The current study aims to analyze the role of socioeconomic inequalities in health-related quality of life (QoL) among Iranian young people in the middle stage of adolescence. Our results show that the majority of participants had moderate levels of HRQL. The component of HRQL was different between female and male adolescents. In males, physical and autonomy components were more than in females, and school environment components had more effect on the HRQL of female adolescents. Moreover, there are positive correlations between socio-economic backgrounds and HRQL.
Many studies highlight the importance of socioeconomic inequality on the adolescent quality of life [5, 15, 17, 20]. In this regard, Hovsepian et al. study reported a positive association between socioeconomic status, school functioning, psychosocial function, and total score of HRQOL in both males, and female adolescents. Moreover, in their study, all components of HRQL except its social subscale were low in female adolescents,  while in our study, boy adolescents only have better scores in the physical and autonomy components of HRQL than girls.
The field of autonomy examines the adolescent’s freedom of choice, self-sufficiency, and independence, and considers the individual’s opportunities to create leisure and social activity . Upon entering this period of life, very profound biological, psychological and social changes occur in adolescents [1, 30]. The need for connection can create a conflict between the desires of the adolescent and their family, thereby putting his or her independence at risk . We observed a lower score of autonomy component in girls, which indicated more communication problems with parents. It seems that socio-cultural issues related to gender role, preference and more attention for the male sex, brain development, and different physiological changes following puberty play an important role in this difference.
The school environment was one of the main components of HRQL and has a greater impact on girls vs. boys. Similar to our results, Gaspar et al. show that female adolescents compared with males had a lower level of quality of life in all domains except school environments . In the same sense, another study revealed that adolescents with positive perceptions about their school climate had good self-rated health, school satisfaction, and quality of life .
Explaining the role of gender differences in health-related quality of life, Hyde states in his gender similarity hypothesis that males and females are similar in most psychological variables. Only in variables such as motor behavior, aggression, and some aspects of sexual activity, there are differences between the two sexes . Furthermore, physical changes during puberty in girls, such as the onset of menstruation and hormonal imbalances, decrease their psychological well-being compared to boys . We also observe those female adolescents compared with males had lower scores in the physical component. In this regard, Michel state that physical changes during puberty and conflict with exaggerated cultural norms of beauty make girls feel more unbalanced in their physical and mental well-being .
In this study, the relationship between income inequality and HRQL was evaluated using the Concentration Index, Ratio (R), and Modified Gini Index. The Gini index as one of the measures of health inequality examines the distribution of income, or in other words, the distribution of wealth among a population. The Gini coefficient is a number between zero and 1(0 denoting complete equality and 1 complete inequality). We observed a modified Gini index of more than 0.5 in females and males, which indicated a severe income gap. Assessing the relationship between these variables, and HRQL reveal that the quality of life in both sexes was affected by economic status. Our finding also reveals that socioeconomic variables that affect HRQL are different between male and female adolescents. Parental education was one of the main factors of female adolescents, and variables such as assets, and family income were effective on HRQL of both groups. These results are consistent with the findings of other studies in this field [5, 15, 17, 20]. In line with our study, Spurrier et al. reported a high level of HRQL among children in families of higher income, educated, as well as employed. Moreover, they reported living in an original family with both parents has a positive impact on HRQL . Also, in Barriuso-Lapresa, et al. study, there was a high quality of life, and mental health for children of mothers who had a university degree, and high social classes.  The results of one path analysis show the major effects of socioeconomic status (e.g., occupational prestige, household income, and parental education), social support on HRQL, and health behavior such as smoking, and toothbrush in adolescents . Another study demonstrated that gender, ethnicity, maternal education level, socio-economic status, and weight status are the main predictors of HRQL .
Our study was conducted during the second peak of the COVID-19 pandemic. Previous literature has documented the negative effects of this pandemic on both HRQL and family income [39,40,41,42]. Studies have shown that the COVID-19 outbreaks have caused the biggest shock to the world economy, so the implementation of government disease control policies, such as social exclusion and quarantine, has led to the temporary closure of businesses [39, 40]. Shrinking the global economy, increasing unemployment, poverty, income inequality, gender inequality, and widening the gap between different countries are just some effects of this pandemic [40, 41]. All of these factors can have adverse effects on a person’s quality of life. Tran et al. study show a negative effect of COVID-19 on household income and psychological health. And they state that having a chronic disease, female gender, and living in a family with 3–5 members were related to low-quality life . In another study, during the outbreak, socio-economic inequality was one of the main predictors of death in Brazilian children . Ravens-Sieberer et al. reported that children and adolescents experienced a high level of anxiety, mental health problems, and low HRQL after the COVID-19 pandemic, and socioeconomic status, migration background, and limited living space had the greatest impact . In Adıbelli et al. study, the score of the quality of life of children was good, but their parents reported that in their children gained weight, tendency to sleep and internet use increased during the pandemic .
Around the world, evidence shows that people with poorer socioeconomic status suffer from lower levels of health, and quality of life. Many of these inequalities, which are the result of socio-economic differences between various groups of people, are unfair and unjust. In any country, along with individual and family factors, the cultural and political factors governing that country, as well as, corruption, and economic interests play an important role in socio-economic inequalities . Therefore, it is not possible to plan to reduce inequalities without considering the role of governments.
One of the limitations of this study is that we didn’t assess the influence of other variables such as psychological wellbeing, parental relationship, and COVID-19-related issues, which can affect the HRQL of adolescents. It has been suggested that future studies consider them in the study design. However, this study was conducted during the QOVID-19 pandemic, but their information (such as disease status, the impact of COVID-19 on their socioeconomic status, quarantine, etc.) is not available. Also, the design of this study is cross-sectional, so the causal relationship between the variables is not predictable.