Commentary: Positive association between different triglyceride glucose index-related indicators and psoriasis: evidence from NHANES

Ping Song^1*Bobiao Ning²Baohua Li³

• ¹Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China
• ²Department of Endocrinology, Guang’anmen Hospital, Beijing University of Chinese Medicine, Beijing, Beijing, China
• ³China Academy of Traditional Chinese Medicine Hospital of Ophthalmology, Beijing, Beijing Municipality, China

The study found that compared with Q1 (1st quintile)，TyG-BMI, TyG-WC and TyG-WHtR of Q2 (2nd-3rd quintiles) and Q3 (4th-5th quintiles) were significantly associated with psoriasis. Furthermore, the authors conducted subgroup analyses of the relationship between the three TyG indices and psoriasis based on all covariates, revealing that most covariates did not exhibit interaction effects on their associations. We must acknowledge the contributions made by all the authors; however, we still have some questions regarding this study.In the statistical analysis, the authors mentioned that they used multivariate logistic regression to examine the associations between the three TyG-related indices and psoriasis. However, since psoriasis, as the outcome variable, is a binary variable, we speculate that the authors may have confused the concepts of multivariate logistic regression and binary logistic regression. To enhance the rigor of the study, the statistical analysis here should be revised to binary logistic regression. In the article, data with missing covariates were directly excluded. The authors should clarify the reasons for excluding participants due to missing covariates to ensure that no selection bias was introduced. In the subgroup analysis, the authors stated that there was no interaction between TyG-BMI and hypertension or hypertriglyceridemia (P for interaction > 0.05). However, this assertion appears to be incorrect, as Figure 3 clearly demonstrates that the relationship between TyG-BMI and psoriasis is influenced by hypertension (P for interaction < 0.001). We believe this error should be avoided to minimize its impact on readers.The article has incorporated covariates such as age, sex, race, education, smoking history, alcohol consumption, hypertension history, and diabetes history，which is commendable. However, since numerous studies have demonstrated that physical activity can improve disease outcomes in patients with psoriasis (2), and psoriasis imposes a long-term and substantial economic burden on patients and their families (3), we strongly suggest that the authors include physical activity and household income as covariates in the analysis.The final conclusion of this study states that TyG-related indices (TyG-BMI, TyG-WC, and TyG-WHtR) exhibit a stable and strong positive correlation with psoriasis.However, this conclusion may leave readers with the impression that the research is incomplete. For example, how do the diagnostic capabilities of these three TyGrelated indices for psorias. Therefore, we encourage the authors to incorporate a combined diagnostic test analysis to compare the diagnostic performance of TyG-BMI, TyG-WC, and TyG-WHtR for psoriasis which will be more helpful in guiding clinical practice.