A new risk grouping for IgD myeloma based on analysis of 165 Japanese patients.

The common staging systems for myeloma do not include IgD myeloma because its rarity makes analysis difficult. We studied a series of 165 Japanese patients with IgD myeloma retrospectively to assess which of the easily assessable parameters present at the time of diagnosis were of prognostic significance. The important individual variables detected in a previous univariate analysis were placed in a multiple regression model to identify the major prognostic factors for survival. This analysis showed that light-chain subtype and white blood cell (WBC) count had a strong predictive relationship for the length of survival. These two factors were used to construct a model containing four categories of patients at increased risk for shortened survival. These categories divided the patients into three groups with respective 5-year survival rates of 66% (low risk), 23% (moderate risk), and 0% (high risk). This new risk grouping showed prognostic validity for IgD myeloma.