Association between C-reactive protein-triglyceride glucose index and depressive symptoms in American adults: results from the NHANES 2005 to 2010.

Background: The novel serum C-reactive protein-triglyceride glucose index (CTI) has been identified as an ideal parameter that integrates inflammation and insulin resistance, which are potential mechanisms underlying depressive symptoms. Our research aimed to investigate the association between CTI and depressive symptoms.

Methods: Our cross-sectional investigation utilized data from the National Health and Nutrition Examination Survey conducted between 2005 and 2010. The integrated CTI was calculated as 0.412 × Ln (C-reactive protein) (mg/dL) + Ln [triglyceride (mg/dL) × fasting glucose (mg/dL)/2]. The severity of depressive symptoms was evaluated through the continuous Patient Health Questionnaire-9 (PHQ-9) scores, and the categorical definition of depressive symptoms (PHQ-9 score ≥ 10) reflected moderate to severe symptoms. Survey-weighted linear and logistic regression models were conducted to establish the correlation between CTI and PHQ-9 scores, and between CTI and depressive symptoms. Moreover, subgroup analyses, interaction tests, and smoothed curve fitting were performed to scrutinize the steadiness of the results.

Results: A total of 5,954 participants were enrolled in our study, including 477 with depressive symptoms and 5,477 without. The results revealed a significant positive relationship between CTI and PHQ-9 scores (β: 0.40, 95% CI: 0.25,0.55, p < 0.001) and depressive symptoms (OR: 1.30, 95% CI: 1.06,1.61, p = 0.02). Additionally, individuals in the fourth quartile of CTI exhibited a higher likelihood of depressive symptoms than those in the first quartile (PHQ-9 score: β: 0.83, 95% CI: 0.39,1.26, p < 0.001; depressive symptoms: OR: 2.00, 95% CI:1.19,3.36, p = 0.01). Smooth curve fitting and subgroup analyses consistently demonstrated the positive relationship.

Conclusions: Elevated CTI was correlated with a higher risk of depressive symptoms, underscoring CTI as a potential clinical indicator for identifying and stratifying depressive symptoms.

Clinical Trial Number: Not applicable.