Socioeconomic inequality in tobacco expenditure in Iran: a cross-sectional analysis at national and subnational levels

Tobacco consumption remains as one of the significant public health problems in many countries around the world [1, 2]. It is one of the leading causes of deaths, accounting for more than seven million deaths globally each year [3]. The negative consequences of tobacco consumption extend beyond health to adverse affects on economic spending in households [4‐7]. There are economic impacts of tobacco use at the individual, households, and national levels [8]. For example, tobacco smoking accounts for about 15% of the total healthcare expenditure in developed countries [9]. In Iran, about 0.26% of gross domestic product (GDP) was attributed to the consumption of tobacco in 2014 [10].

Tobacco expenditure has direct and indirect effects of households’ budget [4‐6, 11]. The direct effect is defined as “crowding out” effect that decreases the share of expenditure on other necessary goods and services. Evidence from 40 low- and-middle income countries shows that spending on tobacco lowers households’ expenditure on education and healthcare [12]. For example, money spent on tobacco significantly reduced spending on healthcare, insurance, education etc. among the rural households in China [5]. The indirect effect could be an increase in healthcare spending of the household budget due to harmful effects of smoking, loss of income due to illness and productivity loss [8].

Generally, households’ share of the budget on purchasing tobacco-related good ranges from 1 and 10% in different countries [13]. However, tobacco expenditure as the proportion of the households’ budget (TEHB) affects poorer and vulnerable populations to a greater extent, both in developed and developing countries [12, 14]. Households with low socioeconomic status (SES) spent a higher proportion of their budgets on tobacco consumption compared to the households with better SES [4, 6, 15]. For instance, low-income Turkish households with smoker members spent about 8% of monthly budgets on smoking [4]. In New Zealand, if poorer households with at least a smoker become smoker-free, about 14% of the non-housing resources in those households could be available to buy other goods and services [14]. Evidence from China showed a negative association between having at least a smoker in the household and money available for basic needs [15]. In Bangladesh, low-income households with tobacco consumers spent less money on education, housing, transportation, communication, clothing, and energy compared to households with no consumers of tobacco [8]. In addition, tobacco expenditure had a negative impact on consumption of food grains among poorer households with smokers in India [16].

Despite increasing efforts to control the consumption of various tobacco products, the prevalence of smoking remains high in Iran (23.4% for men and 1.4% for women) [17]. There exist several Iranian studies on the costs of smoking, total death attributable to tobacco smoking, and the association between smoking and length of stay in hospital [10, 18, 19]. Few studies from Iran and other developing countries also investigated socioeconomic inequalities tobacco consumption [20‐24]. Understanding inequalities in tobacco use and TEHB would allow us to understand the socioeconomic pattern of this problem comprehensively. However, no study has yet examined inequality in TEHB by socioeconomic status in Iran. Using nationally representative data household data, this study aimed to fill this gap in the literature by quantifying the degree of socioeconomic inequality in TEHB and explaining the drivers of this inequality in Iran. We also conducted disaggregated analyses at rural/urban and regional levels based on development status. The results of this study would help designing and implementing policies to decrease the smoking prevalence and increase cessation of smoking. These policies could be helpful to lessen inequalities in tobacco consumption and its expenditures in Iran in the long run.

This study evaluated socioeconomic inequality in tobacco expenditure as the proportion of household budget (TEHB) as well as explained the main determinants of the observed inequality in Iran. The results show that about 20% of the households in Iran spent money from their budget on tobacco consumption, and these households spent about 5.2% of their monthly budget on buying tobacco-related products. This finding is in line with Turkish study, which found households spending about 8% of their monthly income on tobacco [4]. In Egypt, about 10% of household expenditures went to cigarettes or other forms of tobacco among lower-income households [31]. Our results also reveal that urban households in Iran allocated less of their budgets to spend on tobacco products compared to rural households. This finding corroborates a study in China where poorer households in urban and rural areas allocated 6.6 and 11.3% of their budgets to buy tobacco [33].

The most important finding of this study is that inequality in TEHB was pro-poor in Iran. In other words, the distribution of TEHB was more concentrated among the poorer households. Because of the prevalence of tobacco consumption was higher among poorer households and higher budget share of tobacco spending. The higher concentration of TEHB among the poorest could be explained by the fact that wealthier households have more money to purchase goods and services. Our results reflect the conclusion of the study from Hamadan city in Iran, where tobacco consumption was more prevalent among poorer adults [20]. The findings of this study are also consistent with the evidence from other developing countries. For example, tobacco use more prevalent among the poorest and poorer households were more affected by cigarette consumption compared to the wealthier households in Kenya and India [33]. In addition, wealth- and education-related inequalities in tobacco use were also found in 54 low-income countries and low-middle income countries [34]. In most of the countries, inequality of tobacco consumption was biased towards poorer and illiterate people.

