Clinical and Laboratory Characteristics of Prefibrotic and Overt Primary Myelofibrosis in Azerbaijan

Primary myelofibrosis (PMF) is a rare Ph chromosome-negative chronic myeloid neoplasm characterised by the fibrosis of bone marrow and a variety of symptoms that have a negative impact on the quality of life of the patients. In 2016 the WHO revised the classification of myeloid neoplasms. In this classification, primary myelofibrosis is divided into two different stages as prefibrotic and overt primary myelofibrosis according to the bone marrow fibrosis grade. Grade ≤1 bone marrow fibrosis was considered as prefibrotic and grade ≥2-3 fibrosis as overt primary myelofibrosis. Furthermore, peripheral blood leukoerythroblastosis was added to the minor criteria for overt primary myelofibrosis but not for prefibrotic.

Aim. The aim of our study was to understand and identify the demographic, clinical, and laboratory parameters of patients with prefibrotic versus overt primary myelofibrosis in Azerbaijan according WHO 2016 criteria.

Methods. Data on 160 patients registered at the Azerbaijan National Hematology and Transfusion Centre was collected from medical records. Patients' bone marrow biopsy samples were reviewed according to WHO 2016 criteria and identified as early or prefibrotic (pre-PMF) and overt primary myelofibrosis (PMF). Demographics, clinical and laboratory data were compared between pre-PMF and PMF patients.

Results. Of the 160 patient studied, 34(21%) were pre-PMF and 126(79%) were PMF. Compared with PMF, there were slightly more female patients in the pre-PMF group (46.03% vs. 52.94% p=0.601), although not statistically significant. Patients were younger in the pre-PMF group (median age 58.5 vs 60.0; IQR 16.25 and 12; p=0.048). Patients under 40 ages were 1.59% pre-PMF vs 14.71% PMF (p=0.005), and aged 65 years and older did not differ between groups (17.65% and 31.75%, respectively pre-PMF vs PMF; p=0.162). Median Hgb levels were 13.1 and 10.1 (g/dl; IQR 2.35 and 3.45; p<0.001), median PLT counts were 595.5 and 265.0 pre-PMF vs PMF patients (10⁹/l; IQR 443.75 and 309.0; p<0.001). There were fewer anemic and thrombocytopenic patients in pre-PMF compared to PMF (Hgb < 10.0 g/dl were 17.65% and 47.5% (p=0.003), PLT < 100x10⁹/l were 0.0% and 15.13%, respectively (10⁹/l; p=0.013). Median WBC (15.13 vs 13x 10⁹/l; IQR 10.48 and 15.74; p=0.337) and median eosinophil counts(0.33 and 0.2 10⁹/l; IQR 0.49 and 0.52; p=0.518) were not different between groups. Median basophil counts were lower in pre-PMF patients (IQR 0.003 and 0.14; p=0.038). Peripheral blood blast percentage ≥1.0% was 2.94% and 4.8%, respectively (p>0.999). Median LDH values were lower in pre-PMF patients but not statistically significant( 440 and 506.5 (IQR 301.0 and 430.75; p=0.156). There was no significant difference between the groups in terms of JAK2 mutation, 53.85% of pre-PMF and 80.88% of PMF patients were Jak2V617F positive (n=81; p=0.67). CALR was examined in 4 patients, MPL in 3 patients, all patients had PMF. 2 patients were CALR- positive, 1 patient was MPL- positive. Splenomegaly was more common in PMF patients compared to pre-PMF (spleen size >14.0 cm were respectively 96.15% and 83.33%, OR = 0.2 ; CI[0.05 ; 0.8] ; p=0.027). Median spleen size (cm) was 20.8 (IQR 5.25) vs 17.95 (IQR 4.1) (p=0.004).The median values of liver size(cm) weren't different (16. 2 (IQR 3.1) vs 16.1 (IQR 2.55), respectively (p=0.808). The distribution of IPSS was significantly different between groups. IPSS were respectively High- 3.31%, INT2- 30.58%, INT1- 47.11%, Low- 19.01% in PMF vs High- 6.06%, INT2- 9.09%, INT1- 39.39%, Low-45.45% (p=0.005).

After median follow-up 49.3 month, 50(31%) died, of these 10(29.4%) was in pre-PMF(p=0.66). Median OS was not significantly different between pre-PMF and PMF(44 vs 51 month; p=0.203).

Conclusion. Our study showed a significant difference between the two groups in terms of clinical, laboratory and demographic data, but this did not translate into overall survival. Clinical, laboratory and demographic data of both groups and their differences are similar to previous studies in literature, but a difference in overall survival was observed, which may be related to the small number of patients in the pre-PMF group in our study.

No relevant conflicts of interest to declare.