Development and validation of the quality of life scale for Chinese coal miners with pneumoconiosis (QOL-CMP): Measurement method and empirical study

Highlights

• A new scale has been developed for Chinese coal miners with pneumoconiosis.

• Quality of life (QOL) includes five dimensions in this study.

• Social demographic factors are of great significance.

• Participants are divided into five typical clusters.

• It provides a new reference for the occupational health and sustainability.

Abstract

Over the past decades, there has been enormous concern about labor conditions in developing countries particularly around work for the coal production market. Quality of Life (QOL) is of vital importance to be considered and promoted for occupational disease and safety accident prevention, which makes it urgent to undertake research on coal miners’ QOL. This study addresses QOL issues related to Occupational Safety and Health for people suffering occupational disease from work demanded because of energy trade arrangements. The research was designed to develop a scale for coal miners with pneumoconiosis (CMP) for measuring the QOL of these patients. This scale was developed using the combined generic and disease-specific theory. As indicated by the research results based on grounded theory (50 patient in-depth interview records and 322 opening questionnaires) and formal investigation (1345 questionnaires), this scale consists of five dimensions: physiological quality, psychological quality, environmental quality, relationship quality and economic quality based on 63 items. The perceived QOL was found to differ significantly among demographic variables and length of hospital stay. The patients were divided into five clustering groups by K-means cluster analysis: economically comfort (16.51%), physiologically comfort (14.20%), psychologically comfort (18.36%), environmentally comfort (18.36%), and the trapped (37.10%). The overall QOL scores in the psychologically comfort group (2.33) were higher than that in other groups and the scores in the trapped group (highest occupation) were lowest (1.74). The QOL-CMP scale exhibited reasonable degrees of validity and reliability. Management suggestions are proposed to provide a reference for improving the overall QOL of Chinese coal miners with pneumoconiosis, which greatly enhances the research content of occupational health and energy sustainability.

Introduction

China is the largest producer of coal in the world, and coal occupies a major position in China's disposable energy structure, accounting for more than 60% in the production and consumption of disposable energy (Li et al., 2015). Although there is novel proposed biomass method for energy production, as an important traditional resource for a long time to come, coal still plays a dominant role in China's economy and energy development (Alsamawi et al., 2017). China has many coal mines, where a large number of employees are employed. In hundreds of meters underground, like the “hell” in the mine, in addition to facing the direct threat of flooding, gas explosion, roof collapse, and other threats to life safety anytime and anywhere, coal miners have to face hazardous materials such as silica dust and coal dust and so on at any time, so as to catch serious occupational diseases, eventually eroding their health (Wu et al., 2017). Pneumoconiosis is a common disease in coal miners, and it can lead to repeated inflammation, progressive pulmonary fibrosis, lung failure, a reduction in patient survival time, and eventual death. Furthermore, this disease is featured with progressive and irreversible pathological characteristics (Wang et al., 2016). Currently, pneumoconiosis is the most serious occupational disease in China, accounting for approximately 80% of the total number of occupational disease cases (Wang et al., 2016). It was reported that 23,152 new cases were diagnosed with pneumoconiosis in 2013 and 60.28% of these patients were coal miners. In recent years, pneumoconiosis has shown a high incidence and the number of pneumoconiosis patients will continue to increase (Han et al., 2015). However, pneumoconiosis is still considered an incurable disease, and the only effective treatment merely prevents the condition from worsening (Wang et al., 2016). Thus, in addition to enduring a long treatment period with little realistic hope of actual recovery, pneumoconiosis patients suffer many symptoms, including cough, expectoration, and dyspnea (Liu et al., 2011; Miller et al., 1971; Shah et al., 2012). Pneumoconiosis not only seriously affects physiological function and mental health, but also has a negative impact on marriages and social relationships, thereby reducing their perceived QOL. This situation has a negative influence on economic development and social stability, and thus becoming a public health issue meriting worldwide attention.

