Timing of Thrombosis with Myeloproliferative Neoplasm Diagnosis Among Veterans and Civilians

Rates of Arterial (AT) and Venous Thrombosis (VT) are increased in Veterans with Myeloproliferative Neoplasms (Vet-MPN), including Essential Thrombocythemia (ET), Polycythemia Vera (PV), and Primary Myelofibrosis (PMF), compared to matched controls (J Clin Oncology 2023 41:16_suppl, 7011). The timing of first AT or VT episode in Vet-MPNs remains undefined when compared to Civilians with MPN (Civ-MPN). These findings could elucidate optimal timing for risk mitigation strategies to prevent thrombotic complications and should help to determine duration of thrombotic risk and need for systemic anticoagulation prophylaxis.

The Veterans Affairs Informatics and Computing Infrastructure (VINCI) database was queried from January 1, 2006 to January 26, 2023 to identify Vet-MPNs, AT, and VT through ICD-9 and -10 codes. This process yielded 2,752 Vet-MPN and 583,803 Veterans without MPN from Illinois, the state most representative of the US population. These cohorts were compared to data derived from a retrospective chart review of Civ-MPN cared for between January 1, 2019 to December 31, 2022, at MedStar Georgetown University Hospital and MedStar Washington Hospital Center. Service-Connected Exposures (SCE) to potential carcinogens among Veterans were verified through their duration and location of service. We subdivided time to first AT and VT from MPN diagnosis as follows: more than 3 months prior to MPN diagnosis, within 3 months of diagnosis, 3 months to 1 year post diagnosis, 1 to 5 years, and more than 5 years after MPN diagnosis. Mean data from various cohorts were analyzed utilizing Fisher's exact test.

Vet-MPN experienced a statistically higher incidence of AT compared to Civ-MPN (p=.0019) and Civ-MPN experienced a statistically higher incidence of AT compared to Veterans without MPN (p=0.02) which served as a control. In contrast, there was a higher incidence of VT among both Vet- and Civ-MPN cohorts compared to Veterans without MPN (p<.0001) (Table 1).

The mean ages at MPN diagnosis and onset of first AT were similar (≥63 years) in both Civ- and Vet-MPN. In contrast, the mean age of MPN diagnosis and age of first VT were considerably earlier for Civ-MPN (51 years) versus both Vet-MPN with VT and Veterans without MPN with VT (≥67 years).

There was a higher prevalence of hypertension, hyperlipidemia, diabetes, heart failure, and smoking among Veterans with or without MPN compared to Civ-MPN with either AT or VT (Table 1). A trend toward statistical significance was observed for the presence of hypertension and hyperlipidemia (p=0.049 and p=0.02, respectively) in Vet-MPN compared to Civ-MPN, while Veterans without MPN had a statistically higher prevalence of hyperlipidemia (p=0.02) and heart failure (p=0.001) in AT. Notably, a trend toward statistical significance in VT was observed for the presence of diabetes among all Veterans with or without MPN compared to Civ-MPN (p=0.01 and p=0.007, respectively).

There was a biphasic distribution in time to onset of first AT and VT in all Vet- and Civ-MPN cohorts (Figure 1). There was a higher cumulative incidence of first AT and VT in Vet-MPN at more than 3 months prior to MPN diagnosis compared to Civ-MPN with AT and VT (Figure 1).

On the other hand, the Civ-MPN cohort had a late surge of first VT more than 5 years after MPN diagnosis compared to the other MPN cohorts.

A biphasic distribution in time to onset of first AT and VT was also observed among the Vet-MPN cohort when stratified by SCEs from World War II, the Korean War, the Vietnam War, and the Gulf War. The vast majority of both AT and VT in Vet-MPN from all SCE examined experienced onset of thrombotic events more than 3 months prior to MPN diagnosis. Most VT in Gulf War Vet-MPN occurred within 3 months of MPN diagnosis.

In conclusion, the predominant risk for developing thrombotic complications in MPN, particularly in Vet-MPN, occurs in a biphasic pattern, beginning more than 3 months prior to MPN diagnosis and becoming apparent again at more than 5 years after MPN diagnosis. These findings suggest that the MPNs convey an enduring hypercoagulability potential throughout the natural history of the disease. There appears to be an accelerated onset of thrombotic complications earlier in the course of disease in Vet-MPN, perhaps reflecting their SCE with toxic carcinogens. More work is necessary to determine epigenetic influences on MPN natural history.