key: cord-0991441-pgt1x6pv
authors: Malyszko, Jolanta; Grochowiecki, Tadeusz; Krenke, Rafal; Macech, Michal; Oldakowska-Jedynak, Urszula; Rowiński, Olgierd; Wojtaszek, Ewa; Nazarewski, Slawomir
title: Should thorax thin section computed tomography (TSCT) be a standard diagnostic procedure in the evaluation of potential kidney transplant recipients - lessons learnt from COVID-19 pandemia
date: 2022-04-22
journal: Transplant Proc
DOI: 10.1016/j.transproceed.2022.03.044
sha: f6a3c50e021e86dc0ee86fded6c77bab549a52c8
doc_id: 991441
cord_uid: pgt1x6pv

Kidney transplantation is the preferred treatment for most patients with end-stage renal disease (ESRD). As dialyzed often have significant co- or multimorbidities, they should be carefully evaluated before waitlisted for transplantation. The global COVID-19 pandemia presents a major challenge for surgery, including transplant surgery. Due to fear of COVID-19 changes in lungs, thin section computed tomography-TSCT became a standard in potential kidney transplant recipients before surgery. The aim of the study was to evaluate the rationale and usefulness of HRCT in deceased donor kidney transplantation during the COVID‐19 pandemic. All adult patients that underwent deceased donor kidney transplantation from 1.05.2020 to 15/12/2021 were included in the study. Potential kidney transplant recipients upon admission to the Department of General, Vascular, and Transplant Surgery were tested for COVID-19 (fast test CovGenX), blood chemistries were taken, dialysis was performed if needed, and upon the negative RT-PCR test, HRCT was performed. From May 2020 till end of December 2021, 54 patients were transplanted; however, seven were disqualified after TSCT and consult of pulmonary specialist. Disqualification from kidney transplantation accounts for 13% of the potential kidney allograft recipients. Concluding, despite the possibility of overdiagnosis, TSCT is to be considered as standard evaluation imaging in potential kidney transplant recipients. Potential kidney transplant recipients must be periodically reassessed, given the prolonged wait time for a donor kidney and the significant number of comorbid conditions among this patient population. However, more data with longer follow‐up are needed to prove or disprove the rationale to use TSCT in transplant surgery.

Kidney transplantation is the preferred treatment for most patients with end-stage renal disease (ESRD). A successful kidney transplant not only mitigates the mortality and morbidity but also improves quality of life relative to chronic dialysis. As dialyzed often have significant co-or multimorbidities, they should be carefully evaluated before waitlisted for transplantation. The evaluation ought to be efficient and cost effective [1, 2] . Assessment of lung disease pretransplant as per latest KDIGO guidelines from 2020 includes chest imaging in all transplant candidates (level of evidence 2C) and pulmonary function testing in candidates with impaired functional capacity, respiratory symptoms, or known pulmonary disease (level of evidence 1C). Chest CT for current or former heavy tobacco users (≥ 30 pack-years) is suggested as per local guidelines and chest x-ray (CXR) for other potential kidney transplant recipients (2C) [3] . However, data on the evaluation of potential transplant candidates with pulmonary disorders are limited [1, 2] . All patients, not only potential transplant candidate should discontinue smoking [4] since it increases the risk of allograft loss and patient death. It has been reported that 25-pack-year smoking history at the time of transplantation is associated with a 30 percent higher risk of allograft failure when compared to nonsmokers or past smokers [5] . Importantly, the prevalence of serious pulmonary diseases, including chronic obstructive pulmonary disease (COPD) and lung cancer is significantly higher in ever smokers than in never smokers [6, 7] . The global COVID-19 pandemia presents a major challenge for surgery, including transplant surgery [8] . Using Scientific Registry of Transplant Recipients data in USA, Boyarsky et al. [9] reported the decline in new listings and deceased-donor kidney transplants, in particular in states with higher per capita confirmed COVID-19 cases. Similarly, the number of waitlist deaths was higher than expected in the states with highest COVID-19 burden In United Kingdom, Royal College of Surgeons published general surgery guidance on COVID-19 [10] , and Royal College of Radiologists issued a statement on use of CT chest to screen for COVID-19 in preoperative patients [11] . It has been agreed that transplant candidates should be screened for COVID-19 prior surgery [12] . Besides, history of symptoms and exposure, physical examination, chest imaging, and RT-PCR for COVID-19 are prerequisite. At the University of Washington Medical Center (UWMC), potential recipients were screened for COVID-19 risks with at least a CXR, and most of them had a chest CT similarly for donors [13] . In our center, we performed fast RT-PCR (CovGenX) of an upper respiratory tract specimen (nasopharyngeal swab) and if negative followed by thin section CT (TSCT) of the chest. The aim of the study was to evaluate the rationale and usefulness of TSCT in deceased donor kidney transplantation during the COVID-19 pandemic

