Association between extremely high prognostic nutritional index and all-cause mortality in patients with coronary artery disease: secondary analysis of a prospective cohort study in China

Objectives Decreased prognostic nutritional index (PNI) was associated with adverse outcomes in many clinical diseases. This study aimed to evaluate the relationship between baseline PNI value and adverse clinical outcomes in patients with coronary artery disease (CAD). Design The Personalized Antiplatelet Therapy According to CYP2C19 Genotype in Coronary Artery Disease (PRACTICE) study, a prospective cohort study of 15 250 patients with CAD, was performed from December 2016 to October 2021. The longest follow-up period was 5 years. This study was a secondary analysis of the PRACTICE study. Setting The study setting was Xinjiang Medical University Affiliated First Hospital in China. Participants Using the 50th and 90th percentiles of the PNI in the total cohort as two cut-off limits, we divided all participants into three groups: Q1 (PNI <51.35, n = 7515), Q2 (51.35 ≤ PNI < 59.80, n = 5958) and Q3 (PNI ≥ 59.80, n = 1510). The PNI value was calculated as 10 × serum albumin (g/dL) + 0.005 × total lymphocyte count (per mm 3 ). Primary outcome The primary outcome measure was mortality, including all-cause mortality (ACM) and cardiac mortality (CM). Results In 14 983 participants followed for a median of 24 months, a total of 448 ACM, 333 CM, 1162 major adverse cardiovascular events (MACE) and 1276 major adverse cardiovascular and cerebrovascular events (MACCE) were recorded. The incidence of adverse outcomes was significantly different among the three groups (p <0.001). There were 338 (4.5%), 77 (1.3%) and 33 (2.2%) ACM events in the three groups, respectively. A restricted cubic spline displayed a J-shaped relationship between the PNI and worse 5-year outcomes, including ACM, CM, MACE and MACCE. After adjusting for traditional cardiovascular risk factors, we found that only patients with extremely high PNI values in the Q3 subgroup or low PNI values in the Q1 subgroup had a greater risk of ACM (Q3 vs Q2, HR: 1.617, 95% CI 1.012 to 2.585, p=0.045; Q1 vs Q2, HR=1.995, 95% CI 1.532 to 2.598, p <0.001). Conclusion This study revealed a J-shaped relationship between the baseline PNI and ACM in patients with CAD, with a greater risk of ACM at extremely high PNI values. Trial registration number NCT05174143 .