Anxiety disorders, which are characterized primarily by excessive fear and worry, are the most common set of psychiatric disorders and are known to have considerable individual and societal costs [1]. According to the DSM-5, anxiety disorders include generalized anxiety disorder, panic disorder, social anxiety disorder, separation anxiety disorder, selective mutism, and specific phobias [2]. If left untreated, anxiety disorders may become chronic and be associated with cognitive impairment, depression, disability, and poor quality of life [3]. In South Korea, the estimated lifetime prevalence of anxiety disorders was 9.3% and the annual prevalence rate in 2021 was 3.1%. While the highest prevalence occurred in those between 18 and 29 years of age, anxiety disorders were more common in females (4.7%) than in males (1.6%) [4].

Students can experience emotional and academic challenges when they enroll in university programs because they must adapt to a new learning environment, manage tuition fees, assume self-responsibility, develop a career, and attain independence [5]. Although the developmental period of emerging adulthood may be regarded as a period of personal growth, it can also be marked by increased vulnerability and distress. In comparison to other adult age groups, self-reported mental health issues are most prevalent among young adults between the ages of 18 and 29 [6, 7]. Thus, emerging adulthood may present significant mental health risks. Adams et al. [6] found that mental health issues that affect university students include depression, anxiety, and substance abuse. Furthermore, it has become increasingly apparent that the outbreak of the pandemic has posed a threat to university students’ mental health. Because of the mandatory physical distancing measures associated with the pandemic, many students have been confronted with additional challenges, including campus closures and online and distance learning, which have led to a sense of uncertainty related to academic success as well as increasing fear about the uncertainty of their overall learning [8].

The COVID-19 pandemic made anxiety among university students a growing global public concern. Some studies conducted in Korea have also examined the impact of the pandemic on the psychological states of university students. Jung et al. [9] revealed that 20% of a sample of 209 university students experienced severe stress, anxiety, and depression due to COVID-19. Chen et al. [10] found that Korean students decreased their daily activities, visited fewer places, suffered more worry, and reported low levels of happiness. The anxieties experienced by university students are characteristically related to academic failure, criticism, and physical appearance [11]. Therefore, they could differ from the types of anxiety sensed by other general populations including adolescents and older adults, or by vulnerable populations such as clinical patients. Thus, it is imperative to devise accurate screening tools for anxiety disorders to assess the anxieties experienced by university students. These screening instruments would facilitate early intervention in mental health settings on campuses. However, scant screening tools designed to detect the presence and severity of anxiety symptoms exist in Korea owing to the paucity of psychometric validation research [12].

The 14-item Hamilton Anxiety Rating Scale (HAM-A) was developed by Hamilton in 1959 to detect symptoms of anxiety in clinical populations [13]. HAM-A has since been translated into several languages in different cultures. Available studies have attested to the instrument’s robust psychometric properties, including excellent reliability and construct validity in multicultural populations [14-16], psychiatric patients [17, 18] and adolescents [19]. Although the HAM-A is beneficial in determining anxiety in clinical and nonclinical samples, there is no clear consensus about the instrument’s factor structure. While some studies have demonstrated that data favored an optimal two-factor structure [14, 16, 19], others have recommended an optimal three-factor structure [17, 18]. Somatic anxiety symptoms constitute a separate factor in two- and three-factor structures. However, anxiety and depressive symptoms have either represented a unitary factor in two-factor models or denoted as distinctive factors in three-factor models [18].

These differences, however, have partially been due to the use of specific subgroups of individuals that may limit generalizability. Given the controversial conclusions of international studies in relation to the dimensionality of the HAM-A, its factor structure warrants further examination. Moreover, despite the relatively high prevalence of anxiety disorders among university students, this instrument has not been employed among Korean university students. Furthermore, no study to date has examined the factor structure among Korean populations. Accordingly, the purpose of this study was to provide a comprehensive validation of the HAM-A for Koreans. Specifically, the objectives of the study were: (1) to explore the factor structure of the Korean version of HAM-A by employing confirmatory factor analysis (CFA) and (2) to examine the reliability of the Korean version of the HAM-A among Korean university students.

