Daniel Jaechul Ahn

All Publications

• The Accuracy of Nonstandardized MELD/PELD Score Exceptions in the Pediatric Liver Allocation System. Transplantation Ahn, D. J., Zeng, S., Pelzer, K. M., Barth, R. N., Gallo, A., Parker, W. F. 2023

  Abstract

  BACKGROUND: In the United States, over half of pediatric candidates receive exceptions and status upgrades that increase their allocation model of end-stage liver disease/pediatric end-stage liver disease (MELD/PELD) score above their laboratory MELD/PELD score. We determined whether these "nonstandardized" MELD/PELD exceptions accurately depict true pretransplant mortality risk.METHODS: Using data from the Scientific Registry of Transplant Recipients, we identified pediatric candidates (<18 y of age) with chronic liver failure added to the waitlist between June 2016 and September 2021 and estimated all-cause pretransplant mortality with mixed-effects Cox proportional hazards models that treated allocation MELD/PELD and exception status as time-dependent covariates. We also estimated concordance statistics comparing the performance of laboratory MELD/PELD with allocation MELD/PELD. We then compared the proportion of candidates with exceptions before and after the establishment of the National Liver Review Board.RESULTS: Out of 2026 pediatric candidates listed during our study period, 403 (19.9%) received an exception within a week of listing and 1182 (58.3%) received an exception before delisting. Candidates prioritized by their laboratory MELD/PELD scores had an almost 9 times greater risk of pretransplant mortality compared with candidates who received the same allocation score from an exception (hazard ratio 8.69; 95% confidence interval, 4.71-16.03; P < 0.001). The laboratory MELD/PELD score without exceptions was more accurate than the allocation MELD/PELD score with exceptions (Harrell's c-index 0.843 versus 0.763). The proportion of patients with an active exception at the time of transplant decreased significantly after the National Liver Review Board was implemented (67.4% versus 43.4%, P < 0.001).CONCLUSIONS: Nonstandardized exceptions undermine the rank ordering of pediatric candidates with chronic liver failure.

  View details for DOI 10.1097/TP.0000000000004720

  View details for PubMedID 37408100

• Association of High-Priority Exceptions with Waitlist Mortality Among Heart Transplant Candidates. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation Johnson, D. Y., Ahn, D., Lazenby, K., Zeng, S., Zhang, K., Narang, N., Khush, K., Parker, W. F. 2023

  Abstract

  The US heart allocation system ranks candidates using six categorical status levels. Transplant programs can request exceptions to increase a candidate's status level if they believe their candidate has the same medical urgency as candidates who meet the standard criteria for that level. We aimed to determine if exception candidates have the same medical urgency as standard candidates.Using the Scientific Registry of Transplant Recipients, we constructed a longitudinal waitlist history dataset of adult heart-only transplant candidates listed between October 18, 2018 and December 1, 2021. We estimated the association between exceptions and waitlist mortality with a mixed-effects Cox proportional hazards model that treated status and exceptions as time-dependent covariates.Out of 12,458 candidates listed during the study period, 2,273 (18.2%) received an exception at listing and 1,957 (15.7%) received an exception after listing. After controlling for status, exception candidates had approximately half the risk of waitlist mortality as standard candidates (HR 0.55, 95% CI [0.41, 0.73], p < 0.001). Exceptions were associated with a 51% lower risk of waitlist mortality among Status 1 candidates (HR 0.49, 95% CI [0.27, 0.91], p = 0.023) and a 61% lower risk among Status 2 candidates (HR 0.39, 95% CI [0.24, 0.62], p < 0.001).Under the new heart allocation policy, exception candidates had significantly lower waitlist mortality than standard candidates, including exceptions for the highest priority statuses. These results suggest that candidates with exceptions, on average, have a lower level of medical urgency than candidates who meet standard criteria.

