Presentation Details
| Validating the JAKPOT prediction rule for identifying which patients with erythrocytosis are unlikely to have a JAK2 mutation Kevin O'Sullivan1, Roosevelt Lu1, Jason A Freed1, George Goshua2, Justine Ryu2, Rushad Patell1, Barbara D Lam1. 1Beth Israel Deaconess Medical Center, Boston, MA, USA.2Yale Medical Center, New Haven, CT, USA |
Abstract
Background: Erythrocytosis has many causes, including Polycythemia Vera (PV). PV, a type of myeloproliferative neoplasm (MPN), is often driven by a JAK2 mutation and associated with an increased risk of thrombosis. The prediction rule JAKPOT was developed in 2022 to determine which patients with erythrocytosis benefit from JAK2 testing. Patients who met zero criteria (red blood cell count >6.45x1012/L, platelets >350x109/L, and neutrophils >6.2x109/L) were JAKPOT “low-risk” for harboring a JAK2 mutation. JAKPOT has not yet been externally validated. Aims: Externally validate the JAKPOT rule on a cohort of 2000 patients at a tertiary care center in Boston, Massachusetts, USA. Methods: Demographics and laboratory data for 2000 random patients with JAK2 testing were extracted from the hospital data warehouse. Manual chart review identified patients who met inclusion criteria (those evaluated for erythrocytosis who had same-day JAKPOT variables available) and those who met exclusion criteria (a known diagnosis of MPN). Negative predictive value (NPV) was calculated using Python version 3.9. Results: Of 2000 patients, 1502 were excluded (1113 referred for reasons other than erythrocytosis, 247 missing same-day JAKPOT variables, 87 known MPN diagnoses, 55 cancelled tests). Validation of JAKPOT on the remaining 498 patients demonstrated a 98.5% NPV (95% CI: 0.97-0.99). Of the 53 patients found to have a JAK2 mutation, 48 met at least one JAKPOT criteria and all were diagnosed with PV or a PV/Essential Thrombocythemia overlap syndrome. Of the 5 patients with JAK2 mutation who met zero JAKPOT criteria and were incorrectly deemed “low-risk”, all were ultimately diagnosed with PV. Conclusion: The JAKPOT rule is effective at identifying patients with erythrocytosis who are at low risk of harboring a JAK2 mutation. Next steps include expanding the validation cohort to other institutions and conducting a cost-effectiveness analysis.
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