1 Introduction

Coal Workers’ Pneumoconiosis (CWP) is a systemic disease characterized by the diffuse fibrosis of lung tissues, which is mainly caused by the long-term inhalation of mineral dust during occupational activities like coal mining (Qi et al. 2021). To reduce the occurrence of pneumoconiosis, strict exposure limits have been set, and personal protective equipment such as masks, goggles, and protective clothing have been implemented. Currently, the allowable exposure limit for respirable coal mine dust (RCMD) in China is 2.5 mg/m3, and with the upgrading of occupational protection measures, such as the use of masks, the incidence of pneumoconiosis in China has decreased in recent years (Decision of the ministry of emergency management on amending the coal mine safety regulations 2022). Despite a more than 50% reduction in the incidence rate of pneumoconiosis compared to 2012, there were still 11,809 new cases of occupational pneumoconiosis in China in 2021 (The National Health Commission released the 2021 2022). Pneumoconiosis is a chronic disease that can only be 100% cured through lung transplantation (Hall et al. 2019). Patients with pneumoconiosis may experience weakened lung function, decreased immunity, and are susceptible to respiratory infections (Bell and Mazurek 2020). Due to the prolonged and debilitating nature of the disease, patients are prone to negative emotions such as anxiety, fear, pessimism, and depression (Morrison et al. 2017). Miners are a high-risk group for pneumoconiosis, facing various work-related pressures and the risk of occupational disease. The resulting psychological problems not only affect the individual's quality of life but also pose a hidden danger to workplace safety. Therefore, timely identification of the psychological status of miners at different stages of their career and corresponding interventions can prevent adverse events, improve their quality of life, and enhance their well-being.

To assess the psychological state of patients, commonly used tools in China include the Self-rating Anxiety Scale (SAS) (Cheng et al. 2017), Self-rating Depression Scale (SDS) (Smith et al. 2018), and Depression Anxiety Stress Scale-21 (DASS-21) (Jiang et al. 2020), which are widely recognized internationally. However, these tools tend to focus on specific aspects of psychological problems. In contrast, the Somatic Symptom Scale SCL-90 provides a more comprehensive evaluation (Dang et al. 2021), but its extensive item list and lengthy survey process may lead to impatience among respondents, especially in China where outpatient services are heavily burdened due to limited medical resources (Li et al. 2020). Consequently, there is an urgent need to develop a measurement tool that can assess multiple aspects of psychology within a short timeframe, enabling medical professionals to quickly screen for issues in one or more domains.

The Crown–Crisp Experience Index (CCEI) is a quantitative assessment tool that measures patients' phobia levels using a questionnaire (Crown and Crisp 1966). This questionnaire has been widely employed in clinical studies on various conditions such as heart disease (Haines et al. 1987), tinnitus (Stephens and Hallam 1985), anorexia nervosa (Hsu and Crisp 1980), ovarian cancer (Poole et al. 2016), and even attention deficit hyperactivity disorder (ADHD) in children (Bolea-Alamañac et al. 2019). Therefore, in order to assess the psychological status of the miner population, the present study aims to localize and revise the CCEI questionnaire in Chinese and employ factor analysis to test its reliability and validity. The study further aims to investigate and compare anxiety and fear indices among active miners, CWP patients, and retired miners at different career stages, with the objective of laying a foundation for early identification of negative psychological states.

2 Materials and methods

2.1 The CCEI questionnaire

The Crown–Crisp Experience Index is a self-rating scale that was developed in 1966 by Crown and Crisp, psychiatry professors at Middlesex Hospital in London, UK (Crown and Crisp 1966). The questionnaire comprises six dimensions, each with eight items. The six dimensions assessed by the questionnaire are free-floating anxiety (FFA items 1, 7, 13, 19, 25, 31, 37, 43), phobic anxiety (PHO items 2, 8, 14, 20, 26, 32, 38, 44), obsessive–compulsive traits and symptoms (OBS items 3, 9, 15, 21, 27, 33, 39, 45), somatic symptoms (SOM items 4, 10, 16, 22, 28, 34, 40, 46), depressive symptoms (DEP items 5, 11, 17, 23, 29, 35, 41, 47), and hysterical traits and symptoms (HYS items 6, 12, 18, 24, 30, 36, 42, 48). The questionnaire is a concise tool for evaluating common phobias and anxiety disorders, such as claustrophobia, pathophobia, acrophobia, and demophobia levels. Each item has a score range of 0–2 points, and each dimension ranges from 0 to 16 points, with a total score of 0 to 96. The survey also includes "reversed items," where a higher score indicates a greater degree of anxiety and phobia.

