Association of Triglyceride–Glucose Body Mass Index With Target Organ Damage in Essential Hypertension: A Retrospective Cohort Study

To the Editor,

We have read the article “Association of Triglyceride–Glucose Body Mass Index with Target Organ Damage in Essential Hypertension: A Retrospective Cohort Study” by Huang et al. [1] with great interest. We would like to acknowledge the author's rigorous work in this important area that will be appreciated by the readers. We agree with their final conclusion that TyG-BMI is a simple and inexpensive index that measures obesity and incorporates insulin resistance, and that having prognostic ability similar to traditional risk factor models may be helpful in identifying and monitoring children at risk for future poor health outcomes.

We do, however, think that a couple of additional points could potentially strengthen the conclusion of the article.

First, the method of a retrospective cohort study [2] has inherent biases; we need to consider including selection bias and residual confounding. Although the authors describe that multivariable adjustments were made for baseline characteristics, it will be challenging to control for the dynamic nature of the baseline factors, like medication compliance, lifestyle changes, or clinical management over 23 months of follow-up. As with all unmeasured variables, they may have effects on both TyG-BMI and the progression of target organ damage, which limits conclusions of causation. Large-scale prospective studies of long duration need to validate these findings.

Second, even though Huang et al. [1] used TyG-BMI as a surrogate measure for insulin resistance (IR), there are concerns over the generalizability and diagnostic accuracy of the measure. A recent systematic review concluded that the hyperinsulinemic-euglycemic clamp remains the gold standard of assessing IR. While the TyG index had variable performance across different populations, it lacks standardized cut-offs [3]. The absence of the gold-standard assessment in the study prevents us from identifying the true diagnostic accuracy of the TyG-BMI. More importantly, a singular, simplified index may overlook the complexities and relationships between IR, hypertension, and the progression of target organ damage, which could limit its clinical utility across different groups of patients.

Third, metabolic markers, including fasting glucose and triglycerides, which are the fundamental elements of the TyG-BMI calculation, were assessed only once at baseline and do not necessarily reflect long-term changes or variation, which makes them more prone to misclassification risk. For example, one study that investigated the cardiovascular risk with longitudinal comparisons demonstrated that it is useful to repeat key measurements in people with high blood pressure [4]. Future studies should attempt to compare various measurements in order to establish if there is any relationship between multiple parameters with the development of cardiovascular-related outcomes.

Fourth, the study did not include key anthropometric indicators such as BMI, waist circumference, smoking, and drinking, as these factors likely contribute to determining the association between TyG-BMI and organ damage. Another study graciously pointed out how lack of smoking, drinking, and anthropometric data would also reduce the quality of the research [5]. Future studies should include complete patient characteristics to improve accuracy and minimize residual confounding.

In conclusion, Huang et al. [1] provided much value regarding the prognostic utility of TyG-BMI in hypertension. Nonetheless, the incorporation of retrospective design with potential unmeasured confounders, use of single baseline metabolic marker assessments, absence of gold-standard measures for insulin resistance, short follow-up period, and incomplete anthropometric and lifestyle data in future larger prospective studies with extended follow-up and more accurate data collection would yield more robust results and help establish the clinical utility and prognostic validity of TyG-BMI.

Ahmed Bashir: conceptualization, writing – original draft, and literature search. Muhammad Bashir: writing – original draft, writing – review and editing, and validation. Muhammad Aman Rizwan: writing – original draft, supervision, project administration, and final approval. All authors agree to be accountable for all aspects of the work.

The authors declare no conflicts of interest.