Pack Years of Cholesterol?
This has also been published in PracticeUpdate
The risk of cigarette smoking is measured as “pack years of smoking” to include both the magnitude and duration of smoking exposure. We should use the same approach to serum lipids — how high and how long has a patient had a cholesterol problem
The Cardiovascular Risk in Young Finns Study started in 1981 with subjects aged 12 to 18 years. (1) Non-HDL cholesterol (which measures all the deleterious lipid moieties; ie, all particles containing apolipoprotein B) was measured in young Finns at baseline, aged 21 to 30 years, and aged 33 to 45 years. Coronary artery calcification scores were measured in young adulthood in 2008. Non-HDL cholesterol at all measurements was associated with increased coronary artery calcification (CAC), but the baseline value had the strongest association with CAC.
What are the clinical implications? Lipids as a youth matter and have long-term consequences probably because of the “pack years” effect. This is likely due to both genetic hyperlipidemia and early lifestyle behaviors that become habits. I have long been more aggressive when treating genetic hyperlipidemia not only because the lipid levels are so high but also because the patient has been exposed to high levels since before birth. Considering “mg/dL x years” is also useful in counseling patients with acquired hyperlipidemia due to conditions such as hypothyroidism and the nephrotic syndrome. These patients can have remarkably high LDL cholesterol levels, and often require reassurance. Their values need treatment but are much less dangerous than if they were high lifelong. These results also suggest that lipids should be measured in childhood, although this is debated. (1) The National Heart, Lung, and Blood Institute in 2011 recommended universal screening at ages 9 to 11 years and 17 to 19 years, whereas the United States Public Health Services Task Force does not recommend universal screening because of the lack of evidence. The present results argue that clinicians should screen children for hyperlipidemia and initiate treatments that can mitigate its lifelong consequences.
Reference
- Armstrong MK, Fraser BJ, Hartiala O, et al. Association of non-high-density lipoprotein cholesterol measured in adolescence, young adulthood, and mid-adulthood with coronary artery calcification measured in mid-adulthood. JAMA Cardiol. 202 Jan 27. doi: 10.1001/jamacardio.2020.7238. Online ahead of print. https://jamanetwork.com/journals/jamacardiology/article-abstract/2775672
