National and Subnational Burden of Cardiovascular Diseases in Iran from 1990 to 2021: Results from Global Burden of Diseases 2021 study

Decomposition analysis

To assess the factors driving changes in the incidence of CVDs we employed a decomposition analysis using two distinct scenarios. In the first scenario, age-specific incidence rates from 1990 were applied solely to the 2021 population size, thereby estimating the expected number of cases under the assumption that the incidence rates remained unchanged over time. The difference between this estimate and the baseline (1990) case count quantifies the impact of population growth. In the second scenario, the same 1990 age-specific incidence rates were applied to the full 2021 population data—accounting for population size, age structure, and sex distribution—to generate an estimate that reflects both population growth and changes in demographic composition. The difference between the observed 2021 case count and this estimate represents the effect of changes in age-specific incidence rates over time. Finally, the difference between the estimates from the two scenarios was computed to isolate the contribution of population aging, that is, the impact of shifts in the age and sex distribution on the overall CVDs incidence. This analytical framework enables us to disentangle the relative contributions of population growth, changes in incidence rates, and population aging to the observed trends in CVDs incidence (1617).

Sociodemographic index (SDI)

SDI is a composite measure that reflects the development level of countries or regions based on fertility rates among females under the age of 25. Higher income and education levels are fertility rates among females under the age of 25. Higher income and education levels are associated with better health outcomes, while higher fertility rates among young women typically correlate with poorer health outcomes (18).

Software

Data visualizations and analyses were performed using Python (version 3.10.13).

Leading causes

Ischemic heart disease has consistently been the leading cause of CVD burden in Iran from 1990 to 2021. In 1990, the DALYs age-standardized rate (ASR) for ischemic heart disease was approximately 5166.82 (4824.54 to 5465.59), decreasing to 2731.3 (2517.27 to 2920.87) by 2021. Stroke followed a similar trend, dropping from around 2470.21 (2277.04 to 2673.16) to 1229.18 (1119.52 to 1332.6). Aortic aneurysm and lower extremity peripheral artery diseases were the only causes with a significant upward trend in DALYs ASR, while all other causes showed either a decreasing trend or no significant change. The death ASR for ischemic heart disease decreased from approximately 259.88 (238.06 to 276.23) to 146.11 (130.71 to 156.95) in 2021, with stroke deaths declining from about 125 to 65. Similar to the incidence ASR for ischemic heart disease that remained steady at approximately 6,500 and stroke around 125, ASRs of prevalence for ischemic heart disease and stroke were roughly 1,000 and 125 during the study period (Figure 2).

Figure 2

Age and sex differences

For prevalence, females showed an increase in ASR from 8,971.07 (8,248.15 to 9,721.34) to 9,431.32 (8,592.39 to 10,342.17), reflecting a 5.13% rise. Males experienced a slightly greater increase, from 10,876.22 (9,993.32 to 11,835.32) to 11,350.32 (10,307.17 to 12,484.58). Prevalence also rose with age, peaking in the 80+ group and consistently remaining higher in males across all age categories. For incidence, females’ ASIR decreased from 1,167.12 (997.32 to 1,351.08) to 1,060.46 (906.87 to 1,234.36), while males showed a larger decline, going from 1,493.54 (1,248.80 to 1,754.36) to 1,335.70 (1,116.68 to 1,574.31). Like prevalence, ASIR rose with age, and males showed higher incidence rates across all age groups. In terms of deaths, females’ ASDR declined from 432.79 (393.31 to 463.58) 253.68 (223.21 to 274.29), Males experienced a steeper decrease, with ASDR declining from 446.27 (411.54 to 471.33) to 254.52 (230.23 to 271.35). Death rates increased with age, and while rates were initially higher in males, the sex gap narrowed in older age groups, with females exceeding males in the 75+ category. In terms of DALYs, females’ ASR dropped to 3,431.32 (3,052.39 to 3,802.55), while males showed a greater reduction and reached 4,570.16 (4,214.83 to 4,850.91). In all age groups except +80 DALYs were higher in males compared to females (Table 1, Figure 3). YLLs showed a marked ASR decrease for females, reaching 4089.38 (3698.5 to 4395.72), likewise, the ASR YLLs of males fell to 5076.03 (4746.99 to 5399.5). For YLDs, females’ ASR rose modestly to 365.83 (264.52 to 481.51) whereas males experienced a more pronounced increase and reached 448.37 (318.29 to 598.16) (Table 1).

