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Abstract
Objectives Pneumoconiosis remains a major global occupational health hazard and illness. Accurate data on the incidence of pneumoconiosis are critical for health resource planning and development of health policy.
Methods We collected data for the period between 1990 and 2017 on the annual incident cases and the age-standardised incidence rates (ASIR) of pneumoconiosis aetiology from the Global Burden of Disease Study 2017. We calculated the average annual percentage changes of ASIR by sex, region and aetiology in order to determine the trends of pneumoconiosis.
Results Globally, the number of pneumoconiosis cases increased by a measure of 66.0%, from 36 186 in 1990 to 60 055 in 2017. The overall ASIR decreased by an average of 0.6% per year in the same period. The number of pneumoconiosis cases increased across the five sociodemographic index regions, and there was a decrease in the ASIR from 1990 to 2017. The ASIR of silicosis, coal workers’ pneumoconiosis and other pneumoconiosis decreased. In contrast, measures of the ASIR of asbestosis displayed an increasing trend. Patterns of the incidence of pneumoconiosis caused by different aetiologies were found to have been heterogeneous for analyses across regions and among countries.
Conclusion Incidence patterns of pneumoconiosis which were caused by different aetiologies varied considerably across regions and countries of the world. The patterns of incidence and temporal trends should facilitate the establishment of more effective and increasingly targeted methods for prevention of pneumoconiosis and reduce associated disease burden.
- hygiene / occupational hygiene
- epidemiology
- public health
- pneumoconioses
- international occupational health
Statistics from Altmetric.com
- hygiene / occupational hygiene
- epidemiology
- public health
- pneumoconioses
- international occupational health
Key messages
What is already known about this subject?
Despite increasing recognition of pneumoconiosis as a contributor to poor health outcomes, our literature searches identified a relative scarcity of data about the global prevalence of pneumoconiosis.
What are the new findings?
The incidence patterns of pneumoconiosis caused by different aetiologies were found to have been heterogeneous across regions and among countries.
Asbestosis is increasing at a higher rate in some high sociodemographic index (SDI) countries.
Silicosis and coal workers’ pneumoconiosis were found to have been reduced in middle SDI and low SDI regions.
How might this impact on policy or clinical practice in the foreseeable future?
Our novel findings shed new light on measures of the global disease burden of pneumoconiosis, and can be used to help develop increasingly effective and targeted prevention strategies for pneumoconiosis.
Introduction
Pneumoconiosis is inclusive of a group of serious occupational diseases associated with the inhalation of mineral dusts and corresponding reactions of lung tissues.1 Pneumoconiosis can eventually induce irreversible lung damage and has the potential to cause progressive and permanent physical disabilities, and has afflicted tens of millions of workers employed in hazardous occupations globally.2 In 2016, pneumoconiosis was found to have caused 21 488 deaths on a global scale.3 The National Health Commission of China estimated that the total number of reported occupational-based cases up until 2018 was 97 500 and that 90% of reported occupational diseases were identified as pneumoconiosis.4 Between 1975 and 2007 based on an examination of a South African gold mine, the proportions of white miners and black miners with silicosis increased from 18% to 22% and from 3% to 32%, respectively.5
Since the discovery of pneumoconiosis in the 19th century, the prevention of occupational-based hazards and diseases has been mainly focused on control measures meant to help limit and reduce dust-caused, occupational-based hazards.6 The Joint International Labour Organization (ILO)/WHO Committee on Occupational Health established the ILO/WHO Global Programme for the Elimination of Silicosis following the recommendations of the 1995 12th Session, which called on world leaders to take appropriate steps for better prevention of silicosis.7 However, the numbers of newly diagnosed pneumoconiosis cases have increased on a global scale during the recent decades despite major types of public health measures having been made to counter this problem. The aetiologies of pneumoconiosis have been confirmed in previous epidemiological studies.8–11 Therefore, the heterogeneous incidence pattern of pneumoconiosis is directly related to the level of exposure to relevant risk factors in different geographical regions. Knowing the patterns which influence pneumoconiosis incidence and temporal trends can help to facilitate rational allocation of healthcare resources and functions in order to promote accurate and efficient prevention of pneumoconiosis.
