Hgb level, MCV and platelet count and patient characteristics
A total of 150 newly diagnosed MM patients were enrolled in this study, of whom 76 were males and 74 were females; the median age was 62 years (range from 31 to 84). Table 1shows the baseline characteristics and treatment specifics of the patients.According to the results of the routine peripheral blood examinations at the time of diagnosis, 33 patients (22.0%) had WBC counts lower than normal (4 × 10E9/L), 101 patients (67.3%) had an Hgb level lower than 100 g/L, 37 patients (24.7%) had a MCV higher than normal (99.1 fL) and 63 patients (42.0%) had a Plt count lower than 150 × 10E9/L.
A MCV higher than 99.1 fL was common in patients with a Hgb level <100 g/L (32% vs 10%) and bone marrow plasma cells percentage >30% (39% vs 12%). A Hgb level <100 g/L was most common in patients aged >65 years (50% vs 20%) and was also common inpatients with Plt counts <150 × 10E9/L (84% vs 55%); bone marrow plasma cells percentage >30% (79% vs 56%); high-risk Durie-Salmon (76% vs 72% vs 38%), ISS (84% vs 75% vs 37%) and R-ISS (20% vs 72% vs 81%) stages; and elevated red blood cell volumes (86% vs 61%). A Plt count below 150×10E9/L was common in patients with serum LDH levels above normal (63% vs 37%) and high-risk ISS stages (55% vs 40% vs 28%) (Supplementary Table 1).
Haematopoietic score and patient survival
The median duration of follow-up was 42.1 months, the median PFS time was 29.6 (21.8-37.4) months, and the estimated 3-year and 5-year PFS rates were 43.1% and 24.2%, respectively. The median OS was not reached (NR), and the estimated 3-year and 5-year OS rates were 69.3% and 56.6%, respectively. Patient age and bone marrow plasma cell percentage significantly affected patient PFS (P<0.05), and Durie-Salmon stage, R-ISS stage and LDH levels also affected patient PFS (P<0.1) (Table 2,Supplementary Table 2). Moreover age, Durie-Salmon stage, ISS stage, R-ISS stage, bone marrow plasma cell percentage, and serum creatinine level had significant effects on OS (P<0.05) (Table 3, Supplementary Table 2).
Based on univariable analysis, the Hgb level , MCV, and Plt count had significant effects on PFS and OS (Tables 2, 3, and Supplementary Table 2). The median PFS was 41.8 months for patients with Hgb levels≥100 g/L and 24.5 months for Hgb levels<100 g/L (P=0.063), and the median OS was NR and 64.0 months, respectively (P=0.079). The median PFS was 32.6 months for patients with MCVs<99.1 fL and 15.1 months for patients with MCVs≥99.1 fL (P=0.003), and the median OS times were NR and 33.2 months, respectively (P<0.001). Additionally ,the median PFS was 33.3 months for patients with Plt counts≥150×10E9/L and 23.9 months for patients with Plt counts<150×10E9/L (P=0.032), and the median OS times were NR vs 54.2 months, respectively (P=0.022). Each of the above three indicators was assigned a score of 1 to generate the haematopoietic score. The integral values were 0, 1, 2, and 3, and the score significantly affected both PFS and OS (P <0.001) (Tables 2, 3 and Figure 1A, 1B). Overall, 59 (39.3%), 43 (28.7%), 29 (19.3%) and 19 (12.7%) patients had scores of 0, 1, 2 and 3, respectively; the median PFS times were 43.1 months, 24.5 months, 32.6 months and 14.2 months, respectively (P <0.001), and the median OS times were NR, 47.1 months, NR and 31.4 months, respectively (P <0.001). The median PFS was 32.6 months in patients who had a haematopoietic score from 0 to 2,, and the estimated 3-year and 5-year PFS rates were 45.5% and 26.0%, respectively. In patients with a score of 3, the median PFS was only 14.2 months for a score of 3, with estimated 3-year and 5-year PFS rates of 25.3% and 9.5%, respectively (P = 0.001) (Figure 2A, Table 1, Supplementary Table 2). The median OS was NR for patients who had a haematopoietic score from 0 to 2, and the estimated 3-year and 5-year OS rates were 74.0% and 61.6%, respectively. In contrast, the median OS of patients who had a score of 3 was only 31.4 months, with estimated 3-year and 5-year OS rates of 36.8% and 23.7%, respectively (P <0.001) (Figure 2B, Table 2, Supplementary Table 2).
Multivariate analysis using the Cox proportional hazards model included age, Durie-Salmon stage, ISS stage and R-ISS stage, bone marrow plasma cell percentage, blood creatinine and LDH levels, and the haematopoietic score. The results suggested that R-ISS stage (3 vs 1-2, HR, 1.4; P=0.031), haematopoietic score (3 vs 0-2, HR, 1.91; P=0.033) and plasma cell percentage (>30%, HR, 1.96; P =0.003) were independent prognostic predictors of PFS and that patient age(≤65 years, HR, 0.54; P = 0.027), Durie-Salmon stage (3B vs 1-3A, HR, 2.96; P = 0.044), haematopoietic score (3 vs 0-2, HR, 2.53; P = 0.006) and bone marrow plasma cells percentage (> 30%, HR, 2.35; P = 0.005) were independent prognostic predictors of OS (Tables 2, 3).