Teaching meta-analysis using Stata

Systematic reviews and meta-analyses contribute to the objectivity and transparency of literature reviews and play an increasingly important role in evidence-based medicine and public health. In addition to the expertise needed for critical reading of papers using these methodologies, researchers and professionals in areas related to clinical medicine and public health also need to have the appropriate skills to conduct systematic assessments of the published literature and quantitative synthesis of the results through meta-analysis. I describe the use of Stata in a short course aiming to introduce the essential aspects of the computation of summary estimates and the exploration of heterogeneity and publication bias in meta-analyses of observational studies. The course includes three practical exercises built over real data. It starts with a "pen and paper" exercise used to address the basic statistical methods of meta-analysis, and it ends with an introduction to meta-analysis in Stata, including the calculation of summary estimates (fixed- and random-effects models), the appraisal (visual inspection of funnel plots, I2 statistics, and hypothesis testing) and explanation of heterogeneity (subgroup analysis), and the assessment of bias (analysis of funnel plots). I will emphasize the strategies adopted to enable the achievement of the course objectives by participants unfamiliar with Stata.

Associação entre cuidados infantis e diarréia aguda em crianças portuguesas

OBJECTIVE: To quantify the influence of the type of child-care on the occurrence of acute diarrhea with special emphasis on the effect of children grouping during care. METHODS: From October 1998 to January 1999 292 children, aged 24 to 36 months, recruited using a previously assembled cohort of newborns, were evaluated. Information on the type of care and occurrence of diarrhea in the previous year was obtained from parents by telephone interview. The X² and Kruskal-Wallis tests were used to compare proportions and quantitative variables, respectively. The risk of diarrhea was estimated through the calculation of incident odds ratios (OR) and their respective 95% confidence intervals (95% CI), crude and adjusted by unconditional logistic regression. RESULTS: Using as reference category children cared individually at home, the adjusted ORs for diarrhea occurrence were 3.18, 95% CI [1.49, 6.77] for children cared in group at home, 2.28, 95% CI [0.92, 5.67] for children cared in group in day-care homes and 2.54, 95% CI [1.21, 5.33] for children cared in day-care centers. Children that changed from any other type of child-care setting to child-care centers in the year preceding the study showed a risk even higher (OR 7.65, 95% CI [3.25, 18.02]). CONCLUSIONS: Group care increases the risk of acute diarrhea whatsoever the specific setting.OBJETIVO: Quantificar a associação entre o tipo de cuidados infantis e a ocorrência de diarréia aguda, sendo dada especial atenção aos diferentes tipos de cuidados infantis prestados a grupos de crianças. MÉTODOS: De outubro de 1998 a janeiro de 1999, foram avaliadas 292 crianças, com idades entre 24 e 36 meses, recrutadas com base numa coorte de recém-nascidos previamente constituída. Foi obtida informação acerca do tipo de cuidados infantis e da ocorrência de diarréia no ano anterior ao estudo por meio de entrevista telefônica aos pais das crianças participantes. Foram utilizadas as provas do X² e de Kruskal-Wallis para comparar proporções e variáveis quantitativas, respectivamente. O risco de diarréia foi estimado pelo cálculo de odds ratios (OR) incidentes e respectivos intervalos de confiança a 95% (IC 95%), brutos e ajustados por regressão logística não condicional. RESULTADOS: Utilizando como classe de referência as crianças cuidadas sozinhas na própria casa, o OR para a ocorrência de diarréia foi 3,18, IC 95% [1,49-6,77] para as crianças cuidadas na própria casa mas em grupo, 2,28, IC 95% [0,92-5,67] para as cuidadas em casas de amas, em grupo, e 2,54, IC 95% [1,21-5,33] para as cuidadas em creches (instituições de prestação de cuidados infantis, em grupo). Nas crianças que mudaram de qualquer outro tipo de cuidados infantis para creches no ano que antecedeu a entrevista o risco de diarréia foi 7,65, IC 95% [3,25-18.02]. CONCLUSÕES: Os cuidados infantis em grupo associaram-se a um maior risco de diarréia aguda, quer fossem prestados na própria casa, em casas de amas ou em creches

Trends in the prevalence of smoking in Portugal: a systematic review.

BACKGROUND: Understanding the dynamics of smoking at the population level is essential for the planning and evaluation of prevention and control measures. We aimed to describe trends in the prevalence of smoking in Portuguese adults by sex, age-group and birth cohort. METHODS: PubMed was searched from inception up to 2011. Linear regression was used to assess differences in prevalence estimates according to the type of population sampled, and to estimate time trends of smoking prevalence considering only the results of studies on nationally representative samples of the general population. RESULTS: Thirty eligible studies were identified. There were statistically significant differences in the prevalence estimates according to the types of population sampled in the original studies. Between 1987 and 2008, the prevalence of smoking increased significantly among women aged ≤ 70 years; the steepest increase was observed in those aged 31-50 and 51-70 years (from 4.6% and 0.1% in 1988, respectively, to 16.4% and 4.5% in 2008, respectively). The prevalence of smoking increased in all birth cohorts, except for those born before 1926. In the same period, among men, smoking decreased in all age-groups, with steepest declines in those aged ≤ 30 years (from 41.8% in 1988 to 28.8% in 2008) and those aged ≥ 71 years (from 15.1% in 1988 to 4.6% in 2008). The prevalence of smoking declined among men of all birth cohorts. CONCLUSIONS: This study provides robust evidence to place Portuguese women at stage II and men at the later stages of the tobacco epidemic

Trends of BMI and prevalence of overweight and obesity in Portugal (1995-2005): a systematic review.

