The role of serum-free light chain ratios in the prediction of poor prognosis in multiple myeloma patients: a systematic review and meta-analysis

Abstract

Background: The association between the serum free light chain (sFLC) ratio and the prognosis of multiple myeloma (MM) patients is controversial. Aim: The purpose of this study is to explore the relationship between the sFLC ratio and the prognosis of MM patients through meta-analysis. Methods: Online public databases were searched to find relevant studies. The retrieval time is limited from the establishment of the database to July 2021. The overall survival (OS) and progression-free survival (PFS) rates were compared. The results were described using hazard ratio (HR) and a 95% confidence interval (CI). Qualitative studies were also included. Results: A total of 9 studies involving 2864 participants were included. A pooled analysis based on four studies including newly-diagnosed MM patients, demonstrated that an abnormal sFLC ratio was associated with poor outcomes of OS (HR = 1.82, 95% CI: 1.15–2.90) and PFS (HR = 1.87, 95% CI: 1.20–2.90). Three qualitative studies showed that an abnormal sFLC ratio was related with poor outcomes of OS (studies all included newly diagnosed MM patients) and PFS (two studies included newly-diagnosed MM patients and one study included non-newly-diagnosed MM patients). Two studies stated that the sFLC ratio is not associated with OS (both studies included non-newly-diagnosed MM patients) and one study reported that the sFLC ratio is not associated with PFS (study included non-newly-diagnosed MM patients). Conclusion: sFLC ratio could be used to predict adverse outcomes in newly-diagnosed MM patients, but is not suitable for non-newly-diagnosed MM patients.