2.2 The CCEI questionnaire translation and cross-cultural adaptation

In accordance with the principles of cross-cultural adaptation (Guillemin et al. 1993), the localization process of the Chinese version of CCEI is depicted in Fig. 1. A total of 15 experts, as shown in supplementary Table 1 in medical-related fields were invited to evaluate the expression and make it more idiomatic. The invitees completed relevant forms, and the first round of expert consultation was conducted. Controversial items underwent a second round of expert consultation. After two rounds, the expert judgment coefficient (Ca) was 0.93 and the familiarity degree coefficient (Cs) was 0.89, according to the formula authority coefficient (Cr) = (Ca + Cs)/2 (Li et al. 2021), resulting in an expert authority coefficient (Cr) of 0.91. This score is greater than 0.9 and indicates that the experts unanimously suggested deleting item 9, i.e. Do you think that “cleanliness is next to godliness?. Consequently, the questionnaire was reduced to 47 items across six dimensions. It is worth noting that cultural differences were taken into account throughout the localization process.

Fig. 1
figure 1

The localization process of the Chinese CCEI

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2.3 Pre-investigation

In this study, we adopted convenience sampling to distribute a total of 30 questionnaires for pilot study, with 10 questionnaires each given to active miners, CWP patients, and retired miners, respectively. A 3-point scoring method was adopted; that is, answering “yes” tallies 2 points, “sometimes” 1 point, and “no” 0. For reverse items, the scoring is exactly the opposite. Given the low literacy levels and advanced age of the study subjects, the current investigation employed one-to-one surveys conducted by six trained research members, who carefully gathered and incorporated the subjects' opinions and suggestions regarding each questionnaire item. The questionnaire's format, content, item options, and completion time were reported to be reasonable. The questionnaire was found to take approximately 12–15 min to complete.

2.4 Participants

To ensure the reliability and validity of the questionnaire, the study followed the principle that the number of participants should be 5–10 times greater than the number of questionnaire items (Myers et al. 2011). We recruited a total of 900 coal mines from different occupational stages, including 300 active miners, 300 CWP patients, and 300 retired miners, to assess the reliability and validity of the Chinese version of the CCEI questionnaire. A questionnaire survey and subgroup analysis were conducted on three groups of 1000 individuals each, including active miners, CWP patients, and retired miners to explore the primary factors influencing anxiety.

2.5 Data collection

A total of 900 questionnaires were distributed and collected from different occupational stages. Of these, 31 were incomplete and therefore excluded from analysis, leaving a total of 869 valid questionnaires. The survey's effective response rate was 96.6%, meeting the standard criteria for surveys. Additionally, 1000 individuals from each of the active miner, CWP patient, and retired miner groups were recruited, with valid responses obtained from 969, 985, to 910 individuals, respectively. The effective rates of the survey were 96.9%, 98.5%, and 91.0% for the coal miner, CWP patient, and retired miner groups, respectively.

2.6 Statistical analysis methods

The data input was performed by using Epidata 3.1 software, and subsequently, the data were randomly assigned into two groups. One group was used for exploratory factor analysis (EFA) through SPSS 22.0 (n = 435), while the other was used for confirmatory factor analysis (CFA) using AMOS 25.0 (n = 434). The reliability and validity of the study were evaluated using several statistical methods including Cronbach's alpha, composite reliability, and goodness of fit indices (McDonald and Ho 2002). In addition, the content validity index (CVI) and correlation coefficient were used to assess the reliability and validity of the Chinese version of the CCEI. The quantitative aspects of the study were described by the composition ratio, mean, standard deviation, and M (SD).

3 Results

The 869 samples used to test the reliability and validity of the questionnaire were drawn from three groups: 292 active miners, 290 CWP patients, and 287 retired miners. The nature of the work under investigation is specific to certain settings, thus the survey participants were restricted to males aged 25–94, with a mean (SD) age of 55.35 (15.74) years. The majority of miners are exhibit low levels of education, as shown in supplementary Table 2).

