Development of a reliable and valid questionnaire to test the prostate cancer knowledge of men with the disease.

Several prostate cancer knowledge questionnaires exist but none have demonstrated both reliability and validity when used by men with the disease. This study aims to develop a reliable and valid knowledge questionnaire for men with prostate cancer. After developing a 40-item Prostate Cancer Knowledge Questionnaire (PCKQ-40) in phase I, it was piloted in phase II with 391 medical students. This resulted in the reduction of the tool by removing items of poor discriminatory value. A balance between true and false items and content domains was also maintained in the reduced scale. The PCKQ-12 had a moderate internal consistency. Phase III of the study assessed the reliability and construct validity of the tool by measuring the prostate cancer knowledge levels of men with prostate cancer (n=28), men with other cancers (n=10) and men without cancer (n=84). Men with prostate cancer achieved significantly higher PCKQ-12 scores compared with men without cancer, supporting the construct validity of the tool. The tool's reliability was also confirmed with a moderate internal consistency. This study provides some evidence for the reliability and validity of the PCKQ-12 and supports its use with men with prostate cancer in further research.