15250-m-cuypers

50 Chapter 3 2. METHODS 2.1 Participants and recruitment Between January 2013 and May 2014, ten Dutch hospitals participated in this study and recruited 388 patients who were scheduled for a first prostate biopsy due to suspected Pca (M age =66.5, SD=6.6; Figure 1). A host hoc power analysis revealed that this sample size was sufficient to achieve a power of .80 for detecting differences with an effect size fromCohen’s d =.2 (with alpha .05). During consultation, patients were informed that the goal of the study was to investigate quality of care in prostate examination and quality of life of patients undergoing this procedure. Together with an information letter, patients received the first questionnaire (t0) on paper and a pre-stamped envelope to return the questionnaire. Follow-up questionnaires were sent to patients whose biopsy result confirmed Pca. These patients received this second questionnaire and a pre- stamped envelope at their home address within two weeks after treatment decision- making (t1). Diagnosis and the moment of treatment decision-making were monitored for all included patients from their (electronic) medical record. After review of the study protocol, the medical ethics review board of the initiating hospital waived the need for formal ethical approval (reference 2012.103) and all participating hospitals approved conducting the study. All patients signed informed consent. 2.2 Questionnaires 2.2.1 Demographics and clinical data Participants were asked to indicate their age, education, marital status, last known prostate specific antigen (PSA) level, and choice of treatment. PSA levels were asked at both t0 and t1 to control for the possibility that treatment had already taken place before completing the t1 questionnaire. 2.2.2 Health-related quality of life Health-related quality of life (HRQoL) was measured with the Dutch version of the EORTC QLQ-C30 questionnaire, which assesses functional HRQoL aspects (physical, role, cognitive, emotional, and social functioning, and global health) and symptoms common for cancer patients (fatigue, nausea, pain, dyspnea, sleep disturbance, appetite loss, constipation, diarrhea, and financial impact) 26 . The prostate cancer-specific EORTC QLQ-PR25 module was added to assess prostate cancer specific (urinary, bowel, and hormonal) symptoms and (sexual) functioning 27 . Scale reliability was low for the bowel and hormonal symptoms, and sexual activity subscale (alpha’s 0.50-0.60), and adequate (alpha ≥0.70) for all other subscales. Similar scale reliability scores have been found earlier 27 .