Article Text

Original research
Relationship between self-psychological adjustment and post-traumatic growth in patients with lung cancer undergoing chemotherapy: a cross-sectional study
  1. Na Liu1,
  2. Lei Zhang2,
  3. Yaxin Liu1,
  4. Xuemei Ding1,
  5. Qing Li3,
  6. Gao Lixia4,
  7. Xiaoli Zhang1
  1. 1 Binzhou Medical University, Yantai, China
  2. 2 Yan Tai Affiliated Hospital of Bin Zhou Medical University(The Second School clinical Medicine), Yantai, China
  3. 3 The Yantai Affiliated Hospital of Binzhou Medical University, Yantai, China
  4. 4 The Affiliated Hospital of Binzhou Medical University, Binzhou, China
  1. Correspondence to Professor Xiaoli Zhang; zxl7901{at}163.com

Abstract

Objectives This study aimed to determine the potential profiles of self-psychological adjustment in patients with lung cancer undergoing chemotherapy, including sense of coherence (SOC) and positive cognitive emotion regulation (PCER). The relationship between these profiles with post-traumatic growth (PTG) and the relevant factors of self-psychological adjustment in different profiles was analysed.

Design Cross-sectional study.

Setting Patients with lung cancer undergoing chemotherapy in China.

Participants A total of 330 patients with lung cancer undergoing chemotherapy were recruited out of which 321 completed the questionnaires effectively.

Methods Latent profile analysis was used to identify self-psychological adjustment classes based on the two subscales of the Sense of Coherence Scale and Cognitive Emotion Regulation Questionnaire. One-way analysis of variance and multinomial logistic regression were performed to examine the subgroup association with characteristics and PTG.

Results Three latent profiles of self-psychological adjustment were identified: low level (54.5%), high SOC-low PCER (15.6%) and high PCER (29.9%). The results of univariate analysis showed a significant difference in PTG scores among different self-psychological adjustment subgroups (F=11.55, p<0.001). Patients in the high-PCER group were more likely living in urban areas (OR=2.41, 95% CI 1.17 to 4.97, p=0.02), and time since cancer diagnosis was ≥6 months and <1 year (OR=3.54, 95% CI 1.3 to 9.64, p<0.001).

Conclusion This study revealed that most patients with lung cancer undergoing chemotherapy belonged to the low-level group. Three profiles are associated with PTG. There were differences in characteristics between patients treated with chemotherapy for lung cancer in the high-PCER and low-PCER groups. Thus, these profiles provide useful information for developing targeted individualised interventions based on demographic characteristics that would assist PTG in patients with lung cancer undergoing chemotherapy.

  • aged
  • chronic disease
  • lung diseases
  • mental health
  • stress, psychological

Data availability statement

Data are available upon reasonable request.

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STRENGTHS AND LIMITATIONS OF THIS STUDY

  • Latent profile analysis is a person-centred technique and appropriate for explaining the clustering of self-psychological adjustment.

  • Measuring self-psychological adjustment using sense of coherence and positive cognitive emotion regulation makes the data more reliable and the measurements more objective.

  • All participants were only from the Affiliated Hospital of Binzhou Medical University and Yantai Affiliated Hospital of Binzhou Medical University in Shandong, China, which limit the generalisation of the results.

  • Due to the cross-sectional nature of the survey data, we were unable to establish causal relationships between self-psychological adjustment and predictors, including post-traumatic growth.

  • The data of this study were self-reported and not contrasted with any studies.

Introduction

In 2020, the mortality rate due to lung cancer was the highest worldwide at 23%.1 Meanwhile, 710 000 deaths have been reported among patients with lung cancer in China.2 Chemotherapy is the mainstay of treatment for patients with advanced non-small cell lung cancer and small cell lung cancer and a common adjuvant treatment for postoperative patients with lung cancer. Nevertheless, chemotherapy itself is often accompanied by several side effects, such as liver toxicity, nephrotoxicity and immunosuppression.3 4 Thus, patients are exposed to the dual challenges of lung cancer diagnosis and chemotherapy.5 According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, the diagnosis of lung cancer and chemotherapy can be described as a Class A traumatic event.6 Both chemotherapy and diagnosis of lung cancer are traumatic experiences for patients. Previous studies have shown that trauma can result in post-traumatic stress disorder, psychological distress and anxiety.7–9 The incidence of depression and anxiety in patients with lung cancer is approximately 40%.10 However, trauma can also incur post-traumatic growth (PTG), which includes new possibilities and relating to others.11 With the development of psycho-oncology, researchers have observed that psychosocial factors played an important role in the restoration of patients’ health.12 Thus, PTG, as a psychosocial factor, is likely to improve health literacy and rebuild health behaviours in patients with cancer.13 The incidence of PTG in patients with cancer ranges from 60% to 95%.14 Many patients with lung cancer experience PTG, but PTG scores are low; therefore, PTG is gaining attention.15–17 Therefore, PTG in patients with lung cancer undergoing chemotherapy is gaining attention.