  View details for DOI 10.1016/j.healun.2023.05.009

  View details for PubMedID 37225029

• Assessing knowledge of end-stage kidney disease and treatment options in hospitalized African American patients undergoing hemodialysis. Chronic illness King, A., Tanumihardjo, J., Ahn, D., Zasadzinski, L., Robinson, E., Quinn, M., Peek, M., Saunders, M. 2023: 17423953231168803

  Abstract

  African Americans are more likely to develop end-stage kidney disease (ESKD) than whites and face multiple inequities regarding ESKD treatment, renal replacement therapy (RRT), and overall care. This study focused on determining gaps in participants' knowledge of their chronic kidney disease and barriers to RRT selection in an effort to identify how we can improve health care interventions and health outcomes among this population.African American participants undergoing hemodialysis were recruited from an ongoing research study of hospitalized patients at an urban Midwest academic medical center. Thirty-three patients were interviewed, and the transcribed interviews were entered into a software program. The qualitative data were coded using template analysis to analyze text and determine key themes. Medical records were used to obtain demographic and additional medical information.Three major themes emerged from the analysis: patients have limited information on ESKD causes and treatments, patients did not feel they played an active role in selecting their initial dialysis unit, and interpersonal interactions with the dialysis staff play a large role in overall unit satisfaction.Although more research is needed, this study provides information and suggestions to improve future interventions and care quality, specifically for this population.

  View details for DOI 10.1177/17423953231168803

  View details for PubMedID 37106575

• Utility of geriatric assessments in evaluation of older adults for kidney transplantation. Clinical transplantation Campbell, K. H., Ahn, D. J., Enger, F., Zasadzinski, L., Tanumihardjo, J., Becker, Y., Josephson, M., Saunders, M. R. 2022; 36 (12): e14813

  Abstract

  While kidney transplantation has favorable outcomes in patients aged 65 years and older, many are not referred for evaluation despite having no contraindications. We wanted to determine whether incorporating geriatrics and geriatric assessments (GA), as part of kidney transplant evaluation at the University of Chicago Medicine, would help identify suitable candidates and improve transplantation outcomes among older adults.Between 2012 and 2016, as part of their multi-disciplinary transplant evaluation, 171 patients underwent an initial GA with the study geriatrician, who rated them on a five-point scale from "poor" to "excellent," and presented their cases to multidisciplinary transplant review meetings. Patients were followed until June 1st, 2021. Predictor variables included geriatric recommendation, clinical characteristics, and demographics. Outcomes of interest were mortality, receipt of transplant, and waitlist placement.Compared to patients rated "poor," "marginal," or "fair," we found that patients that the geriatrician recommended as "good" or "excellent" were more likely to be waitlisted and receive a transplant. Favorably rated patients were also less likely to be removed from the waitlist due to becoming medically unfit, meaning worsening medical morbidity, frailty, and cognitive status.Including geriatricians to perform GAs as part of the transplant evaluation process can help identify suitable elderly candidates.

  View details for DOI 10.1111/ctr.14813

  View details for PubMedID 36124434

  View details for PubMedCentralID PMC10078529

• Advance care planning among African American patients on haemodialysis and their end-of-life care preferences. Journal of renal care Ahn, D., Williams, S., Stankus, N., Saunders, M. 2021; 47 (4): 265-278

  Abstract

  African Americans in the general population have been shown to be less likely than White ethnic groups to participate in advance care planning; however, advance care planning in the population receiving dialysis has not been well explored.We examined the prevalence of African American patients receiving haemodialysis' advance care planning discussions, and whether advance care planning impacts end-of-life care preferences.In-person interviewer-administered surveys of African American patients receiving in-centre haemodialysis.About 101 participants at three large dialysis organisation units in Chicago.Self-reported advance care planning and preferences for life-extending treatments at end-of-life.Most patients (69%) report no advance care planning discussions with their healthcare providers. Nearly all patients (92%) without prior advance care planning reported their healthcare providers approached them about advance care planning. While the majority of patients indicated preference for aggressive life-extending care, prior conversations about end-of-life care wishes either with family members or a healthcare provider significantly decreased patients' likelihood of choosing aggressive life-extending care across three scenarios (all p < 0.05). Significantly more patients reported that common end-of-life scenarios related to increased dependence/disability were "not worth living through" compared with those associated with increased burden on family, decreased cognitive function, and severe pain/discomfort.African Americans with end-stage renal disease need more frequent, culturally-sensitive advance care planning discussions. Despite a preference for aggressive life-sustaining treatments, individuals with prior advance care planning discussions were significantly less likely to support aggressive end-of-life care. End-of-life care discussions that focus on the impact of life-extending care on patients' independence could be more concordant with the values and priorities of the African American patients.

