Effects of Monoclonal Gammopathy of Undetermined Significance (MGUS) on Outcomes after Solid Organ Transplant

Background:

MGUS is a precancerous condition which can progress to multiple myeloma (MM) or other hematologic malignancy. MGUS increases the risk of developing MM approximately 25-fold, and increases lifetime risk of infection, venous thromboembolism (VTE), and skeletal related events (SRE). Solid organ transplant requires immunosuppression, which is associated with overlapping risks, including hematologic malignancy such as post transplant lymphoproliferative disease (PTLD). Hypothesizing that MGUS would further increase risk of PTLD and other complications after transplant, we described risk of these outcomes in patients with MGUS prior to solid organ transplant (MGUS+) compared to those without MGUS (MGUS-).

Methods:

We used the 2005-2011 California State Inpatient, Emergency, and Ambulatory Databases. MGUS and complications were identified by ICD-9 diagnosis codes, and solid organ transplant by ICD-9 procedure codes. Patients with the ICD-9 diagnosis code 273.1 documented on or before the day of solid organ transplant surgery were defined as MGUS+. We used logistic regression to analyze complications in MGUS+ versus MGUS- transplant patients.

Results:

Of 24,358,669 patients, we identified 22,062 solid organ transplant patients. Transplant patients were 8.8% African American, 29.5% Hispanic, 43.4% White, 15.1% other, and 3.2% had data missing. 72 were MGUS+ prior to solid organ transplant. Median age of MGUS+ was 61.5 years versus 51 years for MGUS-. Outcomes are shown in table 1.

*Frequencies ≤10 are reported as such per the data use agreement.

Conclusions:

Compared to MGUS-, MGUS+ solid organ transplant patients had higher risk of VTE, SRE, and infection, but did not have higher risk of PTLD or other lymphomas. MGUS+ transplant patients are more likely to develop MM than MGUS-; however, this risk is similar to that historically attributed to MGUS, in patients who have not undergone transplant. These data show increased risk of certain complications in MGUS+ patients, and do not support screening for MGUS to assess risk of PTLD prior to solid organ transplant.