COVID-19 burden in Iran: disability-adjusted life years analysis from hospital data, 2020–2021

Abstract

Background

The burden of disease based on disability-adjusted life years (DALYs) is one of the internationally accepted metrics for assessing the impact of a disease or injury on population health. This study aimed to provide evidence of the burden of COVID-19 on health in Iran based on hospital-level data from the Iran Health Insurance Organization (IHIO), which covers almost half of the country’s population.

Methods

The data of all IHIO enrollees who were referred to hospitals across the country from the beginning of the COVID-19 pandemic (February 2020) to December 30, 2021, with assigned diagnosis codes of COVID-19, were extracted from the hospital information processing system. The DALYs due to COVID-19 were estimated using the standard approach of the World Health Organization and the European Burden of Disease Network guideline.

Results

In the years 2020 and 2021, among a population of about 42 million people, 1,040,367 individuals were admitted to the hospital due to COVID-19 infection, of whom 73% were hospitalized (760,963 patients). The total estimated DALYs for these two years were 665,823 and 928,393, respectively (1,603 and 2,234 per 100,000 population). 99.7% of DALYs were attributed to years of life lost due to premature death (YLLs). The share of the disease burden in the age groups of under 20 years, 20–49 years, 50–80 years, and over 80 years was 6.6%, 26.4%, 58.4%, and 8.6%, respectively.

Conclusions

Based on the hospital-level data estimates, COVID-19 has had a significant burden on health in Iran. COVID-19 was identified as the fifth leading cause of disease burden in Iran during the study period, ranking after cardiovascular diseases, psychological disorders, neoplasms, and musculoskeletal disorders. Additionally, COVID-19 was the third major cause of death, following cardiovascular diseases and neoplasms. Policymaking and the implementation of comprehensive programs to enhance the response of the health system and society to outbreaks of emerging and re-emerging infectious diseases are of utmost importance.

Text box 1. Contributions to the literature
• The results of this study are based on real hospital-based data from a large population of approximately 42 million people, providing reliable information about the burden of COVID-19 in Iran.
• DALYs effectively quantify the impact of morbidities and premature death caused by individual causes or illnesses. This metric enables a comprehensive comparison of the burden of COVID-19 with other diseases and injuries.
• In the years 2020 and 2021, the estimated COVID-19 DALYs were 2,234 and 1,603 per 100,000 population, respectively. When compared with the estimated DALYs for all causes of diseases in the 2019 Global Burden of Diseases Study, COVID-19 can be classified as one of the top five major causes of disease burden in Iran during these years.

Introduction

The health perspective in the 21st century rapidly changed upon an increase in the burden of non-communicable diseases and mental health disorders, outbreaks of emerging and re-emerging infectious diseases, antimicrobial resistance, increasing demand from the elderly population, displaced populations, and rising health disparities. All these factors are threats to health security, general health, and well-being of the population [1]. The outbreak of coronaviruses is one of these threatening factors. Human coronaviruses were first identified in the mid-1960s [2]. Although most human coronaviruses cause mild disease, in the past two decades, the world faced two major pandemics of two beta-coronaviruses, including the severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002–2003 and the Middle-East respiratory syndrome coronavirus (MERS-CoV) in 2012, which were responsible for more than 10,000 cumulative infected cases [3]. The most extensive outbreak of coronaviruses is related to the SARS-CoV-2 virus, which is the cause of the COVID-19 disease, which is the seventh member of the coronavirus family that infects humans [4, 5]. The accepted transmission modes of the SARS-CoV-2 virus are droplet particles, direct contact, and inhaling aerosols [6]. Most infected people experience mild to moderate respiratory illness and recover without the need for any special treatment. Older people, those with chronic medical conditions, such as cardiopulmonary disease, diabetes, morbid obesity, or chronic renal or liver disease, and immunocompromised individuals are prone to experiencing severe disease [7].

