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

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 × 109/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.