The prognostic value of the prognostic nutritional index for short- and long-term outcomes in coronary care unit patients

Systemic inflammation is associated with the outcomes of coronary care unit (CCU) patients. We sought to assess the prognostic implication of the prognostic nutritional index (PNI), a surrogate marker of inflammation in CCU patients. The study included 1,158 participants from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database and 342 from the Second Affiliated Hospital of Wenzhou Medical University (WMU), participants were subsequently grouped based on the PNI threshold. Key endpoints were 30-day mortality and major adverse cardiovascular events (MACEs) at 1-year follow-up and were examined with propensity score matching (PSM) and Cox regression analysis. The prognostic implications of PNI and other inflammatory markers were compared using an area under the curve (AUC). A total of 285 participants in the MIMIC-IV cohort developed 30-day mortality, and 139 developed MACEs in WMU, of which 103 (30.12%) died, 19 (5.56%) experienced non-fatal myocardial infarction, and 29 (8.48%) experienced non-fatal stroke. PNI was significantly associated with short-term mortality (HR adjusted 0.64, 95% CI: 0.48–0.87; HR PSM 0.62, 95% CI: 0.42–0.92) and MACEs (HR adjusted 0.56, 95% CI: 0.36–0.87; HR PSM 0.44, 95% CI: 0.23–0.88). PNI exhibited a negative correlation with the C-reactive protein (CRP)/NRS-2002 score according to Spearman’s analysis. Notably, PNI exhibited a slightly higher AUC (0.70) than other inflammatory markers, although the difference was modest. Adding PNI to sequential organ failure assessment yielded an AUC of 0.818, marginally higher than SOFA alone (AUC = 0.805; P < 0.05), suggesting a modest but statistically significant improvement in discrimination. PNI emerges as a potential prognostic marker for anticipating adverse outcomes in CCU patients, the intrinsic cause may attribute to malnourished status and inflammation.