OBJECTIVE: Locale-specific data on BMI and overweight/obesity are necessary to understand how the obesity epidemic is evolving in each setting. We aimed to describe the temporal trends of mean BMI and prevalences of overweight/obesity in studies that evaluated Portuguese adults and older people. DESIGN: Systematic review, conducted via a PubMed search up to January 2011 and independent reference screening and data extraction. Twenty-one eligible studies were identified. Data were extracted from the published reports and obtained from the authors of seven of the largest studies. Adjusted ecological estimates of mean BMI and prevalences of overweight/obesity were computed by linear regression. RESULTS: Between 1995 and 2005, when using data obtained from anthropometric measurements, overweight prevalence increased by 3·2 % and 3·5 % and obesity prevalence by 7·4 % and 1·3 % among women and men, respectively, while mean BMI did not vary meaningfully. When using self-reported information, mean BMI increased by 0·8 kg/m2 and 0·9 kg/m2, overweight prevalence by 3·5 % and 3·7 % and obesity prevalence by 5·8 % and 5·5 % among women and men, respectively. Results from the 20-year-old conscripts (1960-2000) showed a marked increase in these outcomes in the last decades. CONCLUSIONS: Our results show an important increase in overweight/obesity in younger ages. The trends in the indicators derived from self-reported data suggest an increase in awareness of the importance of overweight/obesity among the population

Knowledge about cardiovascular disease in Portugal

To characterize specific knowledge on cardiovascular disease, particularly stroke and myocardial infarction (MI), and its relationship with sociodemographic factors, health literacy and clinical history, among the Portuguese population.info:eu-repo/semantics/publishedVersio

The Sodium and Potassium Content of the Most Commonly Available Street Foods in Tajikistan and Kyrgyzstan in the Context of the FEEDCities Project

This cross-sectional study is aimed at assessing sodium (Na) and potassium (K) content and the molar Na:K ratios of the most commonly available ready-to-eat street foods in Tajikistan and Kyrgyzstan. Four different samples of each of these foods were collected and 62 food categories were evaluated through bromatological analysis. Flame photometry was used to quantify sodium and potassium concentrations. The results show that home-made foods can be important sources of sodium. In particular, main dishes and sandwiches, respectively, contain more than 1400 and nearly 1000 mg Na in an average serving and provide approximately 70% and 50% of the maximum daily recommended values. Wide ranges of sodium content were found between individual samples of the same home-made food collected from different vending sites from both countries. In industrial foods, sodium contents ranged from 1 to 1511 mg/serving in Tajikistan, and from 19 to 658 mg/serving in Kyrgyzstan. Most Na:K ratios exceeded the recommended level of 1.0 and the highest ratios were found in home-made snacks (21.2) from Tajikistan and industrial beverages (16.4) from Kyrgyzstan. These findings not only improve data on the nutritional composition of foods in these countries, but may also serve as baseline information for future policies and interventions. View Full-Tex

Breast-feeding and Helicobacter pylori infection: systematic review and meta-analysis.

OBJECTIVE: To quantify the association between breast-feeding and Helicobacter pylori infection, among children and adolescents. DESIGN: We searched MEDLINE™ and Scopus™ up to January 2013. Summary relative risk estimates (RR) and 95 % confidence intervals were computed through the DerSimonian and Laird method. Heterogeneity was quantified using the I² statistic. SETTING: Twenty-seven countries/regions; four low-income, thirteen middle-income and ten high-income countries/regions. SUBJECTS: Studies involving samples of children and adolescents, aged 0 to 19 years. RESULTS: We identified thirty-eight eligible studies, which is nearly twice the number included in a previous meta-analysis on this topic. Fifteen studies compared ever v. never breast-fed subjects; the summary RR was 0·87 (95% CI 0·57, 1·32; I²=34·4%) in middle-income and 0·85 (95% CI 0·54, 1·34; I²=79·1%) in high-income settings. The effect of breast-feeding for ≥4-6 months was assessed in ten studies from middle-income (summary RR=0·66; 95% CI 0·44, 0·98; I²=65·7%) and two from high-income countries (summary RR=1·56; 95% CI 0·57, 4·26; I²=68·3%). Two studies assessed the effect of exclusive breast-feeding until 6 months (OR=0·91; 95% CI 0·61, 1·34 and OR=1·71; 95% CI 0·66, 4·47, respectively). CONCLUSIONS: Our results suggest a protective effect of breast-feeding in economically less developed settings. However, further research is needed, with a finer assessment of the exposure to breast-feeding and careful control for confounding, before definite conclusions can be reached