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Kidney Week

Abstract: PO2400

Impact of Body Mass Index on Baseline Donor-Derived Cell-Free DNA in Kidney Transplant Recipients

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Aramada, Harsha, Allegheny Health Network, Pittsburgh, Pennsylvania, United States
  • Chopra, Bhavna, Allegheny Health Network, Pittsburgh, Pennsylvania, United States
  • Sureshkumar, Kalathil K., Allegheny Health Network, Pittsburgh, Pennsylvania, United States
Background

Donor derived cell free DNA (dd-cfDNA) is useful in predicting acute rejection in renal allografts. The technology uses next generation sequencing and does not require donor genotyping. dd-cfDNA is expressed as a percentage of the total (including self and non-self) circulating DNA fragments. Since self-portion of cell free DNA can vary according to body size, we aimed to test the hypothesis that expressed percent of baseline dd-cfDNA can vary by the recipient's body mass index (BMI).

Methods

Our center has been doing for-cause as well as surveillance (for high immunologic risk) dd-cfDNA in kidney transplant recipients (KTRs) using AlloSure (CareDx, Brisbane, CA). We identified patients who underwent kidney transplantation between September 2017 and June 2019 and had serial dd-cfDNA levels. A dd-cfDNA value ≥ 1% prompted allograft biopsy. KTR with biopsy evidence for rejection or other injuries were excluded from the analysis. Study subjects were divided into BMI (kg/m2) groups as follow: <25, 25-29.9, ≥30.Baseline dd-cfDNA values were compared between BMI groups.

Results

There were 88 (81 first-time and 7 repeat) KTRs during the study period who had dd-cfDNA measurements and available BMI. We excluded 16 first-time and 3 repeat KTRs from the analysis due to biopsy evidence of rejection. The remaining 69 patients had 227 dd-cfDNA levels available for analysis. Patients were divided based on BMI categories with stratification of baseline dd-cfDNA values as shown in table 1. There were no significant differences in baseline dd-cfDNA values for BMI groups <25 vs. 25-29.9 (0.63 ± 0.63% vs. 0.41±0.27%, p=0.16) and BMI groups 25-29.9 vs. ≥30 (0.41±0.27% vs. 0.33±0.16%, p= 0.22). However, there was a trend towards significantly higher baseline dd-cfDNA values in BMI group <25 vs. ≥30 (0.63±0.63% vs. 0.33±0.16%, p=0.06).

Conclusion

Our study showed a trend towards significant differences in dd-cfDNA values between extremes of BMI groups. These differences could become significant with larger study subjects. Our findings point towards the need for normalization of dd-cfDNA values with respect to body size for reporting purposes.

Table 1. BMI and dd-cfDNA
BMI (kg/m2) categories<2525 -29.9≥30
Number of patients192921
Number of dd-cfDNA tests679664
dd-cfDNA % mean± SD0.63±0.630.41±0.270.33±0.16