[Dynamic models and social networks: a review and reflections on their contribution to understanding the HIV epidemic]

Due to certain specificities in the HIV epidemic, its spread has escaped the random transmission pattern of other infectious diseases. Observation of the epidemic has shown that individual behavior - relational patterns among individuals - plays a crucial role in HIV transmission and that strategies to prevent the epidemic's spread should take this factor into account in order to foster efficient allocation of existing resources. Mathematical and statistical models applying the behavioral approach to the epidemic have estimated interactions between groups whose characteristics and behaviors varied. However, such models have been more "post-dictive" than predictive, due to the inadequate representation of social structures in populations through which infectious agents spread. The social network methodology thus came to be applied to the approach to the HIV epidemic. This article discusses alternatives for the application of this methodology to the Brazilian epidemic, considering that sociometric risk networks structure the flow of infectious agents in communities, creating unique opportunities to interrupt their spread.

[Use of digitalis in elderly patients admitted to a geriatric unit at a general hospital]

PURPOSE

To determine the prevalence of digoxin use as well as its indications in elderly patients at the time of admission to a geriatric unit of a general hospital.

METHODS

One hundred and thirty elderly patients aged 65 and over (mean age = 80 +/- 9 years), 100 women and 30 men were consecutively investigated. Each patient was submitted to a thorough clinical investigation, laboratory work-up, chest X-ray, electrocardiogram and doppler echocardiogram. The use of digoxin was considered appropriate, questionable or inappropriate.

RESULTS

At the time of admission to the geriatric unit 27.6% of the patients were receiving digoxin. The indication was considered appropriate in 36.1%, questionable in 11.1% and inappropriate in 52.7%.

CONCLUSION

We found a high prevalence of digoxin use in elderly patients admitted to a geriatric unit of a general hospital. In most cases its indications were considered inappropriate or questionable. Due to the increased risk of digitalis intoxication in this age group the drug should be prescribed under more strict indications.

Vitamin B12 deficiency and dementia

We set out to investigate the possible beneficial effects on cognitive function of demented patients with cobalamin deficiency after cobalamin replacement. A total of 181 consecutive, demented (DSM-III or DSM-III-R criteria and score below 24 on the Mini-Mental State Examination [MMSE]) outpatients (mean age 77.5 years) were prospectively evaluated and had their vitamin B12 level measured by radioimmunoassay. The frequency of vitamin B12 deficiency (less than 200 pg/mliter) was 25% (46 patients). Treatment outcome was obtained in 19 patients (19 of 46). Despite cobalamin replacement, 16 of 19 patients persisted in showing progressive decline during follow-up visits (3 to 24 months). The nonresponse to vitamin B12 replacement in most cases seems to reflect the presence of associated irreversible dementia or a follow-up of shorter duration in a few patients. All of the patients who showed some improvement (MMSE returned to normal values) had mild dementia with a history of less than 2 years. Thus, screening for B12 deficiency should be considered in patients with recent onset of mild mental status changes.

[Tobacco use by students in the 1st and 2d grades in 10 Brazilian capitals: possible contributions of multivariate statistics to the understanding of the phenomenon]

The use of tobacco among school children in ten Brazilian cities, by means of statistical techniques such as bivariate and multivariate analysis (Logit Model), was analyzed. Bivariate analysis revealed a positive association between the use of tobacco and the school child's non-academic occupation, evening course attendance, poor school performance, and parents' smoking habits. Multivariate techniques and the Logit Model showed that poor school performance (on the evening course) and parents' smoking habits (on the day-time course) were most significant variables. The importance of the utilization of multivariate technics for the real understanding of the various factors involved in complex behavior patterns such as the use of tobacco, alcohol and drugs, was discussed.