Renan Moritz Varnier Rodrigues de Almeida

Computer simulation and discrete-event models in the analysis of a mammography clinic patient flow

OBJECTIVE This work develops a discrete-event computer simulation model for the analysis of a mammography clinic performance. MATERIAL AND METHODS Two mammography clinic computer simulation models were developed, based on an existing public sector clinic of the Brazilian Cancer Institute, located in Rio de Janeiro city, Brazil. Two clinics in a total of seven configurations (number of equipment units and working personnel) were studied. Models tried to simulate changes in patient arrival rates, number of equipment units, available personnel (technicians and physicians), equipment maintenance scheduling schemes and exam repeat rates. Model parameters were obtained by direct measurements and literature reviews. A commercially-available simulation software was used for model building. RESULTS The best patient scheduling (patient arrival rate) for the studied configurations had an average of 29 min for Clinic 1 (consisting of one mammography equipment, one to three technicians and one physician) and 21 min for Clinic 2 (two mammography equipment units, one to four technicians and one physician). The exam repeat rates and equipment maintenance scheduling simulations indicated that a large impact over patient waiting time would appear in the smaller capacity configurations. CONCLUSIONS Discrete-event simulation was a useful tool for defining optimal operating conditions for the studied clinics, indicating the most adequate capacity configurations and equipment maintenance schedules.

The relationship between parental nutritional status and overweight children/adolescents in Rio de Janeiro, Brazil

BACKGROUND The association between overweight parents and overweight children/adolescents was investigated in Rio de Janeiro, Brazil between 1995 and 1996, controlling for the influence of socio-economic and demographic factors. METHODS Data were obtained from a two-stage, residence-based, random sample survey of children and adolescents aged 6-19 years and their parents. Body mass index (BMI) was used to classify nutritional status. Initially, a logistic regression model was built, using an indicator of parental weight (maternal BMI) as one of the independent variables and the child/adolescents BMI as the dependent variable. Following that, the association between socio-economic and demographic variables and overweight children/adolescents was analysed in a univariate analysis. These variables were pre-selected for inclusion in the logistic model, provided that their levels of statistical significance were below P=0.25, and were added to the model individually according to the order of association strength in the univariate analysis. Finally, variables were retained in this model at a significance level of P=0.05. RESULTS This study found that 20.7% of girls and 26.9% of boys were overweight, with a larger prevalence among children aged less than 9 years. In addition to maternal BMI, the predictors of overweight children and adolescents were age, gender and the number of people in a house. CONCLUSIONS These results demonstrate the relationship between maternal nutritional status and overweight children and adolescents, suggesting that obesity-prevention programmes should be focused on the family.

Intraobserver interpretation of breast ultrasonography following the BI-RADS classification.

PURPOSE To use the BI-RADS ultrasound classification in an intraobserver retrospective study of the interpretation of breast images. MATERIALS AND METHODS The study used 40 breast ultrasound images recorded in orthogonal planes, obtained from patients with an indication for surgery. Eight professionals experienced in breast imaging analysis retrospectively reviewed these lesions, in three rounds of image interpretation (with a 3-6 months interval between rounds). Observers had no access to information from medical records or histopathological results, and, without their knowledge, in each new round were assigned the same images previously interpreted by them. Fleiss-modified Kappa measures were the study main concordance index. Besides the BI-RADS, a scale grouping its categories 2-3 and 4-5 was also used. The statistical analysis concerned the intraobserver agreement. RESULTS Kappa values ranged from 0.37 to 0.75 (original categories) and from 0.73 to 0.87 (grouped categories). Overall, out of the 8 observers, 7 presented moderate to substantial concordance (Kappa values 0.51 to 0.74). CONCLUSION The BI-RADS is a reporting tool that provides a standardized terminology for US exams. In this study, moderate to substantial concordance in Kappa values was found, in agreement with other studies of the literature.

The path analysis approach for the multivariate analysis of infant mortality data.

