METHODS

A population based survey was undertaken in 2001 to investigate health behaviours and health status of people aged 25 years and over living in Tirana City. Ethical approval was granted by the Albanian Ministry of Health and the London School of Hygiene and Tropical Medicine.

The least common major condition examined was type 2 diabetes (results will be reported elsewhere¹⁰). This determined the required sample size, estimated to be 1188 people to be able to detect a prevalence of 2.9%, taking 3.7% as the worst value. To allow for non-response, over-sampling of about 25% was undertaken. Given uncertainties about the precise resident population at the time of study, a two stage cluster sampling technique¹¹ was used based on the published list of households for the 1997 general elections (UNDP unpublished data). Tirana is divided into 256 zones (map division). Based on this division 58 zones were randomly selected with probability proportional to size. From each zones, 12 households were chosen at random. This yielded 696 households, which was expected to yield at least 1392 adults (assuming an average of two adults aged 25 years and over per household). Of the 1540 people contacted 1120 (535 men and 585 women) agreed to participate (response rate 72.7%). The final sample tended to be slightly older than the reference population. For this reason, the results presented in this paper are stratified by age group and the overall prevalence rates are age standardised. There were no women known to be pregnant in the study.

All respondents were invited to attend a health centre in Tirana. Interviews were conducted, in three parts: (a) standard questions on demographic and socioeconomic information (sex, age, family status, educational level, family income) and health behaviours (physical activity at work and during leisure time, smoking, alcohol intake, and diet); (b) anthropometric (height, weight, waist, hip circumferences) and blood pressure measurements; and (c) blood samples and a glucose tolerance test.

Questionnaire design drew on earlier surveys conducted in other transition countries.¹³ The questionnaire was translated from English into Albanian by the principal investigator and back translated by another Albanian physician and compared before being distributed. Smoking status was divided into three categories: (a) never smokers; (b) former smokers; and (c) current smokers defined as people smoking at least one cigarette each day.

Anthropometric measurements used standardised procedures.¹⁴ Height was measured without shoes with subjects standing fully erect on a flat surface, with heels, buttocks and shoulders flat to the wall, and the subject looking straight ahead. Measurement was to the nearest centimetre. Weight was to the nearest 0.1 kg using digital scales. Subjects wore light clothing with no shoes. Waist circumference was measured to the nearest centimetre, halfway between the lower border of the ribs and the iliac crest, with the tape horizontal. Hip circumference was measured to the nearest centimetre at the maximum circumference, at the level of the greater trochanter. Body mass index (BMI) was calculated as weight (in kg) divided by height (in metres squared). Participants were categorised according to relative body weight status using WHO criteria¹⁵ (underweight: BMI<18.5 kg/m²; normal: BMI 18.5–24.9; overweight: BMI 25.0–29.9; obese BMI⩾30.0). Participants were considered centrally obese¹⁶ if waist-hip ratio (W/HR) was 0.95 or over for men and 0.85 or over for women.

Blood pressure (BP) was measured twice using an automatic sphygmomanometer, with participants seated after a five minute rest.¹⁷ Hypertension was defined as systolic blood pressure ⩾140 mm Hg and/or diastolic ⩾90 mm Hg or current use of anti-hypertensive drugs.¹⁸ Participants were categorised into four groups based on hypertension status: (a) normotensive; (b) newly diagnosed hypertensive; (c) known untreated hypertensive; and (d) known treated hypertensive.

Glucose tolerance and presence of diabetes were defined using 1999 WHO recommendations.¹⁹ Impaired glucose tolerance (IGT) was defined as fasting glucose of <7.8 mmol/l and two hour post-load plasma glucose concentration between 7.8 and 11.0 mmol/l. Diabetes was defined as two hour post-load plasma glucose concentration ⩾11.1 mmol/l or on treatment for diabetes. Participants with a verified history of diabetes were classified as known diabetics (that is, taking insulin or oral hypoglycaemic agent or diet).²⁰

The fasting blood sample was also analysed for total cholesterol, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, and triglycerides.