QOL, a term coined by Galbraith in the late 1950s (Dolatshahi and Galbraith, 1964), has been a popular issue in both theoretical and practical fields. The World Health Organization (WHO) defines QOL as an individual's perception of his/her position in life in the context of culture and value systems in relation to his/her goals, expectations, standard, and concerns (The WHOQOL Group et al., 1994). When the term was introduced to the field of medical research, it focused on health-related quality of life (HRQOL) by minimizing the large scope of its sociological concept definition (Badia et al., 2007), which specifically refers to evaluation of the state of physiological, psychological, and social functions of individuals (Li et al., 1995; Wan et al., 2014). In the National Occupational Disease Prevention and Control Plan (2016–2020), China's State Council stressed that all tasks should give priority to the prevention and treatment of pneumoconiosis. In 2016, the Healthy China 2030 Program Outline unveiled action plans for key populations in priority areas. Therein, the occupational health action plan was designed to promote the health of the labor force and prolong the lives of patients with occupational diseases by improving work environments, working conditions, and the QOL of patients with occupational diseases. In summary, it is necessary not only to prevent new cases occurring, but also to focus on the living conditions of pneumoconiosis patients in order to improve their overall QOL.

Over the past 30 years, researchers have studied patients' QOL, but they have failed to reach a consensus on the evaluation framework and assessment standard of patients’ QOL, partly because of different measurement tools being adopted. There is a debate regarding what constitutes QOL in the existing literature. This debate can be mainly divided into three approaches to QOL measurement: (1) the health-related quality of life (HRQOL) approach. This approach asks patients to rate the presence of physical symptoms and their functional capacity, such as mobility, daily activities, and pain; (2) the need-based approach. This approach focuses on individuals and their capacity of meeting his/her own needs, such as social needs, sexual needs, and emotional needs; (3) the individualistic approach. This approach asks patients to describe their lives and list the determinants they consider most important. Among existing literature, the dimensions of QOL scales are mainly based on the HRQOL approach rather than the need-based and individualistic approaches, with the focus mainly on the biomedical aspects of the disease, and trying to open up dialogue between the clinician and the patient (Gupta et al., 1998). In addition, existing studies have been performed primarily on patients with non-occupational diseases or directly adopted Western QOL measurement scales for use in Chinese patients. The scales used for Chinese pneumoconiosis patients are mainly generic instruments, i.e., the 26-item abbreviated version of the World Health Organization Quality of Life scale (WHOQOL-BREF) and the short form 36 health survey questionnaire (SF-36) (Qin et al., 2014; Yu et al., 2008), which are applicable to a broad range of conditions and support comparisons among different categories of diseases (Both et al., 2007). However, when applied to Chinese pneumoconiosis patients, generic measures have following drawbacks: (1) the content validity of domains may be doubtful due to the lack of appropriate areas of economic quality from the perspective of need-based approach, for example, the patients need more economical sources to depend on drug and therapy for maintaining their lives; (2) the content validity of the items may not place emphasis on a physical weakness for a specific group of patients with pneumoconiosis (the WHOQOL-BREF, for example, does not include breathing, which is a typical symptom of pneumoconiosis patients); and (3) there is a lack of sensitivity for within-patient change from the perspective of the individualistic approach, which is especially significant in clinical trials¹⁸. Specific HRQOL tools are clinically sensible and more responsive than generic instruments. Therefore, as a follow-up to these existing scales, the disease-specific QOL-CMP scale was developed by taking a combined approach based on HRQOL, need-based, and individualistic approaches.

