Using machine learning to identify important predictors of COVID-19 infection prevention behaviors during the early phase of the pandemic

Before vaccines for coronavirus disease 2019 (COVID-19) became available, a set of infection-prevention behaviors constituted the primary means to mitigate the virus spread. Our study aimed to identify important predictors of this set of behaviors. Whereas social and health psychological theories suggest a limited set of predictors, machine-learning analyses can identify correlates from a larger pool of candidate predictors. We used random forests to rank 115 candidate correlates of infection-prevention behavior in 56,072 participants across 28 countries, administered in March to May 2020. The machine-learning model predicted 52% of the variance in infection-prevention behavior in a separate test sample—exceeding the performance of psychological models of health behavior. Results indicated the two most important predictors related to individual-level injunctive norms. Illustrating how data-driven methods can complement theory, some of the most important predictors were not derived from theories of health behavior—and some theoretically derived predictors were relatively unimportant

Resultados da cirurgia do aneurisma da aorta abdominal em pacientes jovens Outcomes after surgical repair of abdominal aortic aneurysms in young patients

CONTEXTO: A presença de aneurisma da aorta abdominal (AAA) é rara em pacientes jovens. OBJETIVO: Avaliar os resultados da cirurgia do AAA em pacientes com idade < 50 anos. MÉTODOS: De junho de 1979 a janeiro de 2008, 946 pacientes foram operados eletivamente do AAA infrarrenal pelo primeiro autor. Desses, 13 pacientes (1,4%) tinham idade < 50 anos no momento da cirurgia. Foram analisadas as características demográficas e cirúrgicas bem como os resultados precoces e tardios da cirurgia nesses pacientes. RESULTADOS: A média de idade foi 46±3,4 anos (variando de 43 a 50 anos), sendo a maioria homens (76,9%), hipertensos (76,9%) e tabagistas (61,5%). Não ocorreu nenhum óbito perioperatório, e a morbidade cirúrgica atingiu dois pacientes (15,4%) (um paciente com infecção respiratória e outro com angina instável). O seguimento mediano foi de 85,5 meses, ocorrendo dois óbitos devido a cardiopatia isquêmica em um paciente e acidente vascular cerebral em outro, durante o seguimento. CONCLUSÃO: A cirurgia do AAA é um procedimento seguro com bons resultados a longo prazo, pois, em nosso estudo, apresentou mortalidade perioperatória nula e boa sobrevida a longo prazo.<br>BACKGROUND: Abdominal aortic aneurysms (AAA) are rare in young patients. OBJECTIVE: To evaluate outcomes after AAA repair in patients aged < 50 years. METHODS: Between June 1979 and January 2008, 946 patients underwent elective repair for an infrarenal AAA performed by the first author. Of these, 13 patients (1.4%) were < 50 years old at surgery. Demographic characteristics and surgical data were analyzed, as well as early and late outcomes after surgical intervention. RESULTS: Mean age was 46±3.4 years (ranging from 43 to 50 years). Most patients were men (76.9%), hypertensive (76.9%) and smokers (61.5%). Perioperative morbidity and mortality rates were low (15.4% and 0%, respectively); one patient had respiratory infection and another patient had unstable angina. Median follow-up was 85.5 months, and two patients died due to ischemic cardiopathy and cerebrovascular accident during the follow-up period. CONCLUSION: AAA repair in young patients is a safe procedure, with good long-term results. In our study, there were no perioperative deaths, and a good long-term survival was observed

The direct and indirect allogeneic presentation pathway during acute rejection after human cardiac transplantation

Alloreactive T cells may be activated via a direct or an indirect antigen presentation pathway. We questioned whether the frequency of interferon (IFN)-γ producing cells determined by enzyme-linked immunospot (ELISPOT) assay is an effective tool to monitor the direct and/or indirect presentation pathway. Secondly, we wondered whether early and late acute rejection (AR) are associated with both pathways. Before (n = 15), during (n = 18) and after (n = 16) a period of AR, peripheral blood mononuclear cell (PBMC) samples were tested from 13 heart transplant recipients. The direct presentation pathway was always present. The number of IFN-γ producing cells reactive to this pathway increased significantly (P = 0·04) during AR and the number decreased (P = 0·005) after AR therapy. In contrast, the indirect allogeneic presentation pathway was present in only eight of 18 AR samples. When the indirect presentation pathway was detectable, it increased significantly during AR. Five of eight of these AR occurred more than 6 months after transplantation. The ELISPOT assay, enumerating alloreactive IFN-γ producing cells, is a valuable tool to determine the reactivity via both the direct and the indirect presentation pathway. The direct presentation pathway always plays a role in AR, while the indirect pathway contributes especially to late AR