Statistical analysis was undertaken using SPSS version 10.0. As age and sex are strong determinants of hypertension, descriptive results were presented for men and women separately and stratified by age group. In addition, as younger age groups tended to be under-represented in the study sample, age standardised prevalence rates (for the adult population of Tirana City) were calculated for men and women separately by applying age sex specific rates to the standard population of Tirana City (as it was in 1998).

Because the distributions of plasma triglycerides, plasma HDL, and LDL-cholesterol were skewed, log normal values were used; geometric means are presented in the results. The scale and potential impact of clustering of risk factors were examined in three ways. Firstly, age standardised prevalence of having hypertension plus any combination of other risk factors was calculated. Secondly, the likelihood of being hypertensive according to various risk factors was estimated using multiple logistic regression analysis. Because it was not possible to estimate the variance inflation due to within family clustering,²¹ it was decided to use a conservative statistical significance level of p=0.01 to reduce the risk of type I error. Thirdly, as a relatively simple way to place Albania in a comparative perspective in terms of overall burden of risk, people meeting the criteria for the metabolic syndrome (syndrome X), which increases the risk of cardiovascular disease,²² and for which comparative American data are available,²³ were identified. The syndrome is defined as the presence of three of: waist circumference greater than 102 cm in men and 88 cm in women; serum triglycerides level of at least 1.69 mmol/l; HDL cholesterol level of less than 1.04 mmol/l in men and 1.29 mmol/l in women; blood pressure of at least 130/85 mm Hg; or serum glucose level of at least 6.1 mmol/l.

RESULTS

Table 1 shows the distribution of participants according to blood pressure categories. Overall, almost one in three respondents was hypertensive; 12.9% (99% confidence intervals (CI): 12.1% to 13.7%) of the respondents were newly diagnosed with hypertension; 2.8% (99% CI: 1.1% to 4.5%) were known but untreated hypertensive, and 15.9% (99% CI: 15.2% to16.6%) were known treated hypertensive. After standardising for age, the overall prevalence of hypertension age 25+ was 30.2% in men (99% CI=29.8% to 0.6%) and 22.7% in women (22.3% to 23.1%). Men were significantly more likely to be hypertensive than women (age adjusted odds ratio (OR)=1.43, 99% CI: 1.02% to 2.02).

The overall prevalence of hypertension increased with age in both sexes (p value for trend=0.001 in men and <0.0001 in women), peaking at age 55–64 in men and at age 65 and over in women. SBP also increased with age in both men and women (fig 1) while the mean levels of DBP decreased in men after the age of 45–54 and stayed constant in women after the age of 35–44 (fig 2). About half of the respondents reported a family history of hypertension, especially among participants suffering from hypertension (60.8% v 47.7%) (p value <0.0001).

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Figure 1

Mean systolic blood pressure* by sex an age group. *Known hypertensives and people receiving treatment were excluded (n=178).

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Figure 2

Mean diastolic blood pressure* by sex and age group. *Known hypertensives and people receiving treatment were excluded (n=178).

Of respondents who knew they were hypertensive, 87% (369 of 425) were receiving anti-hypertensive therapy, with over half (191 of 369) adequately controlled (defined as SBP <140 mm Hg and DBP <90 mm Hg). Women were better controlled than men (41.4% v 28.5% with normal blood pressure, respectively; p value=0.002). The most common treatment (45% of respondents treated for hypertension) was β blockers.

Tables 2 and 3 examine the frequency of other cardiovascular risk factors in normotensive and hypertensive participants. Those with hypertension, whether male or female, had higher BMIs, waist girth, hip girth and waist/hip ratio in both genders. In hypertensive women, mean plasma total cholesterol, triglycerides and LDL-cholesterol were higher than in normotensive individuals (p value <0.05).

