External Validation of the JAKPOT Score for Diagnosing JAK2-Positive Erythrocytosis: A Retrospective Cohort Study †
Abstract
1. Introduction
2. Methods and Materials
2.1. Study Population
2.2. Data Extraction and Laboratory Assays
2.3. Outcomes
2.4. Statistical Analysis
3. Results
3.1. Performance of Low EPO or JAKPOT to Diagnose JAK2-Positive Erythrocytosis
3.2. Performance of EPO-JAKPOT to Diagnose JAK2-Positive Erythrocytosis
3.3. Univariate Predictors of JAK2-Positive Erythrocytosis
3.4. Adjusted (Multivariate) Predictors of JAK2-Positive Erythrocytosis
4. Discussion
Supplementary Materials
Author Contributions
Funding
Institution Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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All Patients (n = 213) | JAK2 Positive (n = 40) | JAK2 Negative (n = 173) | p Value (Nominal) | p Value (Corrected *) | |
---|---|---|---|---|---|
Age, years (mean [SD]) | 57.7 (15.2) | 66.1 (11.4) | 54 (15.7) | <0.01 | <0.01 |
Male (N [%]) | 163 (69%) | 22 (55%) | 123 (71%) | 0.08 | 1.0 |
BMI, kg/m2 (mean [SD]) | 33.0 (7.9) | 28.4 (4.6) | 32.9 (8.5) | <0.01 | 0.09 |
Weight, kg (mean [SD]) | 91.4 (19.5) | 84.1 (15.1) | 93.2 (20.2) | 0.02 | 0.42 |
Comorbidities | |||||
OSA (N [%]) | 45 (21%) | 3 (8%) | 42 (24%) | 0.02 | 0.34 |
COPD (N [%]) | 18 (8%) | 3 (8%) | 15 (9%) | 1.00 | 1.0 |
Current smoking (N [%]) | 65 (30%) | 4 (10%) | 61 (35%) | <0.01 | 0.03 |
Prior history of smoking (N [%]) | 52 (23%) | 10 (25%) | 42 (24%) | 1.0 | 1.0 |
Any VTE (N [%]) | 17 (8%) | 6 (16%) | 11 (6%) | 0.10 | 1.0 |
Acute coronary syndrome (N [%]) | 16 (8%) | 4 (10%) | 12 (7%) | 0.51 | 1.0 |
Ischemic stroke (N [%]) | 5 (2%) | 2 (5%) | 3 (2%) | 0.24 | 1.0 |
Peripheral arterial disease (N [%]) | 3 (1%) | 1 (3%) | 2 (1%) | 0.47 | 1.0 |
Chronic kidney disease (N [%]) | 3 (1%) | 1 (3%) | 2 (1%) | 1.00 | 1.0 |
Cancer (N [%]) ** | 1 (0.5%) | 1 (3%) | 0 (0%) | 0.19 | 1.0 |
Medications | |||||
Any diuretic (N [%]) | 42 (20%) | 4 (10%) | 38 (22%) | 0.12 | 1.0 |
SGLT2 Inhibitor (N [%]) | 10 (5%) | 0 (0%) | 10 (6%) | 0.21 | 1.0 |
Testosterone (N [%]) | 21 (9%) | 1 (2.5%) | 20 (12%) | 0.14 | 1.0 |
Any antiplatelet (N [%]) | 57 (27%) | 14 (35%) | 43 (25%) | 0.23 | 1.0 |
Any anticoagulant (N [%]) | 23 (11%) | 6 (15%) | 17 (10%) | 0.40 | 1.0 |
Laboratory parameters | |||||
EPO, mU/mL (mean [SD]), reference interval 3.8–16.9 | 10.7 (11.1) | 4.4 (1.4) | 12.3 (12.3) | <0.01 | <0.01 |
Hemoglobin, g/L (mean [SD]), reference interval: 115–180 | 174 (16.3) | 179 (20.1) | 172 (14.7) | 0.05 | 0.83 |
Hematocrit, L/L (mean [SD]), reference interval 0.37–0.54 | 0.52 (0.05) | 0.56 (0.06) | 0.51 (0.05) | <0.01 | <0.01 |
Absolute red blood cells, 109 cells/L (mean [SD]), reference interval 3.8–6.5 | 5.8 (0.74) | 6.4 (0.98) | 5.7 (0.60) | <0.01 | <0.01 |
Platelets, 109 cells/L (mean [SD]), reference interval 150–400 | 279.1 (158.1) | 461.0 (217.4) | 236.9 (103.0) | <0.01 | <0.01 |
