The Work So Far ...
Data from the spreadsheet was abstracted and a new data table was created that contained the following information:
1. The name of the country where the screening for breast cancer,
2. The percentage reduction in the usage of HRT between peak use and the last reported use
3. The percentage reduction in the reported incidence for the corresponding years for the relevant age groups (50-64+)
4. The Age Range at which Screening for Breast Cancer using Mammograms begin. If the age range was 50-64 years, it was given a code of 1, else if the age at which mammogram began was earlier (that is for younger age), the Age range variable was assigned a code of 2.
In addition to this, data from the papers by Verkooijen et al (Verkooijen 2009) and Zbuk et al(Zbuk 2012) were extracted. For each of these data, the following information were abstracted from each paper
1. The name of the country where the study was conducted 2. The percentage of reduction from peak HRT usage till the date when it was reported 3. The reduction in percentage in the corresponding breast cancer incidence as reported in the paper.
These were presented in a corresponding table abstracted from the papers (see Figures 1 and 2). For each of the three data, a linear regression model was run to study the extent to which reduction in the HRT usage might explain the reduction in the incidence of Breast Cancer. For the current dataset, in addition, the relationship between the reduction in Breast Cancer and the HRT usage was further adjusted for by including the age at which screening begins.