As these risk factors vary with age table 4 shows the odds of having hypertension after adjusting for age according to exposure to a range of factors. As expected, hypertension was significantly positively related to family history of hypertension. Men and women who reported a family history were, respectively, 66% and 88% more likely to be hypertensive than their counterparts with no family history. The likelihood of being hypertensive also increased, in both sexes, with excess body weight (p value for trend=0.01; fig 3). The likelihood of being hypertensive was higher in those with increased triglyceride levels, was significant only in men. Hypertension was not significantly associated with glucose intolerance, HDL or LDL cholesterol levels (tables 3 and 4), or with education, income, physical activity, or smoking status (results not shown).

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Figure 3

Distribution of hypertension by body weight categories in men and women.

After adjusting for factors found to be significant (age, family history, weight, and triglycerides), men were 63% more likely than women to be hypertensive (OR=1.63; 99% CI: 1.13% to 2.36). This difference persisted even after sociodemographic (income, education) and lifestyle factors (smoking, sedentary physical activity level during leisure time, frequent alcohol consumption) were adjusted for (results not shown).

The data made it possible to test a hypothesis generated in an earlier study from Bahrain,²⁴ which had shown an inverse association between education and blood pressure. This was taken as evidence in favour of a link between adverse circumstances in childhood and adult hypertension. In this study, however, there was no such association after adjusting for gender, age, and body mass index. The odds ratio for being hypertensive (with primary education as the index category) was 1.19 (95% CI 0.71 to 1.98) for secondary and 0.98 (95% CI 0.59 to 1.62) for higher education.

Given the tendency of risk factors to cluster, the simultaneous occurrence of four major CVD risk factors (hypertension, obesity, smoking, and hypertriglyceridaemia) is described in table 5. Age standardised proportions are given separately for men and wowmen. Men were more likely to be hypertensive, smoke and have high triglycerides levels while women were more likely to be obese. The combination of hypertension with obesity was more likely in women, while men were more likely to have the combination of hypertension with smoking and hypertriglyceridaemia. Men were more likely than women to have clustering of hypertension with two other risk factors (obesity and/or smoking or hypertriglyceridaemia). Finally, the simultaneous occurrence of all four risk factors was rare but much more likely among men than women.

The percentages in each group meeting the criteria for the metabolic syndrome are shown in figures 4 and 5, for comparison, figures from the American National Health and Nutrition Survey, which is one of the few other sources of population prevalence of this syndrome.²⁵

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Figure 4

Prevalence of the metabolic syndrome in men.

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Figure 5

Prevalence of the metabolic syndrome in women.

DISCUSSION

This study provides important new evidence on the prevalence of hypertension and other cardiovascular risk factors in Albania and creates a baseline against which future changes can be assessed. It showed that more than one in three men and one in four women aged 25 years and over in Tirana City suffer from hypertension and that about one in ten people are both hypertensive and obese. These figures are surprising in a society that has relatively recently moved from a very traditional lifestyle. Before the results are discussed further, the strength and limitations of the study must be considered.

A major strength of the survey is its relatively high response rate (72.7%), comparable to the rates achieved in recent surveys conducted in other countries in transition.^26–28 Despite this, the final sample was not entirely representative of the general population in terms of age as it included a lower than expected proportion of younger people. As this might have led to an overestimation of the true prevalence of hypertension, overall prevalence rates were age standardised to the Tirana City population (1998 INSTAT data). Another limitation of the study is the fact while some respondents were from the same households, information on variance inflation due to clustering was not available. As a result, it is possible that the true standard errors of the estimates were underestimated and that the risk of type I error was increased. In an attempt to counterbalance these effects, we have increased the significance level to p=0.01 and calculated 99% confidence intervals. However, it is important to note that most significant findings in this study remained significant at the even smaller significance level of 0.001.

As noted above, Albania has been extremely isolated during much of the 20th century and, to our knowledge this study provides the only data on the prevalence of hypertension and clustering of CVD risk factors in the largest urbanised part of Albania (including nearly 20% of the Albanian population). However, the results cannot be generalised to the whole country, as it is probable that diet, physical activity levels, and consequently the prevalence of hypertension would differ in rural areas. Thus, our estimates may be higher than what would be found in a nationally representative survey. A better understanding of the impact of changing lifestyles in both urban and rural areas is thus urgently needed in this society in transition.

