METHODS
In a single-center, retrospective study approved by the institution’s
Research Ethics Committee, patients less than 18 years old who were
diagnosed with CE and followed up in a pediatric hematology outpatient
unit formed the sample. The paper-based files and electronic medical
records of all such patients diagnosed with CE from 2000 to 2020 were
evaluated by pediatric hematologists to document demographic
characteristics, presenting symptoms, family history, the findings of
physical examinations, and the results of laboratory tests. The center’s
routine practice also entailed screening full blood counts of each
patient’s parents and siblings. Capillary oxygen saturation, venous
blood gas, and serum EPO levels, along with the results of Hgb
electrophoresis and JAK2 mutation analysis, were recorded as
well. Phlebotomy practices and any complications of the disease during
follow-up were assessed. During the study, patients who had aged beyond
20 years and been transferred to adult departments were telephoned to
gather up-to-date medical data.
Erythrocytosis was defined as having hemoglobin levels exceeding the
age- and gender-adjusted 99th percentile or an increase of 2 g/dL in
hemoglobin levels from baseline.3 Hgb percentile
curves were used to evaluate age- and gender-adjusted
values,12 while for diagnosis, full blood counts were
performed at least twice at different times. No patients had serum EPO
levels exceeding laboratory reference levels. Patients with
thrombocytosis, leukocytosis, and/or splenomegaly were excluded from the
sample, as were patients with secondary causes of erythrocytosis (e.g.,
cardiac, pulmonary, renal, and hepatic disorders and malignancies)
according to their history, physical examinations, capillary oxygen
saturation analysis, venous blood gas measurement, and serum levels. In
patients who reported any bleeding-related symptoms, prothrombin time,
activated partial thromboplastin time, and bleeding time assays were
also performed.
Statistical analysis was performed using IBM SPSS version 22.0.
Categorical variables were analyzed as percentages, and quantitative
data were recorded as M ± SD and median using descriptive
statistics.