Introduction
Students are the intellectual and spiritual assets of each country. Promotion of their mental health is one of the important ways for the development of societies [1]. Medical students are more exposed to general and mental health problems compared to students in other fields due to their educational conditions such as internships and apprenticeships, mental and emotional pressure related to emergency situations, and many other job-related issues. Therefore, it is important to pay attention to the health of this group of students [2]. The coronavirus outbreak has caused high a lot of psychological and physical stress since December 2019. Therefore, health anxiety has become very common. Health anxiety is defined as being worry about having a possible disease when there are no symptoms or there are only minor symptoms [3, 4]. Mental health is needed for physical health; therefore, identifying factors that can improve mental health and reduce the risk of mental problems is a public health priority[5]. 
Metacognitive therapy has been used for treatment of a wide range of emotional disorders. Metacognition is impaired in patients with anxiety. Metacognitive therapy includes the modification of people’s beliefs and the strategies they use to control and regulate their thinking process. It focuses on changing how people respond to the beliefs instead of focusing on measuring the reality of their thoughts and beliefs. The present study aims to evaluate the effectiveness of metacognitive training in reducing health anxiety and improving general health of medical students.
Method
This a randomized clinical trial with a pre-test/post-test/follow-up design on medical students in Mashhad University of Medical Sciences (MUMS) in 2020-2021. The eligibility of students was evaluated by a semi-structured interview. Among those who were eligible to participate in the study, 56 were selected based on the inclusion and exclusion criteria. Subjects were randomly divided into intervention and control groups using the block randomization method. Metacognitive training was provided for the intervention group online at 8 sessions, twice a week, each for 60 minutes. The control group did not receive any intervention. Salkovskis and Warwick’s Short Health Anxiety Inventory (SHAI) and the general health questionnaire (GHQ-28) were used for collecting data. The questionnaires were completed by all participants before (pre-test), immediately after (post-test) and one month after (follow-up) the intervention. Repeated measures analysis of variance (ANOVA) was used to analyse the collected data.
Results
There were significant differences between health anxiety and general health scores at three different evaluation times. Metacognitive training significantly reduced health anxiety and increased general health of medical students (Table 1).


There was a significant difference in health anxiety and general health between three time points in the intervention group but no significant difference was observed in the control group (Table 2).


Discussion
The results of this study indicated that metacognitive training was effective in reducing health anxiety and increasing general health of medical students. The effects of training remained significant one month after intervention. A previous study showed that metacognitive training reduced the cognitive attention syndrome of female students [6]. Metacognitive training emphasizes on challenging the metacognitions that are responsible for controlling cognitive processes instead of challenging disturbing thoughts and dysfunctional beliefs. By avoiding complex perceptual analysis, the person can eliminate maladaptive thinking strategies and inflexible control of threats. The processing of worry and rumination and threat monitoring are prevented when people interact with their thoughts in a way that expand their metacognitive control and awareness. In other words, metacognitive approach teaching strategies to free themselves from the mechanisms that cause them to be locked in processing of worry, monitoring threat, and maladaptive self-control [6, 7]. Overall, the results of this study showed that metacognitive training leads to metacognitive awareness and ultimately reduces health anxiety and improves general health in medical students.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of MUMS (Code: IR.MUMS.MEDICAL.REC.1399.826) and was registered by the Iranian Registry of Clinical Trials (ID: IRCT20210424051070N1).

Funding
This study was extracted from a master thesis in clinical psychiatry. It was funded by the Mashhad University of Medical Sciences.

Authors contributions
Conceptualization, Writing-Review & Editing & Supervision: Negar Asgharipour and Nafise Nouri Siahdasht; Methodology, Funding Acquisition, Resources: Nafise Nouri Siahdasht; Investigation, Writing – Original Draft: Negar Asgharipour;

Conflicts of interest
The authors declare no conflict of interest.

Acknowledgements
The authors would like to thank the Mashhad University of Medical Sciences and the students participated in the study for their cooperation.