Burden of Hypertensive Heart Disease in Iran during 1990–2017: Findings from the Global Burden of Disease study 2017

Background Hypertension and its consequent end-organ damage including Hypertensive Heart Disease (HHD) are a major concern that impact health, resulting into impairment and reduced quality of life (QOL). The purpose of this study was to describe the burden of HHD in Iran and comparing it with the World Bank upper middle-income countries (UMICs) in terms of disability-adjusted life years (DALY), mortality and prevalence. Methods Using data from the Global Burden of Disease study 2017, we compared the number of DALYs, deaths and prevalence trends for HHD from 1990 to 2017 in all age groups for both sex in Iran, and compared the epidemiology and trends with UMICs and globally. Results The age-standardized DALY rate for HHD increased by 51.6% for men (95% uncertainty interval [UI] 305.8 to 436.7 per 100,000) and 4.4% for women (95% UI 429.4 to 448.7 per 100,000) in Iran. The age-standardized prevalence of HHD in Iran was almost twice times higher than globally and 1.5-times more than the World Bank UMICs. The age-standardized death rate for HDD increased by 60.1% (95% UI 17.3 to 27.7% per 100,000) for men and by 21.7% (95% UI 25.85 to 31.48 per 100,000) for women from 1990 to 2017. Age-standardized death rate in Iran was 2.4 and 1.9 times higher than globally and UMICs, respectively. Conclusions The higher prevalence and death rate in Iran in comparison with UMICs and globally should encourage health care provider to perform intensive screening activities in at risk population to prevent HHD and mitigate its mortality.


Results
The age-standardized DALY rate for HHD increased by 51.6% for men (95% uncertainty interval [UI] 305.8 to 436.7 per 100,000) and 4.4% for women (95% UI 429.4 to 448.7 per 100,000) in Iran. The age-standardized prevalence of HHD in Iran was almost twice times higher than globally and 1.5-times more than the World Bank UMICs. The age-standardized death rate for HDD increased by 60.1% (95% UI 17.3 to 27.7% per 100,000) for men and by 21.7% (95% UI 25.85 to 31.48 per 100,000) for women from 1990 to 2017. Agestandardized death rate in Iran was 2.4 and 1.9 times higher than globally and UMICs, respectively.

Methods
The Global Burden of Diseases, Injuries, and Risk Factors Study 2017 (GBD 2017) estimates incidence, prevalence and mortality rates, years of life lost (YLLs), years lived with disability (YLDs) and disability-adjusted life years (DALYs), for 354 causes by sex, age, and location for 195 countries and territories for 21 regions and 7 super-regions for the years 1990-2017. Detailed description of the GBD 2017 methodology has been provided in previous publications [13][14][15][16][17].
In the current study, we reported numbers and rates of prevalence, death and DALYs of HHD in 2017 and its temporal changes from 1990 to 2017, according to the GBD 2017 data and methodology. These estimates were disaggregated by age group, sex and geographical regions (Iran and the World Bank UMICs group).
The GBD study methods are compliant with the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER) recommendations [18]. All estimations used in our study are extracted from the GBD 2017 study, the data of which are publicly available online at: http://ghdx.healthdata.org.
The GBD 2017 study uses the International Classification of Diseases (ICD)-9 and ICD-10 codes for HHD with sequelae (severity levels) where each sequela has a specific disability weight ranging from 0.041 to 0.049. DisMod-MR 2.1, a Bayesian meta-regression tool, was used to estimate non-fatal health losses. This method uses heterogeneous epidemiological data from different data sources to produce internally consistent estimates of incidence and prevalence of HHD [14]. HHD DALYs are the sum of YLDs and YLLs for each location, year, sex and age group. All age-standardized rates were calculated using the GBD world population age standard [16].

Comparisons with the World Bank UMICs group
The World Bank UMICs were selected for comparison with Iran: they include 56 countries, such as Brazil, the Russian Federation, Indonesia, Iraq and China. UMICs have a Gross national income (GNI) per capita between $4,046 and $12,535 [19]. We compared Iran and the above-mentioned group by age-standardized rates of death, and DALYs in 1990 and 2017.

