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ORIGINAL ARTICLE
Year : 2021 | Volume
: 46
| Issue : 2 | Page : 70-74
Pulmonary hypertension as a risk factor in JAK2-positive polycythemia rubra vera
Shaimaa A Ahmed1, Alaa Rashad2, Asmaa Nafady MD 3, Asmaa Y Shazly4, Areej Alkhateeb5, Mohamed A Elsenbesya6
1 Haematology Unit, Department of Internal Medicine, Faculty of Medicine, South Valley University, Qena, Egypt
2 Department of Chest Diseases and Tuberculosis, Faculty of Medicine, South Valley University, Qena, Egypt
3 Department of Clinical Pathology, Faculty of Medicine, Assiut University, Assiut; Department of Clinical and Chemical Pathology, Qena Faculty of Medicine, South Valley University, Qena, Egypt
4 Department of Internal Medicine, Faculty of Medicine, South Valley University, Qena, Egypt
5 Cardiology Division, Department of Internal Medicine, Faculty of Medicine, South Valley University, Qena, Egypt
6 Department of Internal Medicine, Faculty of Medicine, South Valley University, Qena; Department of Internal Medicine, Arabian Gulf University (AGU), Bahrain, Egypt
Correspondence Address:
Asmaa Nafady
Clinical and Chemical Pathology, Qena Faculty of Medicine, South Valley University, Qena, Department of Clinical Pathology, Faculty of Medicine, Assiut University, Assiut, 83523
Egypt
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/ejh.ejh_9_21
Introduction The occurrence of primary pulmonary arterial hypertension (PAH (in primary myeloid proliferation neoplasms seems quite high, up to 22% in polycythemia vera. Polycythemia rubra vera (PRV) is one of the myeloproliferative neoplasms. We aimed to study the incidence of PAH among patients with PRV.
Patients and methods A prospective cross-section study was performed on 60 (PRV) patients with PRV confirmed by bone marrow and JAK2 positivity. Abdominal ultrasonography, transthoracic echocardiography, and computed tomography chest were done to estimate the pulmonary hypertension (HTN) and exclude other chest diseases.
Results Among the studied 60 patients, we found 14 patients with pulmonary HTN (23.4%) who had significantly increased incidence of comorbidities than patients with normal pulmonary pressure (P=0.009). Moreover, there were statistically significant differences in the size of spleen by ultrasound between the two groups (P=0.008). Patients with pulmonary HTN had a higher hemoglobin level compared with those with normal pulmonary pressure (P=0.006). There was a significant positive correlation between pulmonary pressure and existing comorbidities (diabetes mellitus, HTN, or both) but no correlation with the size of the spleen, hemoglobin level, or white blood cells.
Conclusion The prevalence of PAH in JAK2-positive patients with PRV is 76.6%, and there was significant relationship between hematological parameters (hemoglobin, white blood cells, lactate dehydrogenase, and urea level and PAH in JAK2-positive patients with PRV.
Keywords: myeloproliferative neoplastic disorder, polycythemia rubra vera, pulmonary artery pressure
Polycythemia rubra vera (PRV) is one of the myeloproliferative neoplasms (MPNs) characterized by increased red blood cell synthesis, resulting in elevated red cell mass. This is also associated with stimulation of myeloid and megakaryocytic lineages, resulting in increased white blood cell (WBC) and platelet production, respectively [1].
Recently it has been obvious that JAK2 (protein tyrosine kinase) is mutated (V617F) in more than ninty percent of patients with polycythemia rubra vera (PRV) [2].
Pulmonary hypertension (HTN) is a heterogenous group of diseases characterized by increased mean pulmonary artery pressure equal to or greater than 25 mmHg [3].
Pulmonary arterial hypertension (PAH) is mainly caused by a vasculopathy affecting the pulmonary vessels. This vascular disorder is characterized by intimal proliferation and fibrosis, which is a common feature of MPNs [3],[4].
The incidence of primary PAH in MPN, after exclusion of 2ry causes, seems to be high [4]. confirmed by transthoracic echocardiography (TTE), the PAH was happened in 22% of PRV patients [5].