The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 assessed 354 types of diseases and injuries across 195 countries and territories, and has therefore provided a unique perspective to help understand the landscape of and the dynamics underlying pneumoconiosis.12 13 Thus, in the current study, we sought to collect detailed information on the incidence of pneumoconiosis caused by four major aetiologies from the GBD Study 2017. We further sought to present results for annual incident cases, for age-standardised incidence rate (ASIR), and to determine the average annual percentage change (AAPC) of pneumoconiosis according to sex, across different regions, among different countries and among variable types of aetiologies, in order to determine trends in incidence of pneumoconiosis.
Methods
Study data
We collected annual incident cases and ASIRs of pneumoconiosis from the period spanning from 1990 to 2017 and according to classifications of sex, geographical region and aetiology (silicosis, asbestosis, coal workers’ pneumoconiosis and other pneumoconiosis) from across 195 countries and territories. The sociodemographic index (SDI) provides summary metrics for lagged distributed income per capita; mean years of education over the age of 15 years; and total fertility rate in women under the age of 25 years. These metrics were used to estimate a position on the development spectrum.12 The 195 countries and regions were classified into broader groups of five regions according to the SDI value, including low, low-middle, middle, high-middle and high SDI (online supplementary figure 1). Moreover, we divided the countries sampled across the world into 21 separate regions in terms of geography. We used data used from the GBD team in order to make estimates of pneumoconiosis derived predominantly from three main sources.12 The first source was based on resultant data from systematic reviews, and these were usually from smaller-scaled and relatively localised studies. The second source of data was derived from inpatient hospital reports, and the third source was based on finely reported claims-based data from the USA and Taiwan. A Bayesian meta-regression model (DisMod-MR V.2.1), as the main method of estimation in the GBD, is a type of mixed-effect model that borrows information across age, time and locations, and which controls and adjusts biases in data, and synthesises multiple sources of data into unified estimates of levels and trends. Final estimates are computed using the mean estimate across 1000 draws, and the 95% uncertainty intervals are determined on the basis of the 25th and 975th ranked values across all 1000 draws. A detailed description of the likelihood used for estimation and a full description of improvements made for DisMod-MR V.2.1 are described among the details within GBD 2017.12 All International Classification of Diseases-10 codes pertaining to pneumoconiosis (J60–J65.0, J92.0) were included in these estimates (online supplementary box 1).
Supplemental material
Statistical analysis
The incidence rate is reported per 100 000 people, and is derived from the number of annual cases divided by the population size. In order to compare several populations with different age structures, we used the GBD 2017 world standard population to calculate ASIRs and to quantify the trends in incidence of pneumoconiosis.14 We used the Joinpoint regression software (V.4.7.0.0), developed by the National Cancer Institute, in order to calculate measures of ‘AAPC of ASIR’, which is a summary of ASIR trends over a prespecified interval. These results are presented as AAPC with corresponding 95% CI. The meaning of results based on AAPC has been reported in previous studies.15 Briefly, if the AAPC and its 95% CI were both >0, the ASIR was indicated to have had a corresponding increasing trend. In contrast, if they were both <0, the ASIR was deemed to have had a corresponding decreasing trend.
We used locally weighted regression and smoothing scatterplot regressions in order to analyse all ASIRs and SDIs at 21 geographical regions across the globe from 1990 to 2017 and to determine expected measures of relationships between them. We compared the observed measures of pneumoconiosis ASIR with the expected levels in order to identify the state of development in regions, whereas performance was determined to have either been better or lower than expected. Additionally, we assessed measures of the association between SDIs (2017) and AAPCs at the national level.