Figure 3

Provincial trends

Examining ASPR across provinces, Ardebil displayed the highest ASPR at 12,247.46 (11,088.94 to 13,495.03), indicating a significant CVD burden. In contrast, Qom had the lowest ASPR at 9,258.99 (8,357.16 to 10,295.48), furthermore, the highest change was observed in Yazd with a 12.45% (8.09 to 17.71) increase North Khorasan led in ASIR with a rate of 1,287.47 (1,081.63 to 1,523.31), followed closely by Golestan at 1,291.81 (1,092.03 to 1,516.18), and Khuzestan at 1,314.8 (1,119.55 to 1,535.96). Tehran reported the lowest ASIR at 1,082.0 (922.58 to 1,278.82), the highest change was observed in Fars (–14.54% (–17.76 to –11.16)) (Supplementary Table 1). Golestan showed the highest ASDR (357.49 (318.3 to 388.99)), followed by West Azarbayejan (347.81 (309.11 to 392.66)), conversely Tehran had the lowest ASDR (161.53 (132.45 to 190.14)). Notably Markazi showed the highest change rate with a –52.15% (–59.55 to –43.41) decrease.

Golestan also experienced the highest age-standardized DALY at 7,409.36 (6,677.39 to 8,085.34), followed by Ardebil at 6,401.14 (5,719.93 to 7,041.38) and Khuzestan at 6,364.1 (5,682.52 to 7,092.16). Conversely, Tehran showed the lowest DALYs at 3100.2 (2659.43 to 3684.6), with similarly low burdens in South Khorasan at 3,944.84 (3,480.92 to 4,402.79) and Yazd at 4,259.58 (3,672.15 to 4,849.31). same as ASDR, Markazi also had the highest change rate for ASR DALY (–53.08% (–60.67 to –43.95)). Across all provinces, YLLs significantly outnumbered YLDs, contributing more to the overall DALYs (Figure 4). While a higher SDI was associated with lower deaths, DALYs, and incidence of CVDs in Iran, it was negatively associated with prevalence (Figure 5).

Figure 4

Figure 5

Decomposition analysis

Decomposition analysis indicated that of the 159.6% increase in CVD incidence rates in Iran, 49.5% and 136.2% were attributed to population growth and changes in age structure, respectively, while changes in incidence rates contributed negatively (–26.1%). A similar pattern was observed in both males and females (Table 2). Decomposition analysis showed an increase in incidence across all provinces in both sexes; moreover, in all provinces incidence rate change had a negative effect on incidence while population age structure and population growth had a positive contribution to incidence (Supplementary Table 2). For ASDR, Golestan showed the highest rate at 357.49 (318.3 to 388.99), followed by West Azarbayejan 347.81 (309.11 to 392.66), and Ardebil at 322.88 (286.55 to 356.66). Tehran had the lowest ASDR at 161.53 (132.45 to 190.14), with low rates also in South Khorasan at 194.76 (166.99 to 218.65) and Markazi at 216.53 (184.37 to 245.65) (Supplementary Table 1).

Risk Factors

The age-standardized DALYs attributed to risk factors for cardiovascular diseases in Iran indicated that high systolic blood pressure was the leading contributor at the national level in both 1990 and 2021, with its impact remaining consistently significant and surpassing other risk factors across all provinces. High LDL cholesterol and dietary risks were the next most prominent contributors to DALYs nationwide (Figure 6).

Figure 6

Subnational trends: Addressing inequities

Provinces with high SDI (e.g., Tehran, Isfahan) exhibited lower mortality but higher CVD prevalence, likely reflecting improved healthcare access and diagnostic capacity In contrast, low-SDI provinces face elevated mortality due to limited access to cardiac surgeries (19202122). essential medications (23) and adherence challenges. These disparities mirror global patterns where socioeconomic inequities amplify CVD outcomes. Prioritizing healthcare infrastructure (e.g., cardiac care units, medication supply chains) in underserved regions could mitigate mortality gaps.

Age and sex disparity

CVD burden disproportionately affects older adults in Iran, contrasting with patterns in many LMICs where younger populations bear a larger burden. This aligns with physiological aging processes (arterial stiffness, chronic inflammation) (2425). and Iran’s demographic transition. Notably, males had higher ASRs across most age groups, likely due to greater tobacco use, abdominal obesity, and lower HDL cholesterol (26). While CVDs in many low- and middle-income countries tend to primarily affect younger, working-age populations, Iran presents a different pattern, with a more significant burden in older age groups. This is partly due to the country’s aging population, where the risk of cardiovascular disease is compounded by the rise in chronic conditions. Moreover, both prevalence and mortality rates from CVD are consistently higher in males across various age groups except the +75 years age group, a pattern that may stem from multiple biological, behavioral, and social factors. Men tend to have higher rates of certain risk factors, such as tobacco use, and abdominal obesity, and also generally have lower levels of HDL cholesterol, increasing their CVD risk (2728). However, after menopause women are at more risk for CVDs (29). These is because premenopausal women have the protective benefits of estrogen which males and post-menopausal women do not (3031).