According to the PTG theory, self-psychological adjustment can facilitate PTG by changing an individual’s cognitive abilities and mobilising internal resources.18 Self-psychological adjustment refers to the process in which individuals adopt a series of positive psychological behaviours and skills to help themselves relieve psychological pressure, improve emotional state, improve self-confidence and efficacy, to better adapt to life and work. Self-psychological adjustment includes many factors, such as a sense of coherence (SOC) and positive cognitive emotion regulation (PCER).19 SOC refers to an individual’s ability to mobilise internal psychological resources to better adapt to the environment.20 PCER is an individual’s ability to manage trauma using positive and active cognitive emotion regulation styles. Previous studies have confirmed that both SOC and PCER positively correlate with PTG levels in patients with cancer21 22; however, their mechanism of action differs. SOC affects PTG by adjusting psychological state and establishing positive attitudes.23 PCER achieves PTG through changes in thinking patterns about trauma and proactive and conscious management of negative emotions.24 Thus, SOC and PCER may have different effects on the PTG levels in patients undergoing chemotherapy for lung cancer. However, research on this topic is lacking. Most current studies do not consider the heterogeneity of patients with cancer and treat them as a homogeneous group. SOC-PCER encompasses multiple features, such as comprehensibility, manageability, acceptance and positive refocusing.15 25 Thus, patients with lung cancer undergoing chemotherapy may have different combinations of features in case of trauma, and the impact on PTG may also vary. Therefore, we identified different potential profiles of SOC-PCER in patients undergoing chemotherapy for lung cancer using latent profile analysis (LPA). In addition, this study explored the differences in PTG between profiles.

LPA is an effective human-centred approach for identifying optimal contours by observing a common distribution of features.26 LPA provides the distribution of characteristics for each profile and the probability that an individual is in a different profile, which helps maximise between-group heterogeneity and within-group homogeneity.27 Thus, LPA can discern the pattern of SOC-PCER responses in patients undergoing chemotherapy for lung cancer with greater accuracy than k-nearest neighbours and better distinguish heterogeneity between individuals. The present study also dissected the characteristics of each profile, which will help clinicians customise preventive measures for relevant groups based on demographic characteristics.

The ecosystem theory model supports the idea that self-psychological adjustment is influenced by individual, family and social factors.28–30 Clinical characteristics, including clinical stage, Eastern Cooperative Oncology Group (ECOG) status.31 Demographic characteristics are important components of personal factors, such as age, gender and educational level.32 33 Thus, clinical and demographic characteristics may influence self-psychological adjustment (SOC-PCER). Several empirical studies have confirmed that SOC and PCER scores in patients with cancer differ with time since cancer diagnosis, therapy method, history of hypertension, place of residence and educational level.34–36 Clinical factors pose different challenges to patients, which may result in differences in SOC and PCER scores.35 37 Characteristics can affect the SOC and PCER by providing different resources and support. Therefore, this study analysed the different characteristics of each profile in patients with lung cancer who were undergoing chemotherapy.

The purpose of this study was to understand the profiles of self-psychological adjustment (SOC-PCER) in patients with lung cancer undergoing chemotherapy through LPA and to explore the link between PTG and these profiles. Additionally, this study examined the link between the characteristics and profiles. This study is important to facilitate the clinical development of more precise psychological interventions to improve PTG in patients with lung cancer undergoing chemotherapy. This study proposed the following three hypotheses based on the PTG and ecosystem theories:

Hypothesis 1: There are different profiles for self-psychological adjustment (SOC-PCER) in patients with lung cancer undergoing chemotherapy.

Hypothesis 2: PTG is significantly different between the identified self-psychological adjustment (SOC-PCER) profiles.

Hypothesis 3: Self-psychological adjustment (SOC-PCER) profiles are associated with specific characteristics.

