Abstract Background: Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm characterized by elevated platelet counts and a predisposition to both thrombotic and hemorrhagic complications. While COVID-19 is independently associated with hypercoagulability and increased morbidity, the impact of coexisting ET on clinical outcomes among hospitalized COVID-19 patients remains poorly understood. Methods: We conducted a retrospective cohort study using the 2016–2022 National Inpatient Sample (NIS) to examine outcomes of patients hospitalized with a primary diagnosis of COVID-19 (ICD-10 U07. 1). Patients with a concurrent diagnosis of essential thrombocythemia (ET; ICD-10 D47. 3) were identified. Discharge weights were applied to generate nationally representative estimates. Baseline characteristics, in-hospital mortality, length of stay (LOS), hospital charges, and thromboembolic complications were compared between ET and non-ET patients. Multivariable logistic and linear regression models were used to adjust for demographics, comorbidities (Charlson Comorbidity Index CCI), and acute complications, including mechanical ventilation, septic shock, and acute kidney injury. Results: Among 5, 934, 565 patients hospitalized with COVID-19, 24, 079 (0. 4%) had ET. Compared to non-ET patients, the ET group was slightly younger (59. 2 vs. 62. 7 years, p0. 001), had a lower mean CCI (1. 5 vs. 2. 0, p0. 001), and a longer average LOS (11. 3 vs. 8. 1 days, p0. 001). ET patients also incurred higher mean hospitalization charges (132, 445 vs. 97, 031, p0. 001). The in-hospital mortality rate was significantly lower in the ET group (9. 6% vs. 11. 3%, p0. 001). After adjustment for confounders, ET was independently associated with decreased odds of mortality (adjusted odds ratio aOR 0. 87, 95% CI 0. 78–0. 98, p=0. 023), reflecting a 12. 9% relative reduction in mortality risk. Despite the lower mortality, ET patients experienced significantly worse thrombotic outcomes. After adjustment, ET was associated with increased odds of several thrombotic complications, including a 65. 3% increase in pulmonary embolism (p0. 001), a 35% increase in ischemic stroke (p=0. 006), and a 203% increase in arterial thrombosis (p0. 001). The risk of transient ischemic attack was marginally higher (4. 5%) but not statistically significant (p=0. 89). Interestingly, ET was associated with a non-significant 13. 2% decrease in the odds of myocardial infarction (p=0. 091). Adjusted analyses also demonstrated an average increase of 2. 91 days in LOS and an additional 24, 621 in total hospital charges for ET patients (p0. 001 for both). Conclusion: In this large, nationally representative cohort, patients with essential thrombocythemia (ET) hospitalized for COVID-19 experienced significantly higher rates of arterial and venous thrombotic complications, prolonged hospital stays, and increased healthcare costs compared to those without ET. Interestingly, ET was independently associated with a modest reduction in in-hospital mortality. This counterintuitive finding may be influenced by residual confounding, differences in baseline comorbidities, or unmeasured variations in clinical management, rather than a true protective effect of ET. These results emphasize the complex clinical profile of ET in the context of COVID-19 and underscore the need for further studies to clarify underlying mechanisms, validate these findings, and inform optimized risk stratification and management strategies for this vulnerable population.
Abdulmoiz Aljafari (Mon,) studied this question.