Several clinical features can be accurate in differentiating between familial chylomicronemia syndrome (FCS) and severe hypertriglyceridemia in the absence of genetic testing, according to study results published in the Journal of the Endocrine Society.
It is difficult to differentiate between severe hypertriglyceridemia and the far more rare entity of FCS as triglyceride levels and clinical symptoms overlap. Since appropriate disease management requires accurate diagnosis, researchers explored whether clinical data — other than fasting triglyceride levels and excluding genetic data — can differentiate between the 2 diseases.
The study included patients with FCS from the APPROACH study (ClinicalTrials.gov Identifier: NCT02211209; 49 patients; 46% men; mean age, 45.4±14 years) and patients with severe hypertriglyceridemia from the COMPASS study (ClinicalTrials.gov Identifier: NCT02300233; 105 patients; 79.2% men; mean age, 51.5±10 years). Both trials evaluated the effects of subcutaneous volanesorsen treatment in adults.
Demographic variables, baseline lipid and laboratory values, prior medication use, and medical history were assessed. Logistic regression methods were used to determine the ability of these variables to differentiate between the disease groups.
The primary logistic regression model, which included all 17 available predictor parameters other than fasting triglycerides, indicated a distinct separation between the FCS and severe hypertriglyceridemia groups. Based on 45 patients with FCS who were correctly classified by the model, the optimal sensitivity was 91.8%. Based on correct diagnosis of 99 patients with severe hypertriglyceridemia, the optimal specificity of the model was 94.3%. The overall accuracy was 93.5%.
While the greatest accuracy was achieved with the primary analysis, this required 17 variables. The parameter with the highest combined sensitivity and specificity outcome was fasting ultracentrifugally determined low-density lipoprotein cholesterol level. A 3-variable set of ultracentrifugally measured low-density lipoprotein cholesterol, body mass index, and pancreatitis history differentiated the groups with a near similar accuracy of 91.0%.
The researchers acknowledged several study limitations, including estimating the accuracy of the model from the data used to create the model, tight inclusion and exclusion criteria for both studies, and the need to validate the analyses in a larger sample.
“[T]his analysis identifies several clinical variables, beyond fasting triglyceride levels, that achieved greater than 90 percent accuracy, with as few as three variables, classifying a patient as having FCS or [severe hypertriglyceridemia],” concluded the researchers.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
O’Dea LSL, MacDougall J, Alexander VJ, et al. Differentiating familial chylomicronemia syndrome from multifactorial severe hypertriglyceridemia by clinical profiles [published online October 11, 2019]. J Endocr Soc. doi:10.1210/js.2019-00214