Is International Prognostic Scoring System (IPSS) still standard in predicting prognosis in patients with myelodysplastic syndrome? External validation of the WHO Classification-Based Prognostic Scoring System (WPSS) and comparison with IPSS

Background: This study was undertaken to evaluate the prognostic value of the WHO Classification-Based Prognostic Scoring System (WPSS) and to compare it with that of the International Prognostic Scoring System (IPSS). Patients and methods: 149 patients de novo diagnosed as having myelodysplastic syndrome between December 1994 and February 2007, were evaluated retrospectively. Results: WPSS presented an excellent method for risk-stratifying patients into five subgroups, with different risks of death and leukaemic evolution. On univariate analysis, three components of WPSS - cytogenetic risk, WHO category and transfusion dependency - had good correlations with overall survival (OS) and time to leukaemic evolution (TTL). However, one component of IPSS - number of peripheral cytopenias - did not correlate with OS or TTL. WPSS could distinguish the truly low-risk patients (very low) who had an excellent long-term survival with rare leukaemic evolution, while IPSS could not. These patients should be managed with clinical observation and delayed treatment strategies. Furthermore, on multivariate analysis for OS, WPSS was found to be an independent prognostic factor for survival along with age [P = 0.04; hazard ratio (HR) = 1.71; 95% confidence interval (CI) 1.02-2.85] and lactate dehydrogenase (LDH) (P = 0.002; HR = 2.47; 95% CI 1.41-4.31). On the other hand, the prognostic significance of IPSS was not confirmed. Conclusion: These results suggest that the WPSS might be a more powerful predictor of prognosis than IPSS and that independent validation of several other, larger data sets should be necessary.