomitant diseases verification of myocardial
ischemia, and coronary anatomy.
The survey (1) will be evaluated descriptively using SPSS25 IBM Corp., United States.
The documents provided by the institutions, the discussion and observation notes from
the on-site audit (2) will be evaluated with MAXQDA 2020 VERBI GmbH Berlin as part
of a document analysis, while the analysis of the diagnostic findings are performed
via the web-based CRF system.
Based on the results of the three data collections (1–3), a standardized survey on
decision-making processes and structures in myocardial revascularization therapy will
be developed and applied in phase 2. Thereafter a nationwide survey of all patient
care providers from the above mentioned four settings will be conducted.
In summary, we expect a clear understanding of the workflow regarding patients care
for myocardial revascularization in different treatment settings, including facilitators
for and barriers against guideline adherence.
Module III: Decision-Making Process from the Patients' Perspective
In module III, a standardized longitudinal patient survey before and six months after
the revascularization therapy will be conducted ([Fig. 4 ]). The aims of this survey are to evaluate how patients perceive the decision-making
process in the context of their myocardial revascularization and to explore the role
of the treatment settings against other determinants (i.e., age and gender).
A total of 1,000 patients via setting 1 to 4 (phase 1 module 2) will be recruited.
In outpatient institutions (settings 1 and 2) at least 25 and in inpatient institutions
(setting 3 and 4), a minimum of 75 patients per institution will be recruited. The
staff of the recruiting institutions will include patients with an indication for
isolated coronary angiography, isolated PCI, combined angiography and PCI or CABG.
Written informed patients consent has to be obtained before enrolment.
For this part of the survey, established instruments of participatory decision-making,
satisfaction with the decision and patient-reported endpoints (disease-specific quality
of life) are used.[18 ]
[19 ] On this, we follow the recommendations of the International Consortium for Health
Outcomes Measurement (ICHOM) on standardized outcome measurement for patients with
CAD.[20 ]
[Table 2 ] gives an overview of the variables assessed in the patient survey on decision making
in myocardial revascularization.[21 ]
[22 ]
[23 ]
[24 ]
[25 ]
[26 ] In addition, sociodemographic factors, such as year of birth, sex, comorbidities,
highest educational qualification, highest professional qualification, employment
status, and migration status will be collected.
Table 2
Patient survey decision making
Dimension
Assessment
Items
Treatment options
Original items
Decision making
Decisional conflict scale (DCS)
16 items, 5-point Likert's scale with response categories from “strongly agree” to
“strongly disagree”
The 9-item shared decision making questionnaire (SDM-Q-9)
Nine items, 6-point Likert's scale with response categories from “completely disagree”
to “completely agree”
Anxiety
Amsterdam preoperative anxiety and information scale (APAIS)
Six items, with 6-point response categories from “not at all” to “extremely”
Quality of life
Seattle angina questionnaire (SAQ-7)
Seven items, with 6-point response categories
Patient health questionnaire (PHQ-4)
Four items, with four point response categories from “not at all” to “nearly every
day”
SOEP: Socio-Economic Panel version of the Short Form 12 (SF-12)
Four questions, different response categories
Social support
Berlin social support scales (BSSS)
Eight items, 4-point Likert's scale with response categories from “wrong” to “correct
exactly”
Taking clustered data into account (similarity of patients from the same treatment
institution vs. patients from different health care sectors) various analyses using
IBM SPSS® and multilevel analysis/hierarchical linear modeling (HLM) will be applied.
Module IV: Guidelines Adherence
At present, there is scarce evidence of when, how, and under which conditions heart
teams are used for interdisciplinary indication in Germany, and to which extent the
decisions on therapeutic indication reached by a heart team differ from those made
without ([Fig. 5 ]).[12 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ] Therefore, in module IV, the primary data from modules II and III are linked with
selected routine SHI data from module I to assess guideline adherence. Furthermore,
the dataset will be supplemented by the quality indicators collected in module III
and the SyS calculated by patient care providers. For the study population from module
II, the aim is to analyze information on the quality of interdisciplinary decision-making
processes for the choice of myocardial revascularization, on the SyS and additional
clinical information (e.g., verification of myocardial ischemia, instantaneous wave-free
ration [iFR], and flow fractional reserve [FFR]). Furthermore, the PCI versus CABG
relationship in the heart team categories (module II) will be analyzed, primary data
(module III) are linked to patient-specific SHI routine data (module IV) and further
various analyses in multivariate statistical models are performed.
