Prognostic relevance of morphological classification models for myelodysplastic syndromes in an era of the revised International Prognostic Scoring System

Numerous morphological classification models have been developed to organise the heterogeneous spectrum of myelodysplastic syndromes (MDS). While the 2008 update of the World Health Organisation (WHO) is the current standard, the publication of the revised International Prognostic Scoring System (IPSS-R) has illustrated the need for supplemental prognostic information. The aim of this study was to investigate whether morphological classification models for MDS - of both the French-American-British (FAB) group and WHO - provide reliable criteria for their classification into homogeneous and clinically relevant categories with prognostic relevance beyond the IPSS-R. We reclassified 238 MDS patients using each of the FAB, WHO 2001 and WHO 2008 criteria and studied classification categories in terms of clinical, haematological and cytogenetic features. Subsequently, we calculated prognostic scores using the IPSS-R and investigated whether the morphological classification models had significantly prognostic value in patients stratified by the IPSS-R and vice versa. By adopting the FAB, WHO 2001 and WHO 2008 classifications, MDS patients were organised into homogeneous categories with intrinsic prognostic information. However, whereas the morphological classification models showed no prognostic value beyond the IPSS-R, the IPSS-R had significant prognostic value beyond the FAB, WHO 2001 and WHO 2008 classifications. Even though morphological classification models for MDS might be clinically relevant from a prognostic point of view, their relevance in terms of risk stratification is evidently limited in light of the IPSS-R. Therefore, we suggest to stop the use of morphological classification models for MDS for risk stratification in routine clinical practice.