Beyond logistic regression: structural equations modelling for binary variables and its application to investigating unobserved confounders

Abstract Background Structural equation modelling (SEM) has been increasingly used in medical statistics for solving a system of related regression equations. However, a great obstacle for its wider use has been its difficulty in handling categorical variables within the framework of generalised linear models. Methods A large data set with a known structure among two related outcomes and three independent variables was generated to investigate the use of Yule's transformation of odds ratio (OR) into Q-metric by (OR-1)/(OR+1) to approximate Pearson's correlation coefficients between binary variables whose covariance structure can be further analysed by SEM. Percent of correctly classified events and non-events was compared with the classification obtained by logistic regression. The performance of SEM based on Q-metric was also checked on a small (N = 100) random sample of the data generated and on a real data set. Results SEM successfully recovered the generated model structure. SEM of real data suggested a significant influence of a latent confounding variable which would have not been detectable by standard logistic regression. SEM classification performance was broadly similar to that of the logistic regression. Conclusion The analysis of binary data can be greatly enhanced by Yule's transformation of odds ratios into estimated correlation matrix that can be further analysed by SEM. The interpretation of results is aided by expressing them as odds ratios which are the most frequently used measure of effect in medical statistics.</p

Baixa cobertura da vacina contra COVID-19 e altas taxas de mortalidade por COVID-19 em idosos no Brazil

Introduction: In 2021, Brazil started a nationwide vaccination against COVID-19 but the emergence of the P.1 variant of SARS-CoV-2, more transmissible and resistant to immunity from the previous infection, rapidly led to a record increase in COVID-19 mortality. Methods: Secondary data on COVID-19 deaths and vaccination coverage were retrieved to examine COVID-19 mortality rate (MR) evolution as anti-COVID-19 vaccination advanced in Brazil in 2021. Poisson regression with adjustment for age and federal states was used to calculate the MR. Results; By mid-April 2021, MR increased 2-3 times compared to the already high level in January for the people of 60 years or older, reaching the highest epidemic level of 5-15 per 100.000 in this age group. Despite a declining time trend followed, by the end of May, the MR level was still about 50% and 80% higher for the 40-79 and 80 years or older. The first dose of anti-COVID-19 coverage reached 80% for the 60-69 years old and exceeded 95% for those of 70 years or older, but the second dose was applied to only 26%, 76%, and 64% of the 60-69, 70-79, and 80 years or older, respectively. The average age-standardized MR over the study time was the highest in northern Brazilian states of Rondônia, Amazonas, Acre, and Roraima (range 6-8.4 per 100.000). Conclusion: Anti-COVID-19 vaccination coverage was below the level necessary to protect Brazilians from rising MR between January and May 2021. Urgent measures are needed to increase the vaccine supply and the adherence to non-pharmacological protective measures.Introdução: Brasil começou vacinar contra COVID-19 em 2021, mas o surgimento da variante P.1 do SARS-Cov-2, mais transmissível e resistente, rapidamente levou a aumento recorde em mortalidade por COVID-19. Métodos – Foram levantados dados secundários sobre mortes e cobertura vacinal relacionadas a COVID-19, para examinar a evolução da taxa de mortalidade (TM) com avanço da vacinação. Utilizou-se a regressão de Poisson com ajuste para idade e as unidades federadas. Resultados – Em abril, a TM aumentou 2-3 vezes comparado com começo do ano 2021 em pessoas com 60 ou mais anos de idade (60+), atingindo o nível recorde de 5-15 por 100.000. Apesar do subsequente declínio, no final de maio a taxa ainda estava aproximadamente 50% e 80% mais alta que no começo do ano para faixas etárias de 40-79 e 80+ anos, respectivamente. As pessoas com 70+ anos ultrapassaram a cobertura vacinal de 95%, enquanto aqueles de 60-69 anos chegaram à 80% da cobertura com a primeira dose da vacina. Porém, a segunda dose foi aplicada a somente 26%, 76%, e 64% das pessoas com 60-69, 70-79, e 80+ anos, respectivamente. As mais altas taxas de 6 a 8.4 per 100.000, ajustadas por faixa etária, foram registradas em Rondônia, Amazonas, Acre, e Roraima. Conclusão – Cobertura vacinal contra COVID-19 não atingiu os níveis necessários para proteger os Brasileiros contra crescente mortalidade por esta doença entre janeiro e maio de 2021. É preciso tomar medidas urgentes para aumentar o suprimento das vacinas e aderência às medidas preventivas não farmacológicas

Epidemiological trends and risk factors for tobacco, alcohol and drug use among adolescents in Scotland, 2002–13

