Estabelecimento de uma tabela normativa para a classificação do percentual de gordura corporal em adolescentes

Introduction: The prevalence of obesity in adolescents has increased worldwide, which is closely related to comorbidities in adulthood. Despite the severity of this pathology and its significant impacts on the health system, there is no international consensus on the cut-off point for the percentage of body fat for Brazilian children and adolescents, making it difficult to make an accurate and early diagnosis addition to assertive treatment. Objective: This study aimed to establish cut-off points for body fat percentage in male and female adolescents aged 16 to 19 years using bioelectrical impedance (InBody 570®). Methods: Gender-specific tables were proposed based on the percentiles 3, 5, 10, 15, 25, 50, 75, 85, 95, and 97. A total of 546 adolescents were included. Results: The body fat percentage cut-off points for the male group were: P3 = 6.0-7.0%; P5 = 7.1-8.9%; P10 = 9.0-9.8%; P15 = 9.9-11.7%; P25 = 11.8-15.5%; P50 = 15.6-21.9%; P75 = 22.0-27.8%; P85 = 27.9-36.0%; P95 = 36.1-38.0% and P97 ≥ 38.1%. For females, the cut-off points were: P3 = 9.5-10.0%; P5 = 10.1-11.0%; P10 = 11.1-11.8%; P15 = 11.9-14.0%; P25 = 14.1-19.0%; P50 = 19.1-27.1%; P75 = 27.2-29.0%; P85 = 29.1-39.9%; P95 = 40.0-51.0% and P97 ≥ 51.0%. Conclusion: The establishment of cut-off points for body fat percentage may improve the clinical assessment and management of overweight and obese adolescents.Introdução: A Organização Mundial da Saúde (OMS) recomenda o uso do índice de massa corporal (IMC) como método custo-efetivo nível 1 para avaliar o estado nutricional na população. O aumento do IMC está associado a um maior risco de outras doenças crônicas não transmissíveis (DCNT), particularmente a hipertensão arterial sistêmica (HAS), diabetes mellitus tipo 2 (DM2), dislipidemias e alguns tipos de cânceres. A prevalência da obesidade tem aumentado em todo o mundo e essa condição tem afetado dramaticamente crianças e adolescentes. A obesidade em jovens, por sua vez, aumenta as chances de obesidade grave e suas complicações em adultos. Objetivo: Este estudo teve como objetivo estabelecer pontos de corte para o percentual de gordura corporal em adolescentes do sexo masculino e feminino de 16 a 18 anos, utilizando a bioimpedância elétrica (InBody 570®). Método: Tabelas específicas para o sexo masculino e feminino foram propostas, com base nos percentis 3, 5, 10, 15, 25, 50, 75, 85, 95 e 97. Foram incluídos 546 adolescentes. Resultados: Os pontos de corte do percentual de gordura corporal para o grupo masculino foram: P3 = 6,0-7,0%; P5 = 7,1-8,9%; P10 = 9,0-9,8%; P15 = 9,9-11,7%; P25 = 11,8-15,5%; P50 = 15,6-21,9%; P75 = 22,0-27,8%; P85 = 27,9-36,0%; P95 = 36,1-38,0% and P97 ≥ 38,1%. Para as mulheres, os pontos de corte foram: P3 = 9,5-10,0%; P5 = 10,1-11,0%; P10 = 11,1-11,8%; P15 = 11,9-14,0%; P25 = 14,1-19,0%; P50 = 19,1-27,1%; P75 = 27,2-29,0%; P85 = 29,1-39,9%; P95 = 40,0-51,0% e P97 ≥ 51,0%. Conclusão: O estabelecimento de pontos de corte para percentual de gordura corporal pode propiciar parâmetros para a melhoria da avaliação clínica, bem como para o tratamento da obesidade em adolescentes

High anti-SARS-CoV-2 antibody seroconversion rates before the second wave in Manaus, Brazil, and the protective effect of social behaviour measures: results from the prospective DETECTCoV-19 cohort

Background: The city of Manaus, Brazil, has seen two collapses of the health system due to the COVID-19 pandemic. We report anti-SARS-CoV-2 nucleocapsid IgG antibody seroconversion rates and associated risk factors in Manaus residents before the second wave of the epidemic in Brazil. Methods: A convenience sample of adult (aged ≥18 years) residents of Manaus was recruited through online and university website advertising into the DETECTCoV-19 study cohort. The current analysis of seroconversion included a subgroup of DETECTCoV-19 participants who had at least two serum sample collections separated by at least 4 weeks between Aug 19 and Oct 2, 2020 (visit 1), and Oct 19 and Nov 27, 2020 (visit 2). Those who reported (or had no data on) having a COVID-19 diagnosis before visit 1, and who were positive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at visit 1 were excluded. Using an in-house ELISA, the reactivity index (RI; calculated as the optical density ratio of the sample to the negative control) for serum anti-SARS-CoV-2 nucleocapsid IgG antibodies was measured at both visits. We calculated the incidence of seroconversion (defined as RI values ≤1·5 at visit 1 and ≥1·5 at visit 2, and a ratio >2 between the visit 2 and visit 1 RI values) during the study period, as well as incidence rate ratios (IRRs) through cluster-corrected and adjusted Poisson regression models to analyse associations between seroconversion and variables related to sociodemographic characteristics, health access, comorbidities, COVID-19 exposure, protective behaviours, and symptoms. Findings: 2496 DETECTCoV-19 cohort participants returned for a follow-up visit between Oct 19 and Nov 27, 2020, of whom 204 reported having COVID-19 before the first visit and 24 had no data regarding previous disease status. 559 participants were seropositive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at baseline. Of the remaining 1709 participants who were seronegative at baseline, 71 did not meet the criteria for seroconversion and were excluded from the analyses. Among the remaining 1638 participants who were seronegative at baseline, 214 showed seroconversion at visit 2. The seroconversion incidence was 13·06% (95% CI 11·52–14·79) overall and 6·78% (5·61–8·10) for symptomatic seroconversion, over a median follow-up period of 57 days (IQR 54–61). 48·1% of seroconversion events were estimated to be asymptomatic. The sample had higher proportions of affluent and higher-educated people than those reported for the Manaus city population. In the fully adjusted and corrected model, risk factors for seroconversion before visit 2 were having a COVID-19 case in the household (IRR 1·49 [95% CI 1·21–1·83]), not wearing a mask during contact with a person with COVID-19 (1·25 [1·09–1·45]), relaxation of physical distancing (1·31 [1·05–1·64]), and having flu-like symptoms (1·79 [1·23–2·59]) or a COVID-19 diagnosis (3·57 [2·27–5·63]) between the first and second visits, whereas working remotely was associated with lower incidence (0·74 [0·56–0·97]). Interpretation: An intense infection transmission period preceded the second wave of COVID-19 in Manaus. Several modifiable behaviours increased the risk of seroconversion, including non-compliance with non-pharmaceutical interventions measures such as not wearing a mask during contact, relaxation of protective measures, and non-remote working. Increased testing in high-transmission areas is needed to provide timely information about ongoing transmission and aid appropriate implementation of transmission mitigation measures. Funding: Ministry of Education, Brazil; Fundação de Amparo à Pesquisa do Estado do Amazonas; Pan American Health Organization (PAHO)/WHO.World Health OrganizationRevisión por pare