Researching COVID to Enhance Recovery (RECOVER) adult study protocol: Rationale, objectives, and design

IMPORTANCE

SARS-CoV-2 infection can result in ongoing, relapsing, or new symptoms or other health effects after the acute phase of infection; termed post-acute sequelae of SARS-CoV-2 infection (PASC), or long COVID. The characteristics, prevalence, trajectory and mechanisms of PASC are ill-defined. The objectives of the Researching COVID to Enhance Recovery (RECOVER) Multi-site Observational Study of PASC in Adults (RECOVER-Adult) are to: (1) characterize PASC prevalence; (2) characterize the symptoms, organ dysfunction, natural history, and distinct phenotypes of PASC; (3) identify demographic, social and clinical risk factors for PASC onset and recovery; and (4) define the biological mechanisms underlying PASC pathogenesis.

METHODS

RECOVER-Adult is a combined prospective/retrospective cohort currently planned to enroll 14,880 adults aged ≥18 years. Eligible participants either must meet WHO criteria for suspected, probable, or confirmed infection; or must have evidence of no prior infection. Recruitment occurs at 86 sites in 33 U.S. states, Washington, DC and Puerto Rico, via facility- and community-based outreach. Participants complete quarterly questionnaires about symptoms, social determinants, vaccination status, and interim SARS-CoV-2 infections. In addition, participants contribute biospecimens and undergo physical and laboratory examinations at approximately 0, 90 and 180 days from infection or negative test date, and yearly thereafter. Some participants undergo additional testing based on specific criteria or random sampling. Patient representatives provide input on all study processes. The primary study outcome is onset of PASC, measured by signs and symptoms. A paradigm for identifying PASC cases will be defined and updated using supervised and unsupervised learning approaches with cross-validation. Logistic regression and proportional hazards regression will be conducted to investigate associations between risk factors, onset, and resolution of PASC symptoms.

DISCUSSION

RECOVER-Adult is the first national, prospective, longitudinal cohort of PASC among US adults. Results of this study are intended to inform public health, spur clinical trials, and expand treatment options.

REGISTRATION

NCT05172024.

Nitric Oxide Contributes to Vasomotor Tone in Hypertensive African Americans Treated With Nebivolol and Metoprolol

Endothelial dysfunction is more prevalent in African Americans (AAs) compared with whites. The authors hypothesized that nebivolol, a selective β1 -antagonist that stimulates nitric oxide (NO), will improve endothelial function in AAs with hypertension when compared with metoprolol. In a double-blind, randomized, crossover study, 19 AA hypertensive patients were randomized to a 12-week treatment period with either nebivolol 10 mg or metoprolol succinate 100 mg daily. Forearm blood flow (FBF) was measured using plethysmography at rest and after intra-arterial infusion of acetylcholine and sodium nitroprusside to estimate endothelium-dependent and independent vasodilation, respectively. Physiologic vasodilation was assessed during hand-grip exercise. Measurements were repeated after NO blockade with L-N(G) -monomethylarginine (L-NMMA) and after inhibition of endothelium-derived hyperpolarizing factor (EDHF) with tetraethylammonium chloride (TEA). NO blockade with L-NMMA produced a trend toward greater vasoconstriction during nebivolol compared with metoprolol treatment (21% vs 12% reduction in FBF, P=.06, respectively). This difference was more significant after combined administration of L-NMMA and TEA (P<.001). Similarly, there was a contribution of NO to exercise-induced vasodilation during nebivolol but not during metoprolol treatment. There were significantly greater contributions of NO and EDHF to resting vasodilator tone and of NO to exercise-induced vasodilation with nebivolol compared with metoprolol in AAs with hypertension.

Insufficient nitric oxide bioavailability: a hypothesis to explain adverse effects of red blood cell transfusion

While transfusion of red blood cells (RBCs) is effective at preventing morbidity and mortality in anemic patients, studies have indicated that some RBC components have functional defects ("RBC storage lesions") that may actually cause adverse events when transfused. For example, in some studies patients transfused with RBCs stored more than 14 days have had statistically worse outcomes than those receiving "fresher" RBC units. Recipient-specific factors may also contribute to the occurrence of these adverse events. Unfortunately, these events have been difficult to investigate because up to now they have existed primarily as "statistical occurrences" of increased morbidity and mortality in large data sets. There are currently no clinical or laboratory methods to detect or study them in individual transfusion recipients. We propose a unifying hypothesis, centered on insufficient nitric oxide bioavailability (INOBA), to explain the increased morbidity and mortality observed in some patients after RBC transfusion. In this model, variables associated with RBC units (storage time; 2,3-diphosphoglycerate acid concentration) and transfusion recipients (endothelial dysfunction) collectively lead to changes in nitric oxide (NO) levels in vascular beds. Under certain circumstances, these variables are "aligned" such that NO concentrations are markedly reduced, leading to vasoconstriction, decreased local blood flow, and insufficient O(2) delivery to end organs. Under these circumstances, the likelihood of morbidity and mortality escalates. If the key tenets of the INOBA hypothesis are confirmed, it may lead to improved transfusion methods including altered RBC storage and/or processing conditions, novel transfusion recipient screening methods, and improved RBC-recipient matching.

Oxidative stress markers are associated with persistent atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) has been associated with myocardial oxidative stress, and antioxidant agents have demonstrated antiarrhythmic benefit in humans. We compared serum markers of oxidation and associated inflammation in individuals with or without AF.

METHODS

Serum markers of oxidative stress and inflammation were compared in a cross-sectional, case-control design study of 40 male individuals, with or without persistent or permanent AF, who were matched for age, sex, diabetes, and smoking status, known confounding variables for the measurement of oxidative stress. We used derivatives of reactive oxidative metabolites (DROMs) and ratios of oxidized to reduced glutathione (E(h) GSH) and cysteine (E(h) CySH) to quantify oxidative stress. We also measured inflammatory markers, including high-sensitivity C-reactive protein, interleukins 1beta and 6, and tumor necrosis factor alpha.

RESULTS

Univariate, conditional logistical regression analysis showed that oxidative stress but not inflammatory markers were statistically associated with AF (P <0.05). The increase in the odds ratios for AF for E(h) GSH, E(h) CySH, and DROMs were 6.1 (95% CI, 1.3-28.3; P = 0.02), 13.6 (95% CI, 2.5-74.1; P = 0.01), and 15.9 (95% CI, 1.7-153.9; P = 0.02), respectively. There was a stronger correlation between E(h) GSH and E(h) CySH (r = 0.66) than between E(h) GSH and DROMs (r = 0.41). In multivariate analysis corrected for statins and other AF risk factors differing between the groups, the association of AF and oxidative stress remained significant.

CONCLUSIONS

These data suggest that oxidative stress markers may have predictive value in AF management.