Risk factors and policy implications

In a study on burden of CVDs in USA, Ford et al. estimated that 47% of the observed decline in coronary heart disease (CHD) mortality was as a result of medical and surgical treatments, while 44% was caused by reductions in major risk factors (30). Studies on primary prevention, such as one by O’Flaherty, indicate that substantial dietary improvements could prevent up to 30,000 cardiovascular deaths in the UK between 2006 and 2015, compared to just 12,500 fewer deaths if current trends continued (31). Similar findings have been reported in studies analyzing European (32) and American (33) data. In Iran, where dietary risks remain the leading contributor to CVD burden, policy action must expand beyond existing efforts. These findings are comparable to Iran since the risk factor with the most burden was dietary risk in the country. To address this, policymakers should prioritize stricter regulations on ultra-processed foods, including mandatory front-of-package warning labels and taxes on high-sodium and high-sugar products, alongside subsidies for healthy foods like fruits and whole grains. Until now, the country has implemented an NCDs roadmap aligned with WHO best-buy recommendations, which includes policies aimed at reducing sugar, fat, and salt intake (32). Over the past decade, studies have reported significant improvements in blood lipid profiles within the Iranian population. This progress can be attributed to efforts such as reducing Trans Fatty Acids (TFA) in the oil industry and raising public awareness about the adverse health effects of TFA consumption (33). As a result, levels of total cholesterol and non-HDL cholesterol have decreased, while HDL cholesterol levels have increased (34). High BMI and HTN rank among the leading contributors to Iran’s CVD burden. Despite national efforts to develop nutrition-oriented policies and integrate dietary strategies into development programs, obesity rates remain persistently high due to a lack of targeted, actionable interventions (3536). For instance, while initiatives to reduce salt and trans-fatty acids have shown success (3233) dedicated policies to curb obesity—such as regulating ultra-processed foods or promoting physical activity—are notably absent. This gap underscores the need for a holistic approach involving multisectoral collaboration (e.g., food industry regulations, urban planning, public education) to address obesity’s root causes. Compounding this issue is the rise in physical inactivity, as evidenced by the STEPS study, which reported increased sedentary behavior in Iran between 2016 and 2021 (25). Among the various challenges, barriers to physical activity among the elderly in Iran and globally can be categorized into three main areas: interpersonal factors, such as lack of a companion, absence of professional guidance, family responsibilities, and social pressures; intrapersonal factors, including physical limitations, time constraints, lack of interest, laziness, financial cost, security concerns, and fear of falling; and environmental factors, such as traffic, weather conditions, and physical barriers to walking (26). To combat this, multisectoral collaboration is critical—for example, enforcing urban planning policies that create walkable communities and green spaces, specially in high-risk provinces like Golestan and Ardebil, and launching nationwide campaigns to reduce sedentary behavior. Moreover, subsidizing gym memberships for low-income populations and integrating physical activity programs into primary healthcare services could be beneficial.

For HTN, it is worth emphasizing that despite breakthroughs in technology, treatment, care, and disease prevention, the prevalence of HTN has not reduced over time in Iran (3738). This highlights the need for more effective preventive and treatment-focused strategies. Policy-makers should adopt province-specific strategies: expanding access to affordable antihypertensive medications in low-SDI provinces and enhancing community-based screening programs in high-SDI provinces like. Campaigns to raise public awareness of the dangers of hypertension and the significance healthy lifestyle can be effective (39). Stricter regulations on food labeling, especially regarding sodium content, and initiatives to reduce the consumption of unhealthy foods could further help decrease hypertension rates (40).

Limitations and strengths

Despite many strengths of this study, several limitations should be noted. GBD project provided the data used in this analysis, which may not fully represent regional variations in health determinants or healthcare quality. Additionally, this study does not account for other socioeconomic determinants of health, such as income and education, which may significantly impact CVD outcomes. These societal aspects should be investigated in future studies to give a more thorough picture of Iran’s CVD burden. Additionally, longitudinal studies would be valuable for evaluating how risk variables and health outcomes vary over time. Notwithstanding these drawbacks, this study has a number of advantages, such as a broad timeframe and the application of age-standardized rates, which enable insightful comparisons across time and between geographical areas. Additionally, the provincial-level data offer insightful information on regional inequities, enabling focused health initiatives. These understandings are essential for creating plans that take into account the particular requirements of different groups and geographical areas, which will ultimately result in public health programs that are more successful.