As members of a healthcare team, both physicians and nurses need to have high critical thinking skills, to increase the quality of care and improve treatment outcomes. Medical students' critical thinking abilities affect the professional decision-making process and may have direct and indirect effects on medical care quality. Therefore, strengthening critical thinking skills and identifying the influential and related factors are very important (
21). The results of the present study showed that the average score of critical thinking of approximately 88% of the medical students of this university was negative, and about 12% of them had an ambivalent inclination towards critical thinking. None of the 380 participants had a positive inclination towards critical thinking. In line with the results of the current study, the investigation of the critical thinking skills of medical students of an Iranian university stated that 98.6% of students had negative critical thinking, 1.4% had ambivalence thinking, and none of them had a definite tendency to use critical thinking skills (
19). In other studies, postgraduate students, especially doctoral students, were more inclined to critical thinking and self-esteem. It may indicate that thinking and reasoning processes and argumentative discussions are more emphasized in higher education than primary education (
22,
23). A study conducted in China showed that critical thinking was positive in medical and nursing students. Gender and age significantly impacted critical thinking abilities of students and critical thinking score was higher in medical students than nursing students (
24). Due to the differences in the number of medical students participating in different studies, more research is needed to compare the differences in critical thinking of different medical students in several regions.
In the present study, there was a direct and significant relationship between self-esteem with students' age and grade level, so that increasing age and grade level increased self-esteem scores. A study examining the relationship between age and self-esteem revealed that self-esteem is independent of age and that individuals have reported varying degrees of self-esteem as they age (
25). Critical thinking also had a significant and direct relationship with the grade level, but no significant relationship was observed between students' age and critical thinking scores. The reason can be attributed to the fact that because medical students are usually expected to gain more experience as they learn skills and continue their higher education, they seem logical. So, educational strategies during acquisition improve students' critical thinking skills. In general, similar results are obtained in our country, indicating a low level of critical thinking skills in medical students. A similar study examined the effect of parenting skills on the critical thinking of medical students and revealed that overprotective parents, emotional warmth and understanding, rejection, and over-interference were significant predictors of critical thinking in medical students (
26). A study in Iran examined the barriers of critical thinking in medical students' curriculum. The barriers included the resistance to critical society, intellectual tension, personality characteristics, lack of understanding of society’s need for criticism, the rule of traditional teaching patterns, lack of critical thinking skills, ineffective evaluation, and difficulty of critical thinking training (
12). A review study investigated the critical thinking skills of Asian and non-Asian nursing students and reported that Asian nursing students often had a lower score of critical thinking. In contrast, non-Asian nations had positive inclinations. These variations could be due to problems such as environmental issues, educational programs, and cultural differences (
27).
As expected, the mean scores of the two questionnaires of critical thinking and self-esteem in male and female students were not significantly different. Many studies have shown that critical thinking and self-esteem are not affected by gender (
28,
29). In the present inquiry, marital status, and place of residence (dormitory/other places) had no significant relationship with the critical thinking and self-esteem of medical students. Since self-esteem is a yield of social life and the social environment has a significant impact on the development of self-esteem, it can be considered as one of the components of motivation in educational contexts and the instruments that are correlated with its promotion should be emphasized (
15,
30).
There was a positive relationship between self-esteem and empathy. Self-esteem is one of the many factors that increase medical students' empathy. Age, academic pressure, attitude towards empathy, and future career also play a critical role in medical students' empathy. Enhancing medical students' self-esteem may be effective in improving medical students' empathy (
31).
It seems that self-esteem is one of the emotional dimensions of critical thinking that should be developed or strengthened. In this regard, faculty heads have a supportive role in developing the critical thinking skills of students in line with professional principles and foundations. In other words, independence and self-esteem are essential to developing critical thinking skills.
4.2. Conclusion
The current study showed that the mean scores of the inclination towards critical thinking in medical students of Ahvaz Jundishapur University of Medical Sciences were low, and none of them had a strong and positive inclination towards critical thinking, and the self-esteem scores of these students were relatively moderate. There was also a direct and significant relationship between critical thinking and the self-esteem of these students. Therefore, considering the positive effects of critical thinking on the education process, it is possible to promote and improve students' critical thinking by strengthening and raising self-esteem.