This study examined the construct validity of the HAM-A 14 by exploring the instrument’s factor structure with a sample of Korean university students. The HAM-A exhibited satisfactory internal consistency and construct validity, thus revealing its utility for measuring anxiety in this population. This is the first study in which factor analytic findings for the HAM-A have been provided in a nonclinical sample in Korea. The Korean university students who completed the survey belonged to the frequently studied group who suffer myriad stressors, including university transition, academic demands independence/autonomy, intimate relationships, and responsibility that can lead to anxiety [25]. It is imperative that more effort needs to be expended to detect anxiety and implement treatment among university students timeously because they are particularly at risk for psychiatric disorders in comparison to other adult age groups [6, 7].

The study results on the scale’s dimensionality suggest a two-factor structure for the HAM-A as evidenced by CFA. These findings concur with previous findings that the HAM-A is best understood as a multidimensional factor structure [14, 16-19], representing the psychic/ psychological and somatic dimensions of anxiety (i.e., the two-factor model). Moreover, the results of exploring the HAM-A factor structure were similar to those of studies that have included general adult populations [18, 20]. Although this study’s findings challenge Leentjens et al.’s assertion that a unidimensional or one-factor model was a better fit than two- or three-factor models, these contra- dictory findings may be attributed to the fact that the student sample in this study may have differed significantly from clinical samples of Parkinson’s disease in Leentjens et al. [17].

Classifying anxiety into the two separate factors of the psychic/psychological and somatic moderately correlated constructs may provide a useful model to investigate the impact of interventions for anxiety such as psycho- pharmacological treatment [16]. Although the medication could have an effect on the psychological dimension of anxiety, it may not affect the cognitive dimension of anxiety. An exploration of how different therapeutic dimensions of anxiety may facilitate a comprehensive understanding of effective treatment, identify predictors of relapse, enhance the identification of individuals at increased risk, and inform new approaches to prevent it or discontinue treatment [16].

Regarding estimates of internal consistency for the HAM-A, the scale scores were in the good to excellent range. In particular, the high estimates of internal consistency reliability for the two scales and total scores in both community and clinical samples have ranged between good and excellent and concur with those reported for the HAM-A [14-18]. These findings suggest that the HAM-A exhibits good internal consistency across different populations and languages. Simultaneously, with the exception of Cronbach’s alpha of individual items, the coefficient values were lower than the total coefficient value. This indicates that removing any item may decrease the overall credibility value of the scale. Thus, one may deduce that each item of the HAM-A scale is essential and of equal importance to assess the symptoms of anxiety in Korean university students.

Although the prevalence of anxiety was relatively higher in this study than that reported in nonclinical samples [26, 27], it was lower than that of a clinical sample of patients [28, 29]. Because our online survey was conducted during the COVID-19 pandemic in Korea when the campus was closed and social distancing restrictions were still in place, this is expected. The stresses and restrictions associated with the pandemic may have caused many students to suffer heightened levels of anxiety. However, these findings should be cautiously interpreted with due consideration to the prevalence of COVID-19 in Korea when the data for the study were collected.

This study has several limitations. First, as our sample consisted of undergraduate students, it is not clear whether the pattern of findings and the factorial structure can be generalized across populations of different ages and backgrounds. Also, it is uncertain whether our findings can be generalizable over time even after the pandemic. Although our study supported the two-factor model of the HAM-A as a valid and reliable measure for young adults, the competing two-factor models may be more feasible for other populations. Nevertheless, future research must replicate the study across diverse samples. Second, a cross-sectional design was employed in this study and thus, a causal relationship could not be determined. Prospective follow-up studies may help to address the issues of causality. Third, because the data had to be collected by means of an online survey due to COVID-19, those without internet access may have been unable to participate [8]. However, as the target population was university students, this limitation possibly only influenced the results slightly.

The factor structure of the Korean version of the HAM-A was explored so as to provide more empirical data for the development of the HAM-A and the advancement of mental health measurement. The findings support Hamilton’s original theoretical model that revealed two distinct categories of psychic/psychological and somatic symptoms. The items of the Korean version of HAM-A were also found to have high internal consistency and be psychometrically sound. The availability of the Korean version of the HAM-A for clinical and campus outreach screening can enhance the identification of students who need assistance.