Clinical outcomes and predictors of mortality in patients with essential thrombocytosis and concurrent myocardial infarction: A nationwide analysis

Abstract

Abstract Introduction: Essential thrombocytosis (ET) is a myeloproliferative neoplasm associated with an increased risk of both arterial thrombosis and bleeding. Acute myocardial infarction (MI) in ET is rare, and real-world data on outcomes and management remain limited. Thus, we aim to examine the clinical characteristics, outcomes, and predictors of mortality in patients hospitalized with ET and concurrent MI using a National Inpatient Sample (NIS) database. Methods: We conducted a retrospective analysis of the NIS database from 2015 to 2022. The Institutional Review Board (IRB) approval was not mandatory since the NIS contains deidentified data. We compared demographics, comorbidities, hospital outcomes, complications, and cost metrics between the ET+MI and ET-only groups. The primary outcome was in-hospital mortality, and the secondary outcomes were length of stay (LOS), total hospital charges (THC), and in-hospital complications. All statistical analyses were done using STATA version 17.0. Multivariate analyses were conducted to assess independent predictors of in-hospital mortality. Results: We identified a cohort of 3,625 adult patients hospitalized with ET from 2015 to 2022. Among these, 165 patients (4.6%) had a concurrent diagnosis of MI. Patients within the ET+MI group were more frequently male (60% vs. 41%, p = 0.0286) and aged over 70 years (49% vs. 37%, p = 0.42), though age distribution did not reach statistical significance. The ET+MI group demonstrated a significantly greater comorbidity burden, with fewer patients having a Charlson Comorbidity Index (CCI) of 0–3 compared to the ET-only group (64% vs. 85%, p = 0.001); they demonstrated significantly higher prevalence of congestive heart failure (6.9% vs. 3.02%, p < 0.0003) and chronic kidney disease (33% vs. 13%, p < 0.001). No significant differences were observed in racial distribution, primary payer status, or ZIP income quartile. A detailed comparison of in-hospital complications showed that acute kidney injury (AKI) occurred more frequently in the ET+MI group (30% vs. 13.4%, p < 0.008); the rates of other complications, including cardiogenic shock, pulmonary edema, respiratory failure, stroke, hemorrhagic stroke, tamponade, pneumonia, bleeding, sepsis, and delirium, did not differ significantly. Despite a higher complication rate and comorbidity burden, there were no in-hospital deaths observed among the ET+MI group. Furthermore, hospital resource use was significantly higher in the ET+MI cohort, with a mean LOS of 5.24 days (95% CI: 3.45–7.03) and a higher mean THC of $56,737 (95% CI: $35,276–$78,198). Multivariate analysis identified increasing age (OR: 1.08, 95% CI: 1.04–1.13, p < 0.001), higher CCI (OR: 1.64, 95% CI: 1.19–2.75, p = 0.003), race (Asian/Pacific Islander: OR: 21.63, p = 0.026), and primary payer (private insurance: OR: 36.45, p = 0.007) as independent predictors of in-hospital mortality across the entire ET cohort. However, upon performing Firth logistic regression to account for the rarity of mortality events, we found that none of the evaluated variables, including age, race, MI, or comorbidity burden, were statistically significant. Conclusion: Our findings suggest that although patients with ET and MI present with greater comorbidities and require higher healthcare utilization, they do not experience an increase in in-hospital mortality. The Firth model did not reveal any significant predictors of mortality, highlighting the rarity of in-hospital death in this population. This result also points out the limitations of standard regression approaches in low-event datasets. Future studies should utilize larger, longitudinal datasets and incorporate disease-specific clinical variables to better evaluate long-term outcomes in ET patients.