Associations Between Hematologic Parameters and All‐Cause Death in Individuals With Cardio‐Renal–Metabolic Multimorbidity: A National Cohort Study

Background Cardio‐renal–metabolic multimorbidity is common and a major cause of death. This study investigates the associations between hematologic parameters and all‐cause death, aiming to redefine complete blood count reference intervals for individuals with cardio‐renal–metabolic multimorbidity. Methods The study cohort consisted of 4482 adults drawn from the National Health and Nutrition Examination Survey conducted between 1999 and 2018. To assess the associations of hemoglobin concentration, platelet count, white blood cell count, and systemic inflammatory response index with the risk of all‐cause death, multivariable Cox regression and restricted cubic spline regression analyses were used. Subgroup and sensitivity analyses were performed to ensure the robustness of the findings. Results Over a median follow‐up of 71 (36–121) months, 2025 deaths (42%) occurred. After adjusting for potential confounding variables, participants with hemoglobin of ≥13.7 g/dL, platelet count of 228–356×10 3 cells/μL, and white blood cell count of ≤10.1×10 3 cells/μL exhibited a 28% (hazard ratio [HR], 0.72 [95% CI, 0.63–0.81]; P <0.001), 15% (HR, 0.85 [95% CI, 0.74–0.98]; P =0.023), and 19% (HR, 0.81 [95% CI, 0.69–0.96]; P =0.013) reduction in the risk of all‐cause death, respectively. Conversely, participants in the highest systemic inflammatory response index tertile experienced a 52% increased risk of all‐cause death compared with those in the lowest tertile (HR, 1.52 [95% CI, 1.29–1.78]; P <0.001). Conclusions Alterations in hematologic parameters are significantly correlated with all‐cause death in patients with cardio‐renal–metabolic multimorbidity. Keeping these parameters within optimal ranges greatly reduces the mortality rate, highlighting the importance for clinicians managing patients with cardio‐renal–metabolic multimorbidity to closely monitor hematologic changes and implement appropriate interventions.