Background This study estimates trends in prevalence, and patterns, of individual and multiple substance use between 2002 and 2013 amongst adolescents in Scotland. Methods The study uses data from 134 387 participants of the biennial national ‘Scottish Schools Adolescent Lifestyle and Substance Use Survey’ on smoking, alcohol and illicit drug use. Current regular use and current heavy use of smoking, alcohol, illicit drugs and multiple substances was measured. Time trends in the prevalence of each outcome were estimated using univariate and multivariate logistic regression. Results Regular smoking, alcohol, illicit drug and multiple substance use declined significantly amongst adolescents in Scotland. However, multivariate analyses that focussed upon high-risk levels of these behaviours revealed an upward linear trend in heavy alcohol (OR = 1.06; 95% CI: 1.04, 1.07) and heavy illicit drug (OR = 1.04; 95% CI: 1.00, 1.08) use (P < 0.05). Non-white pupils were more likely to be involved in individual and multiple substance use than ethnically white British pupils. In comparison to pupils from the least deprived socioeconomic quintile, pupils from the most deprived quintile had increased odds of 1.41 (95% CI: 1.02, 1.97; P < 0.05) and 1.62 (95% CI: 1.14, 2.29; P < 0.05) of being regular and heavy multiple substance users, respectively. Conclusions Further effort is required to tackle heavy alcohol and heavy illicit drug use amongst adolescents in Scotland. Prevention strategies should be informed by the risk profiles of substance misusers and evidence around the clinical and cost-effectiveness of preventive interventions

Self-reported health and socio-economic inequalities in England, 1996–2009 : repeated national cross-sectional study

Tackling social inequalities in health has been a priority for recent UK governments. We used repeated national cross-sectional data for 155,311 participants (aged ≥16 years) in the Health Survey of England to examine trends in socio-economic inequalities in self-reported health over a recent period of sustained policy focus by successive UK governments aimed at tackling social inequalities in health. Socio-economic related inequalities in self-reported health were estimated using the Registrar General's occupational classification (1996–2009), and for sensitivity analyses, the National Statistics Socio-Economic Classification (NS-SEC; 2001–2011). Multi-level regression was used to evaluate time trends in General Health Questionnaire (GHQ-12) scores and bad or very bad self-assessed health (SAH), as well as EQ-5D utility scores. The study found that the probability of reporting GHQ-12 scores ≥4 and ≥ 1 was higher in those from lower social classes, and decreased for all social classes between 1997 and 2009. For SAH, the probability of reporting bad or very bad health remained relatively constant for social class I (professional) [0.028 (95%CI: 0.026, 0.029) in 1996 compared to 0.028 (95%CI: 0.024, 0.032) in 2009], but increased in lower social classes, with the greatest increase observed amongst those in social class V (unskilled manual) [0.089 (95%CI: 0.085, 0.093) in 1996 compared to 0.155 (95%CI: 0.141, 0.168) in 2009]. EQ-5D utility scores were lower for those in lower social classes, but remained comparable across survey years. In sensitivity analyses using the NS-SEC, health outcomes improved from 2001 to 2011, with no evidence of widening socio-economic inequalities. Our findings suggest that socio-economic inequalities have persisted, with evidence of widening for some adverse self-reported health outcomes

Prevalência e fatores de risco relacionados ao uso de drogas entre escolares

OBJECTIVE: To assess prevalence and risk factors associated with drug abuse among public elementary and high school students in the southern city of Florianópolis, Brazil. METHODS: A descriptive cross-sectional study was carried out using a standardized questionnaire created during the 4th National Survey on Drug Abuse. Four hundred and seventy-eight students were interviewed by trained college students. Of the interviewees, 43% aged 13--15 years and 32% aged 16--18 years and they had a higher socioeconomic status than the national average. RESULTS: Ever use prevalence for alcohol, marijuana, solvent drugs and amphetamines was 86.8%, 19.9%, 18.2% and 8.4%, respectively. Regular use (6 or more times per month) of alcohol, marijuana, solvent drugs and amphetamines was found in 24.2%, 4.9%, 2.5% and 2.3% of students, respectively, a higher percentage when compared to other southern states' capitals and the national average. Age, sex, social status and living with both parents were significantly associated with drug abuse. Girls were twice as likely to consume weight loss drugs and stimulants, and almost three times more likely to use tranquilizers without medical prescription. Boys were almost twice as likely to use solvent drugs. Higher social students were twice as likely to consume alcohol than those of lower social status. Cigarette and marijuana smoking, respectively, were 84% and 67% more likely among students whose parents were separated. CONCLUSIONS: There is a high prevalence of drug use among elementary and high school students in Florianópolis.OBJETIVO: Analisar a prevalência e os fatores de risco relacionados ao uso indevido de drogas entre estudantes de uma escola pública de primeiro e segundo graus. MÉTODOS: Foi realizado estudo descritivo transversal, utilizando, como instrumento de pesquisa, um questionário anônimo, padronizado e amplamente testado no Brasil para levantamento do uso de drogas. A população estudada foi constituída de 478 estudantes de escola pública de primeiro e segundo graus, de Florianópolis, SC. Os questionários foram aplicados por estudantes universitários devidamente treinados. Entre os estudantes pesquisados, 43% e 32% foram de faixa etária de 13 a 15 anos e de 16 a 18 anos, respectivamente, com predomínio de classes socioeconômicas mais altas. RESULTADOS: A prevalência de uso de maconha na vida (19,9%), solventes (18,2%), anfetamínicos (8,4%) e álcool (86,8%) foi elevada em Florianópolis, comparada a outras capitais da região Sul e à média brasileira. Notou-se elevado e freqüente uso (seis ou mais vezes por mês) de álcool (24,2%), maconha (4,9%), solventes (2,5%) e anfetamínicos (2,3%). Os fatores demográficos relacionados ao uso de drogas na vida foram idade, sexo, classe socioeconômica e vida junto aos pais. A chance de garotas usarem remédios para emagrecer ou ficarem acordadas foi o dobro da chance de garotos e, quanto ao uso de tranqüilizantes, quase o triplo. Os garotos tinham um risco quase duas vezes maior de uso de solvente do que as garotas. A classe socioeconômica alta foi associada a um risco duas vezes maior do uso de álcool do que a classe baixa. O risco de uso de cigarro e maconha na vida foi 84% e 67% maior, respectivamente, para alunos cujos pais estavam separados. CONCLUSÃO: Constatou-se alta prevalência de uso de várias drogas entre os alunos de primeiro e segundo graus

