Systemic arterial hypertension in Brazil: temporal trends
Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brasil. firstname.lastname@example.org
The first temporal trend curve on proportional mortality in Brazil was published in 1984 (1930-1980) (Bayer GF, Paula SG. RADIS Dados 1984; 7:1-8), causing widespread surprise due to the decline in mortality from infectious and parasitic diseases and the rapid rise in mortality from cardiovascular diseases. The curves had crossed in 1964-1965, shifting the country's main morbidity and mortality epidemiological profile from diseases of underdevelopment to diseases of modernity.
As a silent condition, systemic arterial hypertension (SAH) is the most widely prevalent vascular disease in the world and the most powerful risk factor for cerebrovascular diseases, the leading cause of death in Brazil. In 2008, 2,969 more deaths were reported from cerebrovascular diseases as compared to all ischemic heart diseases, so the social relevance of SAH in Brazil is beyond question.
In the 20 years since publication of the curve, a few researchers have produced some scattered information on SAH in the Brazilian population. The studies were methodologically incomparable, were conducted without specific funding, and reported a wide variation in prevalence rates (from 15% to 43%), but they laid important groundwork for SAH epidemiology in Brazil and contributed to health policies and programs in the late 1980s and early 1990s.
Acting on this new pattern of diseases without essential knowledge of their scope, complexity, and interrelations has not been easy!
The failure of attempts to control SAH through programs that are often poorly administered in the various States finally led to the realization that methodologically standardized and comprehensive data are indispensable for monitoring SAH in the population, from the perspective of successfully controlling the disease. A survey was thus conducted in 2003 on self-reported cancer, hypertension, and diabetes in 16 of Brazil's 27 capital cities, including not only State capitals but the Federal District or national capital, Brasilia. Three telephone surveys (VIGITEL 2006, 2007, and 2008) were conducted by the Ministry of Health to measure SAH rates, reported according to "medical diagnosis". However, SAH is silent, and a medical diagnosis implies that the interviewees consulted a physician shortly before the interview and were informed about having versus not having high blood pressure, including their individual pressure levels. The method also requires ruling out at least a dozen different biases related to the research instruments, measurement technique, socio-demographic and socio-medical sample profiles, and participants' recall, among others.
Self-reporting surveys are not the best choice for obtaining information on measurable risk factors, but in the case of SAH they are the only available standardized option for all the capital cities in Brazil, regardless of the social discrepancies. According to the VIGITEL surveys, the SAH prevalence rates for Brazil as a whole were 22% (2006), 21% (2007), and 24% (2008). This period is too short to infer a trend for a non-communicable disease, besides the fact that the data were produced in consecutive years, thus not contributing to the inference of a trend. While we await further results, we should positively consider drawing on the VIGITEL data, making the best possible use of them, as the Ministry of Health is doing.