Methods

Study design and participants

Using non-probability convenience methods, patients with lung cancer undergoing chemotherapy were simultaneously recruited from two tertiary general hospitals in Shandong Province, China from April to September 2022. The inclusion criteria were as follows: diagnosis of primary lung cancer based on histopathology or cytology; ages 18–75 years; having clear consciousness, with normal communication ability, stage II–IV cancer; willingness to participate in the study; and being treated with chemotherapy. The exclusion criteria were presence of other tumours or psychiatric disorders. Based on the number of items on a 10-fold scale and a non-response rate of 20%, at least 336 participants were required.38 The estimation formula for cross-sectional sample size was as follows: taking μ=1.96, σ=68.7839 and δ as 0.1–0.2 times σ, the calculated sample size was 96–384. The study recruited 330 patients, nine of whom were excluded. Finally, 321 patients were selected as research participants (97.27% response rate).

Patient and public involvement

Neither patients nor the public were involved in the design, conduct, reporting or dissemination plans associated with this research.

Measures

Characteristics

The self-reported demographic characteristics included gender, occupational status, residence, medical insurance, smoking status, caregivers and educational level. Clinical characteristics were collected from medical records, including the time since cancer diagnosis, histological type, clinical stage, therapy method, cycles of chemotherapy completed, comorbidities and ECOG performance status.

Self-psychological adjustment

The Chinese version of the Sense of Coherence Scale was used to assess the SOC. It was designed by Antonovsky et al 40 and revised into Chinese by Bao Leiping et al 41. Permission from the copyright holder was required to use the questionnaire. It has good reliability and validity in Chinese patients with cancer. This instrument contains three subscales, including comprehensibility (5 items), manageability (5 items) and meaningfulness (3 items). 13 items were rated with 7-point Likert scale ranging from 1 (never) to 7 (often). The total score ranged from 7 to 91, with higher scores indicating higher SOC. The Cronbach’s alpha was 0.831 in this study.

PCER was assessed using the Positive Cognitive Emotion Scale of the Cognitive Emotion Regulation Questionnaire, which required permission from the copyright holder before use. It was designed by Garnifski42 and translated into Chinese by Zhaoxiong.25 This 20-item scale consists of five dimensions: acceptance (4 items), positive refocusing (4 items), refocusing on planning (4 items), positive reappraisal (4 items) and being placed in perspective (4 items). Each item was rated from 1 (never) to 5 (always). The total score ranged from 20 to 100, with higher scores representing a greater likelihood of patients using PCER. In this study, Cronbach’s alpha was 0.802.

PTG inventory

The Chinese version of the 21-item Post-Traumatic Growth Inventory was used to assess PTG. This tool was designed and compiled by Tedeschi.43 The Chinese version of this scale has been widely used and has been confirmed to be reliable and valid. Permission was required from the copyright holder to use the questionnaire. The scale was divided into spiritual change (6 items), personal strength (3 items), new possibilities (4 items), relationships with others (3 items) and appreciation of life (4 items). Each item is rated on a 6-point Likert scale ranging from 0 (not at all) to 5 (very much). The total score ranged from 0 to 105. Higher scores indicate higher PTG. The Cronbach’s alpha for this scale was 0.760 in this study.

Data analysis

All data were analysed using Mplus V.8.0 (Muthén & Muthén, Los Angeles, California) and SPSS V.26.0 (IBM). First, LPA was used to determine subgroups of patients with self-psychological adjustment, and the SOC-PCER was used as an evaluation index. LPA was conducted using Mplus V.8.0. Data for self-psychological adjustment entered the LPA from the first category, and then additional categories were added. Second, the Akaike information criterion (AIC), Bayesian information criterion (BIC), sample size-adjusted BIC (aBIC), entropy, Lo-Mendell-Rubin (LMR) test and bootstrap likelihood ratio test (BLRT) were used to select the best LPA model.44 Lower AIC, BIC and aBIC indicated a better LPA model. Entropy above 0.8 implies accurate classification. A higher entropy indicates a more accurate classification.45 LMR and BLRT were used to compare the k model with the k-1 model, and the p value significance indicated that the k model was better.46 However, in practice, these indicators are not always consistent. Thus, the selection of the optimal model should be based on the practical significance of the indicators, absolute frequency for the smallest class, probability of the smallest class and the principle of minimalisation.

