Pan-immune-inflammation value as a predictor of loss of ambulation in duchenne muscular dystrophy: a retrospective cohort study

Duchenne muscular dystrophy (DMD) is a progressive X-linked neuromuscular disorder marked by early functional decline and considerable variability in the timing of loss of ambulation (LOA). Readily accessible biomarkers to predict this decline remain limited. The pan-immune-inflammation value (PIV), derived from routine blood counts, has been studied in various inflammatory conditions, but its relevance in DMD is not yet well defined. This retrospective cohort study included 86 children and adolescents with genetically or biopsy-confirmed DMD followed between 2010 and 2025. Baseline neutrophil, lymphocyte, monocyte and platelet counts were used to calculate PIV and other systemic inflammation indices (NLR, PLR, MLR, SII, SIRI). Fifty-two patients (60.5%) experienced LOA during follow-up. Those who developed LOA had significantly higher neutrophil (4.6 ± 1.8 vs. 3.4 ± 1.2 × 10⁹/L, p = 0.001), monocyte (0.58 ± 0.20 vs. 0.46 ± 0.14 × 10⁹/L, p = 0.006) and platelet counts (351 ± 82 vs. 308 ± 65 × 10⁹/L, p = 0.02), along with lower lymphocyte counts (2.7 ± 0.8 vs. 3.4 ± 0.7 × 10⁹/L, p < 0.001). Median PIV was higher in the LOA group (312.5 [256–412] vs. 158.7 [106–209], p < 0.001). In ROC analysis, PIV showed the highest discriminative performance (AUC = 0.84; 95% CI, 0.76–0.91) compared with NLR, PLR, MLR, SII and SIRI. In multivariable Cox regression, PIV was independently associated with earlier LOA (HR = 1.42 per 100-unit increase; 95% CI, 1.18–1.72; p < 0.001). Age-stratified analyses suggested a stronger association between elevated PIV and earlier LOA in younger children (2–6 and 7–9 years; p = 0.006 and p = 0.018), whereas this association did not reach statistical significance in patients aged ≥ 10 years. In this cohort, PIV was significantly associated with loss of ambulation and demonstrated higher discriminative performance than other hematologic inflammation indices. The observed age-dependent pattern suggests that elevated PIV at younger ages may be linked to early inflammatory activity relevant to disease progression. However, given the retrospective design, exploratory subgroup analyses, and the multifactorial nature of DMD, these findings should be interpreted with caution. PIV may represent an adjunctive and accessible marker for early risk stratification, but larger prospective studies with longitudinal inflammatory assessment are required to validate its prognostic value and clarify its role in clinical practice.