Coronary calcium scoring as first-line test to detect and exclude coronary artery disease in GP patients with stable chest pain

CONCRETE is an implementation study, focused on the Dutch health care system in
which the GP is usually the first physician a patient consults with non-acute
chest discomfort. At the moment, the impact of implementation of calcium
scoring in GP setting on CAD diagnosis and treatment rate are unknown. The
exercise test is the most commonly performed test in cardiology outpatient
clinics in referred patients. The CT calcium score is an existing test, which
is part of the cardiac CT examination as requested in outpatient clinics (scan
without contrast for calcium score determination, followed by scan with
contrast for evaluation of coronary stenosis). In Dutch outpatient studies, CT
calcium scoring proved to have high accuracy in diagnosing or excluding CAD. A
zero CS makes the probability of CAD very low, while especially from a CS of
100 the risk of relevant CAD and cardiovascular events increases. We have,
based on clinical outcomes in calcium score categories of these prospective
outpatient studies, prepared advice for the GP to reassure, consider drug
treatment, or consider referral to a cardiologist based on the patient*s CS.
The optimization of cut-off values for CT calcium score in men and women is
part of this study. It is uncertain whether the diagnostic accuracy of CT
calcium scoring is the same in GP setting, although prior outpatient studies
included mainly low and intermediate probability patients.
The choice of the NHG Standard Committee to have the GP refer directly
to the cardiologist instead of testing in GP setting is partly due to the fact
that advanced diagnostics such as CT are now not accessible in primary care. It
is not certain that direct referral to the cardiologist is a better strategy
for diagnosis and prognosis of CAD than an initial policy based on calcium
score measurement by the GP. Recently published Dutch research has shown that
the calcium score can play an important stratifying role in patients with chest
pain (Rijlaarsdam-Hermsen, Neth Heart J 2019; Lo-Kioeng-Shioe, Int J Cardiol
2019). There is a situation of equipoise, where there are 2 competing
strategies about which experts disagree which initial strategy can best be used
in the indicated patient group.
In contrast to ischemia tests, CT calcium scoring detects also early
stages of CAD. It is possible that treatment of early CAD may prevent
myocardial infarction or sudden cardiac death in the future due to early
treatment, although at this moment this is still unclear.
Before wide-spread implementation in GP setting can take place, we
intend to perform a pragmatic cluster-randomized trial to evaluate the clinical
utility of calcium scoring in terms of 1. the diagnosis/treatment rate of early
CAD, and 2. referral rate, downstream testing, further treatment, quality of
life, cardiac events and costs, compared to the standard of care as recommended
by the NHG. The expected result of CONCRETE is cost-effective implementation of
the calcium score in the GP setting that will lead to early diagnosis and
treatment of CAD causing AP and subclinical atherosclerosis, and on the other
hand, safe exclusion of CAD, avoiding unnecessary referrals.

CONCRETE aims to: (1) evaluate whether GP access to CT calcium scoring leads to
earlier CAD diagnosis and treatment, (2) assess and optimize gender-specific
diagnostic stratification based on the calcium score, (3) determine which
(cluster of) symptoms and risk factors could assist in web-based
self-assessment of CAD, and (4) translate study findings to initiate a change
in Dutch health care policy by providing data on cost-effectiveness.

CONCRETE is an implementation study of CT calcium scoring in GP setting. The
design is a pragmatic cluster randomized trial in which direct access to CT
calcium scoring is compared to the standard strategy (direct referral to the
cardiologist) in patients with chest discomfort. Randomization will take place
at GP level.

Implementation of direct access to CT calcium scoring for patients with chest
discomfort in GP setting. Patients in both clusters will be asked for consent
to fill in questionnaires regarding complaints, and quality of life and for the
researchers to gather data on work-up and follow-up.

The purpose of CONCRETE is to study the implementation of calcium scoring in GP
setting, and determine the effects on GP level. In half of the GP offices, CT
calcium scoring will be implemented, and compared to the standard of care as
recommended by the NHG. The risk due to the implementation of CT calcium
scoring in GP setting is considered negligible for the following reasons. The
risk of the diagnostic test, in terms of false positives and false negatives,
as well as test related risks, is expected to be no worse for CT calcium
scoring compared to evaluation (with or without non-invasive diagnostic
testing) in the cardiology outpatient clinic. In outpatient cardiology clinic
setting, CT calcium scoring has been found to have high diagnostic accuracy to
detect or exclude CAD. It is uncertain whether this is the same in GP setting,
although prior outpatient studies included mainly low and intermediate
probability patients. The management advice given in the CONCRETE study for the
calcium score categories have been based on discussions with cardiologists,
general practitioners and radiologists, and are meant for guidance, but are not
obligatory. These categories are based on recent literature from important
Dutch studies (Dedic, IJC 2013; Lubbers, Circ imaging 2017;
Rijlaarsdam-Hermsen, Neth Heart J 2019; Lo-Kioeng-Shioe, Int J Cardiol 2019)
and on the experience of physicians who have been applying the calcium score
for years in practice. Based on all this, the stratification based on the CT
calcium score can be considered safe. Moreover, the choice of the NHG Standard
Committee to have the GP refer directly to the cardiologist instead of testing
in GP setting is partly due to the fact that advanced diagnostics such as CT
are now not accessible in primary care. It is not certain that direct referral
to the cardiologist is a better strategy for diagnosis and prognosis of CAD
than an initial policy based on calcium score measurement by the GP. Recently
published Dutch research has shown that the calcium score can play an important
stratifying role in patients with chest pain (Rijlaarsdam-Hermsen, Neth Heart J
2019; Lo-Kioeng-Shioe, Int J Cardiol 2019). There is a situation of equipoise,
where there are 2 competing strategies about which experts disagree which
initial strategy can best be used in the indicated patient group. In contrast
to ischemia tests, CT calcium scoring detects also early stages of CAD. It is
possible that treatment of early CAD may prevent myocardial infarction or
sudden cardiac death in the future due to early treatment, although at this
moment this is still unclear. The radiation dose of CT calcium scoring is very
low, less than 1 mSv (below half of annual background radiation). Also,
patients may benefit from detection of early stages of CAD, with subsequent
early treatment. The burden for patients in the individual-level outcomes is
minimal, and involves willingness to share data from GP and hospital files, and
filling in questionnaires on complaints, and quality of life.