Fig. 5 REVASK data flow/management module IV. PHFR, data collection center of the University
of Education Freiburg; ZKS, Centre for Clinical Studies, University of Cologne.
Data Protection
The study has been approved by the Federal Office for Social Security (AZ 116–8261–2443/2019),
by the Ethics Review Committee of the University of Freiburg Medical Centre (number:
501/19) and is registered in the German Clinical Trials Register (ID: DRKS00022175).
All persons involved in the research project are bound to data secrecy (§5 BDSG and
§35 SGB I) by the evaluating agency or the trust agency and the data receiving office.
In addition, all employees involved in the evaluation are bound to medical confidentiality[27 ].
The following independent organizations serve as independent data collection centers:
ZKS and the data collection center of the University of Education Freiburg (PHFR).
The independent evaluation centers are PMV research group of the University of Cologne,
PHFR, the Foundation Institute for Heart Attack Research in Luwigshafen, and the German
Society for Thoracic and Cardiovascular Surgery in Berlin.
The confidential center at ZKS is physically and personally separated from the above-mentioned
evaluation centers and is not bound by instructions and is independent of PMV. Its
employees are not involved in data analysis.
The data collection center at PHFR, located in the Public Health and Health Education
Department, pseudonymized the original data of the insured patients and the patient
care providers before transmission to the PHFR evaluation center.
The CRF data inclusion is performed via a project-related case number, thereby data
entry is pseudonymized. Based on the project-related case number, data analyses are
performed at the Foundation Institute for Heart attack Research (IHF) and the DGTHG
(de facto anonymized, since there is no link to the patient list). The statistical
datasets are linked again to the survey data at patient level via project-related
case number after transmission to the PHFR evaluation center.
Discussion
As a direct result of the project, findings will be available regarding the role of
the heart team concerning decision making for myocardial revascularization and on
the application of SyS I and II in everyday care. With these findings, guideline adherence
might be optimized, thereby creating the prerequisites for increased adherence to
guidelines in revascularization therapy. In addition, the project results may be transferred
to everyday care at various levels. On the one hand, they could be used by health
care providers to improve their processes with regard to participatory decision making
to optimize the outcome of patients and to improve the overall quality of care for
CAD.[28 ]
[29 ]
[30 ] On the other hand, the results could be relevant for politics and legislation. Thus,
the project may contribute to an improvement of patient-related outcome quality.
Limitations
Challenges arise, among other things, from the system-immanent nature of routine SHI
data. This primarily includes the lack of clinical data and uncertainties in the coding
quality of billing data. This can be partially compensated by supplementing primary
data. However, it must be taken into account that selection effects arise in the context
of primary data collection, which are compensated by adjustment procedures.
Obtaining the consent of the insured persons in accordance with §75 SGB X results
in methodological restrictions. Potential selection effects caused by a differentiation
of the overall population of interest from the obtained sample with given consent
cannot be excluded, a compensation by statistical methods is not possible. Since the
relevant characteristics are often unknown, the weight of such a selection effect
cannot be quantified.
In view of the importance for the patients concerned, the consent process is worthy
of reflection. A critical examination of the frequency of cardiac catheter examinations,
their determinants and, as far as possible, the appropriateness of the indication
on the level of pseudonymized care data are useful and do not represent any impairment.
On the other hand, obtaining consent, which would refer to examinations performed
in the recent past, could lead to anxiety on the part of those affected and potential
irritation, possibly even to a disruption of the doctor–patient relationship. In addition,
the results of the REVASK study also obtain useful information for medical care or
generates scientific contributions for guidelines and focus on the system level.
