Social disparities and inequalities in healthcare access and expenditures among Iranians exposed to sulfur mustard: a national study using spatio-temporal analysis

Exposure to chemical warfare agents results in serious acute and chronic health consequences. Sulfur Mustard (SM) is a cytotoxic and alkylating compound that has been repeatedly used as a chemical weapon in numerous battles. Hundreds of thousands of people have been exposed to SM since the time the German army unleashed it on a large scale during World War I in 1917 [1]. During the Iraq-Iran conflict in 1980s, Iraq often used SM as a weapon to bombard Iranian border towns and made over 400,000 unmasked residents vulnerable to SM [2‐4]. Meanwhile, SM exposure is strongly linked to the emergence of serious complications and injuries in eyes [5], lung [6, 7], and skin [8].

Given that over half of the world's population still does not have complete access to basic health care, it is critical to recognize that these services must be provided to achieve Universal Health Coverage (UHC) [9]. Iranian exposed individuals still seek healthcare services in order to preserve or restore good health, as well as to prevent and treat diseases caused by SM. Healthcare Utilization (HCU) is a fine measure of the number of healthcare services individuals consume [10, 11]. Furthermore, target 3.8 of the Sustainable Development Goals (SDG) is to provide health care to all people regardless of their ability to pay and HCU is a key component of this aim [12].

Significant changes were made to the healthcare system in Iran following the Islamic Revolution of 1979. These changes included incorporating provincial health organizations into medical sciences universities and creating a primary health care network. As a result, from 2000 to 2019, Iran increased its Domestic general government health expenditure (GGHE-D) per capita from 188.23 to 429.78 United States Dollar (USD) [13] while 7% of Iran's GDP goes for healthcare [14]. These changes were made to improve health equity and provide essential healthcare services [15]. Inequality in the usage of healthcare services in Iran has been investigated elsewhere [16, 17]. However, the effectiveness of these programs in promoting the HCU of SM-exposed people and declining inequalities remains unknown, even though these programs expand access to basic healthcare services.

HCU of people involved in military conflicts has been investigated in Asia [18‐23], America [24‐29], and Europe [30‐33]. Aside from a few descriptive studies, to our knowledge, there has been no comprehensive study on tracking social inequalities in different types of HCU among SM-exposed citizens in any country. This study aims to 1) provide a comprehensive description of healthcare utilization of SM-exposed survivors in Iran, and its changes from 2018 to 2021; 2); measure the subnational concentration indices in terms of successful HCU to identify high-risk areas; and 3) apply an association analysis of HCU using the personal characteristics of exposed people along with the environment determinants to estimate the adjusted effects controlled for confounding variables.

Although nursing services are the cheapest among healthcare services, only about 10% of HCU received by SM-exposed people are under the nursing category. This might be due to a large amount of informal nursing care. The informal caregivers of SM survivors endure a disproportionally large share of the responsibility for the survivors' care. They often become the primary healthcare providers for their own family members, despite having no formal medical training and little access to financial, emotional, or social support themselves. Caretakers may need to work evenings, weekends, and holidays to meet the 24-h care needs of SM survivors. Aware of the strain imposed on informal caregivers, providers in the health care system should develop solutions to back them up. Nursing professionals should assist in developing interdisciplinary care for disabled SM survivors. The extra guidance might come in the form of supplementary care instructions. Both victims and caregivers should schedule regular check-ups with general practitioners and nurses.

The average cost for receiving one healthcare service was highest in Tehran (the capital of Iran) and surrounding provinces (Fig. 2). It can be justified by the fact that typically high-price services are mostly provided in high-quality medical centers and such centers are more accessible in mega-cities and wealthier divisions. We also assessed this using the concentration index and found a pro-rich inequality in HCU of SM-exposed veterans, which is in line with a number of studies in different countries [38‐41].

Unlike LOS and BOR, we found greater HCU in places with more patients relative to their hospital beds, while inhabitants in areas with fewer patients pay the majority of the expenses. The cause might be connected to the Iranian medical insurance policies. Based on UHC, Iran's government launched the Health Sector Evolution Plan (HSEP) to prioritize emergency treatment. Individuals in rural Iran who are only covered by a minimal insurance plan will have the most out-of-pocket expenditures. Besides, high-level hospitals are associated with higher levels of healthcare quality; therefore, patients are more likely to seek treatment in high-level hospitals if they have the option. Consequently, those covered by supplemental insurance firms prefer to seek treatment in high-level hospitals where they believe they will receive the most benefit, resulting in increased medical expenditures and a major pro-rich inequality [42].

