Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access
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Letter to the Editor

Volume 6, Number 5, October 2014, pages 395-397

Secondary Polycythemia and the Risk of Venous Thromboembolism


Table 1. Secondary Polycythemia and the Risk of Venous Thromboembolism in Adults
Author, yearStudy groups (N)Age in yearsEtiology of PCTDefinition of PCTAverage HCTOutcomesStrengthLimitation
CHD: congenital heart disease; Comp: compensated; COPD: chronic obstructive pulmonary disease; DVT: deep venous thrombosis; HCT: hematocrit; Hgb: hemoglobin; N: number of patients; NS: not significant; PCT: polycythemia; PE: pulmonary embolism; PV: polycythemia vera; RBC: red blood cell; SP: secondary polycythemia; Uncomp: uncompensated; VTE: venous thromboembolism. All studies, except by Ristic et al [4], were retrospective. *The study included patients who presented with respiratory distress, and were found to have elevated D-dimer. †Obesity was identified as a possible risk factor for venous thromboembolism in secondary polycythemia. ‡A 28-year-old female with iron-deficient polycythemia had four episodes of amaurosis fugax during few months when hematocrit level ranged between 63% and 73%. §In smoking-related secondary polycythemia, there was only one venous thromboembolism and 11 arterial events (myocardial infarction, stroke or transient ischemic attacks). Risk of venous thromboembolism was 4% vs. 21% in secondary polycythemia compared to polycythemia vera. The incidence of recurrent events was higher in polycythemia vera compared to secondary polycythemia (28% vs. 7%). Within secondary polycythemia, patients who had an event had lower hematocrit and platelet count than those who did not have an event.
Ristic et al, 2013 [4]PCT (100) vs. non-PCT (262)66 vs. 63COPD/respiratory failureHCT > 50%58% vs. 40%PE 39% vs. 11% (P < 0.001); DVT 5% vs. 4% (P = 0.87)Only prospective studyInclusion criteria,* unmatched groups, smoking habits not assessed
Nadeem et al, 2013 [1]PCT (86) vs. non-PCT (86)68 vs. 68COPDHCT ≥ 50% on two occasions53% vs. 43%VTE 19% vs. 14% (P = 0.42) †Well-matched groupsNo data on the use of phlebotomy
Perloff et al, 1993 [2]Comp (101) vs. Uncomp (11) PCT36 (19 - 74)Cyanotic CHDHCT > 45%57% vs. 69%Stroke 0% ‡High-risk patients with hyperviscosity symptoms; long follow-upPhlebotomy at 3 - 6 months interval for symptom relief (20% vs. 80%)
Schwarcz et al, 1993 [5]SP (27) vs. PV (43)55 vs. 59Smoking vs. PVIncreased RBC volume59% vs. 59%Arterial or venous thrombosis 41% vs. 60% (P < 0.05) §PV is more hypercoagulable than SPDiagnostic criteria, smoking as a confounder
Lubarsky et al, 1991 [3]PCT (100) vs. non-PCT (100)57 vs. 60COPDHgb > 16 g/dLHgb 17 vs. 13 g/dLArterial or venous thrombosis 0% vs. 3%; (P = NS)No thrombotic complications even during surgeryFollow-up limited to 30 days postoperatively; significant postoperative blood loss in 25% patients with PCT