COVID-19 spread rapidly all over the world and caused numerous health, economic, and social challenges for everyone in such a way that it has been considered the most important threat of the last century since World War II [8]. The World Health Organization (WHO) reported 766,440,796 cases of COVID-19 infection and 6,932,591 related deaths as of May 17, 2023 [9]. The extent of this pandemic can be better understood when this death rate is compared with the total number of deaths caused by all infectious diseases per year (around 10 million) [10]. It is estimated that following the lockdowns imposed to control the speed of the spread of COVID-19, the rate of extreme poverty in the world increased from 8.4% in 2019 to 9.3% in 2020 so that about 70 million people across the globe pushed into extreme poverty [11]. In these years, the average annual growth rate of the world economy also decreased from 2.6% to -3.1% [12].

Iran was among the first countries that faced a rapid increase in the rates of COVID-19 infections and deaths [13]. According to the Global Health Security Index, which provides the first and most detailed assessment of countries’ performance in terms of prevention, diagnosis, and response to infectious diseases, Iran, with a score of 37.7 (out of 100), ranks 97th among 195 countries. Iran’s performance scores in the three dimensions of prevention, early detection, and quick response were reported as 44.7 (rank 50th ), 37.7 (rank 103rd ), and 33.7 (rank 109th ), respectively [14]. As of May 17, 2023, according to official reports, the number of confirmed COVID-19 cases in Iran has been 7,610,676, with a related death toll of 146,204 [9]. To better understand the great impact of this pandemic on public health, it is important to quantify the health and economic burden of this disease [15], which can reflect the ramifications of implemented policies [16]. The disease burden can be expressed in several ways. Although prevalence and incidence can explain the magnitude and severity of a health condition, there is also a need to define other abridged metrics that allow the comparison of the health and economic consequences of diseases. Disability-adjusted life years (DALYs) present a summarized population health metric that is increasingly used to express the burden of disease. The Harvard School of Public Health, the World Bank, and the WHO developed this concept. One DALY is one lost year of a healthy life. DALYs for a given condition in a population is the sum of YLLs (years of life lost) and YLDs (years lived with disability) [17]. Using DALYs to proportionally weigh the impact of morbidities and premature death caused by individual causes or illnesses, it is applicable to comprehensively compare the burden of COVID-19 with other diseases and injuries [15]. This study provides evidence for the COVID-19 burden among hospitalized patients covered by the Iranian Health Insurance Organization (IHIO), an organization covering almost half of Iran’s population.

Methods

Study setting and data collection

Basic health insurance in Iran is provided by three organizations, which are: the Iran Health Insurance Organization (IHIO), Social Security Organization(SSO), and Armed Forces Medical Service Insurance Organization (AFMSIO) [18]. Following the policies made to achieve universal health coverage, which are reflected in national laws and development programs, almost the entire population of Iran is currently covered by basic health insurance [19]. IHIO, which is a government health insurance organization affiliated with the Ministry of Health, has several sub-funds to cover different population groups, including Civil Servants, rural residents, the self-employed and their dependents, the poor, and other groups (college students, seminary students, clergymen, and some professional associations, etc.) [18, 20]. Therefore, IHIO-insured persons are a sample that can be generalized to the entire population of Iran due to the diversity of the population groups covered. According to the latest available statistics, in 2021,42,158,468 people were covered by IHIO [21], and insurance coverage is provided for the rest of the population by SSO and AFMSIO.