Pulmonary HTN is a condition of high blood pressure in the arteries of the lungs. Pulmonary blood pressure is lower than systemic blood pressure, and normal pulmonary-artery pressure is ∼14 mmHg at rest. If the pressure in the pulmonary artery is more than 25 mmHg, it is considered abnormally raised high and called pulmonary HTN, with prevalence of 10–20% among general population [6]. Several causes of pulmonary HTN have been identified in patients with MPN such as veno-occlusive disease, pulmonary thromboembolism, and extramedullary hematopoiesis of the lungs [7].
The aim of our study was to screening for PAH in PRV, as well as to assess predictors for occurrence of PAH in PRV.
Patients and methodsThis Prospective cross-sectional study was conducted on 60 polycythemia rubra vera outpatient at the hematology and chest Clinics in the time from May 2019 to August 2020 Qena university hospital after obtaining an informed written consent from each patient.
Patients with polycythemia rubra vera confirmed by World Health Organization (WHO) classification 2016 for Philadelphia-negative myeloproliferative neoplasms (MPNs).
Any patients known to have pulmonary hypertension secondary toheart disease, COPD, interstitial pulmonary fibrosis (IPF) or other chest diseases and recurrent venous thrombosis were excluded from the study.
Each patient underwent Clinical Examination: which include plethoric facies and hand, purpura and ecchymotic patches, systolic murmur, lower limb edema, organomegaly, lymph node enlargement, ascites, bilateral basal crepitations.
Routine laboratory investigations
Complete blood picture (CBC), Liver profile: alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum albumin, total bilirubin, direct bilirubin, prothrombin time and INR. Renal function tests: serum creatinine, Uric acid and LDH serum levels.
Morphological Bone marrow examination JAK2 gene study
Bone marrow aspiration and trephine biopsies were performed to all patients. Examination of Leishman stained BM films and comparison of the cellularity for age with erythroid and myeloid hyperplasia without any evidence of dysplasia or increased blasts. Screening for JAK2 V617F gene Mutation was performed in DNA from peripheralbblood granulocytes from 63 consecutive patients.
Mononuclear cells prepared by double‐density gradient centrifuge (Sigma Diagnostics, St. Louis, MO). Genomic DNA was extracted by the QIAamp Blood Mini Kit (Qiagen, Valencia, CA) and amplified with PCR. Amplification was confirmed by electrophoresis on an ethidium bromide‐impregnated 1.5% agarose gel. and finally human genomic DNA was analyzed using ABI PRISM 3700 DNA Analyzer (Applied Biosystems, Foster City, CA) [8].
Transthoracic Echocardiography at chest clinic to assess the diameter of pulmonary artery and probability of pulmonary hypertension and chest CT to exclude other chest diseases.
Abdominal, ultrasonography was performed to assess splenic diameter.
Ethical considerations
An official permission was obtained from The Hematology and chest Clinics in Qena university hospital, Faculty of Medicine, Qena University, Qena, Egypt. Approval from ethical committee in the faculty of medicine (Institutional Research Board IRB) and obtaining a written consent from each participant in accordance with Helsinki guidelines.
Methods
Each patient underwent clinical examination, which included plethoric facies and hand, purpura and ecchymotic patches, systolic murmur, lower limb edema, organomegaly, lymph node enlargement, ascites, and bilateral basal crepitations. Laboratory investigations included the following: (a) complete blood picture, including hemoglobin concentration (Hb %), red blood cells, WBCs, and platelet count; (b) liver profile, including alanine aminotransferase, aspartate aminotransferase, serum albumin, total bilirubin and direct bilirubin, prothrombin time, and international normalized ratio; (c) renal function tests, including serum creatinine; (d-) morphological bone marrow examination; (e) uric acid; (f) lactate dehydrogenase (LDH); (g) JAK2 gene study; (h) imaging, including abdominal ultrasonography to assess splenic diameter, transthoracic Echocardiography at the chest clinic to estimate the tricuspid regurgitation velocity (m/s) as well as to assess the diameter of pulmonary artery and probability of pulmonary HTN, and chest computed tomography to exclude other chest diseases.
