Abstract: TH-PO791
Carboxyhemoglobin and Smoking Status in Kidney Transplant Recipients
Session Information
- Transplantation: Clinical - 2
October 24, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 2102 Transplantation: Clinical
Authors
- Salamah, Sovia, Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
- Gomes Neto, Antonio Wouter, Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
- Alkaff, Firas F., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
- Kootstra-Ros, Jenny E., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
- Touw, Daniel J., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
- Franssen, Casper F.M., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
- Bakker, Stephan J.L., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
Background
Smoking is a risk factor for graft failure and death in kidney transplant recipients (KTRs). Nicotine addiction complicates quitting and self-reported smoking status is unreliable. Urinary cotinine is the gold standard for identifying active smokers, but is costly, infrequently measured, and prone to false positivity in nicotine patch or gum users. We aimed to investigate carboxyhemoglobin (COHb) as a potential biomarker for assessing smoking in KTRs.
Methods
We used data from KTRs in the TransplantLines Biobank and Cohort. Smoking status was determined by a questionnaire. Urinary cotinine was measured with Enzyme Multiplied Immunoassay Technique (LLQ 100 µg/L) and plasma COHb was obtained from blood gas analysis. The ROC curve evaluated the diagnostic performance.
Results
Among 404 KTRs (mean age 56 ± 13 years, 43% female, median time post-transplant 89 months [interquartile range (IQR) 36-157]), the prevalence of KTRs with urinary cotinine > 100 µg/L was 15.1%, and the median COHb was 0.92% [IQR 0.82-1.14%] (Table). COHb was strongly correlated with urinary cotinine (R=0.61; P<0.001). The area under the curve (AUC) of urinary cotinine and COHb was comparable (Figure). Using the Youden index, the COHb cut-off was 1.5%. With this cut-off, the specificity and sensitivity of COHb were 94% and 72%, respectively.
Conclusion
Carboxyhemoglobin, which is more accessible than urinary cotinine, is just as effective in identifying smoking in KTRs.
Urinary cotinine and COHb of KTRs according to their answer on smoking questionnaire.
| Total N=404 | Non-smoker N=107 | Ex-smoker N=153 | Smoker N=36 | Unkonwn N=28 | P-value | |
| Detectable urinary cotinine concentration, n (%) | 61 (15.1%) | 3 (1.6%) | 19 (12.4%) | 32 (88.9%) | 7 (25%) | <0.001 |
| Detectable Urinary cotinine, µg/L [IQR] | 660 [434-1009] | 395 [305-921] | 564 [388-829] | 705 [484-994] | 952 [766-1433] | <0.001 |
| COHb, % [IQR] | 0.92 [0.82-1.14] | 0.92 [0.72-1.11] | 0.92 [0.82-1.11] | 2.27 [1.21-3.84] | 0.96 [0.82-1.36] | <0.001 |
ROC curve of urinary cotinine and COHb to identify active smokers in KTRs.