This study also found that the extent of pro-poor inequality in TEHB was greater in urban areas and provinces with lower HDI. The reason is that TEHB significantly varied across the Iranian provinces. For example, TEHB among the households in Kohgiluyeh Buyer Ahmad was the lowest while it was the highest among the households from North Khorasan. Several factors could explain this variation in TEHB. For example, the development status of the province based on their HDI, proportion of households with tobacco expenditure more than zero (8.3% for north Khorasan vs 3.3% for that one) and sociocultural characteristics. The geographic location of the provinces could also be another factor behind this difference. For instance, North Khorasan is located the north-eastern region while Kohgiluyeh Buyer Ahmad is in the south-western region.

Findings from the decomposition analysis reveal that the wealth status of the households was the main contributor to the concentration of TEHB among the poorer households. This result is in line with findings from China, where economic status was found to be the main contributor to socioeconomic inequality tobacco consumption [24]. In Kenya, about 41% of the SES-related inequality in tobacco smoking was explained by the income of households [33]. Besides SES, education household heads and provincial development were the two most significant factors contributing to inequality in TEHB among the households with lower SES. Our empirical analysis suggests that if education status of head of the households and development status of provinces were equally distributed across socioeconomic groups, the SES-related inequality in TEHB in Iran would have been declined by 5.5 and 2.9%, respectively. This finding follows the results of the previous studies, which demonstrated a higher prevalence of smoking among low educated people [35].

The findings of our study have important implications for policymakers at national and sub-national levels in Iran. Although there are some studies on socioeconomic-related inequalities in the prevalence of tobacco consumption in Iran [20, 32, 36], this study presented the first empirical evidence on socioeconomic inequality in tobacco expenditure as the share of the households’ budget using nationally representative n data. Since tobacco expenditure was more concentrated among the poorest households, necessary policy interventions are needed to reduce tobacco use among them. Following WHO Framework Convention on Tobacco Control (FCTC) [37], one of the policies to reduce tobacco consumption could be increasing the price of tobacco products by imposing higher taxes on tobacco products mainly consumed by the poorest in Iran. Previous studies showed that low-income people change their tobacco consumption behaviour more due to price change [38, 39]. Therefore, increasing taxes on tobacco products would encourage poorer people to reduce or quit tobacco use and to spend less of their income on tobacco. This policy would help to protect socioeconomically disadvantage households from the financial burden of tobacco consumption. Besides raising taxes, another policy could be the banning of tobacco advertising in mass media and tobacco use in the public setting (https://​www.​who.​int/​news-room/​detail/​10-01-2017-tobacco-control-can-save-billions-of-dollars-and-millions-of-lives). In general, policies should be implemented to reduce the financial burden of tobacco consumption among the poorer households residing in rural areas and less developed provinces of Iran.

There are a few limitations that should be considered when interpreting the findings of this study. First, our findings are based on data from a cross-sectional survey, which limits the causal interpretation of the relationship between tobacco expenditure and its determinants. Second, self-reported data used in this study might underestimate or overestimate tobacco expenditures for the households. Besides, there could be a recall bias problem in our study. For example, poorer and low educated household heads might forget to report information related to tobacco expenditure. Third, other important determinants (e.g. occupation of the respondents) were not included in the analysis due to data limitation. The omission of such factors might have limited the decomposition of SES-related inequality in TEHB. Finally, the IHIES collected information at the household level. Therefore, we could not examine socioeconomic inequalities in tobacco expenditure at the individual level. Despite these limitations, our study contributed to the broader literature on SES-related inequalities in tobacco consumption in developing countries. Future studies should consider addressing above-mentioned limitations to offer robust empirical evidence in this area of research.

To the best of our knowledge, our study is first of its kind to examine socioeconomic inequality in TEHB at national and subnational levels in Iran. We found evidence of SES-related inequality in cigarette expenditure in Iran, which was more concentrated among socioeconomically disadvantaged households. The wealth status of the households was the main contributing factor to the concentration of TEHB among the poorer households. The present study offers useful information for the policymakers to design and implement necessary interventions to reduce tobacco consumption among socioeconomically disadvantaged households. Further studies could consider examining the crowding-out effect of cigarette spending on the consumption of other goods in Iran.