Differences in Quality of Life between German and Dutch Patients with Prostate Cancer Treated with Robot-assisted Radical Prostatectomy: Implications for International Multicenter Randomized Controlled Trials.

BACKGROUND: As a local treatment for prostate cancer (PCa), robot-assisted radical prostatectomy (RARP) may have a quality of life (QoL) benefit over open surgery. Recent analyses revealed substantial between-country differences in the function and symptom scale scores for the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30), which is typically used to assess patient-reported QoL. Such differences could have implications for multinational studies in PCa. OBJECTIVE: To examine whether nationality is significantly associated with patient-reported QoL. DESIGN, SETTING, AND PARTICIPANTS: The study cohort comprised Dutch and German patients with PCa treated with RARP in a single high-volume prostate center from 2006 to 2018. Analyses were restricted to patients who were preoperatively continent with at least one follow-up time point. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: QoL was measured in terms of the global Quality of Life (QL) scale score and the overall summary score for the EORTC QLQ-C30. Linear mixed models for repeated-measures multivariable analyses (MVAs) were used to examine the association between nationality and both the global QL score and the summary score. MVAs were further adjusted for QLQ-C30 baseline values, age, Charlson comorbidity index, preoperative prostate-specific antigen, surgical expertise, pathological tumor and nodal stage, Gleason grade, degree of nerve-sparing, surgical margin status, 30-d Clavien-Dindo grade complications, urinary continence recovery, and biochemical recurrence/postoperative radiotherapy. RESULTS AND LIMITATIONS: For Dutch (n = 1938) versus German (n = 6410) men, the mean baseline scores were 82.8 versus 71.9 for the global QL scale score and 93.4 versus 89.7 for the QLQ-C30 summary score. Urinary continence recovery (QL: +8.9, 95% confidence interval [CI] 8.1-9.8; p < 0001) and Dutch nationality (QL: +6.9, 95% CI 6.1-7.6; p < 0001) were the strongest positive contributors to the global QL and summary scores, respectively. The main limitation is the retrospective study design. In addition, our Dutch cohort may not be representative of the general Dutch population and reporting bias cannot be ruled out. CONCLUSIONS: Our findings provide observational evidence under specific conditions involving the same setting for patients of two different nationalities suggesting that cross-national patient-reported QoL differences appear to be real and may need to be taken into consideration in multinational studies. PATIENT SUMMARY: We observed differences in the quality-of-life scores reported by Dutch and German patients with prostate cancer after they underwent robot-assisted removal of the prostate. These findings should be taken into consideration in cross-national studies.