The findings also indicate considerable disparities in HCU according to YOS quantiles, implying that low-educated zones have greater HCU. Other researches indicated that less-educated persons use more health resources and have lower health conditions than citizens with higher educational degrees [43, 44]. This might be attributed to the extra healthcare requirements of people with such characteristics that have led to an excess HCU. Higher-educated survivors are better able to manage their own health, adopt healthier habits, and make effective use of healthcare resources because of their increased awareness of these topics and their ability to apply this information. Some diseases, including diabetes and heart disease, may be avoided or kept under control with the support of a healthy lifestyle. Also, mild to moderate SM complications in vital organs may be avoided or mitigated from becoming severe by prompt diagnosis and treatment [45, 46].

The CInd representing HCU equity based on residing area urbanization was negative, indicating that SM-exposed survivors in less urbanized provinces used more care than inhabitants in more urbanized provinces. This gap might be explained by a decrease in low-cost services (e.g., family practitioners) after the implementation of HSEP, which has resulted in excess HCU by rural inhabitants. Although the costs of family doctor appointments in rural Iran have decreased generally, some low-income people still cannot afford them. Most people with basic insurance seek outpatient treatment in village clinics. This might also justify the positive CInd value we estimated for health expenditures based on the urbanization index.

The primary goal of UHC programs is to remove financial obstacles to accessing healthcare for everybody. HSEP was Iran's UHC program established in May 2014 to guarantee citizens access to high-quality medical treatment [47]. In this program, various measures were taken to expand access to basic health insurance, improve the quality of care provided by hospitals, lower patients' out-of-pocket costs for hospital stays, enhance primary care, and finally revise tariffs for healthcare services to more reasonable rates. Our results speak to the fact that the basic insurance coverage has very little to do with the healthcare costs of SM-exposed people, implying that HSEP's goals are not sufficiently fulfilled for these people. A major obstacle to the effectiveness of the goals might be the healthcare stakeholders' worries.

Our results also show that the potential healthcare needs of SM-exposed people (especially severely injured ones) can lead to regressive payments in the future. On the other side, the history of UHC programs in Iran has shown that attempts to increase access to health insurance have the potential to undermine financial justice by regressively paying for healthcare. People's contributions to new initiatives should grow progressively in line with their income and wealth to provide stable funding and improve equity. In other words, future programs should adjust the healthcare financing to reduce the inequity according to certain neglected vulnerable groups. We believe that the ideal funding mechanism would be a targeted progressive tax based on wealth status. However, this is unrealistic in the near term due to the catastrophic economic level of the general population in recent years [48]. A gradual rise in the progressiveness of finance must be implemented instead.

Our study has a few potential limitations that should be minded when interpreting the results. First, since we did not measure the individual-level socioeconomic determinants of the survivors, it is hard to judge whether the caregivers' personal socioeconomic status is directly associated with HCU. Second, in this study, we focused on the costs paid by insurance companies for caregiving; however, some evidence suggests that indirect expenditures (e.g., for traveling to well-equipped health centers) may also induce a higher burden on survivors and their families. Third, we didn't check whether the SM survivors had formal training in caring. It is becoming more evident that years of education is a helpful index for examining the provincial-level connection with HCU-related factors, yet despite this, it is typically overlooked and not included in policy decisions. More research must be conducted to learn what survivors know about the healthcare services and facilities they need. Moreover, we could not access a group of determinants assumed to aggravate the complications of SM-exposed people and we plan to examine their association in future studies.

In general, this study is the first to extract the socioeconomic inequalities among SM-exposed survivors on both individual and subnational scales. Poor, less educated and least urbanized areas significantly worse in receiving HCU than prospering regions. Taken together, HCU of SM-exposed survivors is spatially clustered shows significant pro-rich inequity based on most determinants. The findings of the study can role as a guideline for health policymakers in Iran to promote their UHC plans and allocate resources in a more appropriate manner to finally reduce the inequity gaps.