This study was conducted based on the data extracted from the hospital claims management system database( [22]. This system receives the data of IHIO-insured patients who have been admitted to all hospitals in Iran from the integrated electronic health record of Iran (which is locally known as SEPAS) and uses it to manage hospital claims and determine the amount payable to them. In 2007, Iran’s electronic health record project (SEPAS) was approved by the Ministry of Health to create a national health information network and also a health information record for the entire population [23]. Some of the domain services in SEPAS include Inpatient Service, Medication Prescription Service, Dispensed Prescription Service, Laboratory Prescription Service & Laboratory Result Service [24]. Currently, in the domain of hospital services, it is the mandate that all types of data of patients admitted to hospitals (identity and insurance data, all services provided and their costs, clinical diagnoses, and their status at the time of discharge) e.g. death) are collected in the form of electronic records by hospital information systems (HIS) and after the patient’s discharge, they are sent to SEPAS and for claims processing and accounting affairs of insurance organizations, they are sent from SEPAS to insurance organizations. In IHIO, these received data are rearranged and used in the claims management system platform and stored in a related database. In this study, the data of all IHIO-insured persons who were admitted and cared for in hospitals across the country with the ICD-10 codes of COVID-19 (U07.1 & U07.2) in 2020 and 2021 (from February 19, 2020, to December 30, 2021) were extracted from this database. U07.1 & U07.2 are emergency International Classification of Diseases (ICD) codes for COVID-19 disease outbreak introduced by WHO [25], which is the basis for identifying patients with COVID-19 in health facilities. In this study, the discharge status of patients (recovery or death) is considered as the basis for identifying deceased patients and because it was not available from the death certificates developed based on the methodology proposed by the World Health Organization, it cannot be determined with certainty that in each patient, COVID-19 was the direct/immediate cause of death or the underlying cause. The patients admitted to the hospital included in this study can be divided into two main groups, the first group is the patients who were referred to the emergency department received the necessary care on an outpatient basis, and stayed less than 24 h. The second group is patients who have stayed in the hospital for more than 24 h and have been cared for inpatients.

Data analysis

Based on the method provided by the WHO, DALYs was calculated as follows [26]:

DALYs (c, s, a, t) = YLLs (c, s, a, t) + YLDs (c, s, a, t) for given cause c, age a, sex s and year t.

YLLs (c, s, a, t) = N (c, s, a, t) x L (s, a)

where: N (c, s, a, t) is the number of deaths due to the cause c for the given age a and sex s in year t L (s, a) is a standard loss function specifying years of life lost for a death at age a for sex s.

In the study to determine the global burden of diseases (2010) and subsequent studies, the normative standard life table was used instead of the loss function to simplify the calculation of DALYs. In the present study, this parameter was extracted from the WHO website [27].

Considering that the disability weight reflects the health loss associated with each health condition, its value influences the estimated YLDs. The disability weights related to a significant number of health conditions are annually published in parallel with reporting the global burden of diseases (GBD) and are publicly available. However, no specific disability weight has been reported for COVID-19 so far. Some researchers, including Gianino et al [28]. , used the disability weights related to lower respiratory tract infections (0.133), which largely resemble the COVID-19 condition, to estimate YLDs. In the present study, the weights agreed for DALYs calculation and the protocol proposed by the European Burden of Disease Network were employed to estimate the burden of COVID-19 [19, 29]. The disability weights for different health states represented in Table 1.

Table 1 COVID-19 health states and disability weights

$$\begin{aligned}{DALY\left(per\:\text{100,000}\right)}_{a,\:s}\\&=\frac{\sum\:{DALY}_{a,\:s}}{{population}_{a,\:s}}{YLL\left(per\:\text{100,000}\right)}_{a,\:s}\\&=\frac{\sum\:{YLL}_{a,\:s}}{{population}_{a,\:s}}{YLD\left(per\:\text{100,000}\right)}_{a,\:s}\\&=\frac{\sum\:{YLD}_{a,\:s}}{{population}_{a,\:s}}\end{aligned}$$

In the above equation, $\:{\text{p}\text{o}\text{p}\text{u}\text{l}\text{a}\text{t}\text{i}\text{o}\text{n}}_{\text{a},\:\text{s}}$ is the insured population of Iran Health Insurance Organization in age group a and gender group s.

Results

During 2020 and 2021, 1,040,367 of the IHIO population were admitted to the hospital with the assigned ICD-10 codes of COVID-19. Out of these, 27% stayed in the hospital for less than six hours (As an outpatient case), of whom 1% died. Other hospital admitted patients (73%) stayed at least one day (As an inpatient case). Of the inpatient cases, 19% were admitted to the ICU due to critical conditions, 39% of whom died and 618,208 people of inpatient cases were only cared for in the general hospital wards and were not under critical care, 5% of whom died. Therefore, out of all the hospital-admitted patients, 89,556 (8.6%) died due to COVID-19 (Fig. 1). (Additional descriptive information, including trends in the number of hospital admissions and deaths, as well as the number of inpatients and outpatients and ICU admissions, are available in Additional Files 1 and 2, respectively).