Statistical analysis
Data were analyzed using IBM-SPSS version 21.0 (IBM-SPSS Inc., Chicago, Illinois, USA). Descriptive statistics were presented in the form of means, SDs, medians, ranges, and percentages. Test of significancesused were χ2 test to compare the distribution of frequencies among the study groups and for continuous variables, independent t test analysis was performed to compare the means of dichotomous data. A significant P value was considered when it is ≤ 0.05.
ResultsA total of 60 patients with PRV were included in this cross-sectional study, comprising 31 females and 29 males. Regarding associated morbidities, 39 patients were free of comorbidities, 13 had HTN, four had diabetes mellitus (DM), and four had both HTN and DM. Abdominal ultrasound showed that all patients had hepatomegaly, where 52 patients had moderate hepatomegaly, and eight had mild hepatomegaly. Imaging of the spleen showed that 26 patients had normal spleen size and 34 patients had enlarged spleen with variable size ([Table 1]).
Table 1 Comparison of clinical manifestations and findings according to pulmonary hypertensionOnly 19 of our patients had tricuspid valve regurge of mild degree.
Our studied patients were divided into two groups according to pulmonary HTN: 14 (23.4) patients with normal pulmonary artery pressure and 46 (76.6%) patients with pulmonary HTN of different severity.
In our study, we divide the patients into two groups according to pulmonary artery pressure: group of PRV with pulmonary HTN and group of PRV without pulmonary HTN. The female-to-male ratio in patients with normal pulmonary pressure and patients with pulmonary HTN was 53.8–46.2% and 51.1–48.9%, respectively, with no statistically significant difference (P=0.57). Moreover, there were no significant differences in age between the two groups (P=0.09). The mean age of patients with normal pulmonary pressure and patients with pulmonary HTN was 59.8±7.2 and 58.3±9.2, respectively.
Regarding comorbidities, there were statistically significant differences between patients with normal pulmonary pressure and patients with pulmonary HTN (P=0.009). Moreover, there were statistically significant differences in the size of spleen by ultrasound between the two groups (P=0.008) ([Table 1]).
Patients with pulmonary HTN had a higher Hb (g/dl) level compared with normal pulmonary pressure (P=0.006). WBCs were found to be significantly higher in patients with pulmonary HTN compared with those with normal pulmonary pressure (P=0.008) ([Table 2]).
Table 2 Comparison of patients’ investigation according to pulmonary hypertensionThe JAK2V617F mutation was detected in 58 of the 60 patients (96.7%), 49 of whom (81.7%) were homozygous for the mutant allele. And 9 patients were heterozygous (18.3%). A comparison between the two patient groups revealed that significantly higher occurrence of homozygous JAK2V617F mutations among patients with pulmonary hypertension than those with normal pulmonary artery pressure (P=0.000) ([Table 2]).
Correlation test was done between the two groups regarding pulmonary HTN comorbidities, spleen by ultrasound, and laboratory investigations. We found a significantly positive correlation between pulmonary pressure and existing comorbidities (DM, HTN or both) (r=0.256, P=0.049), and no correlation with the size of the spleen, Hb level, or WBC count ([Table 3]).
Table 3 Correlation between comorbidities, spleen by ultrasound, laboratory investigations, and pulmonary hypertension Discussion Our study represents a cooperation between hematology, chest, and clinical pathology departments in a prospective cross-sectional study, which was conducted on patients attending hematological and chest clinics in Qena University Hospital with PRV confirmed by bone marrow and JAK2 positivity in the clinical pathology laboratory. A total of 60 patients with PRV were enrolled during the study period.
We found that 14 (23.3%) patients had no pulmonary HTN and 46 patients had pulmonary HTN of variable severity (31.7% had mild pulmonary HTN, 38.3% had moderate pulmonary HTN, but only 6.7% had severe pulmonary HTN), and 68.3% of cases have no valvular diseases.