PURPOSE This paper reviews the use of the Path Analysis (PA) methodology in health determinants modeling, with special reference to infant mortality modeling. METHODS A review of the literature on PA applications in the modeling of infant mortality and similar problems is presented, together with a discussion of the conceptual basis of PA and its relation to other multivariate statistical techniques. Important aspects of the technique are discussed: 1) criteria for path formulation; 2) parameter estimation methods; 3) direct, indirect, spurious, and joint effects; and 4) goodness-of-fit and modification indices. RESULTS AND CONCLUSION The review of the literature suggests that PA represents a methodological improvement regarding multivariate techniques used in modeling some health-related issues. PA allows investigation of more complex models, providing information that could have been previously overlooked, such as how the interrelations among independent variables in a model affect the dependent ones.

Análise Envoltória de Dados na avaliação de hospitais públicos nas capitais brasileiras

OBJETIVO: Aplicar a metodologia de Analise Envoltoria de Dados na avaliacao do desempenho de hospitais publicos em termos das internacoes em suas clinicas medicas. METODOS: A eficiencia dos hospitais foi medida a partir do desempenho de unidades de decisao nas variaveis estudadas para cada hospital, no ano 2000. Foram analisados dados referentes as internacoes em clinica medica dos hospitais SUS das capitais estaduais do Brasil e Distrito Federal (taxas de mortalidade e tempo medio de internacao, valor medio da internacao e perfil de doencas). A tecnica de analise de correlacao canonica foi introduzida na restricao do intervalo de variacao das variaveis. O modelo Constant Returns to Scale foi utilizado para gerar escores que permitissem avaliar a eficiencia das unidades. A partir dos escores obtidos, os municipios foram classificados de acordo com seu desempenho relativo nas variaveis analisadas. Procurou-se correlacao entre os escores de classificacao com variaveis exogenas: despesas com programas de saude basica por habitante e indice de desenvolvimento humano das capitais. RESULTADOS: Nos hospitais estudados se destacaram as doencas do aparelho circulatorio (23,6% das internacoes); e a taxa de mortalidade foi de 10,3% das internacoes. Das 27 capitais, quatro alcancaram 100% de eficiencia (Palmas, Macapa, Teresina e Goiânia), sete ficaram entre 85% e 100%, dez entre 70% e 85% e dez com menos de 70%. CONCLUSOES: A ferramenta utilizada mostrou ser aplicavel para a avaliacao de desempenho de hospitais publicos, revelando a grande variabilidade entre as capitais brasileiras, no que se refere as internacoes em clinica medica.

Discrete-event computer simulation methods in the optimisation of a physiotherapy clinic

OBJECTIVE To develop a computer model to analyse the performance of a standard physiotherapy clinic in the city of Rio de Janeiro, Brazil. DESIGN AND SETTING The clinic receives an average of 80 patients/day and offers 10 treatment modalities. Details of patient procedures and treatment routines were obtained from direct interviews with clinic staff. Additional data (e.g. arrival time, treatment duration, length of stay) were obtained for 2000 patients from the clinics computerised records from November 2005 to February 2006. METHODS AND MAIN OUTCOME MEASURES A discrete-event model was used to simulate the clinics operational routine. The initial model was built to reproduce the actual configuration of the clinic, and five simulation strategies were subsequently implemented, representing changes in the number of patients, human resources of the clinic and the scheduling of patient arrivals. RESULTS Findings indicated that the actual clinic configuration could accept up to 89 patients/day, with an average length of stay of 119minutes and an average patient waiting time of 3minutes. When the scheduling of patient arrivals was increased to an interval of 6.5minutes, maximum attendance increased to 114 patients/day. For the actual clinic configuration, optimal staffing consisted of three physiotherapists and 12 students. According to the simulation, the same 89 patients could be attended when the infrastructure was decreased to five kinesiotherapy rooms, two cardiotherapy rooms and three global postural reeducation rooms. CONCLUSIONS The model was able to evaluate the capacity of the actual clinic configuration, and additional simulation strategies indicated how the operation of the clinic depended on the main study variables.

