Exploratory Pressure Injury Prognostic Index for In-Hospital Mortality and Wound-Related Outcomes in Patients Receiving Negative Pressure Wound Therapy: A Retrospective Cohort Study.

Background: Pressure injuries are common in elderly and immobile patients and are associated with substantial clinical burden and mortality. This study evaluated an exploratory multidimensional prognostic index for in-hospital mortality and wound-related clinical outcomes in patients with advanced pressure injuries receiving negative pressure wound therapy (NPWT). Methods: This retrospective, single-center cohort study included 86 patients with stage III-IV pressure injuries treated with NPWT in a palliative care unit. The Pressure Injury Prognostic Index incorporated age, Nutritional Risk Screening 2002 (NRS-2002), Karnofsky Performance Scale (KPS), and Braden Scale scores. The primary outcome was in-hospital mortality, and the secondary outcome was a pragmatically defined favorable wound-related clinical outcome. Mortality discrimination was evaluated using receiver operating characteristic analysis, direct AUC comparisons, and bootstrap-based assessment of internal optimism. Sensitivity analyses examined alternative NRS-2002 weighting values. Results: Twenty-seven patients (31.4%) died during hospitalization. Each 10-point increase in the index was associated with higher odds of in-hospital mortality (OR 1.71, 95% CI: 1.23-2.37; p = 0.001). The index yielded an AUC of 0.768 (95% CI: 0.659-0.871), with an optimism-corrected bootstrap AUC of 0.765. Its discrimination did not differ significantly from age alone (AUC 0.773; DeLong p = 0.890). The post hoc threshold of 192 yielded 77.8% sensitivity and 72.9% specificity. Mortality was higher among patients with scores ≥192 (56.8% vs. 12.2%), whereas favorable wound-related clinical outcomes were less frequent (45.9% vs. 79.6%). Conclusions: The Pressure Injury Prognostic Index was associated with in-hospital mortality and wound-related clinical outcomes and may provide a multidimensional summary of clinical vulnerability in patients already receiving NPWT. However, it did not demonstrate superior mortality discrimination compared with age alone. The findings remain exploratory, and external validation, formal calibration assessment, and evaluation of clinical utility are required before routine clinical application.