Coal Workers Pneumoconiosis (CWP) Research Plan

Coal Workers Pneumoconiosis (CWP) Research Plan MOHAMMAD FAISAL Collection of Data A.1. What were the objectives of the study? What was the association of interest? The objectives of the study were to examine the association of the prevalence of coal workers pneumoconiosis (CWP) in the USA and different contributing factors such as level of dust exposure, mine size, low seam mining and other factors. Also the regional differences in CWP were compared. The association of interest is between CWP and various contributing factors and also between different MSHA district regions. It was a cross-sectional study. A.2. What was the primary outcome (usually a disease, health condition, or other dependent variable) of interest? Briefly explain how the outcome was measured. The primary outcomes were observed and predicted prevalence in CWP prevalence in miners who participated in this study. Attfield and Morring Exposure response model was utilized to measure the predicted prevalence in CWP and the Chi-square test was used to compare the predicted and observed prevalences in CWP in miners. Radiographs were used to determine the presence of lung parenchymal abnormalities that are consistent with pneumoconiosis obtained from CWHSP. A.3. What was the primary exposure (actual exposure such as chemical, other risk factor, or other independent variable) of interest? Briefly explain how exposure was measured. The primary exposures were level of dust exposure concentration, mine size, tenure, seam height. These data were collected from CWHSP, approved by the NIOSH Human Subjects Review Board. Coal mine dust concentration and seam height data were obtained from MSIS. A.4. What type of study was conducted (study design)? This was a cross sectional study, which was done with a large number of participants from survey data. A.5. Describe the process of subject selection.   Define the source population for this study, if possible. The study participants were 12,408 underground coal miners from the MSHA districts. Participation in this CWHSP study were voluntary and study participants were 16 years and older. Due to small number of participants and different type of coal type (anthracite rather than bituminous), MSHA district 1 participants were excluded. The source population was all the underground coal miners in MSHA districts in USA. A.6. Selection bias: What are possible sources in this study? Examples: in a case-control study, how were the study subjects included? In a cohort study, is there loss to follow-up?   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   The study participants (underground coal miners) in this CWHSP study were stratified by MSHA districts. Since stratified analyses are important in this study, the probability of being selected in a specific stratum might be different from another stratum and thus a selection bias might have happened. A.7. Information bias: What are some of the sources of information (measurement) error, for either the exposure or outcome measurement? Are these differential with respect to the exposure or outcome of interest? For exposure measurement, the investigators analyzed the self reported tenure in mining to derive the cumulative exposures. Also current exposures were examined for CWP which may not establish temporal relationship due to lack of allowance for lag time. A.8. Confounding: Did the authors consider potential confounders in the design of the study? The authors considered the following confounders: miner age and coal rank because the effect of respirable coal mine dust can be modified by the rank of the coal.   Ã‚  Ã‚   B. Analysis of Data B.1. What methods were used to control confounding? Were these sufficient (as far as you can tell)? As mentioned in the report the investigators incorporated all of the above mentioned covariates in their exposure-response statistical models to control for confounding. No detailed description is found about controlling the confounders. B.2. What measure of association (e.g. odds ratio, risk ratio, rate difference, etc.) was reported in the study? Was this appropriate? The authors reported the prevalence of the CWP and prevalence ratio between different MSHA district regions in this study. Since this is a survey based study, prevalence ratio is appropriate. B.3. How was the uncertainty of the measure of association (effect of random error or statistical significance) reported in this study? Are the conclusions of the study consistent with the uncertainty of the measure of association? The authors did not report 95% confidence intervals to report the uncertainty of the measure. However they reported the range of measured dust concentration level, worked hours per miners and tenure median. The prevalence ratio was statistically significant (p