3.1 Exploratory factor analysis of CCEI Chinese version

The Kaiser–Meyer–Olkin (KMO) measure and Bartlett's test of sphericity for the Coal Workers' Pneumoconiosis Cognitive Emotion Inventory (CCEI) questionnaire yielded a value of 0.904, exceeding the threshold of 0.9, indicating suitability for factor analysis. Varimax with Kaiser normalization is then applied to extract 6 factors from 47 items (Fig. 2). The six factors are: DEP (items 5, 11, 17, 23, 29, 35, 41, 47), FFA (items 1, 7, 13, 20, 25, 31, 37, 43), PHO (items 2, 8, 14, 19, 26, 32, 38, 44), SOM (items 4, 10, 16, 22, 28, 34, 40, 46), HYS (items 6, 12, 18, 24, 30, 36, 42, 48), and OBS (items 3, 15, 21, 27, 33, 39, 45). According to the study, a total of 79.389% variance is explained. We have recoded the items in the questionnaire. The detailed information of six factors is shown in Table 1, including FFA (items from FFA1 to FFA8), PHO ((items from PHO1 to PHO8), OBS (items from OBS1 to OBS7), SOM (items from SOM1 to SOM8), DEP (items from DEP1 to DEP8), HYS (items from HYS1 to HYS8).

Fig. 2
figure 2

Scree plot of CCEI

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Table 1 Component matrix of each dimension of the CCEI (n = 435)
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3.2 Confirmatory factor analysis of CCEI Chinese version

Structural Equation Modeling (SEM) is a statistical modeling approach that involves the analysis of the relationships between latent variables and observed variables, which are measured by multiple indicators (Alavi et al. 2020). In this study, a total of 47 observed variables were used, with FFA, PHO, OBS, SOM, DEP, and HYS serving as latent variables. AMOS 25.0 was utilized to construct a path diagram to confirm the theoretical structure of exploratory factor analysis (Fig. 3). Confirmatory factor analysis fit indices presented in Table 2. The estimation results of the parameters indicate that the six dimensions of the CCEI scale exhibit CR value exceeding 0.6 and AVE value exceeding 0.5, and the correlation coefficients among the factors are lower than the AVE value, as shown in Table 3.

Fig. 3
figure 3

Path diagram of each dimension

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Table 2 Fit indexes of Chinese CCEI (n = 434)
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Table 3 Parameters estimation result (n = 434)
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3.3 Internal consistency coefficient of CCEI Chinese version

The internal consistency of the questionnaire and each dimension was evaluated using Cronbach's α coefficient, as shown in Table 4, with values ranging from 0.899 to 0.936, exceeding the threshold of 0.90. Split-half reliability was also assessed and found to be greater than 0.8, indicating excellent internal consistency of the questionnaire (Terwee et al. 2007).

Table 4 Reliability result of the CCEI (n = 435)
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3.4 Content validity index of CCEI Chinese version

Content validity index (CVI) is sub-divided into item-level CVI (I-CVI) and scale-level CVI (S-CVI). Typically, the validity is based on expert comment. I-CVI equals to the number of the experts scoring 4 or 5 for the importance of the research/total number of the experts. S-CVI equals to the number of items with a 4 or 5 scores/total number of items. In this research, the results show that I-CVI is 0.73–1.00, S-CVI is 0.88, all greater than 0.7, indicating good content validity (Zhong et al. 2020).

3.5 Mental disorder between miner workers and CWP patients and retired miners

In order to further clarify the actual application of the scale, we compared the detection rates of psychological disorders among miners, pneumoconiosis patients, and retired miners (supplementary Table 3). The detection rates of psychological disorders in active miners, pneumoconiosis patients and retired miners were 35.8%, 21.0%, and 13.6%, respectively. In addition, in order to further understand the proportion of factors affecting psychological problems in different populations, we conducted a subgroup analysis for each group. Taking 20% as the cut-off value, it shows that the psychological barriers among miners mainly focus on DEP, FFA and SOM dimensions, and the positive rates are 35.1%, 36.4% and 33.2%, respectively. The pneumoconiosis population mainly focused on PHO and SOM, and the positive detection rates were 39.5% and 29.2%, respectively. The detection rate of retired miners is below 20% in all dimensions, as shown in Fig. 4.

