Objective: To study some of the epidemiological aspects of hepatitis B in a non-representative sample of patients seen in health care clinics.
Methods: The study population comprised 632 patients who were seen at health care clinics in the city of Ribeirão Preto, Brazil, for the purpose of blood testing, regardless the reason. After signing a written consent, an additional amount of blood was drawn from the same venous puncture site used to collect the original sample for the testing assigned to the patient at the health care clinic. A questionnaire was applied to each participant, looking for the presence of risk factors for hepatitis B. The blood samples were tested for HBV markers, using immunoenzimatic techniques.
Results: The prevalences of HBsAg and anti-HBcAg were 0.3% and 13.9%, respectively. By a logistic regression model, the following variables were significantly associated with the infection: age, time of residency in the city (higher risk among those living for a period less than one year), past history of hepatitis, incarceration and sexual behavior (higher risk among homosexual and bisexual males).
Conclusions: The growing difficulties in obtaining blood samples from a representative group of patients, as done in classic surveys, make it necessary to look for alternative methodologies which can provide information concerning the presence of infectious agents in a community. Though the results cannot be generalized to the population as a whole, the methodology used conveyed some knowledge regarding the circulation of hepatitis B virus. In addition, it makes much easier to obtain agreement from the participants, since it does not add any invasive procedure. Despite the limitations, this methodology may be helpful in epidemiological surveillance of infectious agents known as producing asymptomatic infections in much of the population.