SPSS (V.26.0) was used to analyse the relationship between the latent profiles, PTG and characteristics. First, histograms and Q-Q plots were used to explore the distribution of PTG, which showed approximate normality. Second, one-way analysis of variance was used to analyse the differences in PTG between profiles. Third, multivariate logistic regression was used to analyse the relationship between the characteristics and profiles. P<0.05 was considered statistically significant.

Results

Latent profiles of self-psychological adjustment

Table 1 depicts the model for profiles 1–5. The lowest values of AIC, BIC and aBIC were observed in profile 5. The entropy values of all profiles were above 0.8. However, the LMR and BLRT p values were significant in profile 3. Finally, based on the principle of minimisation, the three-profile model was selected as the best model. The responses of the three profiles for all subscales of the SOC and PCER are shown in table 2 and figure 1.

Figure 1

Line graph comparing profiles for sense of coherence-positive cognitive emotion regulation (SOC-PCER) (n=321).

Table 1

Fit indices for profile structure of sense of coherence-positive cognitive emotion regulation model (n=321)

Table 2

Analysis of variance for each scale between latent profiles (n=321)

Profile 1 was defined as the low overall score group (n=175, 54.5%) and had the lowest scores for the SOC and PCER dimensions (p<0.001).

Profile 2 was defined as the high-SOC and low-PCER group (n=50, 15.6%). It had the highest scores on all the SOC subscales (p<0.001) but the PCER scores were moderate. The scores for almost all subscales of the PCER were similar to those of profile 1 and were still at a low level (figure 1).

Profile 3 was defined as the high-PCER group (n=96; 29.9%), which had moderate levels of SOC and the highest levels of PCER.

Differences in PTG

As listed in table 3, significant differences among latent profiles were found in appreciation of life (F=9.64, p<0.001), personal strength (F=8.85, p<0.001), new possibilities (F=4.34, p=0.014), spiritual changes (F=3.81, p=0.023) and PTG total score (F=3.81, p<0.001). Patients in the low overall score group had the lowest total PTG score (M=62.97, SD=6.98).

Table 3

Mean differences across SOC-PCER profiles of patients with lung cancer in terms of post-traumatic growth (n=321)

Differences in characteristics

As shown in table 4 and online supplemental file 1, there were significant differences among the three profiles with respect to time since cancer diagnosis (χ2=14.746, p=0.022).

Supplemental material

Table 4

Descriptive statistics for the full sample and each latent profile (n=321)

As shown in table 5 and online supplemental file 1, patients with lung cancer undergoing chemotherapy in the high-PCER group mostly lived in urban areas (OR=2.41, 95% CI 1.17 to 4.97, p=0.02). Furthermore, their time since cancer diagnosis was more likely ≥6 months and <1 year (OR=3.54, 95% CI 1.30 to 9.64, p=0.01).

Table 5

Multivariate multinomial logistic regression results of the latent profiles of the SOC-PCER (n=321)

Discussion

To our knowledge, this is the first study to identify subgroups of patients with lung cancer undergoing chemotherapy based on SOC-PCER profiles and to analyse the differences in PTG and characteristics of these subgroups. Thus, the findings of this study will guide clinicians in developing individualised intervention programmes.

Three distinct profiles were identified, including low overall score, high-SOC and low-PCER, and high-PCER groups. Thus, hypothesis 1 was confirmed. More than half of the patients with lung cancer undergoing chemotherapy (54.5%) belonged to the low overall score group. This suggests that most had low SOC and PCER scores, which is consistent with the findings of Chen et al. This finding is also consistent with the theory of resource conservation, which supports the notion that a lack of resources affects individuals’ mental health.46 Patients with lung cancer undergoing chemotherapy lack health resources.47 48 Therefore, they experience strong psychological shock and difficulty in mobilising internal psychological resources. Trauma also causes a great sense of uncertainty, which prevents them from adopting a PCER approach to recognising and treating illness.49 In addition, patients with lung cancer undergoing chemotherapy often experience haemoptysis, pain, infection, hair loss and other symptoms, which lead to an increased fear of the disease and a decreased sense of control over trauma. Eventually, they have low levels of SOC and PCER.50 51 Therefore, personal nutrition programmes, pain control and other nursing measures should be taken to alleviate somatic diseases caused by trauma. Positive psychological interventions that focus on promoting SOC and elevating PCER growth should be provided.

