Investigating the relationship between mild traumatic brain injury and Alzheimer's disease and related dementias: a systematic review.

The objective of this systematic review is to synthesize the relevant literature published after 2016 to ascertain the current landscape of science that relates mild traumatic brain injury (mTBI) to the onset of Alzheimer's disease and related dementias (ADRD) and identify areas of need for future research. We conducted database searches and retrieved articles that were published after 2016 that utilized cognitive assessments to understand the relationship between mTBI and ADRD. We identified eight relevant articles in the review process, four of which presented a significant relationship between mTBI and disease or cognitive impairment outcomes. The studies included in this systematic review underscore the need for future research investigating a possible causal relationship between mTBI and ADRDs given the high prevalence of mTBI among brain injury patients and the lack of literature specifically addressing this issue. Future research should standardize the definitions of mTBI, AD, and ADRDs to create reliable and reproducible results that more comprehensively capture the nuances of this relationship.

Donor-derived cell-free DNA as a composite marker of acute lung allograft dysfunction in clinical care.

BACKGROUND: As a marker of underlying lung allograft injury, donor-derived cell-free DNA (dd-cfDNA) may be used to identify episodes of acute allograft injury in lung transplant recipients. We investigated the utility of dd-cfDNA to monitor subjects at risk of acute rejection or infection in routine clinical practice. METHODS: This multicenter, retrospective cohort study collected data from lung transplant recipients within 3 years of transplant at 4 centers between March 24, 2020 and September 1, 2020. During this period, as part of routine care during the COVID-19 pandemic, these centers implemented a home-based surveillance program using plasma dd-cfDNA in preference to surveillance bronchoscopy. Dd-cfDNA was used to detect acute lung allograft dysfunction (ALAD) - a composite endpoint of acute rejection and infection. dd-cfDNA levels in patients with ALAD were compared to stable patients. The performance characteristics of dd-cfDNA ≥ 1.0% to detect ALAD were estimated. RESULTS: A total of 175 patients underwent 380 dd-cfDNA measurements, of which 290 were for routine surveillance purposes. dd-cfDNA was higher in patients with ALAD than stable patients (Median (IQR) 1.7% (0.63, 3.1) vs 0.35% (0.22, 0.79), p < 0.001). As an indication of underlying ALAD during surveillance testing, the estimated sensitivity of dd-cfDNA ≥1% was 73.9%, specificity of 87.7%, positive predictive value of 43.4% and negative predictive value of 96.5%. CONCLUSIONS: dd-cfDNA identified acute lung allograft dysfunction in asymptomatic lung transplant patients that may not have been identified by using a clinically indicated biopsy strategy alone. dd-cfDNA <1.0% may be useful in ruling out acute rejection and infection, supporting its use as a potential noninvasive marker for surveillance monitoring.

Biological Variation of Donor-Derived Cell-Free DNA in Stable Lung Transplant Recipients.

BACKGROUND: Prior studies demonstrate that donor-derived cell-free DNA (dd-cfDNA) in lung transplant recipients may serve as a marker of allograft injury for detecting allograft rejection and infection. Clinical interpretation of dd-cfDNA requires understanding its biological variation in stable lung transplant patients in order to identify abnormal results suggesting underlying allograft dysfunction. This study establishes the biological variation and reference change values (RCV) of dd-cfDNA in stable lung transplant recipients using an analytically validated assay with an established analytic coefficient of variation (CVA). METHODS: The AlloSure® assay, a targeted, sequencing-based approach, was used to measure plasma dd-cfDNA in a cohort of lung transplant patients at 4 centers that used dd-cfDNA to monitor for allograft dysfunction in preference to surveillance transbronchial biopsy. Patients with stable allograft function and ≥3 dd-cfDNA samples were included. Intraindividual coefficient of variation (CVI), interindividual CV (CVG), index of individuality (II) and the RCV were calculated. RESULTS: Thirty-five patients with a combined 124 dd-cfDNA samples were included in the final analysis. The median dd-cfDNA was 0.31% (interquartile range 0.18%-0.68%), the 97.5th percentile and 95th percentile were 1.3% and 1.0%, respectively. In 30 stable patients with an average of 3.7 tests, the CVI was 25%, CVG 19%, II 1.33, and RCV 70%. CONCLUSION: In stable lung transplant patients, fluctuations in dd-cfDNA levels of up to 70% or levels less than 1% are within normal biological variation. With further validation, these thresholds may be incorporated into surveillance monitoring algorithms to identify potentially abnormal results indicating allograft dysfunction.

Donor-derived cell-free DNA accurately detects acute rejection in lung transplant patients, a multicenter cohort study.

