Immature platelet fraction predicts differential platelet recovery trajectories in dengue fever: A longitudinal analysis

Summary Dengue commonly causes thrombocytopenia, but platelet count alone may not reflect marrow thrombopoiesis. Immature platelet fraction (IPF) is a potential marker of platelet regeneration, though longitudinal data are limited. We thus aimed to evaluate whether Day 1 IPF predicts subsequent platelet recovery trajectory and to describe longitudinal trends in clinical, biochemical and platelet indices. This was a retrospective longitudinal analytical study conducted at a tertiary care hospital in Western Maharashtra, India. Six hundred and sixty‐seven patients with confirmed dengue, with platelet count, IPF and World Health Organization (WHO) classification recorded on Day 1, with follow‐up at Day 3 and 5. Log‐transformed platelet counts at Day 3 and Day 5 were analysed using generalized least squares regression. Longitudinal changes were assessed using the Friedman test. Median age was 31 years, with 81.4% males. Platelet counts declined from 118 to 98 × 10 9 /L ( p = 0.0017), while IPF increased from 9.7% to 12.9% ( p < 0.0001). Higher baseline IPF predicted faster platelet recovery ( p < 0.0001). Continued platelet decline at Day 5 was lower in the high‐IPF group than the low‐IPF group (28.6% vs. 47.8%; Kruskal–Wallis p = 0.013). We thus conclude that IPF is a dynamic biomarker that predicts platelet recovery trajectory in dengue.