In Estonia, cardiovascular diseases (including hypertension) are the most common cause of death both in men and women . Despite the fact that the prevalence of cardiovascular diseases as a cause for loss of life years has decreased significantly during the past decade in Estonia, it is still nearly two times higher than in other European countries . A clear need exists for a more systematic understanding of the epidemiology, diagnosis, and management of hypertension in Estonia. We established HYPEST sample collection, which provides a good resource for studying genetic-epidemiological component of HTN in Estonian population. This report is focused on the comparative analysis of disease and lifestyle profiles of Estonian male and female hypertensive patients, who were enrolled during the HYPEST study from 2004 to 2007. Patients were recruited in two main healthcare centers covering major part of Estonia. In most published epidemiological studies BP measurements were conducted during a single visit . In HYPEST study, the diagnosis of hypertension was defined by cardiologist and relies on several consecutive BP measurements. The overall fraction of female patients among invited (~ 59%) and recruited (61%) study participants was higher compared to male hypertensives. This bias was introduced due to higher proportion of women with available clinically diagnosed essential hypertension records in participating centers. Also, the age distribution is different between genders; with much less men belonging to the age group 60+. The lower proportion of elderly male patients could be influenced by the fact that, in Estonia, the mean life expectancy in men is considerably shorter than in women (67.1 years in men vs 78.7 years in women), which makes it difficult to include older men into the study .
Men and women differ in the pathophysiology, risks and treatment of essential hypertension. The prevalence of hypertension increases with age and is higher among men than women before the age of 55 years, but slightly higher among women thereafter . Similar trend was detected in current study, where the age of hypertension diagnosis in male patients was around 5 years earlier compared to female cases. The higher age of female population could reflect, in part, the protective hormone effect before menopause, which could postpone the onset of hypertension [10, 19]. The elevated blood pressure is a high risk factor for later cardiovascular and renal diseases and therefore it was not surprising that patients had markedly higher prevalence of cardiovascular diseases compared to general population . The most common self-reported cardiovascular problem for both sexes was heart arrhythmia, followed by ischemic heart disease. The observed earlier occurrence of the first myocardial infarction as well as higher number of incidences in male patients is probably related to the earlier onset of hypertension in men. This is consistent with previous studies done in Estonia, showing that in case of men, cardiovascular diseases occur earlier compared to women [21, 22]. Problems with cardiovascular system were also reflected in serum biomarker analysis, showing increased total and LDL-cholesterol levels among patients compared to normal laboratory reference range. In general, women seem to be keener to monitor their health compared to men, which is reflected in higher number of reported incidences of other diseases in the self-reported questionnaire.
It is widely known that lifestyle behaviors such as reducing weight and alcohol intake, quitting smoking, increasing physical activity and eating a healthy diet are related to the prevention and control of elevated blood pressure [22, 23]. Current study clearly demonstrates that reducing the conventional lifestyle risk factors could delay the age of hypertension onset. This effect was most significant with smoking status, which is concordant with recent study done in Japanese population . Another generally accepted risk factor for increased blood pressure is elevated BMI [8, 11]. One limitation of the current study is unavailable BMI data at the time of HTN diagnosis. Thus, to assess the effect of excess weight on the onset of hypertension, we used in our analysis stringent criteria to subdivide HYPEST HTN patients based on BMI data collected at the recruitment (obese ≥ 30 kg/m2 and non-obese < 30 kg/m2). In general, study participants appeared to be aware of the risk factors and seemed to consciously reduce them in their everyday life. For example, among hypertensive patients the number of current smokers is two times lower compared to general Estonian population [24, 25]. Furthermore, almost half of the male patients who reported current smoking habit during the diagnosis of hypertension had quit smoking after diagnosis.
Unfortunately excessive weight gain shows increasing trend in general Estonian population, which is also reflected in HYPEST data [3, 24, 26]. The majority of HYPEST patients are overweight (BMI ≥ 25 kg/m2) and this proportion is approximately 20% higher than average in 40-70 years old Estonian people . Observed mean values for BMI among the recruited HYPEST patients were higher (29.8 ± 5.0 kg/m2 for males; 30.4 ± 5.5 kg/m2 for females) than respective means of age and gender in general Estonian population (27.8 ± 4.2 kg/m2 for males; and 28.4 ± 5.6 kg/m2 for females) in age group 50-60 years . Probably problems with overweight among HTN patients have encouraged them to pay more attention to the everyday diet as well on the physical activity. However, although dietary habits in Estonia have improved during the last decade, one third of all participated patients (33.72%) notified periods of malnourishment during their lifetime. This could be explained by the fact that most of study participants belong to age groups where they could have been influenced by the period of Second World War. Maternal diet during the pregnancy and/or poor nutrition in early childhood could both influence the development of cardiovascular disease (including hypertension) in adulthood . Finally, the hypertensive patients, who participated in the HYPEST study show awareness of their health conditions and have been responsive in adopting healthy lifestyle recommendations given by their physicians.
The present study has certain limitations that should be taken into account for interpretation of the results. First, the retrospective self-reported epidemiological data may be biased and tend to exaggerate the occurrence of events. Second, the non-equal distribution of men/women patients as well as the age distribution among sexes might affect the gender-related differences and bias the estimate. In addition, the study sample is only representative of volunteers and findings may therefore not be generalized to all Estonian hypertension patients. Finally, the retrospective BP data extracted from patient's clinical records were measured with different clinical settings (investigators, devices, laboratories) and thus, certain undefined measurement variability could have been introduced into the estimates. Despite these limitations, the present study gives a profile of Estonian hypertensive patients by analyzing considerably larger number of subjects than earlier investigations [6, 7, 24].