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Table 8 Summary of the scope of the analysis: The most important limitations and research needs

From: The burden of chronic mercury intoxication in artisanal small-scale gold mining in Zimbabwe: data availability and preliminary estimates

Scope of the analysis Limitations Research needs
Research aim: A first estimate of the DALYs of chronic mercury intoxication following occupational mercury use in ASGM on a national scale by using the methods applied in the GBD 2004 update and by using available data and information. Data from earlier research projects are used while no special data survey was done to achieve the research aim. Conduct surveys to improve the data basis for DALY estimates.
Use the advanced methods to determine DALYs.
Applying the methods of the GBD 2004 update because of the consistent reference year (2004) to enable comparisons while more advanced methods are available (GBD 2010 study [87]).
Conduct research to develop the DALY method (already started within the GBD 2010 study [87]).
Specific limitations of the summary measure DALY (e.g., ethical concerns about using disability weights) are included in the analysis.
Subgroup of interest: ASG miners (panners and smelter workers) with occupational exposure to mercury who work and live at a mining site. Miners with acute, temporary or ending involvement in mining were not considered. Conduct surveys to differentiate between subgroups of miners (duration of involvement, type of work, etc.) and to determine the burden of other exposed subgroups not or no longer actively involved in mining.
No differentiation of burden between panners and smelter workers.
Other exposed subgroups (retired miners, residents at mining sites like the families of miners, etc.) were not considered.
Underlying sample: 181 ASG miners in Kadoma; 91 controls from Chikwaka; surveyed in 2004 and 2006. Small sample size. Conduct comprehensive surveys at several mining sites in Zimbabwe using samples of adequate size.
The sample included data from two projects conducted during two different survey periods.
All the information came from just one mining site in Zimbabwe (Kadoma).
Study population, country of interest, and reference year: ASG miners in Zimbabwe in 2004. Contradictory information on number, age, and sex distribution of ASG miners in Zimbabwe. Verify the estimates of the number, age, and sex distribution of ASG miners in Zimbabwe.
No information about the burden in other years (e.g., the current burden) and other countries (e.g., Colombia).
Quantify DALYs from other years and mining sites for comparison.
No information about the burden when using mining methods and tools different from those in Kadoma.
Determine the health burden resulting from different mining methods and tools.
Health outcome: Chronic mercury intoxication as defined using the diagnostic tool developed by Drasch et al. [32]; assessed with a DW of 0.18; no remission; no mortality; no treatment. Specific limitations of the diagnostic tool are included in the analysis (e.g., no correcting factor for health effects unrelated to mercury; all items of the medical score sum are weighted equally). Conduct research to develop an improved diagnostic tool.
There is no established and internationally accepted diagnosis for chronic mercury intoxication.
Establish an internationally accepted algorithm diagnosis for chronic mercury intoxication.
There is no DW for chronic mercury intoxication; a provisional DW was used.
Derive a DW for chronic mercury intoxication.
Remission and mortality data are scarce.
Conduct cohort studies to verify the assumptions of no remission and no mortality.
Data modeling: Lacking data were modeled using DisMod II. It was necessary to model missing data. Improve the data basis to allow analyses without modeled data.
Specific limitations of DisMod II are included in the analysis.
  1. ASG: artisanal small-scale gold; ASGM: artisanal small-scale gold miners; DALYs: disability-adjusted life years; DisMod II: Disease Model, second version, a software tool developed by the World Health Organization; DW: Disability Weight; GBD: Global Burden of Disease and Injury.