The association between socioeconomic indicators and cardiovascular disease risk factors in Rio de janeiro, Brazil

The objective of this study was to analyse the association between socioeconomic indicators and cardiovascular disease risk factors in adult residents of Rio de Janeiro city, Brazil. Data were obtained by direct interview and physical examination in a population-based cross-sectional study in the city of Rio de Janeiro, 1995-96. Subjects were selected by two-stage random sampling and information was collected on socioeconomic, anthropometric and demographic characteristics, as well as on existing risk factors for cardiovascular disease. An index to express the risk of cardiovascular disease (CVD) was built, based on the presence of two or more of the following risk factors: overweight (measured by the body mass index, BMI), fat location (measured by the waist-hip ratio index, WHR), smoking, hypertension, sedentary lifestyle and alcohol consumption. The association between this risk index and the socioeconomic variables level of schooling, per capita income and residence location (slum vs non-slum) was evaluated through logistic regression models that controlled for the age of the subjects. Two separate models were built, according to the gender of the subjects. Complete data were collected for 1413 males and 1866 females over the age of 20 years (82% of the intended sample). In the studied population, a considerable prevalence of risk for CVD was found: 42.2% among males and 65.4% among females. For males, the socioeconomic and demographic indicators retained in the logistic model were age (OR 1.01, 95% CI 1.00-1.01), level of schooling (1.77, 95% CI 1.39-2.26) and per capita income (OR 0.77, 95% CI 0.61-0.97). For females, the indicators retained were age (OR 1.02, 95% CI 1.01-1.02) and level of schooling (OR 2.26, 95% CI 1.84-2.77). The findings indicate that cardiovascular disease risk is already an alarming problem in the urban populations of developing countries, and that educational level is the most important socioeconomic factor associated with its presence.

Overweight and risk of overweight in schoolchildren in the city of Rio de Janeiro, Brazil: prevalence and characteristics

Abstract The association of overweight and risk of overweight with socio-economic and demographic variables was investigated among schoolchildren in the city of Rio de Janeiro, Brazil between 1995 and 1996. Data were obtained by direct interview and physical examination of boys and girls aged between 6 and 11 years in a two-stage, random sample, population-based survey. Univariate analysis was performed on the association between socio-economic and demographic predictors of overweight/risk of overweight and the dependent variables, i.e. body mass index (BMI), triceps skinfold and subscapular skinfold. Based on this analysis, logistic regression models were developed. The prevalence of overweight and risk of overweight was 37.8% in girls and 36.4% in boys. For the BMI model, the variables retained were age and number of persons per household; for the triceps skinfold model, the variables were age, gender and area of residence; and age, gender and persons/household were the variables for the subscapular skinfold model. The results suggest that both BMI and skinfold indicators should be used to assess overweight/risk of overweight and that public health programmes for schoolchildren should be developed to combat the alarming increase in obesity.

Geographic accessibility to obstetric care and maternal mortality in a large metropolitan area of Brazil

To assess maternal mortality and its association with accessibility to obstetric care in the metropolitan region of Rio de Janeiro, Brazil.

Comorbidity adjustment index for the international classification of diseases, 10

OBJECTIVE To develop a Charlson-like comorbidity index based on clinical conditions and weights of the original Charlson comorbidity index. METHODS Clinical conditions and weights were adapted from the International Classification of Diseases, 10th revision and applied to a single hospital admission diagnosis. The study included 3,733 patients over 18 years of age who were admitted to a public general hospital in the city of Rio de Janeiro, southeast Brazil, between Jan 2001 and Jan 2003. The index distribution was analyzed by gender, type of admission, blood transfusion, intensive care unit admission, age and length of hospital stay. Two logistic regression models were developed to predict in-hospital mortality including: a) the aforementioned variables and the risk-adjustment index (full model); and b) the risk-adjustment index and patients age (reduced model). RESULTS Of all patients analyzed, 22.3% had risk scores > or = 1, and their mortality rate was 4.5% (66.0% of them had scores > or = 1). Except for gender and type of admission, all variables were retained in the logistic regression. The models including the developed risk index had an area under the receiver operating characteristic curve of 0.86 (full model), and 0.76 (reduced model). Each unit increase in the risk score was associated with nearly 50% increase in the odds of in-hospital death. CONCLUSIONS The risk index developed was able to effectively discriminate the odds of in-hospital death which can be useful when limited information is available from hospital databases.OBJECTIVE: To develop a Charlson-like comorbidity index based on clinical conditions and weights of the original Charlson comorbidity index.