13.3.4. MGUS is associated with increased mortality
Kristinsson et al.  compared the survival of MGUS patients (n=4,259) with matched controls from the general population in Sweden (n=16,151). After 15 years follow-up, the cumulative relative survival ratio of MGUS patients compared to controls was 0.7, and confirmed that MGUS patients have increased mortality. When the causes of death were examined, MGUS patients had an increased risk of dying from a number of haematological conditions, including MM, IgM lymphoma and AL amyloidosis. But there was also an increased risk of MGUS patients dying from non-lymphoproliferative diseases such as bacterial infections and heart, liver and kidney diseases. Similar findings were reported by Kyle et al., who suggest that the increased risk of death from non-haematological causes may be due to the fact that MGUS is often diagnosed as an incidental finding following investigation of other potentially serious conditions that may be associated with increased mortality. Kristinsson et al.  conclude that a diagnosis of MGUS is of significance, not only with regard to the increased risk of malignant transformation but also with regard to an excess mortality from other causes.
Despite MGUS being a common condition that is associated with increased mortality, there is currently no evidence to recommend screening for this condition. However, a trial is currently in progress in Iceland (iStopMM: www.blodskimun.is) that hopes to screen approximately 120,000 adults over the age of 40 for MGUS. Once participants are identified as having either MGUS or SMM, they will be invited to join a randomised clinical trial that aims to define optimum MGUS monitoring protocols and the benefits of screening and early intervention.