[The utility of joint sensitivity and specificity curves applied to a diagnostic test]. / Utilidad de las curvas de sensibilidad y especificidad conjunta en la aplicación de una prueba de diagnóstico.

The aim of this study was to obtain the cut point to determine an individual's seronegativity with respect to measles using commercial reagents. To determine the test sensitivity, the serum of 22 individuals 21 years of age or older, and a positive history of measles (positive control group) was studied. For specificity, the serum of 22 children 15 to 24 months old, and no measles vaccination record nor positive history of measles (negative control group), was analyzed. The antibodies titer determination for both groups was done using the ELISA technique and the Brunell method, subsequently, as well as a ROC curve (Received Operating Curve). When the Brunell method was used, the cut points were 0.4090 (sensitivity 1.0 and specificity 0.95) and 0.5042 (sensitivity 0.95 and specificity 1.0). When a ROC curve was done the cut point was 0.4500, with a sensitivity and specificity of 100 per cent. It was also concluded that the latter is the best method to obtain this cut point, because it does not establish arbitrary values when the data distribution does not follow a normal pattern.

[Regionalization]. / Regionalización.

Health services regionalization is analyzed in its concept, components, characteristics and variations through literature review of experiences in different countries. It is concluded that regionalization means ordering or reordering resources and services within an area, provided that physical installations and personnel are already organized in order to assure health services at the highest quality. Those services must be economical, accesible and established in a comprehensive, coherent set with different levels of care in order to meet patients' needs. A regionalization model based on silos is presented, including functions, strategies and policies. Reasons to encourage the regionalization are also presented, such as the decrease in costs, increasing of program effectiveness and the potential development of the regionalized areas.

[Therapeutic effectiveness of anticoagulation in acute myocardial infarction: a case-control study]. / Efectividad terapéutica de la anticoagulación en el infarto agudo del miocardio: un estudio de casos y controles.

The main aim was to assess the role of anticoagulant therapy (AT) in reducing the mortality for patients with acute myocardial infarction (AMI). A pair-matched case-control study was designed according to three confounding factors: gender, age (+/- 5 years), and hospitalization date (+/- 13 months). Cases were defined as patients with AMI who died during hospitalization and controls were those patients with AMI who survived. Excluded from the study were patients with strong indications or contraindications for use of AT, and also those with early death (less than 12 hr). The study undertaken at the National Institute of Cardiology "Ignacio Chávez" of Mexico City and all necessary information was obtained from clinical charts of patients discharged between the period from January 1, 1975 to December 31, 1985. Complete information was accomplished for 212 pairs of cases and controls. A protective odds ratio (favoring use of AT) = 12.1 (p less than 0.0001, 95% CI 4.2-34.9) was obtained by means of a multiple logistic regression analysis by conditional method. Other variables that entered into the logistic model were: antithrombotic therapy, severity measured by Killip scale and by Norris index. Such findings support the favorable therapeutic role of AT in patients with AMI.

[Susceptibility to measles in the adolescent population of the Federal District]. / Susceptibilidad al sarampión en la población adolescente del Distrito Federal.

It is well known that in developing countries, measles disease is frequently increasing among adolescents. In Mexico, it is also thought that this problem is moving in such a way; however, this can not be proven with the statistical information at hand. For this reason a serum-survey was carried out in a sample of 870 healthy teenagers drawn from public and private secondary schools in Mexico City, in order to know if they were susceptible to measles disease and in that way make the right decisions. The information background related to the vaccination and information about previously having the disease was obtained from a questionnaire that was given to the parents of the studied teenagers. In order to get de immune state of the studied group, measles antibody titles were quantified using the ELISA technique. The findings shown that the susceptibility in this group was of 21.4%, which is certainly higher than the ones that have been found in some other countries where measles epidemics in people at this age have been well documented. Accordingly, it is thought that the displacing of this illness can be found in teenagers of Mexico City. An association was found with male sex and having the illness before. Teenagers that studied in public secondary schools reported more frequently, they had had the illness than the ones who studied at private schools. It was also found that these teenagers had a higher probability of having antimeasles antibody titles which are considered non protective; that is why it is thought these students are more likely to become ill during the adolescence stage than those who already have had the illness and the consequent protection.

[Infection in pregnancy as a causal factor in premature membrane rupture and preterm labor]. / Infección durante el embarazo como factor causal de ruptura prematura de membranas y de parto pretérmino.

This article discusses recent evidence pointing to an infectious etiology of premature rupture of the membranes and preterm labor. We conclude that antepartum infection is strongly related to preterm labor, premature rupture of the membranes and perinatal morbidity and mortality.

[Differential mortality by sex. Causes and behavior of respiratory and gastroenteric infections in Mexico]. / Mortalidad diferencial por sexo. Causas y comportamiento de las infecciones respiratorias y gastroenterales en México.

The differential in mortality by sex has not been broadly studied in Mexico. In this work mortality by sex in under one year old children and infants by federal entity for the main infectious diseases during 1980-1982 was analyzed. The results showed that the rate of mortality by sex (RMS) for under one year old children was higher than one, which means that there is a male over-mortality for that group of age. In the one to four year old children group, there were three entities that showed over-mortality among women. The analysis of the proportional mortality revealed that 40 to 50 percent of deaths in under one year old children were due to gastroenteral and respiratory infections. The probable causes of the male over-mortality observed and the need to determine the regional patterns of mortality are also discussed.