Platelet-lymphocyte ratio (PLR) and all-cause mortality in general population: insights from national health and nutrition education survey

Abstract

Platelet lymphocyte ratio (PLR) is a novel marker of inflammation that has gained popularity, especially in prognostication of cardiac diseases and malignant conditions. Several studies have examined the relationship between PLR and disease-specific mortality but none has examined this relationship with all-cause mortality in general population. Therefore, we examined the relationship between PLR and all-cause mortality using data from the National Health and Nutrition Examination Survey (NHANES) from the year 1999 to 2010. The role of PLR in predicting all-cause mortality was evaluated using Cox proportional hazards model adjusting for age, race, gender, smoking history, diabetes, hypertension, serum cholesterol, estimated glomerular filtration rate, serum c-reactive protein, and body mass index. Differential effect of age was examined using difference of differences analysis. Of the 27321 individuals, 2581 died during 171223 person-year follow-up. Mean PLR was significantly higher in participants who died than those who were living at the end of follow-up (145.7 vs. 133.0, respectively, p < 0.001). Individuals in the fourth quartile of PLR were at significantly higher risk of mortality than those in the first quartile (HR = 1.26, 95% CI: 1.08–1.47, p = 0.004 and adjusted HR = 1.33, HR, 95% CI: 1.15–1.54, p < 0.001, respectively). When examining the differential effect of age, association between PLR and mortality was seen in the elderly but not in the middle age or younger participants. Elevated PLR is associated with increased all-cause mortality, especially in the elderly. Further studies examining the mechanism through which PLR may increase mortality are needed.