Risk of Wernicke’s Encephalopathy in Patients with Myeloproliferative Neoplasm

Background :Wernicke’s encephalopathy (WE) is an acute neuropsychiatric syndrome resulting from thiamine deficiency. This neurological deterioration is potentially dangerous because it predisposes the patient to hypothermia and decreased immunity. Cancer patients are at high risk of WE due to chronic malnutrition, chemotherapy-induced nausea and vomiting, and consumption of thiamine by rapidly growing tumors. Very little published research addresses the risk of WE in patients with myeloproliferative neoplasm (MPN).

Objectives: To estimate the incidence of WE among patients with MPN, and compare it with those without MPN.

Methods: Patients with a diagnosis of MPN, including polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) were identified from 1/1/2003 to 03/31/2013 using the US MarketScan database. The control cohort consisted of a random sample matched to the MPN cohort by age and gender in a 1:1 ratio. Diagnosis of WE was ascertained using ICD-9-CM 265.0, 265.1, 291.1, 294.0 or J code J3411. The two study cohorts were followed for WE from the index date. Cox proportional hazards modeling was used to compare the rates between two cohorts and also control for confounding variables.

Results: A total of 39,761 MPN patients, including PV (51%), ET (42%), post-PV MF (0.2%), post-ET MF (1%), and PMF (2.8%) were identified. Approximately 27% of them were > 65 years of age, and 51% were male. Patients with MPN had higher rates of WE, compared to those without MPN (MPN vs. non-MPN: 1.09 vs. 0.39/1000 person-year, hazard ratio = 2.19, 95% confidence interval 1.43-3.34). The incidence rate of WE was higher in males (male vs. female: 0.93 vs. 0.55/1000 person-year). No specific pattern was observed in age subgroups for both cohorts (e.g. MPN: age <18 vs. 18-39 vs. 40-49 vs. 50-59 vs. 60-69 vs. >70 = 0 vs. 0.85 vs. 1.09 vs. 1.16 vs. 0.72 vs. 0.86/1000 person-year).

Conclusions: Patients with MPN had higher incidence rates of WE, compared to those without MPN. Given the potentially dangerous outcomes associated with WE, physicians who care for patients with MPN should be aware of the risk of WE in this population.