Fig. 4
figure 4

The detection rate of mental disorders a The detection of the total score of the three groups of mental disorders; b The detection of psychological disorders in each dimension of the active miners; c The detection of psychological disorders in each dimension of CWP: d The detection of each dimension of retired miner detection of mental disorders

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4 Discussions

4.1 Reliability and validity of Chinese CCEI

Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) are widely recognized as reliable methods for evaluating the stability and structural validity of questionnaires. EFA assesses the relationship between observed and latent variables through factor loading (DeVon et al. 2007), and the sampling adequacy is first determined using Kaiser–Meyer–Olkin before data analysis. A result greater than 0.90 indicates that the sample is suitable for factor analysis. In conducting EFA, the cumulative variance contribution rate of the common factors must exceed 60%, and the factor load of each item on its common factor must be greater than 0.4, indicating that each item reflects the information of a particular dimension. In this study, the factor load of each item and its dimensions exceeded 0.5, except for item 19, which was transferred from FFA to PHO, and item 20, which was transferred from PHO to FFA, based on content relevance. The communalities of each dimension and the CCEI were all greater than 0.5, indicating that the components were adequately explained.

Confirmatory Factor Analysis (CFA) is a reliable method for testing the structural assumptions of an established model by evaluating goodness of fit (Bagozzi et al. 1981). For ease of identification, the serial numbers of each item were recoded. The results of the CFA indicate that the fit indices in Table 2 are consistent with the reference values. In conjunction with the results in Table 3, each item has a loading above 0.6 under its respective factor, with CR values greater than 0.8 and AVE greater than 0.5. This indicates that the items in the CCEI scale have a certain degree of discrimination, and the model has an ideal structure capable of identifying the degree of response of different investigators.

Table 4 shows that the reliability indicators of the Chinese version of the CCEI are higher compared to the original study conducted by Crown and Crisp in 1966, which may be attributed to the significant increase in sample size in this study. The Cronbach's α coefficients of the total questionnaire and each dimension were all greater than 0.9, and the split-half reliability coefficients obtained by grouping odd and even numbered items were all greater than 0.8, indicating good internal consistency of the questionnaire (Boparai et al. 2018).

Content validity is typically assessed through expert reviews, which serve as an indication of the accuracy of the measured content or topic (Hayes and Preacher 2010). In general, content validity is established based on experts' comments, with I-CVI representing the number of experts who score 4 or 5 for the importance of the research divided by the total number of experts, and S-CVI representing the number of items with a score of 4 or 5 divided by the total number of items (Egger-Rainer 2018). In this study, both I-CVI and S-CVI exceeded 0.7, indicating that the Chinese CCEI has strong content validity.

4.2 Coal miners mental disorder

Miners working underground are all male. The results of the comparison among active miners, CWP patients, and retired miners show that the highest detection rate of psychological problems in active miners is 35.8%, mainly focusing on the dimensions of DEP, FFA, and SOM. The main reasons for the high prevalence of psychological issues in active miners are likely due to the harsh operating environment underground and the pressure from work management. These findings are consistent with the research reported by Ailing Fu et al. (2022). The second is the detection rate of psychological disorders in CWP patients, which is 21%, mainly focusing on the dimensions of PHO and SOM. According to the national policy (Shi et al. 2020), once pneumoconiosis is diagnosed, patients can enjoy free medical treatment, which largely eliminates patients’ concerns. But pneumoconiosis will have the symptoms of respiratory disorder and hypoxia. For those suffering from pneumoconiosis, they are worried that they will not get timely help, especially when they live alone, which will cause fear to patients. It is worth noting that the detection rate of psychological problems in retired miners without pneumoconiosis is only 13.6%, which is lower than the incidence of psychological problems in the general elderly. It shows that the quality of life of retired miners is quite satisfactory after retiring from their posts. On the one hand, they are out of the high-risk occupational environment, and can freely spend their time while receiving monthly pensions. Compared with the stress during work, it is a state from bitter to sweet. This study suggests that miners have different psychological problems at different career stages. Coal operators should pay attention to the psychological problems of miners and formulate targeted psychological intervention measures to improve the mental health and quality of life of miners.

5 Conclusions

The dimensions as well as the questionnaire in this study enjoy sound internal consistency and good structural validity and reliability. It thus can be used as one of the measurement tools to assess the phobia indexes of coal miners at different periods of their working and retirement life. Though this study is based on coal miners, it is expected the Chinese CCEI can be applied to other types of patients in the future, for whom it is critical to assess psychological problems in a short period of time.

It should be noted that this study has some limitations. The limitations may include: (1) Although the sample size is relatively considerable, the study focuses on the population of only one city, which may have potential environmental impacts. (2) The questionnaires involved in this study are all men, and whether it can be applied to the female population still needs to be further explored.