In this systematic review, we aimed to assess the sensitivity of serum and urine immunofixation (IFE) and serum free light chain (sFLC) in detecting plasma cell dyscrasia (PCD) associated with light chain (AL) amyloidosis. We searched the literature using PubMed, Embase, and CENTRAL databases since inception through March 2024. We included studies reporting the diagnostic accuracy of IFE and/or sFLC in patients with AL amyloidosis. We used the GRADE approach to assess the certainty of evidence and QUADAS-2 to assess the risk of bias. After deduplication, 29,237 records were screened, and 44 studies (n = 18,071) were included. For the meta-analysis, 28 studies reported sensitivity for SIFE (n = 3,390), 24 studies for UIFE (n = 2,830), 19 studies for SIFE and UIFE (n = 2,819), 21 studies for sFLC ratio (n = 3,678), 6 studies for SIFE and sFLC ratio (n = 372), 3 studies for UIFE and sFLC ratio (n = 242), and 10 studies for all three tests (n = 1,430). Pooled sensitivities were: SIFE 0.68 (95% CI 0.62-0.73), UIFE 0.77 (0.72-0.81), SIFE and UIFE 0.89 (0.84-0.93), sFLC ratio 0.82 (0.78-0.86). When SIFE, UIFE, and sFLC ratio were combined, the sensitivity reached 0.99 (0.96-1.00). The high sensitivity of combining SIFE, UIFE, and sFLC ratio supports their use as a reliable initial testing strategy to raise suspicion for AL amyloidosis and guide decisions regarding future diagnostic modalities.
Azzam et al. (Tue,) studied this question.