Neoplastic and non‐neoplastic complications of solid organ transplantation in patients with preexisting monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance ( MGUS ) occurs in 3–7% of the elderly population, with higher prevalence in renal failure patients, and is associated with a 25‐fold increased lifetime risk for plasma cell myeloma ( PCM ), also known as multiple myeloma. Using the C alifornia S tate I npatient, E mergency D epartment, and A mbulatory S urgery D atabases components of the H ealthcare C ost and U tilization P roject ( HCUP ), we sought to determine whether patients with MGUS who undergo solid organ allograft (n = 22 062) are at increased adjusted relative risk ( aRR ) for hematologic malignancy and other complications. Among solid organ transplant patients, patients with preexisting MGUS had higher aRR of PCM ( aRR 19.46; 95% CI 7.05, 53.73; p < 0.001), venous thromboembolic events ( aRR 1.66; 95% CI 1.15, 2.41; p = 0.007), and infection ( aRR 1.24; 95% CI 1.06, 1.45; p = 0.007). However, when comparing MGUS patients with and without solid organ transplant, there was decreased aRR for PCM with transplant ( aRR 0.34; 95% CI 0.13, 0.88; p = 0.027), and increased venous thromboembolic events ( aRR 2.33; 95% CI 1.58, 3.44; p < 0.001) and infectious risks ( aRR 1.44; 95% CI 1.23, 1.70; p < 0.001). While MGUS increased the risk of PCM overall following solid organ transplantation, there was lower risk of PCM development compared to MGUS patients who did not receive a transplant. MGUS should not preclude solid organ transplant.