Validation of a scoring system to establish the probability of myelodysplastic syndrome in patients with unexplained cytopenias or macrocytosis.

Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders primarily seen in the elderly that are characterized by ineffective hematopoiesis and a propensity to develop AML. Clinicians may be hesitant to refer older patients with unexplained cytopenias and/or macrocytosis for a bone marrow biopsy (BM), and consequently undiagnosed patients may be deprived access to effective treatments. Previously, we described factors which were independently predictive of a diagnosis of MDS at time of bone marrow: age ≥65, mean cell volume (MCV), red cell distribution width (RDW), and lactate dehydrogenase (LDH), and suggested a scoring system to calculate the post-test probability of MDS [1]. In this study we validate this scoring system in a cohort of 313 individuals who underwent bone marrow examinations for the investigation of unexplained cytopenias and or macrocytosis over a 3 year period at our institution (2006-2008). Thirty-two percent of all patients were diagnosed with MDS and 9% had suspected MDS. The post-test likelihood of a diagnosis of MDS increased from 12% when none of the four identified factors were present to 48% when 3 or more factors were present. This scoring system can be used to guide the diagnostic testing of patients presenting with unexplained cytopenias or macrocytosis.