The influence of baseline platelet on mortality risk in stroke and cancer patients: a cross-sectional analysis of the NHANES database.

Background: Platelet count and function may be closely related to survival and prognosis of stroke and cancer. However, little is known on the impact of platelet count on the patients with a history of stroke and cancer. This study aimed to examine the association between baseline platelet level and all-cause mortality in this population using a cross-sectional analysis.

Methods: Participants with a history of stroke and cancer were selected from the database of the National Health and Nutrition Examination Survey from 2007 to 2018. A maximum selected rank statistic was conducted to determine platelet cutoff with the most significant association with mortality. The association between platelet and mortality was characterized visually using restricted cubic spline (RCS). Weighted multivariable Cox regression models were performed to evaluate the association between platelet count and mortality. Time-dependent receiver operating characteristic (ROC) analysis was conducted to assess the accuracy of platelet count in predicting mortality.

Results: Forty-three (43/113, 38.05%) stroke patients with cancer were alive at a median follow-up of 42 months (interquartile range, 23-74 months). The RCS analysis demonstrated a linear relationship between platelet and mortality (nonlinear, p = 0.352). Mortality in higher-platelet group (> 209 × 10⁹/L, n = 57) was decreased than lower-platelet group (≤ 209 × 10⁹/L, n = 56) (Model 1 HR 0.43, 95% CI 0.24-0.77, p = 0.005) (Model 2 HR 0.58, 95% CI 0.35-0.96, p = 0.03). Subgroup analyses showed no significant interaction between platelet and age, sex, BMI, WBC and neutrophil. The areas under time-dependent ROC curve of the 1-, 2-, 3-, 4- and 5-year survival rates were 0.54, 0.55, 0.57, 0.53, 0.59 for mortality of stroke patients with cancer.

Conclusions: Lower platelet count may be an independent predictor of all-cause mortality in population with a history of stroke and cancer. This result may provide valuable insights for the long-term management in stroke patients with cancer.