Most Doctors Still Don't Test ApoB — A Dangerous Knowledge Gap in Heart Risk Assessment

Cardiovascular disease remains the leading cause of death globally, and dyslipidemia is a primary modifiable driver. Traditional lipid panels focus on LDL cholesterol, but LDL-C measures cholesterol mass rather than the number of circulating atherogenic particles — a meaningful distinction in patients with metabolic syndrome, hypertriglyceridemia, diabetes, or obesity, where LDL-C can significantly underestimate actual cardiovascular risk. ApoB, present as a single molecule on every atherogenic lipoprotein particle, directly quantifies this particle burden. A Korean population-based study cited in this paper found that 17.5% of individuals with normal lipid panels were reclassified as high-risk based on ApoB alone — a striking illustration of the real-world stakes.

Despite endorsement from major guidelines including the 2018 ACC/AHA, 2019 ESC/EAS, 2022 Saudi National Guidelines, and the 2024 National Lipid Association consensus, ApoB testing remains dramatically underutilized. In the United States, a 2019 claims analysis of over 7 million adults found that only 0.21% received ApoB measurement. This new study, conducted between February and May 2025, is the first to systematically examine ApoB knowledge and practice among healthcare professionals specifically in Saudi Arabia, a country with high rates of metabolic syndrome and cardiovascular disease.

The survey recruited 158 licensed physicians (n=80, 50.6%) and pharmacists (n=78, 49.4%) across cardiac centers, academic medical centers, outpatient clinics, and general hospitals in Saudi Arabia. A validated 10-item knowledge questionnaire was used, with a Cronbach's alpha of 0.887 indicating strong internal reliability. The overall mean knowledge score was 4.70 ± 3.13 out of 10 — a failing grade by any measure. Physicians significantly outperformed pharmacists (6.00 ± 2.99 vs 3.36 ± 2.69; p<0.001). Among specialty subgroups, family medicine physicians, cardiologists, and ambulatory care pharmacists demonstrated the highest knowledge scores.

Several specific knowledge deficiencies stood out. While 69.6% of participants correctly recognized ApoB as a direct measure of atherogenic lipoprotein particles, only 53.8% could correctly identify it as the most reliable residual ASCVD risk marker in patients with lipid profile discordance — a core clinical scenario where ApoB testing adds unique value. Practice patterns closely mirrored knowledge levels: among high-knowledge participants, 88.2% reported measuring or considering ApoB in practice, compared to 53.1% of moderate-knowledge and only 24.1% of low-knowledge participants (p<0.001). This dose-response relationship between knowledge and clinical action is a powerful finding with direct implications for medical education.

The study does carry notable limitations. The convenience sampling approach recruited only 158 participants against a calculated target of 384, limiting statistical power and generalizability. The online survey format and self-reported practices introduce potential response and social desirability bias. The cross-sectional design prevents causal inference about whether education would translate to changed practice. Nevertheless, the study fills a genuine evidence gap and provides actionable data: targeted continuing medical education campaigns, integration of ApoB into clinical decision support tools, and national-level policy updates incorporating ApoB testing into routine cardiovascular risk assessment workflows are needed to close the gap between guideline recommendations and clinical reality.