Fig. 1

Outcomes of patients with COVID-19 admitted to hospitals in the IHIO population in 2020 & 2021

Figure 2 shows the time trend of the DALYs rate (per 100,000 population). Three major surges were observed over time, which were in November 2020 (313), April 2021 (251) and August 2021(547).

Fig. 2

Trend of DALYs rate (per 100,000 population) attributable to COVID-19 in IHIO-insured population based on hospital-level data

Total DALYs (in both sexes and all age groups) of COVID-19 in 2020 were 665,823 (1,603 years per 100,000 population), of which 99.8% were YLLs (664,230 years). The rate of YLLs and YLDs per 100,000 population in this year was 1,599 and 3.8, respectively. In 2020, the total number of deaths was 39,192 (94 deaths per 100,000 population). The lowest absolute number of deaths has been observed in the age groups 5 to 19 years. The death rate per 100,000 population in age groups 5–9, 10–14 and 15–19 was 2, 3 and 3, respectively. The highest death rate was seen in the age groups older than 80 years, so in the age groups 80–84, 85–90, and ≥ 90, it was 1,183, 1,656, and 1,740 per 100,000 population. The highest rates of YLLs have been observed in the age groups 50–79 years such that 60% of the total YLLs are related to them. The highest rate of YLLs was observed in the age group of 75–79 years (10,052 years per 100,000 population). As mentioned, a small share of the total DALYs was related to YLDs, but the highest YLD was observed in the age group of 65–69 (178 years in the IHIO beneficiary population). The lowest and highest rates of YLDs in the 100,000 population were related to the age groups of 10–14 (0.3) and 85–89 (37.5 ((Table 2).

Table 2 Disease burden of COVID-19 in the IHIO-insured population by age groups for both sexes*, in 2020

Total DALYs (in both sexes and all age groups) of COVID-19 in 2021 were 928,393 (2,234 years per 100,000 population), of which 99.7% were YLLs (925,457 years). The rate of YLLs and YLDs per 100,000 population in this year was 2,227 and 7.1, respectively. The total number of deaths was 50,331(121 per 100,000 population). The lowest absolute number of deaths has been observed in the age groups 5–19 years (94 cases). The death rate per 100,000 people in age groups 5–9, 10–14 and 15–19 was 3, 3 and 5, respectively. The highest death rate was seen in the age groups older than 75 years, so that in the age groups 75–79, 80–84, 85–90, and ≥ 90, it was 1,079, 1,283, 1,913 & 2,155 per 100,000 population, respectively. About 60% of all estimated YLLs were related to 45–74-year-olds. The highest rate of YLLs was observed in the age group 75–79 years (11,501 years per 100,000 population). The highest YLDs were observed in the age group 65–69 (305 years in the IHIO beneficiary population). The lowest and highest rates of YLDs in the 100,000 population were observed in the age groups 10–14 (0.5) and 85–89 (50.5) (Table 3).

Table 3 Disease burden of COVID-19 in the IHIO-insured population by age groups for both sexes^*, 2021

To enable a better comparison, Fig. 3 presents the distribution of DALY rates based on age-sex groups in 2020 and 2021.