Elsewhere we have reported how this population has experienced a rapid increase in the prevalence of diabetes since the transition.¹⁰ Unfortunately, as already noted, we do not have historical data with which to compare our findings. However, data are available from the Seven Country Study, which had study sites in Greece and Italy. Data on a range of risk factors were recorded at entry in 1960–1961 and repeated 10 years later. The data in the present survey indicate that the urban population of Albania exhibit a risk profile that is consistent with what existed in Greece and Italy in the early 1960s (table 6).²⁹

However, a different pattern is seen when the percentage of people classified as hypertensive is considered, rather than the mean blood pressure. In this case, the percentage that is hypertensive is identical among men (30.2%) although rather lower (22.7% versus 27.1%) among women in comparison with contemporary Greeks.³⁰ However, the prevalence of hypertension is still considerably lower than in other, albeit rather more industrialised former communist countries, such as Hungary (37.2%)³¹ or in Russia (36%).³²

As expected, this study showed clear gender differences in the prevalence of hypertension, with men being more likely to be hypertensive than women, even after adjusting for various sociodemographic and lifestyle factors, family history of hypertension, and excess body weight. Surveys conducted in other countries in transition^33–35 found similar gender differences in the prevalence of hypertension.

In our study population, we observed that more than half the respondents treated for hypertension were adequately controlled. This is more than what was expected based on findings from surveys conducted in Hungary,²⁶ Belgium,³⁶ or China²⁹ that reported much higher unsatisfactory levels of blood pressure control (20%–30%) in respondents receiving treatment for hypertension.

The lack of an association between education and hypertension was not entirely surprising. The massive scale of transition in Albania means that earlier social hierarchies have been almost entirely disrupted.

In recent years it has been proposed that hypertension is part of a cluster of metabolic risk factors (syndrome X) involving hyperlipidaemia (raised plasma triglycerides and low HDL cholesterol levels) and hyperglycaemia, with hyperinsulinaemia as the common link.^37–39 In this survey, only excess weight, family history of hypertension and, among men, increased triglycerides, were associated with hypertension. The association with a positive family history of hypertension and excess weight has been reported in many studies.^40–42

To place Albania in a comparative perspective in terms of overall risk factors, given that the effects of cardiovascular risk factors tend to be synergic,⁴³ other studies that had looked at the combination of factors were identified. The prevalence of a combination of risk factors (obesity, hypertension, smoking) was considerably lower than in Hungary,³¹ in what was the most comparable study from a society in transition, although the Hungarian study did not report lipid levels. However, what was most striking was that the combination of risk factors that make up the metabolic syndrome, which can be considered a proxy indicator of overall cardiovascular risk, was very much lower than in the American population.

In conclusion, these findings provide important new evidence on the prevalence of hypertension and its association with other cardiovascular risk factors in Albania. Albania is changing rapidly. The prevalence of hypertension is, as in other societies in transition, a cause for concern but the levels of other cardiovascular risk factors remain somewhat lower than in other industrialised and transition countries, suggesting that Albania has so far not entirely lost its relative advantage.

These findings have important implications for both health care and health promotion. Although there was a relatively low frequency of undiagnosed hypertension, a substantial number of those affected had not achieved adequate control. There is now compelling evidence from several countries in this region that have experienced a turbulent transition that the management of longstanding diseases often suffers.⁴⁴ It will be important that future Albanian health care reforms, which in other post-transition countries have tended to focus on acute care, do not make the management of longstanding disorders more difficult. The risks are particularly great because those suffering from chronic diseases are often old and with limited resources. It is almost inevitable that the risk factor profile in Albania will worsen in the coming years. Given the many profound challenges facing Albania the development and implementation of an effective health strategy will inevitably be very difficult. However, it is essential not to allow the magnitude of the task to prevent any action. It may not be easy to influence the changing pattern of nutrition but other risk factors, such as smoking, whose actions are synergistic with those discussed here, can be tackled now.