Uncertainty interval
All data in this study are computed with their 95% uncertainty intervals (UIs) [13][14][15][16][17]. Each parameter was calculated 1,000 times and a distribution with 1,000 samples was produced. The 95% UIs were used to better capture the degree of uncertainty due to the lack of data for some geographic locations (countries/territories) and time periods, and heterogeneity of sources combined together. UIs were derived from the 2.5 th and 97.5 th values of the 1,000 draws to determine the upper and lower intervals of the 95% UI for each parameter. Table 1 shows that there were 276,641(95% UI 235,496-321,324) cases of HHD in 2017 in Iran. Crude prevalence numbers for men and women for all ages increased by 197% and 214.9%, respectively and the age-standardized prevalence rate for HHD increased by 6.2% (95% UI 291.6 to 309.9 per 100,000) for men and 7.2% (95% UI 494.4 to 530.3 per 100,000) for women from 1990 to 2017. Table 2 shows that crude death number for men and women for all ages increased by 398.6% and 284.4%, respectively. The most increasing death numbers for men and women are in the octogenarians, respectively (1142% and 553.2%). The age-standardized death rate for  Table 5 compares the indices between Iran, the UMICs and globally. Data shows that the age-standardized prevalence rate (per 100,000) of HHD in Iran has been about two times  (-19%). The pattern of the change in DALYs rate is similar to the death rate mentioned above. The age-standardized DALY rate was two times higher in Iran than in the world. Also, between 1990 to 2017, DALYs rate increased in Iran, but it decreased in the world.

Discussion
This is the first report evaluating the epidemiology and trends of HHD in Iran and UMICs over the past 27 years.
One of the key findings of the present study is that the number of DALYs has increased from 1990 to 2017 in all age groups for both men and women in Iran. Age-standardized DALY increased in both sexes, more in males than female (51.6% vs. 4. 4%) in Iran. Age-standardized DALY rate was higher in females compared with males (448.7 vs. 436.7) in 2017. The percentage of changes for DALY rate was lower in females during the 27-year period and this could be due to higher baseline DALY rates in 1990. The increase in DALY in both sexes could be attributed to aging, prevalence of hypertension and higher life expectancy [12,20]. According to the World Bank United Nations Population division data, total life expectancy in Iran increased from 63.8 in 1990 to 75.7 years in 2017. Due to population growth in Iran, 24 million additional people were exposed to HHD in 2017 [20].
The other main finding of the present report was that age-standardized death rate in both sexes increased from 1990 to 2017 in Iran and the increase had a steeper slope in males. The potential cause for higher death rates in females could be explained taking into account the higher prevalence of hypertension and obesity [12,21]. The increases in death attributed to HHD could be explained by the increase in prevalence of hypertension and improvement in detection of hypertension induced end-organ damage.
The prevalence of HHD increased from 1990 to 2017 in all age groups despite the availability of preventive interventions and potent versatile antihypertensive medications. The higher prevalence in women could be explained by aging (63.8-77) and obesity. These findings support the observation that dietary salt intake, fruit and vegetable consumption, overweight and obesity, and physical activity have also changed substantially over the same time period [12]. Among major cardiovascular risk factors at the global scale, the prevalence of obesity and overweight increased substantially over the last two decades [12]. Overall, about 13% of the world's Also, there was a significant difference between the prevalence of obesity among males and females in Iran [21][22][23].
The proportion of HHD attributed mortality to all-cause mortality has increased in Iran from 1990 to 2017. Compared with the UMICs and globally, the proportion of attributed death in Iran was 1.89 and 2.73 times respectively. DALY proportion of HHD to all-cause increased in Iran, UMICs and globally during the aforementioned period, however the proportion of HHD induced disability in Iran in 2017 was 1.38 and 2.16 times higher than UMICs and globally, respectively.
The age-standardized rates demonstrated that the indices in Iran were higher than those of UMICs and globally in 2017. Age-standardized prevalence rate of HHD increased by 15.1% in UMICs. The higher rate of prevalence in Iran compared with UMICs and globally could be explained by higher prevalence of obesity in Iran. The age-standardized prevalence of HHD in Iran was almost twice times higher than globally and 1.5-times more than World Bank UMICs. Age-standardized death rate in Iran was 2.4 and 1.9 times higher than globally and UMICs respectively. Also, age-standardized DALY rate in Iran was 2.11 and 1.8 times higher than globally and UMICs respectively. Comparing results globally and with UMICs during the aforementioned period demonstrated that the age-standardized death and DALY rate per 100,000 decreased from 1990 to 2017 globally and in UMICs, while these trends increased in Iran. This should encourage public health policy-providers to develop and implement robust screening and follow-up program among the general population.
This study and GBD studies used vital registration and administrative hospital data as well as data from representative cross-sectional surveys to inform disease trends across geography and time; these data were adjusted to account for differences in reporting of disease across health systems. Varying practices, resources, patient populations, and quality of data recording, however, likely cause differences in the quality and uniformity of data.

Conclusions
Age standardized DALY and death rate increased in both sexes from 1990 to 2017 in Iran and this increase was steeper in males. The age-standardized prevalence and death rate of HHD in Iran were almost twice times higher than globally. The higher prevalence and death rates in Iran in comparison with UMICs and globally should encourage public health decision-makers to perform intensive screening activities in at risk population to prevent HHD and mitigate its mortality, specifically, adopting an age and a gender-specific perspective.