All 62 adult patients who were evaluated for deceased donor kidney transplantation from 1.05.2020 to 15/12/2021 were included in the study and followed until 30.12.2021. We analyzed the medical data from the central transplant waiting list (rejestry.gov.pl) to obtain demographic data (age, gender, cause of ESKD, mode of dialysis, dialysis vintage, etc.), as well as imaging, endoscopy studies and all required consults, and checked their validity. Sixty two potential kidney transplant recipients were admitted to the Department of General, Vascular, and Transplant Surgery and were tested for COVID-19 (fast RT-PCR test CovGenX), blood chemistries were taken, dialysis was performed if needed, and upon the negative RT-PCR test, TSCT was performed before elective transplant surgery. All of the 62 patients had negative RT-PCR test for COVID-19. All tomography examinations were performed with 64-row multidetector computed tomography scanners (Optima CT 660 -General Electric, Milwaukee, WI, USA). Studies were carried out without intravenous contrast medium administration using the following settings: 120 kVp, 150-300 mAs, pitch 0.938-0.984 and a reconstruction interval of 1.25 mm. Acquisition of continuous, 0.623 mm thick sections was started at peak inspiration and was performed in the cranio-caudal direction. The image data were reconstructed with a high spatial frequency algorithm and analyzed at a window width (WW) of 1500 Hounsfield units (HU) and a window level (WL) of 600 HU. As transplantation is a standard procedure performed in the hospital, additional ethical approval is not required. Content of each informed consent is approved by ethical hospital board. However, special additional informed written consent for transplantation during the pandemic, besides surgery, was obtained. Physical examination and investigations for the following symptoms: cough, dyspnea, fevers, chills, chest pain, fatigue, headaches, body aches, rhinorrhea, sore throat, conjunctivitis, anosmia, dysgeusia, altered mental status, nausea/vomiting, abdominal pain, and diarrhea was performed. All of the 62 patients were negative for these symptoms, including 8 disqualified on the basis of TSCT. The immunosuppression was written by a consulting nephrologist prior transplant surgery. In case of doubtful TSCT, pulmonary specialist consult was requested, and then the team decision followed whether to proceed or disqualify from transplantation.

From May 2020 till end of December 2021, 54 patients were transplanted; however, eight were disqualified after TSCT and consult of pulmonary specialist due to relevant pathologies found in the chest imaging after thorough examination of all available data including previous thorax CT scans or CXRs. Disqualification from kidney transplantation accounts for 15% of the potential kidney allograft recipients. After negative pulmonary consult, another potential recipient was called and evaluated for possible transplantation following the same procedure (RT-PCT COVID-19 test, physical examination and TSCT). All of the potential recipients had CXR performed at the time of evaluation before being waitlisted, only two of them had TSCT with the results provided in the transplant registry. Overall, in our cohort there were no pathologies detected on the CXR, except for one patient with pleural thickening and subpleural fibrotic changes in the upper parts of the lungs. All the TSCT data are presented in the Table 1. In the Table 2 we presented laboratory data, and pulmonary consult if present for the disqualified patients. Fig 1 presents the TSCT at the time of hospital admission for kidney transplantation, after this imaging and pulmonary consult, potential recipient was disqualified (patient nr 7 in the Table) Discussion As we were obliged to use TSCT to detect changes suggestive of COVID-19 in the lungs to prevent transplantation in patients with possible infection, it appeared that we did detect several pathologies, not present, on the standard chest radiographs, all of them unrelated to COVID-19.