BACKGROUND: Acute rejection, which includes antibody-mediated rejection and acute cellular rejection, is a risk factor for lung allograft loss. Lung transplant patients often undergo surveillance transbronchial biopsies to detect and treat acute rejection before irreversible chronic rejection develops. Limitations of this approach include its invasiveness and high interobserver variability. We tested the performance of percent donor-derived cell-free DNA (%ddcfDNA), a non-invasive blood test, to detect acute rejection. METHODS: This multicenter cohort study monitored 148 lung transplant subjects over a median of 19.6 months. We collected serial plasma samples contemporaneously with TBBx to measure %ddcfDNA. Clinical data was collected to adjudicate for acute rejection. The primary analysis consisted of computing the area-under-the-receiver-operating-characteristic-curve of %ddcfDNA to detect acute rejection. Secondary analysis determined %ddcfDNA rule-out thresholds for acute rejection. RESULTS: ddcfDNA levels were high after transplant surgery and decayed logarithmically. With acute rejection, ddcfDNA levels rose six-fold higher than controls. ddcfDNA levels also correlated with severity of lung function decline and histological grading of rejection. %ddcfDNA area-under-the-receiver-operating-characteristic-curve for acute rejection, AMR, and ACR were 0.89, 0.93, and 0.83, respectively. ddcfDNA levels of <0.5% and <1.0% showed a negative predictive value of 96% and 90% for acute rejection, respectively. Histopathology detected one-third of episodes with ddcfDNA levels ≥1.0%, even though >90% of these events were coincident to clinical complications missed by histopathology. CONCLUSIONS: This study demonstrates that %ddcfDNA reliably detects acute rejection and other clinical complications potentially missed by histopathology, lending support to its use as a non-invasive marker of allograft injury.

Cell-Free DNA to Detect Heart Allograft Acute Rejection.

BACKGROUND: After heart transplantation, endomyocardial biopsy (EMBx) is used to monitor for acute rejection (AR). Unfortunately, EMBx is invasive, and its conventional histological interpretation has limitations. This is a validation study to assess the performance of a sensitive blood biomarker-percent donor-derived cell-free DNA (%ddcfDNA)-for detection of AR in cardiac transplant recipients. METHODS: This multicenter, prospective cohort study recruited heart transplant subjects and collected plasma samples contemporaneously with EMBx for %ddcfDNA measurement by shotgun sequencing. Histopathology data were collected to define AR, its 2 phenotypes (acute cellular rejection [ACR] and antibody-mediated rejection [AMR]), and controls without rejection. The primary analysis was to compare %ddcfDNA levels (median and interquartile range [IQR]) for AR, AMR, and ACR with controls and to determine %ddcfDNA test characteristics using receiver-operator characteristics analysis. RESULTS: The study included 171 subjects with median posttransplant follow-up of 17.7 months (IQR, 12.1-23.6), with 1392 EMBx, and 1834 %ddcfDNA measures available for analysis. Median %ddcfDNA levels decayed after surgery to 0.13% (IQR, 0.03%-0.21%) by 28 days. Also, %ddcfDNA increased again with AR compared with control values (0.38% [IQR, 0.31-0.83%], versus 0.03% [IQR, 0.01-0.14%]; P<0.001). The rise was detected 0.5 and 3.2 months before histopathologic diagnosis of ACR and AMR. The area under the receiver operator characteristic curve for AR was 0.92. A 0.25%ddcfDNA threshold had a negative predictive value for AR of 99% and would have safely eliminated 81% of EMBx. In addition, %ddcfDNA showed distinctive characteristics comparing AMR with ACR, including 5-fold higher levels (AMR ≥2, 1.68% [IQR, 0.49-2.79%] versus ACR grade ≥2R, 0.34% [IQR, 0.28-0.72%]), higher area under the receiver operator characteristic curve (0.95 versus 0.85), higher guanosine-cytosine content, and higher percentage of short ddcfDNA fragments. CONCLUSIONS: We found that %ddcfDNA detected AR with a high area under the receiver operator characteristic curve and negative predictive value. Monitoring with ddcfDNA demonstrated excellent performance characteristics for both ACR and AMR and led to earlier detection than the EMBx-based monitoring. This study supports the use of %ddcfDNA to monitor for AR in patients with heart transplant and paves the way for a clinical utility study. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02423070.

Acceptance of Rapid Human Immunodeficiency Virus Testing in an Urban Emergency Department.

Rapid HIV testing programs in emergency departments (EDs) have been shown to promote early diagnosis and linkage to specialty care. However, sensitivity of the subject-matter and stigmatization of disclosing associated risk factors may make patients reluctant to consent to testing in this setting. This study sought to determine whether men are more likely to refuse rapid HIV testing in the ED as compared to women and to analyze the influence of tester gender on the response. This retroactive study utilized demographic and testing information from a rapid HIV testing program housed within two urban EDs for a 5-month period. Gender and age were collected for both testers and patients, along with patient consent outcome. A total of 5358 patients (males = 2230; females = 3128) were approached and offered an HIV test by one of 19 testers during the study period. From the sample population, male and female patient refusal rates were similar (30.0% vs 29.1%, respectively). Female testers approached 57.8% (n = 3,095) of the patients; however, they had a significantly higher refusal rate compared to male testers (35.6% vs 21.4%; p < 0.001). We found a potential gender effect on HIV test consenting. Such a finding could have important implications on HIV screening program effectiveness and warrants further investigation.