Associations Between Patient Characteristics and Progression to Multiple Myeloma Among Patients With Monoclonal Gammopathy of Undetermined Significance: A Systematic Review

Monoclonal gammopathy of undetermined significance (MGUS) is a pre-malignant condition of multiple myeloma (MM). Evidence suggested old age, black race, male gender, and obesity as risk factors for MGUS development; however, whether they are associated with an increased risk of progression to MM among patients with MGUS is unclear. A systematic search of PUBMED and EMBASE for cohort studies investigating the association between age/race/gender/obesity and progression to MM. We used the Newcastle-Ottawa Scale (NOS) to assess the methodologic quality of the included studies. Summary risk ratios were calculated using random-effects models. We identified 24 publications, of which 17 articles were included in the main analyses. Overall, the quality of the studies was fair (mean NOS = 5.5). Our meta-analyses showed that old age was positively associated with the risk of the MGUS-MM progression (risk ratio: 2.38; 95% confidence interval [CI] 1.59-3.57), while race was not statistically significantly associated with the risk (blacks vs whites: 1.09; 95% CI: 0.77-1.54). Males had a lower risk of MGUS-MM progression, compared to females (risk ratio: 0.70; 95% CI 0.50-1.0; P -value = .048). High body mass index was significantly associated with an increased risk of MGUS-MM progression (risk ratio: 1.32; 95% CI 1.12-1.57). Based on extant research, old age, female sex, and obesity may be implicated in MGUS-MM progression. However, several studies which found an insignificant association between age/gender and progression did not report the risk estimates. Publication bias exists and our risk estimates may be overestimated. More studies are warranted to confirm our findings.