In contrast to profile 1, there was a similar proportion of participants in the high-SOC/low-PCER group (15.6%) and the high-PCER group (29.9%). In the high-SOC/low-PCER group, although the patients had a high level of SOC, they had low levels of PCER. This differs from previous quantitative studies that support the positive correlation between SOC and PCER.52 A possible explanation may be that in patients in the high-SOC/low-PCER group, trauma may motivate them to take positive coping measures to solve problems (eg, adjusting their diet, increasing physical exercise and learning about the disease), which enhances SOC.53 Furthermore, patients adopt PCER to reassess the impact of trauma and analyse the reason for trauma. This can form a positive feedback mechanism between SOC and PCER.54 However, positive coping styles and SOC are not always helpful in alleviating trauma. Thus, patients with lung cancer undergoing chemotherapy may lose confidence in treatment and develop sadness and despair, which impacts the level of PCER.55 Therefore, among this group of patients, self-confidence should be developed while invoking the power of anticancer role models to foster PCER.56

Patients in the high-PCER group had moderate and high levels of SOC and PCER, respectively. One possible explanation is that patients in the high-PCER group could establish a healthy lifestyle, enhance disease management and actively seek social support, which could help reduce psychological stress caused by a lack of health resources and increase SOC and PCER.57 However, personality traits differ in patients with lung cancer undergoing chemotherapy, leading to differences in SOC and PCER enhancements, which can be explained by these profiles. The diagnosis of lung cancer and chemotherapy are grade A trauma, which have high uncertainty and uncontrollability.6 In this context, although patients adopt positive coping styles, their comprehensibility and control cannot be enhanced. However, positive coping styles facilitate learning to manage negative emotions and adaptation to the environment, which is beneficial for promoting.58 In conclusion, for patients with lung cancer undergoing chemotherapy in the high-PCER group, personalised care should be provided according to personality traits, and health education should be provided to enhance their sense of illness. Ultimately, this leads to a higher SOC level.

Compared with the high-SOC/low-PCER group and the high-PCER group, PTG was the lowest in the low overall group (p<0.05), which is consistent with hypothesis 2. According to the PTG theory, trauma inspires individuals to adapt to trauma and achieve PTG through intraindividual strengths, positive coping and emotion regulation.59 Thus, SOC is an intraindividual strength that can alleviate the fear of trauma. It can also help them satisfy their emotional needs by seeking support that enhance their meaning in life.60 PCER is a form of emotion regulation that leads patients with lung cancer undergoing chemotherapy to consider the positive impact of disease pain and chemotherapy toxicity on life.61 Therefore, both positively contribute to PTG. This implies that PTG is the lowest when the levels of SOC and PCER are low in patients with lung cancer undergoing chemotherapy.62 Therefore, the patients in the low overall group had the lowest PTG scores. In summary, concurrent enhancement of SOC and PCER can maximise PTG in patients with lung cancer undergoing chemotherapy.

In addition, the results of the study showed that patients with lung cancer undergoing chemotherapy who lived in a city and were first diagnosed between 6 months and 1 year were more likely to belong to the high-PCER group, which is in line with hypothesis 3. According to ecosystem theory, social and personal factors impact self-psychological adjustment.63 Residence in a city and time to first diagnosis ≥6 months and <1 year were important social and personal factors; thus, both became unique demographic characteristics of patients in the high-PCER group, which is similar to the findings of Liu et al.64 Patients with lung cancer undergoing chemotherapy living in urban areas were categorised into the high-PCER group for three reasons. First, they have a better economic status and lower financial burden of treatment, which is favourable for PCER modelling.65 Second, they engage in more social activities that are conducive to realising their personal values, seeking meaning in life and managing sadness in interpersonal interactions.66 Third, they have a high awareness of healthcare and more access to knowledge about the disease (eg, online services, community hospitals for help), which facilitates their assessment of trauma, analysis of trauma and evaluation of trauma.67 Therefore, clinicians can identify lung patients undergoing cancer chemotherapy in the high-PCER group according to the patients’ residence. Furthermore, they can provide psychological care for patients living in rural areas and help patients by establishing a good and effective social support system as well as a harmonious relationship between nurses and patients to mobilise PCER. Patients with lung cancer undergoing chemotherapy with a first diagnosis between 6 months and 1 year were attributed to the high-PCER group, which can be attributed to the following two reasons. First, patients with lung cancer undergoing chemotherapy at this stage have fewer toxic side effects and slower disease progression, which gives them more energy to manage the negative emotions generated by the disease and adopt PCER.68 Second, patients in this period temporarily put aside the trauma of their lung cancer diagnosis, reversed their own perception of the disease and established PCER through physical exercise, meditation and other means.69 Therefore, clinicians should focus on patients with lung cancer undergoing chemotherapy whose first diagnosis time is 6 months to 1 year, maintain their cognitive and emotional regulation and avoid the decline in their cognitive and emotional regulation. In summary, healthcare professionals should identify patients with lung cancer undergoing chemotherapy in the high-PCER group as early as possible based on their characteristics and develop PTG based on the latent profiles of self-psychological adjustment in the high-PCER group.