Guilpain et al. [9] found four of 10 patients with MPNs had pulmonary HTN, which occurred several years after the diagnosis. All patients with PAH revealed myeloid metaplasia but none in the CTEPH group.
In other studies, pulmonary HTN was described in 12 (48%) of 25 patients with MPNs and 22 (47.8%) of 46 patients with ET [10],[11]. However, in a larger study by Chebrek et al. [12] who examined 68 MPNs patients (27 with Essential thrombocythaemia (ET), 15 with Primary Myelofibrosis (PMF), and 26 with polycythemia rubra vera), the authors found a lower prevalence (7%) of pulmonary HTN, However, this study did not correlate pulmonary HTN with JAK2 allele burden.
In our study, we divide the patients into two groups according to pulmonary artery pressure: group of PRV with pulmonary HTN and group of PRV without pulmonary HTN. The female-to-male ratio in patients with normal pulmonary pressure and patients with pulmonary HTN was 53.8–46.2% and 51.1–48.9%, respectively, with no statistically significant difference (P=0.57). Moreover, there were no significant differences in age between the two groups (P=0.09). The mean age of patients with normal pulmonary pressure and patients with pulmonary HTN was 59.8±7.2 and 58.3±9.2 years, respectively.
In our study, regarding comorbidities, the percentages of patients who had no comorbidities, that is, HTN, DM, or both, were 38.5%, in patients with normal pulmonary pressure were 72.3% in patients with pulmonary HTN, with a statistically significant difference (P=0.00). Moreover, there were statistically significant differences in the size of spleen by ultrasound (P=0.008), where percent of patients with moderate enlarged spleen where 34 and 7.7%, respectively, in patients with pulmonary HTN have and those with normal pulmonary pressure, respectively.
Our results are in contrast with those obtained by Mattar et al.’s [13] study where none of the studied parameters including age, sex, splenic diameter, were predictive of the presence of pulmonary HTN among the two groups of pulmonary HTN.
In the present study, patients with pulmonary HTN had a higher Hb (g/dl) level compared with normal pulmonary pressure group (P=0.006). WBCs (×103/cm3) were found to be significantly higher in patients with pulmonary HTN compared with those with normal pulmonary pressure (P=0.008). Moreover, LDH (μ/l) levels were higher in patients with pulmonary HTN compared with those with normal pulmonary pressure. However, there was no significant relationship between platelet level and pulmonary HTN.
Our finding that significantly higher occurrence of homozygous JAK2V617F mutations among pulmonary hypertension patients than those without came in contrast with previous study who did not find correlation between the JAK2 burden and pulmonary HTN [13].
Correlation test was done between the two groups regarding pulmonary HTN comorbidities, spleen by ultrasound, and laboratory investigations. We found a significantly positive correlation between pulmonary pressure and existing comorbidities (DM, HTN, or both) (r=0.256, P=0.049), and no correlation with the size of the spleen, Hb level, or WBCs.
A study conducted by Mattar et al. [13] found that none of the studied items such as Hb levels or platelet count were predictors of pulmonary HTN, only WBC count, which was significantly different between the two groups of pulmonary HTN, also this finding was in agreement with other study [10], and on the contrary,it is not consistent with Altintas et al. [11], who found a significant correlation between increased platelet counts and pulmonary HTN.
These variations might be owing to the differences between researches in the demographic features of the patients, whether treated or not, different treatment modalities, and the number of studied patients. We think that a meta-analysis of similar studies is needed to know the exact incidence and prevalence of pulmonary HTN in those patients and study the correlation with other parameters.
ConclusionThe prevalence of PAH in JAK2-positive patients with PRV is 76.6%, and there was significant homozygous relationship between hematological parameters (Hb and WBCs,) LDH, and urea level and PAH in JAK2-positive patients with PRV. There was a significant positive correlation between pulmonary pressure and existing comorbidities (DM, HTN, or both), but no correlation with the size of the spleen, Hb level, or WBCs.
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Conflicts of interest
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