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Published on: August 9, 2024
Evaluation of risk factor-weighted and coronary artery calcium score-weighted clinical likelihoods as gatekeepers
Simon M Frey1, Igor G Schneider2, Ann-Sophie Otto2
1Department of Cardiology, University Hospital Basel, University of Basel, Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, University of Basel, Basel, Switzerland; Department of Internal Medicine, Division of Cardiology, Cantonal Hospital Baden, Baden, Switzerland.
Insights
Optimizing gatekeeper strategies using risk factor-weighted clinical likelihood (RF-CL) and coronary artery calcium score-weighted clinical likelihood (CACS-CL) can significantly reduce unnecessary scans and costs. Algorithm 3, deferring testing when CACS-CL is ≤ 5%, proved most effective.
Area of Science:
- Cardiology
- Radiology
- Health Economics
Background:
- Current gatekeeper strategies for suspected chronic coronary syndromes may lead to excessive normal scans, radiation exposure, and healthcare costs.
- Risk factor-weighted clinical likelihood (RF-CL) and coronary artery calcium score-weighted clinical likelihood (CACS-CL) offer potential for optimizing diagnostic pathways.
Purpose of the Study:
- To evaluate the effectiveness of gatekeeper strategies employing RF-CL and CACS-CL in reducing unnecessary rubidium-82 positron emission tomography (PET) scans.
- To compare diagnostic accuracy, radiation exposure, and costs associated with different gatekeeper algorithms.
Main Methods:
- Three diagnostic algorithms utilizing RF-CL and CACS-CL were assessed in 1792 patients referred for rubidium-82 PET.
- Algorithms varied in deferring testing based on RF-CL thresholds (Algorithm 1), combined RF-CL and CACS-CL (Algorithm 2), or CACS-CL alone (Algorithm 3).
- Outcomes including missed diagnoses, normal scans, radiation exposure, and costs were compared against CACS plus PET as the reference standard.
Main Results:
- Algorithm 3, deferring testing when CACS-CL ≤ 5%, demonstrated the highest gatekeeper performance, reducing radiation exposure by 28.7% and costs by 29.7%.
- This strategy maintained high diagnostic accuracy, with sensitivity/negative predictive value (NPV) of 93.2%/98.4% for small ischemia and 97.0%/99.7% for relevant ischemia.
- Algorithm 1 achieved a 22.0% reduction in exposure and costs with good performance (sensitivity/NPV: 92.7%/98.2%).
Conclusions:
- Refining RF-CL for all patients and deferring testing based on a CACS-CL ≤ 5% threshold represents the most effective gatekeeper strategy.
- This approach optimizes patient selection for cardiac imaging, leading to significant reductions in resource utilization and radiation exposure for suspected chronic coronary syndromes.
Introduction And Objectives:
Gatekeeper strategies using risk factor-weighted clinical likelihood (RF-CL), alone or combined with coronary artery calcium score-weighted clinical likelihood (CACS-CL), may reduce the number of normal scans, radiation exposure, and health care costs.
Methods:
Three diagnostic algorithms based on RF-CL and CACS-CL were evaluated in 1792 patients (mean age 65± 11 years; 43% female) referred for rubidium-82 (82Rb) positron emission tomography (PET). Algorithm 1 deferred testing if RF-CL ≤ 5%. Algorithm 2 reclassified patients with RF-CL >5%-15% using CACS-CL and deferred testing if either RF-CL or CACS-CL was ≤ 5%. Algorithm 3 deferred testing if CACS-CL ≤ 5%. Missed diagnoses, normal scans, radiation exposure, and costs were compared with the current reference standard (CACS+PET). Endpoints were defined as small ischemia (summed difference score [SDS] ≥ 2) and relevant ischemia (≥ 10% of the myocardium).
Results:
Median RF-CL and CACS-CL were 11% [6-19] and 12% [3-28], respectively. Algorithm 1 reduced radiation exposure and costs by 22.0% while maintaining high gatekeeper performance (sensitivity/negative predictive value [NPV]: 92.7%/98.2%). Algorithm 2 deferred the largest proportion of patients (36.4%) but missed small ischemia in 2.0%. Algorithm 3 demonstrated the best overall gatekeeper performance, reducing radiation exposure by 28.7% and costs by 29.7% without compromising diagnostic accuracy (sensitivity/NPV: 93.2%/98.4% for small ischemia and 97.0%/99.7% for relevant ischemia).
Conclusions:
Refining RF-CL in all patients and deferring testing when CACS-CL ≤ 5% provided the most effective gatekeeper strategy in patients with suspected chronic coronary syndromes.
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