The Accuracy of Nonstandardized MELD/PELD Score Exceptions in the Pediatric Liver Allocation System.

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.

Association of high-priority exceptions with waitlist mortality among heart transplant candidates.

BACKGROUND: 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. METHODS: 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. RESULTS: Out of 12,458 candidates listed during the study period, 2273 (18.2%) received an exception at listing and 1957 (15.7%) received an exception after listing. After controlling for status, exception candidates had approximately half the risk of waitlist mortality as standard candidates (hazard ratio [HR] 0.55, 95% confidence interval [CI] [0.41, 0.73], p < .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 = .023) and a 61% lower risk among Status 2 candidates (HR 0.39, 95% CI [0.24, 0.62], p < .001). CONCLUSIONS: 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.

The endogenous repertoire harbors self-reactive CD4+ T cell clones that adopt a follicular helper T cell-like phenotype at steady state.

The T cell repertoire of healthy mice and humans harbors self-reactive CD4+ conventional T (Tconv) cells capable of inducing autoimmunity. Using T cell receptor profiling paired with in vivo clonal analysis of T cell differentiation, we identified Tconv cell clones that are recurrently enriched in non-lymphoid organs following ablation of Foxp3+ regulatory T (Treg) cells. A subset of these clones was highly proliferative in the lymphoid organs at steady state and exhibited overt reactivity to self-ligands displayed by dendritic cells, yet were not purged by clonal deletion. These clones spontaneously adopted numerous hallmarks of follicular helper T (TFH) cells, including expression of Bcl6 and PD-1, exhibited an elevated propensity to localize within B cell follicles at steady state, and produced interferon-γ in non-lymphoid organs following sustained Treg cell depletion. Our work identifies a naturally occurring population of self-reactive TFH-like cells and delineates a previously unappreciated fate for self-specific Tconv cells.

The social vulnerability metric (SVM) as a new tool for public health.

OBJECTIVE: To derive and validate a new ecological measure of the social determinants of health (SDoH), calculable at the zip code or county level. DATA SOURCES AND STUDY SETTING: The most recent releases of secondary, publicly available data were collected from national U.S. health agencies as well as state and city public health departments. STUDY DESIGN: The Social Vulnerability Metric (SVM) was constructed from U.S. zip-code level measures (2018) from survey data using multidimensional Item Response Theory and validated using outcomes including all-cause mortality (2016), COVID-19 vaccination (2021), and emergency department visits for asthma (2018). The SVM was also compared with the existing Centers for Disease Control and Prevention's Social Vulnerability Index (SVI) to determine convergent validity and differential predictive validity. DATA COLLECTION/EXTRACTION METHODS: The data were collected directly from published files available to the public online from national U.S. health agencies as well as state and city public health departments. PRINCIPAL FINDINGS: The correlation between SVM scores and national age-adjusted county all-cause mortality was r = 0.68. This correlation demonstrated the SVM's robust validity and outperformed the SVI with an almost four-fold increase in explained variance (46% vs. 12%). The SVM was also highly correlated (r ≥ 0.60) to zip-code level health outcomes for the state of California and city of Chicago. CONCLUSIONS: The SVM offers a measurement tool improving upon the performance of existing SDoH composite measures and has broad applicability to public health that may help in directing future policies and interventions. The SVM provides a single measure of SDoH that better quantifies associations with health outcomes.

Association of Zip Code Vaccination Rate With COVID-19 Mortality in Chicago, Illinois.

Importance: There has been large geographic inequity in vaccination coverage across Chicago, Illinois, with higher vaccination rates in zip codes with residents who predominantly have high incomes and are White. Objective: To determine the association between inequitable zip code-level vaccination coverage and COVID-19 mortality in Chicago. Design, Setting, and Participants: This retrospective cohort study used Chicago Department of Public Health vaccination and mortality data and Cook County Medical Examiner mortality data from March 1, 2020, through November 6, 2021, to assess the association of COVID-19 mortality with zip code-level vaccination rates. Data were analyzed from June 1, 2021, to April 13, 2022. Exposures: Zip code-level first-dose vaccination rates before the Alpha and Delta waves of COVID-19. Main Outcomes and Measures: The primary outcome was deaths from COVID-19 during the Alpha and Delta waves. The association of a marginal increase in zip code-level vaccination rate with weekly mortality rates was estimated with a mixed-effects Poisson regression model, and the total number of preventable deaths in the least vaccinated quartile of zip codes was estimated with a linear difference-in-difference design. Results: The study population was 2 686 355 Chicago residents in 52 zip codes (median [IQR] age 34 [32-38] years; 1 378 658 [51%] women; 773 938 Hispanic residents [29%]; 783 916 non-Hispanic Black residents [29%]; 894 555 non-Hispanic White residents [33%]). Among residents in the least vaccinated quartile, 80% were non-Hispanic Black, compared with 8% of residents identifying as non-Hispanic Black in the most vaccinated quartile (P < .001). After controlling for age distribution and recovery from COVID-19, a 10-percentage point increase in zip code-level vaccination 6 weeks before the peak of the Alpha wave was associated with a 39% lower relative risk of death from COVID-19 (incidence rate ratio [IRR], 0.61 [95% CI, 0.52-0.72]). A 10-percentage point increase in zip code vaccination rate 6 weeks before the peak of the Delta wave was associated with a 24% lower relative risk of death (IRR, 0.76 [95% CI, 0.66-0.87]). The difference-in-difference estimate was that 119 Alpha wave deaths (72% [95% CI, 63%-81%]) and 108 Delta wave deaths (75% [95% CI, 66%-84%]) might have been prevented in the least vaccinated quartile of zip codes if it had had the vaccination coverage of the most vaccinated quartile. Conclusions and Relevance: These findings suggest that low zip code-level vaccination rates in Chicago were associated with more deaths during the Alpha and Delta waves of COVID-19 and that inequitable vaccination coverage exacerbated existing racial and ethnic disparities in COVID-19 deaths.

Eomes identifies thymic precursors of self-specific memory-phenotype CD8+ T cells.

Unprimed mice harbor a substantial population of 'memory-phenotype' CD8+ T cells (CD8-MP cells) that exhibit hallmarks of activation and innate-like functional properties. Due to the lack of faithful markers to distinguish CD8-MP cells from bona fide CD8+ memory T cells, the developmental origins and antigen specificities of CD8-MP cells remain incompletely defined. Using deep T cell antigen receptor (TCR) sequencing, we found that the TCRs expressed by CD8-MP cells are highly recurrent and distinct from the TCRs expressed by naive-phenotype CD8+ T cells. CD8-MP clones exhibited reactivity to widely expressed self-ligands. T cell precursors expressing CD8-MP TCRs showed upregulation of the transcription factor Eomes during maturation in the thymus, prior to induction of the full memory phenotype, which is suggestive of a unique program triggered by recognition of self-ligands. Moreover, CD8-MP cells infiltrate oncogene-driven prostate tumors and express high densities of PD-1, which suggests potential roles in antitumor immunity and the response to immunotherapy.