Derived metabolic indices and poor early response to corticosteroids in adults with primary immune thrombocytopenia: a retrospective cohort study

Objective To evaluate the associations of the pretreatment atherogenic index of plasma (AIP), triglyceride–glucose index (TyG), and log-transformed blood urea nitrogen-to-high-density lipoprotein cholesterol ratio (logBHR) with poor early response to corticosteroid therapy in adults with primary immune thrombocytopenia (ITP). Methods This single-center retrospective cohort study included 259 patients with ITP. Multivariable logistic regression was used to evaluate the associations of AIP, TyG, and logBHR with early treatment response. Three-knot restricted cubic spline models were used to examine the functional forms of the associations. Receiver operating characteristic curve analysis was performed to explore the ability of each derived index to discriminate early treatment response. Results Among the 259 patients, 66 (25.5%) had a poor early response. AIP, TyG, and logBHR levels were higher in nonresponders than in responders. After adjustment for the prespecified covariates, the ORs for day-7 nonresponse per one-unit increase in AIP, TyG, and logBHR were 5.726 (95% CI, 1.711–20.150), 2.105 (95% CI, 1.194–3.780), and 2.331 (95% CI, 1.093–5.075), respectively. Compared with the lowest quartile, the adjusted ORs for the highest quartile were 3.247 (95% CI, 1.384–8.105), 2.363 (95% CI, 1.051–5.531), and 4.272 (95% CI, 1.716–11.560), respectively. Restricted cubic spline analyses showed overall associations of AIP, TyG, and logBHR with day-7 nonresponse ( P for overall association = 0.021, 0.034, and 0.047, respectively), with no clear evidence of nonlinearity ( P for nonlinearity = 0.495, 0.353, and 0.142, respectively). The adjusted models incorporating the corresponding indices yielded AUCs ranging from 0.658 to 0.675. Conclusions To our knowledge, this is the first study linking higher pretreatment AIP, TyG, and logBHR to day-7 nonresponse to corticosteroid therapy in adults with primary ITP. These exploratory findings require prospective validation before clinical application.