The impact of body mass index on treatment response to high-dose dexamethasone in adult primary immune thrombocytopenia patients: A two-center retrospective study

High-dose dexamethasone (HDD) is widely used as first-line therapy for immune thrombocytopenia (ITP) and is administered at a fixed dose regardless of body weight. The impact of body mass index (BMI) on treatment response to HDD remains unclear. This retrospective, two-center study included 60 adult patients with newly diagnosed ITP who received HDD as first-line therapy. Demographic characteristics, BMI, baseline laboratory values, and treatment responses at 1, 6, and 12 months were analyzed. BMI was evaluated using cut-off values of 25, 27, and 30. The median number of HDD cycles administered was 1 (range: 1-4), and the median BMI at diagnosis was 27.0 kg/m² (range: 18.0-44.0). No significant differences were observed between BMI categories with regard to treatment responses at months 1 and 6 (p > 0.05 for both). However, at month 12, a complete response (CR) was more likely in patients with BMI < 30, and a partial response (PR) in those with BMI ≥ 30 (p = 0.023). Across all time points, no other demographic or clinical variable emerged as an independent predictor of treatment response (p > 0.05). The results of this study indicate that in newly diagnosed ITP patients receiving HDD as first-line treatment, BMI does not influence early or durable treatment responses, although it may have a modest adverse effect on late response. Larger prospective studies are needed to clarify underlying mechanisms and assess whether obesity-related factors should inform individualized treatment.