AI Insight
This retrospective cohort study of 144 non-diabetic patients with fibrotic lung disease receiving antifibrotic therapy examined whether the triglyceride-glucose (TyG) index, a marker of insulin resistance, predicts mortality over a median follow-up of 33.8 months. The TyG index showed no significant association with all-cause mortality in multivariable analysis, while lower forced vital capacity and greater smoking exposure were associated with increased mortality. The study suggests that within the non-diabetic range, the TyG index may have limited prognostic value in this specific patient population, though the restricted metabolic variability and modest sample size may have limited detection of smaller effects.
Why it matters
The findings indicate that the TyG index, despite being a useful metabolic marker in other diseases, may not serve as a reliable prognostic tool for non-diabetic patients with fibrotic lung disease on antifibrotic therapy. This helps clinicians focus on established prognostic indicators like pulmonary function tests rather than metabolic markers when assessing these patients.
Understand the Science
by Aysegul Erinc, Ali Kirac, Fatma Ezgi Altun Acar, Abdullah Cagri Onal, Erdogan Cetinkaya
Introduction
Fibrotic lung diseases are associated with significant morbidity and mortality, with a rising prevalence. Prognostic indicators for these diseases include thoracic computed tomography (CT) findings and pulmonary function test (PFT) measures. The triglyceride-glucose (TyG) index, a fasting triglyceride- and glucose-derived surrogate marker of insulin resistance, has been associated with several clinical outcomes; however, its relationship with pulmonary function and all-cause mortality within the non-diabetic range in patients with fibrotic lung disease remains inadequately studied. This study aimed to investigate the association between variability in the TyG index within the non-diabetic range, baseline pulmonary function measures, and all-cause mortality in patients with fibrotic lung disease receiving antifibrotic therapy.
Methods
This retrospective cohort study was conducted on 144 patients with fibrotic lung disease who received antifibrotic therapy between 1 January 2015 and 1 June 2023. Demographic data, comorbidities, smoking status, PFT measures, fasting glucose, triglyceride levels, and survival data were collected. The TyG index was calculated using the formula: Ln [(fasting triglycerides (mg/dL) × fasting glucose (mg/dL)) / 2]. Survival time was calculated from initiation of antifibrotic therapy to death from any cause or last clinical follow-up, with a median follow-up duration of 33.8 months.
Results
The mean age of the cohort was 67.4 years, and 31.9% of the patients were female. The mean TyG index was 8.78. During follow-up, 54 of 144 patients (37.5%) died. In the multivariable Cox regression analysis, the TyG index was not significantly associated with all-cause mortality (adjusted HR = 0.80, 95% CI: 0.40–1.60, p = 0.54). Lower FVC% and greater cumulative smoking exposure were associated with all-cause mortality in the adjusted model.
Conclusions
In this selected cohort of non-diabetic patients with fibrotic lung disease receiving antifibrotic therapy, the TyG index was not significantly associated with all-cause mortality. No consistent association with baseline pulmonary function measures was observed, apart from a weak exploratory inverse correlation with DLCO. However, the restricted metabolic variability and limited statistical precision of the cohort may have reduced the ability to detect modest but potentially clinically meaningful associations. Further prospective studies are needed to clarify the potential prognostic relevance of the TyG index in broader fibrotic lung disease populations.