Fig. 3

DALY rate (per 100,000 population) of COVID-19 in IHIO insured population by age and sex: A-2020, B-2021

Discussion

This study aimed to estimate the burden of the COVID-19 disease in the IHIO-insured population who were admitted in hospitals across Iran in 2020 and 2021. For the total IHIO-insured population (Almost 42 million people), 1,040,367 hospital admissions due to COVID-19 were recorded for 2020 and 2021. The DALYs calculated for this population during these two years were 1,594,216 years)928,393 years in 2021, and 665,823 years in 2020(. The total IHIO insured population was 42,278,338 and 42,158,648 individuals in 2020 and 2021, respectively [21] and total population of the country was 84,038,000 in 2020 and 84,055,000 in 2021 [30]. Therefore, the estimated DALYs in this study are based on the real hospital data of about half of the country’s population. The rest of the population is covered by two large basic insurance organizations, including the SSO and the AFMSI. If the hospital-based estimated DALYs for COVID-19 in this study are generalized to the entire population, it seems that the total COVID-19 attributable DALYs for Iran will be about 3.2 million years. To better understand the significant impact of COVID-19 based on disease burden, the COVID-19 estimated DALYs can be compared with DALYs imposed by other diseases Based on the latest published Global Burden of Diseases (GBD) study reports. According to the 2019 GBD report the total DALYs attributable to all respiratory infections and tuberculosis were 377,692 and for all causes classified under group A (including all communicable diseases, as well as maternal, neonatal, and nutritional disorders) were 1,775,950 [31]. These findings indicate the substantial burden of COVID-19 in Iran. In fact, after cardiovascular diseases (3,603,912 years), psychological disorders (2,053,871 years), neoplasms (1,801,835 years), and musculoskeletal disorders (1,771,348 years), COVID-19 can be placed in the fifth rank among the major cause of disease burden in Iran.

According to estimates, the burden of COVID-19 in Iran per 100,000 population was 1,603 years in 2020 and 2,234 years in 2021 (Overall, an average of 1,918 years). Corresponding to the respective raw values of disease burden, COVID-19 reclaimed its position at the fifth rank of diseases inflicting the population health after cardiovascular diseases (4,275 years), psychological disorders (2,436 years), neoplasms (2,137 years), and musculoskeletal abnormalities (2,101 years). Different degrees of impact of COVID-19 on population health have been reported around the world. For example, Nurchis in Italy and at the beginning of the pandemic estimated that the burden of this disease would be 2.01 years per 1000 people (i.e., 201 years per 100,000 population) [7]. In a study by Singh et al. in India, the DALYs of COVID-19 were estimated at 1,022 in 2020 [32]. Cuschieri et al. demonstrated that COVID-19 was the fourth cause of disease burden in Malta in 2020 [19]. According to a study by Min-Woo, the COVID-19 burden was reported as 4.930 per 100,000 population from January to April 2020 [33]. In the Netherlands, McDonald estimated the COVID-19 disease burden at 1,640 years per 100,000 population in 2020 [34]. In another study by Haneef et al. in 2020, this value was estimated at 1,472 [35]. Although most of these studies have shown the significant burden imposed by COVID-19 on health, due to variabilities in studies’ periods, the demographic-epidemiological characteristics of the population studied (age, gender, and other contextual characteristics) and methods used, it is not possible to judge with certainty about the similarities and differences in the disease-imposed burden.

According to our observations, the greatest disease burden (99.7%) was related to YLLs. Other studies have also reported such a pattern following the calculation of the disease burden of COVID-19 [32, 33, 35,36,37]. According to the results of this study, 89,556 patients admitted to the hospital have died, which is 8.6% of all patients and about 0.2% of the IHIO population. The trend of DALYs rate by month during 2020 and 2021 revealed considerable variability at different periods, showing an increasing trend from one year in January 2020 to 134 years in January 2020, then a fluctuating trend between 74 and 313 until November 2020, followed by Declining trend until February 2021. Then, with an increasing trend but with fluctuations, it reaches the highest level in August 2021 (574 years per 100,000 population). The results of the recent study indicated that the odds ratio for death among hospitalized patients was a function of age, gender, geographic location, hospital type, and time and severity of the infection (captured by admission/non-admission to the critical care units as a proxy) [20]. Considering the difference in the trend of reported cases of COVID-19 infection and deaths attributable to it in different countries of the world [9], it is expected that the disease burden based on DALYs will be different in absolute and relative terms between countries and in different periods. According to the reports of the Ministry of Health of Iran, by the end of December 2020, 6,194,401 cases of COVID-19 were confirmed in Iran, of which 131,606 cases have died, giving an overall mortality rate of 2.21% [38]. The raw numbers of deaths caused by COVID-19 in 2020 and 2021 were almost equal to the death rate related to neoplasms (66,792 deaths in 2019, accounting for the second cause of death in the country after cardiovascular diseases; 173,601 deaths in 2019) [31]. Thus, COVID-19 can be considered the third cause of death in Iran in 2020 and 2021.