Previously we reported our preliminary data from May-December 2020 underlying the role of TSCT and issue of disqualification of 5 potential kidney transplant recipients [14] . Here, we present data from two years of transplant activity during COVID-19 pandemic (2020 and 2021) with follow-up of disqualified potential recipients. In general data on the use of TSCT as an imaging study prior to transplantation in the published literature are very limited. At the University of Washington Medical Center, chest CT was used to rule out COVID-19 infections in some kidney donors [13] , whereas in Jackson Memorial-Miami Transplant Institute, Miami, Florida, USA kidney transplant recipients were evaluated for symptoms of COVID-29, underwent RT-PCT test, and CXRs [15] . In Baylor College of Medicine, transplant candidates must have had a negative SARS-CoV2 nasopharyngeal swab and normal chest CT for COVID-19 prior transplant surgery [16] . The authors of the above study stressed that chest CT in asymptomatic patients admitted for SOT has low specificity for COVID-19 and should be interpreted with caution [17] . KDIGO guidelines recommend a chest radiograph in general and CT in selected cases (heavy smokers) during evaluation for kidney transplantation. KDIGO transplant guidelines were prepared before the pandemic and published in April 2020, therefore they did not deal with COVID-19 screening [3] . A chest radiograph is cost-effective and easy to perform; however, it has its limitations. If there is a doubt after CXR, TSCT is used to clarify the pathology. It provides more information than conventional CT and certainly standard chest x-rays. Chetan et al. reported as normal, 7 as indeterminate, 3 as classic/probable COVID-19, and 7 were reported as non-COVID-19 (four fluid overload, three infection). As a result, 8 out of 9 patients were suspended from the transplant waiting list because of the report (of classic/probable COVID-19 or indeterminate for COVID-19). Only one patient was COVID-19 positive in PCR (initial report was indeterminate by non-thoracic cross-sectional radiologist and negative-other infection by two thoracic radiologists). Of interest that there was a 48.15% overall agreement amongst the three raters (original report and rereview).

We are fully aware that our present study has several limitations. Firstly, this was a retrospective study, and the data are reliant on documentation in clinical notes. Secondly, there are inter-and intra-reader variability in reporting lung findings by radiologists and pulmonologists on duty. Our sample size was relatively small, however, we could not find larger in the published literature in patients undergoing kidney transplantation. The study follow-up time was more than 1

year. On the basis of our study and scarce data available from the published literature, we are fully aware that the utility of any preoperative chest CT, including TSCT needs to be balanced against the potential harm of a delayed operation or disqualification and suspension from the transplant active waiting list. In addition, as considering specificity of chest CT in the diagnosis of COVID-19 maybe not appropriate, it is unknown whether CT findings in fact are related to COVID-19 or other diseases of the patients. Potential fluid overload from end-stage renal disease, may overlap with findings of COVID-19 overlap, similarly vasculitis may present as ground-glass opacity [21] as we had in one of our patients. This cohort of patients is also more susceptible to bacterial infection and other comorbidities or medication effect, which may challenge interpretation. In addition, with more widespread availability of fast RT-PCR and its increased use in screening, it remains to be demonstrated when preoperative chest imaging in transplant surgery will be of value. However, although specific, RT-PCR testing has a reported sensitivity of only 60-70% [22] . Meanwhile, the relatively high incidence of other findings warranting further action, for example malignancy or tuberculosis, needs to be considered. Additionally, we have to take into account that with normal chest x-ray, we may miss important pathology resulting in fatal outcomes after transplantation, in particular with an induction regimen. Therefore, this decision warrants close discussion between the surgical, radiology, pulmonology and transplant physician teams working together. However, as Tsakok et al. [20] stated that National Institute for Health and Care Excellence (NICE) guidelines [23] , do not routinely request chest CT scans to screen for COVID-19 in patients with no symptoms.

Similarly, Weiss et la [12] recently recommended against routine thoracic computed tomography scans for COVID-19 screening for potential deceased organ donors (strong recommendation, low certainty of evidence).

In conclusion, we showed that deceased-donor kidney transplantation could be safely The whole image is uncertain and require the differential diagnostics mainly between imflammation of fungal, opportunistic origin and bronchoalveolar hemorrhage, urgent further pulmonary diagnostic is needed in the HD unit of origin before transplantation.

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