  View details for DOI 10.1111/jorc.12368

  View details for PubMedID 33616278

  View details for PubMedCentralID PMC9237830

• Where Do I Fit In? A Perspective on Challenges Faced by Asian American Medical Students. Health equity Ahn, D. J., Garg, N., Naik, A. G., Fan, J., Wei, H., Song, B. B., Chung, K., Vela, M. B., Kim, K. E. 2021; 5 (1): 324-328

  Abstract

  Asian American medical students (AAMSs) face significant bias in the medical learning environment and are more likely than White students to perceive their school climate negatively. Little is known about the factors that contribute to AAMSs' negative experiences. This perspective aims to describe AAMSs' experiences with diversity and inclusion efforts using survey data from a midwest regional conference, Asians in Medicine: A Conference on Advocacy and Allyship. AAMS respondents reported feeling excluded from diversity and inclusion efforts and conference participants advocated for institutional culture and climate assessments stratified by race and disaggregated into Asian subgroups.

  View details for DOI 10.1089/heq.2020.0158

  View details for PubMedID 34036216

  View details for PubMedCentralID PMC8140354

• ABHD10 is an S-depalmitoylase affecting redox homeostasis through peroxiredoxin-5. Nature chemical biology Cao, Y., Qiu, T., Kathayat, R. S., Azizi, S. A., Thorne, A. K., Ahn, D., Fukata, Y., Fukata, M., Rice, P. A., Dickinson, B. C. 2019; 15 (12): 1232-1240

  Abstract

  S-Palmitoylation is a reversible lipid post-translational modification that has been observed on mitochondrial proteins, but both the regulation and functional consequences of mitochondrial S-palmitoylation are poorly understood. Here, we show that perturbing the 'erasers' of S-palmitoylation, acyl protein thioesterases (APTs), with either pan-active inhibitors or a mitochondrial-targeted APT inhibitor, diminishes the antioxidant buffering capacity of mitochondria. Surprisingly, this effect was not mediated by the only known mitochondrial APT, but rather by a resident mitochondrial protein with no known endogenous function, ABHD10. We show that ABHD10 is a member of the APT family of regulatory proteins and identify peroxiredoxin-5 (PRDX5), a key antioxidant protein, as a target of ABHD10 S-depalmitoylase activity. We then find that ABHD10 regulates the S-palmitoylation status of the nucleophilic active site residue of PRDX5, providing a direct mechanistic connection between ABHD10-mediated S-depalmitoylation of PRDX5 and its antioxidant capacity.

  View details for DOI 10.1038/s41589-019-0399-y

  View details for PubMedID 31740833

  View details for PubMedCentralID PMC6871660

• A Panel of Protease-Responsive RNA Polymerases Respond to Biochemical Signals by Production of Defined RNA Outputs in Live Cells. Journal of the American Chemical Society Pu, J., Chronis, I., Ahn, D., Dickinson, B. C. 2015; 137 (51): 15996-9

  Abstract

  RNA is an attractive biomolecule for biosensing and engineering applications due to its information storage capacity and ability to drive gene expression or knockdown. However, methods to link chemical signals to the production of specific RNAs are lacking. Here, we develop protease-responsive RNA polymerases (PRs) as a strategy to encode multiple specific proteolytic events in defined sequences of RNA in live mammalian cells. This work demonstrates that RNAP-based molecular recording devices can be deployed for multimodal analyses of biochemical activities or to trigger gene circuits using measured signaling events.

  View details for DOI 10.1021/jacs.5b10290

  View details for PubMedID 26652972

  View details for PubMedCentralID PMC5070793