Results
Globally, the incident cases of pneumoconiosis increased by a measure of 66.0%, from 36 186 cases in 1990 to 60 055 cases in 2017. The ASIR was found to have decreased by an average of 0.6% per year in the same period (from 0.86 per 100 000 in 1990 to 0.75 per 100 000 in 2017; table 1). In 2017, the incident cases and ASIR of pneumoconiosis were significantly higher in men than in women and were found to have peaked in individuals aged 65–69 years, followed by the highest incidences in the 70–74 years age group and then by the 80+ years age group (table 1, online supplementary figure 2). For SDI regions, the number of pneumoconiosis cases was found to have increased (figure 1), and there was a decrease in the ASIR from 1990 to 2017 (table 1). For geographical regions, except for three regions namely Central Europe, Eastern Europe and Western Europe, the absolute numbers of pneumoconiosis cases increased (table 1). As for measures of the ASIR, except for six regions namely Southeast Asia, Oceania, Australasia, high-income North America, North Africa and Middle East, and Western Sub-Saharan Africa, the ASIR of pneumoconiosis decreased (online supplementary figure 3). The most significant decrease was detected in Western Europe, and the most significant increase was detected in Australasia (table 1).
Pneumoconiosis cases caused by different aetiologies and by SDI regions from 1990 to 2017. CWP, coal workers’ pneumoconiosis; OP, other pneumoconiosis; SDI, sociodemographic index.
Incident cases and age-standardised incidence rate of pneumoconiosis in 1990 and 2017, and its temporal trends from 1990 to 2017
At the national and territorial level, the highest ASIR in 2017 was observed in Taiwan (China), followed by Papua New Guinea and then by China (figure 2A, online supplementary table 2). As for measures of the absolute number on a global scale, more than half of newly diagnosed pneumoconioses were recorded in China in 2017 (32 205), followed by India (5160) and then the USA (3324) (online supplementary table 2). The Netherlands and Belgium reported the largest decreases in pneumoconiosis ASIR between the measure in 1990 compared with the measure in 2017. In contrast, the largest increase in ASIR was observed in New Zealand (figure 2B, online supplementary table 2).
The global disease burden of pneumoconiosis for both sexes assessed for 195 countries and territories. (A) The ASIR of pneumoconiosis in 2017. (B) The AAPC of pneumoconiosis ASIR from 1990 to 2017. Countries with an extreme number of cases were annotated. ASIR, age-standardised incidence rate; AAPC, average annual percentage change of ASIR.
The proportions of pneumoconiosis caused by specific aetiologies at the global and regional level in 1990 and 2017 are presented in figure 3. Globally, approximately 40% of pneumoconioses were caused by crystalline silica, followed by coal dust, asbestos and other causes. The proportions significantly changed in some regions over time. For example, globally the proportion of asbestosis increased from 12% in 1990 to 16% in 2017, while the proportion specific to coal workers’ pneumoconiosis decreased from 27% to 25% during the same period. In the data for Australia, the proportion of asbestosis increased from 46% in 1990 to 78% in 2017, while the proportion for coal workers in this country for pneumoconiosis decreased from 27% to 8% during the same period. Similar results were observed in the high-income North American data set.
Contribution of the different types of pneumoconiosis to the absolute measures of incident cases of pneumoconiosis by region in 1990 and 2017. CWP, coal workers’ pneumoconiosis; OP, other pneumoconiosis; SDI, sociodemographic index.
Silicosis
Globally, 39% of the total pneumoconiosis cases (23 695) were ascribed to silicosis in 2017 (figure 3, table 1). From the period ranging from 1990 to 2017, the ASIR of silicosis displayed a decreasing trend. Silicosis cases increased and the ASIR decreased in all SDI regions (figure 1, online supplementary table 1). For geographical regions, five regions namely Central Europe, Eastern Europe, high-income Asia Pacific, Western Europe and Caribbean all reported a decrease in silicosis cases. Across the period from 1990 to 2017, the ASIR of silicosis displayed a minor increasing trend in Southeast Asia, North Africa and Middle East, and Western Sub-Saharan Africa, and indicated that AAPC of silicosis decreased in other regions (online supplementary table 1). At the national and territorial level, the highest measure of ASIR in 2017 was observed in China, and the highest AAPC was found in Singapore, followed in order by New Zealand and the American Samoa (online supplementary table 2).