Compared with these instruments, specific HRQOL tools are clinically sensible and more responsive than generic instruments (Wiebe et al., 2003). For this reason, it is generally recommended that generic-to-specific health profiles are used (Wiebe et al., 2003). These may better measure patients' health status in general terms and in situations, where pneumoconiosis has a substantial disease-specific impact. Some new dimensions and concepts were provided for our CMP-QOL scale. Specifically, (1) expiratory dyspnea, as a feature common in pneumoconiosis patients, was measured in the physical dimension of our scale. The measurement items of respiratory conditions had not appeared in previous QOL scales. (2) Furthermore, respect and discrimination, as a measurement index in the psychological dimension was reported by our participants, and Chinese coal-miners with pneumoconiosis often feel failing to receive enough respect from others, such as collectivity and society. In this case, it can be partly and culturally explained that the profession of coal miners is considered an indecent job, and furthermore, pneumoconiosis and its serious complications would cause patients to lie in bed for a long time. Most of the participants reported that they often feel very isolated and regard themselves as members in the bottom of the population as time goes on. The measurement items of respect and discrimination had not been found in previous QOL scales, especially in WHOQOL-BREF and SF-36. (3) The social relation, as a measurement index in the relationship dimension, was to explore the pneumoconiosis patients’ perception of relationship closeness with assistance institutions, like governments, employment units, nonprofit organizations and the whole society, because they eager to receive the assistance from such state-level institutions due to the inherent logic of Chinese collectivism. However, the measurement of the social relation in previous scales mainly concentrated on the relationship with families and friends on an individual basis, which was a major difference between our scales and previous scales. Regarding the dimensions of other items in our manuscript, the relevant important information was from large-scale interviews, and then the factors were extracted from the qualitative analysis. Although the naming of some dimensions seemed to be consistent with the previous scales, the content in our developed scale was more targeted.

From the content mentioned above, it can be found that these Western scales fail to consider the specific cultural context, which differs significantly between Western and Eastern countries (Lee et al., 2014; Wan et al., 2008; Xiang et al., 2010). QOL measurement is profoundly influenced by the cultural background (Kagawa-Singer et al., 2010; Xiang et al., 2010). For instance, WHOQOL-100 (The World Health Organization Quality of Life assessment) includes points on the sexual function, but many Chinese respondents feel ashamed to discuss their sex lives. Thus, they lie on reflex or even refuse to answer, which impacts the final questionnaire results. A similar situation has been found in research on QOL scale development for cancer patients (Wu et al., 2016). Additionally, in China, most people tend to embrace traditional family values and believe that the family takes priority over everything else in their lives. Therefore, the demographic variables (i.e., the number of children and the spouses’ health status) were included in our scale. Given that the majority of Chinese coal-miners tend to have the low literacy rate, we have measured the educational level and reading and writing skills of the participants investigated. Such questions could hardly be found in the previous QOL scales. Furthermore, the convergent validity of the WHOQOL-BREF cannot be proven to be optimal as its correlation is not consistent with the SF-36 as expected in the research of validation for US respondents (Bonomi et al., 2000). In addition, Noerholm et al. (2004) expressed doubt regarding the interpretability of the questionnaire score produced from the research using WHOQOL-BREF. Consequently, these scales may not be suitable for the comprehensive evaluation of QOL among Chinese pneumoconiosis patients. Therefore, Chinese-specific instruments should be developed.

However, to date, there have been few studies on the content, measurement scales, and factors influencing the QOL of coal miners with pneumoconiosis in China. Thus, it is necessary to develop the indigenous occupational QOL-CMP (quality of life of coal miners with pneumoconiosis) scale, which can be employed to carry out empirical studies in the field of occupational disease prevention and treatment in China. By virtue of questionnaire surveys and interviews with coal miners suffering from pneumoconiosis, we assessed the reliability and validity of the scale and removed nonconforming items, thereby producing the final QOL-CMP scale, which was then used to further study the perceived QOL of coal miners with pneumoconiosis in China (Fig. 1). By empirical research, this study determined the interactions between demographic variables and mean values of QOL and its dimensions, and further divided the patients into five representative clusters, with a view to providing new references for comprehensive improvement of QOL among Chinese pneumoconiosis patients.