Approximately 38,000 males were randomized into the intervention arm. Each was expected to comply with up to four (T0-T3) digital rectal exams (DREs) and, depending on when he was randomized, between four (T0-T3) and six (T0-T5) annual blood draws. Each draw was sent to a central lab to assess the level of prostate specific antigen (PSA). Overall, about 177,000 PSA exams and 128,000 DREs (almost always concurrent with the PSA exam) were conducted among 36,000 men who complied with at least one screen.
PSA results are contained in the data in both numeric/quantitative form (e.g., 2.6 ng/ml) and summarized/qualitative result (i.e., negative, positive, inadequate), where levels above 4.0 ng/ml are considered positive. DRE cancer screening results are contained in the data as a summarized/qualitative result (i.e., negative, abnormal suspicious, abnormal non-suspicious, inadequate). Additional findings (e.g., prostate size, number of indurations) are also captured.
In the data, a DRE result in a study year is almost always given as the result of one DRE done during one visit to the screening center. However, there are some exceptions. For one, about 4700 DREs had an accompanying quality assurance (QA) DRE. For these screens, if the QA result was more severe than that of the scheduled protocol screen (severity: abnormal suspicious > abnormal non-suspicious > negative > inadequate) then the DRE result for that year is that of the QA screen. This occurred in about 550 of the 4700 DREs with QA. A much more infrequent exception regards a handful of inadequate DREs that were reattempted at a later visit. If the second attempt yielded an adequate result, then the DRE result for that year is that adequate result.
For most purposes, screening data can be obtained within the Prostate dataset. Additional details are contained within the Prostate Screening dataset (one record per screening study year per person) or the Prostate Screening Abnormalities dataset (one record per DRE abnormality per person).