Asbestosis
In 2017, asbestosis accounted for nearly 16% (9397) of the total number of pneumoconiosis cases (figure 3, table 1). Globally, the ASIR of asbestosis displayed an increasing trend from the period spanning from 1990 to 2017, with an AAPC of 0.6 (table 1). This was despite the incidence of pneumoconiosis due to asbestosis being under 0.10 per 100 000 in 2017 in most countries. For SDI regions, an increasing trend in asbestosis was observed in high SDI regions and low-middle SDI regions (online supplementary table 1). For geographical regions, except for the two regions, namely Eastern Europe and Western Sub-Saharan Africa, the absolute numbers of asbestosis cases increased in other regions. The greatest increase was found in Australasia (online supplementary table 1). At the national and territorial level, the highest rate in 2017 was observed in South Africa, followed by Swaziland and the USA, and the highest increase in asbestosis ASIR was observed in Australia, followed in order by New Zealand and Spain (online supplementary table 2).
Coal workers’ pneumoconiosis
In 2017, coal workers’ pneumoconiosis accounted for 25% (15 080) of the total pneumoconiosis cases, despite only 78 countries and territories reporting coal workers’ pneumoconiosis cases (figure 3, table 1). From the period spanning from 1990 to 2017, the ASIR of coal workers’ pneumoconiosis displayed a decreasing trend (table 1). The ASIR of coal workers’ pneumoconiosis decreased in all SDI regions over this period (online supplementary table 1). For geographical regions, only four regions namely Oceania, Western Sub-Saharan Africa, North Africa and Middle East, and Southeast Asia reported an increasing ASIR of coal workers’ pneumoconiosis, whereby the greatest increase was found in Oceania, and the AAPC of coal workers’ pneumoconiosis decreased in other regions (online supplementary table 1). With respect to countries and territories, the highest absolute numbers were observed in China (10 287), and relatively high ASIRs in 2017 were observed in Taiwan (China), followed by China and North Korea, with the highest increase in ASIR observed in New Zealand, followed next in order by Taiwan (China) and Montenegro (online supplementary table 2).
Other pneumoconiosis
In 2017, other pneumoconiosis accounted for 20% (11 883) of the total pneumoconiosis cases (figure 3, table 1). The global ASIR of other pneumoconiosis decreased by an average of 0.5% (table 1) per year from the period spanning from 1990 to 2017. The ASIR of other pneumoconiosis remained stable in high SDI regions and was found to have decreased in other SDI regions (online supplementary table 1). For geographical regions, data indicated that only five regions namely high-income North America, Southeast Asia, Oceania, Andean Latin America, and North Africa and Middle East reported an increasing ASIR of other pneumoconiosis, and the greatest increase was found in high-income North America, whereas AAPC of other pneumoconiosis was found to have decreased in other regions (online supplementary table 1). At the national and territorial level, the highest measures of ASIR were observed in Taiwan (China), followed next in order by Papua New Guinea (online supplementary table 2).
ASIRs, AAPCs and SDIs
The GBD regions of East Asia, Oceania, Southern Sub-Saharan Africa, Central Europe, Central Latin America, high-income Asia Pacific and high-income North America had higher observed ASIRs due to pneumoconiosis than was expected based on their SDI. Regions with better-than-expected pneumoconiosis ASIRs included the Caribbean, Western Europe, Western Sub-Saharan Africa, Central Asia, Andean Latin America, North and Middle Eastern Africa, and Southeast Asia (figure 4A). As shown in figure 4B, data indicated that there was a significantly negative association between AAPCs and SDIs in 2017 when the SDI value was above 0.7. In contrast, when SDI was limited to below 0.7, the association disappeared. A detailed result of the correlation between AAPC, ASIR and SDI, by specific aetiology, is provided in online supplementary figures 4 and 5.