Study limitations

This study has several limitations. First, it was a cross-sectional study. Therefore, definitive causality between self-psychological adjustment (SOC-PCER) and PTG could not be established. Future studies should include randomised controlled trials and longitudinal studies, which should be continued to further validate the relationship between self-psychological adjustment (SOC-PCER) and PTG. Second, the participants were recruited from only two tertiary general hospitals in Shandong Province, which is not sufficiently representative. Future studies should recruit participants with different grades of cancer from different regions and hospitals to ensure representativeness. Third, in this study, the non-probability convenience sampling method was choosed to select the study subjects, and there could be a selection shift, which would lead to under-representation. Therefore, in a future study, we will select study subjects by random sampling. Fourth, this study did not collect prechemotherapy data for patients with lung cancer undergoing chemotherapy. In future studies, we will pay special attention to the control of the study data.

Clinical implication

Despite its limitations, this study elucidated three profiles of self-psychological adjustment in patients with lung cancer undergoing chemotherapy and indicated that patients in the low overall group had the lowest level of PTG. Patients who lived in an urban area and were first diagnosed between 6 months and 1 year were more likely to belong to the high-PCER group. Overall, personalised interventions should be developed according to the characteristics of each profile to effectively promote PTG in patients with lung cancer who are undergoing chemotherapy. The different classification characteristics of self-psychological adjustment in patients with lung cancer undergoing chemotherapy can help medical staff identify the high-PCER group as early as possible and take preventive interventions to avoid damaging their SOC.

Conclusion

Our results suggest that patients with lung cancer undergoing chemotherapy can be categorised into three different profiles based on their response patterns on self-psychological adjustment, and patients with lung cancer undergoing chemotherapy who lived in a city and were first diagnosed between 6 months and 1 year were more likely to belong to the high-PCER group. Our findings also supported the utility of the PTG theory model and the ecosystem theory model in the study of emotional regulation in patients with lung cancer undergoing chemotherapy. By potential profile analysis, comparison of variance and multivariate logistic regression analyses, we found that patients undergoing chemotherapy for lung cancer in the relief of psychological stress had different characteristics and were closely related to PTG. This study helps explain the characteristics and heterogeneity of different categories of populations of patients with lung cancer undergoing chemotherapy and helps them reasonably control and regulate their emotions.

Data availability statement

Data are available upon reasonable request.

Ethics statements

Patient consent for publication

Ethics approval

This study involves human participants and was approved by the Ethics Committee of Binzhou Medical University (approval number: 2021-566). All participants provided informed verbal consent at the beginning of the study, which was approved by the Ethics Committee of Binzhou Medical University (approval number: 2022-02). The current study was conducted in accordance with the guidelines of the Declaration of Helsinki. Participants gave informed consent to participate in the study before taking part.

References

Supplementary materials

  • Supplementary Data

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Footnotes

  • NL, LZ and YL are joint first authors.

  • NL, LZ and YL contributed equally.

  • Contributors Xiaoli Zhang and Xuemei Ding contributed to study conception and design. Material preparation was conducted by Lei Zhang, Na Liu and Yaxin Liu. Data collection was performed by Gao Lixia and Qing Li. Data analysis was performed by Lei Zhang and Yaxin Liu. The manuscript was written by Na Liu. Xiaoli Zhang gave useful comments to the first manuscript. Lei Zhang helped revise the manuscript for several times. All authors read and approved the final manuscript.

  • Funding This study was supported by the Shandong Provincial Graduate Education Quality Improvement Program (SDYJG19163) and the Shandong Provincial Undergraduate Teaching Reform Research Program (M2020018).

  • Competing interests None declared.

  • Patient and public involvement Neither patients nor the public were involved in the design, conduct, reporting, or dissemination plans associated with this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.