The age groups of < 20, 20–49, 50–80, and > 80 years accounted for 6.6%, 26.4%, 58.4%, and 8.6% of the total DALYs, respectively. Also, women and men shared 53.7% and 46.3% of the total DALYs, respectively. Individuals younger than 20 years and older than 80 years accounted for a smaller ratio of the disease burden. MacDonald et al. described a rapid rise in disease burden with advancing age, reporting that the highest disease burden was related to the age group of 60–64 years, while the disease burden share of people younger than 50 years old was low [34]. In a study by Haneef et al., 74% of the total YLLs were attributed to the age group of 70 years and older [35].

Even though the present study, based on real and reliable data on a large scale, drew a relatively realistic picture of the burden of COVID-19 in Iran, it faced some limitations. First, due to restricted access to the data, only hospital-admitted patients with assigned ICD-10 codes of COVID-19 were included in this study. So, the disease burden calculated did not include clinic outpatients, Cases for which the diagnostic codes of COVID-19 have not been reported and recorded for several reasons., and patients who did not refer to the hospital (due to receiving care at home or other health care facilities or dying). Second, the estimations provided only accounted for the direct impact of the acute form of the infectious disease, while the COVID-19 disease could lead to long-term and chronic complications in some individuals. Psychological health conditions and delayed diagnosis or treatment initiation (due to fear of referring to health centers, and occupied beds due to an overwhelming number of COVID-19 patients) are among some indirect health consequences of this disease [39]. Third, many of those recovering from this disease may develop long-term complications up to six months after hospital discharge (i.e., prolonged COVID-19) [40, 41]. For example, Ahmadi Gohari et al. showed by modeling all-cause mortality based on past trends that the ratio of reported COVID-19 deaths to total excess deaths ranged from 45.2–49.4% [42]. On the other hand, in this current study, the psychological burden caused by the anxiety related to taking care of a COVID-19 patient or losing a family member due to the disease is not considered. Fourth, as mentioned, the main burden of the estimated COVID-19 was YLLs, which was calculated based on the number of deaths and the age of the patients at the time of death. For this study, hospital data were used and the data of the patient’s condition at the time of discharge (recovery or death) were considered as the basis for identifying the deceased patients, and it cannot be stated with certainty that COVID-19 is the direct cause of death or the underlying cause. At the overall level of the data included in this study, COVID-19 can be a combination of direct and background causes of death. Taking into account all the mentioned limitations, it should be stated that despite the efforts made to present a picture of the burden of COVID-19 in Iran based on the hospital-based data of about half of the country’s population, the presented results have degrees of underestimation. But in general, it can be claimed that according to the available evidence, COVID-19 was one of the 5 major causes of disease burden in Iran in 2020 and 2021.

Conclusion

The COVID-19 disease inflicted a substantial burden on the health of Iranians. In our study, COVID-19 was found to be the fifth leading cause of disease burden in Iran during the study period, ranking after cardiovascular diseases, psychological disorders, neoplasms, and musculoskeletal disorders. Additionally, COVID-19 was the third major cause of death, following cardiovascular diseases and neoplasms. Based on our results, it is evident how the emergence of an infectious disease in a short time period can affect the composition of disease burden and mortality rates in the population. Therefore, the country’s health policies should be directed in such a way that, simultaneously with efforts to manage non-communicable diseases, coordinated programs to develop and strengthen health structures and processes to control communicable diseases are designed and implemented. In this way, a health system with high resilience against the shocks caused by outbreaks of emerging and re-emerging infectious diseases will be created, which will subsequently reduce possible damages such as mortality and morbidity caused by future outbreaks.