(A) ASIR and the expected value based on the SDI, by regions from 1990 to 2017. The black line represents the expected value of an incidence rate based on a LOESS regression of all years of available estimates by GBD locations and by their SDI value. (B) Measures of correlation between AAPC and SDI in 2017. Circles represent countries and territories available on GBD data. The relative size of circles increased correspondingly with increases in the cases of pneumoconiosis in 2017. The blue line represents the expected value of AAPC based on a LOESS regression of all years of available estimates by SDI value in 2017. ASIR, age-standardised incidence rate; AAPC, average annual percentage change of ASIR; GBD, global burden of disease; LOESS, locally weighted regression and smoothing scatterplots; SDI, sociodemographic index.
Discussion
In this study, we comprehensively analysed trends in the incidence of pneumoconiosis caused by four aetiologies at the global, regional and national levels. Globally, there was a decrease in the ASIR of pneumoconiosis across all the years from 1990 to 2017. However, there were significant differences in the trends of incidence across the world. This can be illustrated briefly by the observance of a significant decrease in the trends of pneumoconiosis ASIR in middle SDI and low SDI regions, which were primarily dominated by the reductions in silicosis and coal workers’ pneumoconiosis. Conversely, in high SDI regions, there was a minor decreasing trend in pneumoconiosis ASIR, which was mostly attributed to a dramatic decrease in silicosis and an increase in asbestosis. The pattern of incidence of exposure to risk factors was heterogeneous16 17; however, if we had only looked at the total number or the rate of pneumoconiosis cases as a whole, important findings and actual trends of individual types of pneumoconiosis may have been missed, and such dynamics can lead to complications in efforts to prevent pneumoconiosis across the world. Therefore, knowing the exact patterns of incidence of pneumoconiosis and corresponding temporal trends is critical for the accurate prevention of pneumoconiosis.
These findings are in agreement with those from previous research suggesting that crystalline silica remains the most important risk factor for pneumoconiosis.18 Although silicosis had higher ASIRs in both high and middle SDI regions, including East Asia (mainly China) and Oceania, they have been declining overall during the recent decades. A possible explanation for this finding might be that the prevention of pneumoconiosis through specific steps and increasing awareness of self-protection have greatly improved during these decades. For example, in order to strengthen surveillance for this and other types of occupational diseases, the Network Direct Report System of Occupational Diseases was constructed in 2006 in China.2 6 Surprisingly, a significantly negative association was found between AAPCs and SDIs when measures of the SDI were above 0.7 in silicosis, although the rate of incidence of silicosis was found to have had relatively fast growth in some high and high-middle SDI countries, including Singapore and New Zealand. Additionally, in recent years, an increasing level of attention has been paid to rapidly emerging problems related to silicosis, including shorter latency periods, that is, 4–10 years, which are associated with occupational exposure to silica dust generated by manufacturing, finishing and installation of artificial stone.19 20 It is possible that as a result, peaks in the rates of this new silicosis epidemic might be observed in the next 3–5 years, most notably perhaps in Israel, Spain and Australia.20 21
Asbestosis was found to have had higher numbers of cases and ASIRs in high SDI regions, including Australasia (mainly Australia) and high-income North America. Mining, processing and transportation of raw asbestos are high-risk occupations for asbestosis.22–24 Moreover, economic issues surrounding asbestos and the financial implications from growing worldwide legal implications have largely affected changes in the incidence of asbestosis.23–26 For example, mainly due to the ban on the use of asbestos in Europe for about the last 30 years,22 we found that the incidence of asbestosis has decreased significantly. Despite these promising advances and our positively oriented results, questions remain, such as when we found that the Netherlands reported the largest decrease in pneumoconiosis ASIR between 1990 and 2017 while the ASIR of asbestosis increased during the same period. Australia is one of the countries with the highest incidence of asbestos-related lung disease in the world, and the ban on the importation of asbestos was issued only in 2004. Lessons taken from Australia might have important implications for countries currently still using asbestos, whereby reducing asbestos use, implementation of careful monitoring, and improving the levels of management, diagnosis, treatment and compensation for asbestosis cases can further the prevention of asbestosis and accelerate progress towards ‘Sustainable Development Goal 8’, which promotes ‘full and productive employment and decent work for all’.