Preditores biopsicossociais de incapacidade física e depressão em trabalhadores do setor de frigoríficos atendidos em um programa de reabilitação profissional

A large number of workers are afflicted by occupational diseases that have chronic pain, disability, and depression among their symptoms. Although there is evidence on contributory factors related to the working environment as well as physical factors involved in occupational diseases, disability and depression associated with these conditions are multidimensional phenomena mediated by bio-psycho-social aspects. This paper examines the relationships between clinical, environmental, and demographics factors, and disability and depression in a sample of workers from the meatpacking industry (n=234) attended by an occupational rehabilitation program. This study can be described as cross-sectional, and uses descriptive and inferential statistics (multivariate regressions). Data was collected using a demographic and clinical questionnaire, the Roland-Morris Questionnaire, the HADS depression scale, and the Measure of Functional Independence (MFI). The results show that, by all measurements used, the final score (post-rehab.) was strongly determined by the initial score (pre-rehab.) with little influence from other independent variables. Changes in the levels of disability appeared to be associated with financial gain (p=0.057). The final score on the MFI was inversely related to the time off work (p=0.006). Variations among the final scores of the CID-10 categories were not conclusive. On the whole there was a preponderance of women among those on sick leave, also with high incidence of musculoskeletal disorders and depression or both. The age variable was the predictor for RM disability, whereas time off work was the predictor for disability by MFI. None of the variables analyzed affected the depression scores. Generally these results are consistent with those found in the literature and confirm that diverse factors contribute to the disability and depression of workers with occupational diseases, as predicted by the bio-psycho-social model.Um grande número de trabalhadores é acometido por doenças ocupacionais que tem, dentre seus sintomas, dores crônicas, incapacidade e depressão. Embora existam evidências sobre a contribuição de fatores relacionados ao ambiente de trabalho e fatores orgânicos em quadros de doenças ocupacionais, a incapacidade e a presença de depressão associadas a essas condições são fenômenos multifatoriais mediados por aspectos biopsicossociais. O presente artigo examina as relações entre fatores clínicos, ambientais, demográficos e incapacidade, depressão em uma população de trabalhadores do setor de frigoríficos (n=234) atendidos por um programa de reabilitação profissional. Este estudo pode ser descrito como de corte transversal, utilizando análises estatísticas descritivas e inferenciais (regressões multivariadas). Os dados foram coletados utilizando um questionário demográfico e clínico, o Questionário Roland e Morris, a escala de depressão do HADS e a Medida de Independência Funcional – MIF. Os resultados demonstraram que em todos os instrumentos utilizados, o escore final (após reabilitação) foi fortemente determinado pelo escore inicial (antes da reabilitação), com pouca influência das outras variáveis independentes. A mudança nos níveis de incapacidade parece estar associada a presença de ganho financeiro (p=0.057). O escore final do MIF foi inversamente relacionado com o tempo de afastamento (p=0.006). A variação dos escores finais entre as categorias do CID-10 não foi estatisticamente significativa para nenhum desfecho. De maneira geral, a maior prevalência de mulheres dentre os trabalhadores afastados, e a prevalência de doenças músculo-esqueléticas e depressão, ou a associação de ambas. A variável idade foi preditor de incapacidade (RM) e a variável tempo de afastamento foi preditora de incapacidade para o trabalho medida pelo MIF. Nenhuma das variáveis examinadas contribuiu para a mudança dos escores de depressão. De maneira geral, os resultados são consistentes com os achados descritos na literatura e, confirmam que diversos fatores contribuem para a incapacidade e depressão de trabalhadores com diagnóstico de doenças ocupacionais, tal como preconizado pelo modelo biopsicossocial