Absolute neutrophils, 109 cells/L (mean [SD]), reference interval 2.0–7.5 | 6.0 (4.5) | 8.5 (8.0) | 5.5 (2.9) | 0.02 | 0.42 |
Ferritin, μg/L (mean [SD]), reference interval 30–100 | 151.3 (181.7) | 63.1 (75.9) | 170.6 (192.2) | <0.01 | <0.01 |
Imaging studies | |||||
Spleen size, cm (mean [SD]) 71 patients | 12.0 (2.5) | 13.7 (3.0) | 11.4 (2.1) | 0.01 | 0.19 |
Liver size, cm (mean [SD]) 71 patients | 16.7 (2.3) | 16.1 (2.9) | 16.9 (2.2) | 0.37 | 1.0 |
Number of Patients (N [%]) | JAK2+ (N [%]) | Sensitivity (95% CI) | Specificity (95% CI) | Negative Likelihood Ratio (95% CI) | Positive Likelihood Ratio (95% CI) | |
EPO | ||||||
Low (<3.8 mU/mL) | 35 (16%) | 31 (88%) | 0.77 (0.62–0.87) | 0.98 (0.94–0.99) | 0.23 (0.13–0.41) | 33 (12.5–89.6) |
Normal (3.8–16.9 mU/mL) | 150 (70%) | 9 (6%) | ||||
High (>16.9 mU/mL) | 28 (13%) | 0 (0%) | ||||
JAKPOT * | ||||||
Positive | 95 (45%) | 35 (36%) | 0.88 (0.73–0.94) | 0.65 (0.57–0.72) | 0.19 (0.08–0.44) | 2.5 (2.0–3.2) |
Negative | 118 (55%) | 5 (4%) | ||||
EPO-JAKPOT ** | ||||||
Positive | 98 (46%) | 38 (39%) | 0.95 (0.83–0.98) | 0.66 (0.58–0.72) | 0.07 (0.02–0.30) | 2.7 (2.2–3.4) |
Negative | 115 (54%) | 2 (2%) |
Odds for JAK2-Positive Erythrocytosis (95% CI) | p Value | |
---|---|---|
Age (years) | 1.10 (1.04–1.16) | <0.01 |
Male sex | 1.12 (0.28–4.37) | 0.88 |
EPO (mU/mL) | 0.50 (0.32–0.76) | <0.01 |
ANC (109 cells/L) | 1.06 (0.84–1.33) | 0.63 |
RBC (109 cells/L) | 1.69 (0.61–4.63) | 0.31 |
Platelets (109 cells/L) | 1.01 (1.00–1.01) | <0.01 |
Ferritin (μg/L) * | 0.99 (0.98–1.00) | 0.06 |
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Senecal, J.B.; Madan, Y.; Tahir, R.; Rajkumar, S.; Lim, W.; Crowther, M.; Mithoowani, S. External Validation of the JAKPOT Score for Diagnosing JAK2-Positive Erythrocytosis: A Retrospective Cohort Study. J. Clin. Med. 2025, 14, 5173. https://doi.org/10.3390/jcm14155173
Senecal JB, Madan Y, Tahir R, Rajkumar S, Lim W, Crowther M, Mithoowani S. External Validation of the JAKPOT Score for Diagnosing JAK2-Positive Erythrocytosis: A Retrospective Cohort Study. Journal of Clinical Medicine. 2025; 14(15):5173. https://doi.org/10.3390/jcm14155173
Chicago/Turabian StyleSenecal, Justin Bruni, Yasmine Madan, Rabia Tahir, Sabina Rajkumar, Wendy Lim, Mark Crowther, and Siraj Mithoowani. 2025. "External Validation of the JAKPOT Score for Diagnosing JAK2-Positive Erythrocytosis: A Retrospective Cohort Study" Journal of Clinical Medicine 14, no. 15: 5173. https://doi.org/10.3390/jcm14155173
APA StyleSenecal, J. B., Madan, Y., Tahir, R., Rajkumar, S., Lim, W., Crowther, M., & Mithoowani, S. (2025). External Validation of the JAKPOT Score for Diagnosing JAK2-Positive Erythrocytosis: A Retrospective Cohort Study. Journal of Clinical Medicine, 14(15), 5173. https://doi.org/10.3390/jcm14155173