In 2017, coal workers’ pneumoconiosis accounted for 25.11% of the total pneumoconiosis cases, despite only 78 countries and territories reporting coal workers’ pneumoconiosis cases. Correspondingly, coal workers’ pneumoconiosis had the highest absolute numbers in China, while the ASIR was also found to have been decreasing over the last couple of decades. In contrast, in New Zealand, Taiwan (China) and Montenegro, there has been an increasing trend. Government-based operations and progressive coal mining companies have recently chosen to put more energy and money into production safety with respect to trade-offs between ‘visible and immediate accidents’ and ‘invisible and chronic lung diseases’, which can seriously damage coal miners’ lives and health.27–30
Apart from silicosis, asbestosis and coal workers’ pneumoconiosis, diseases such as aluminosis, berylliosis, siderosis and stannosis were integrated into the category of ‘other types of pneumoconiosis’ in the 2017 GBD study.13 From 1990 to 2017, the overall ASIR of other types of pneumoconiosis showed a minor decreasing trend. However, a study showed that, although 23% of pneumoconiosis cases are attributed to other pneumoconiosis, most are actually due to silicosis, asbestos or coal workers’ pneumoconiosis and related to incomplete coding in the source data.3 Therefore, we should consider the findings in light of the totality of evidence which has provided these specific types of, and other forms of, data on the incidence of pneumoconiosis.
It should be noted that our study has several limitations. First, the GBD 2017 measures are probably underestimates of cases and ASIRs associated with pneumoconiosis, and because the quality and quantity of data used in modelling to determine the accuracy and robustness of GBD estimation of a number of cases are not perfect.12 13 For example, clinical data records have been demonstrated to have selection biases based on the subsets of the population who have access to healthcare.31 Further, data reported by some countries and territories are based on only diagnosed cases, and the low frequency of occupational-oriented health checks as well as the narrow range of diseases defined within the occupational diseases list. Thus, there are still a high number of unreported and undiagnosed cases. Second, we have not performed a detailed analysis of the occupational risk factors for our pneumoconiosis-related results. Additionally, although reflecting a certain and identifiable trend, the results for pneumoconiosis should be considered as largely reflecting past exposures, and this aspect requires further analysis.
Conclusions
In summary, pneumoconiosis continues to be one of the major and significant occupational health-related hazards and subsequent illnesses in the world. On one hand, although the world has attained great achievements in the prevention of silicosis and coal workers’ pneumoconiosis, these remain as important health problems in some countries and territories. On the other hand, asbestosis is increasing at a higher rate in some high SDI countries. The novel findings reported herein help to shed new light on the global disease burden of pneumoconiosis. Our hope is that these estimates of pneumoconiosis incidence and their longer-term trends will help public health officials, scholars and policymakers to better assess and identify more effective and targeted pneumoconiosis prevention and intervention strategies at national and international scales in order to reduce the burden of disease from pneumoconiosis.
Acknowledgments
We appreciate the work by the Global Burden of Disease Study 2017 collaborators. We express our gratitude to the reviewers and editor of the journal for their valuable comments for improvement of the paper.
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
PS and XX contributed equally.
Contributors All authors contributed to the study concept and design. PS wrote the first draft of the report. PS, XX, HJ, JY, ZF and HZ did the collection and analysis. PS, XX and SX reviewed and revised the manuscript before submission. All authors approved the final submitted version.
Funding This work was supported by the National Natural Science Foundation of China (NSFC) (81673207 and 81373023).
Disclaimer This manuscript has been posted to Research Square as a pre-print (https://www.researchsquare.com/article/df29da45-60d0-43cc-a6b1-4b5d18231674/v1).
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available in a public, open access repository. The data sets generated and/or analysed during the current study are available in the Global Health Data Exchange (GHDx) query tool (http://ghdx.healthdata.org/gbd-results-tool).