Patients
The South Australian Prostate Cancer Clinical Outcomes Collaborative (SA-PCCOC) prospectively collects clinical and oncological information on RALP cases performed in both the public and private sector in South Australia, Australia. Utilising this database, we identified patients who fulfilled the following inclusion criteria: they had undergone RALP by a high volume surgeon (> 50 cases per annum), received an assessment and education by a specialist pelvic floor physiotherapist, had completed EPIC questionnaires before treatment and did not have radiotherapy treatment within 12 months of surgery.
MUL Measurements
Accurate MUL measurements were taken from the patients’ pre-operative magnetic resonance imaging (MRI) scans. To maintain consistency with the published literature, measurements were taken in an identical fashion to other authors. The MUL was measured along a straight line between the prostatic apex and the penile bulb in both the mid-sagittal plane and the coronal plane. A consultant radiologist demonstrated how measurements should be taken and the readings were recorded separately by two independent reviewers (DL and RD) and cross-checked. Any discrepancy of more than 10% resulted in a repeat measurement to obtain a third reading.
Patient Reported Outcome Measures
The 26-item short-form version of the Expanded Prostate Cancer Index Composite (EPIC-26) was used to measure outcomes. The EPIC is a validated tool used to assess quality of life outcomes in men who have undergone treatment for prostate cancer.3 The four questions listed below from EPIC-26 pertain to urinary continence:
• Q23: Over the past 4 weeks how often have you leaked urine?
More than once a day (1); Once a day (2); More than once a week (3); About once a week (4); Rarely or never (5)
• Q26: Which of the following best describes your control during the last 4 weeks?
None (1) ; Frequent dribbling (2); Occasional dribbling (3); Total control (4)
• Q27: How many pads or diapers per day did you use during the last 4 weeks?
None (0) ; 1 per day (1) ; 2 per day (2) ; 3 or more (3)
• Q28: How big a problem during the last 4 weeks had dripping or leaking of urine been?
No problem (0) ; Very small problem (1) ; Small problem (2) ; Moderate problem (3); Big problem (4)
The highest mark for each question was given 100 points. The total score was calculated as an average of each question. Continence was defined as 100/100 in the EPIC26 Urinary Continence domain score. The EPIC26 was repeated at baseline, 3, 6 and 12 months. Baseline was defined as any time after the date of diagnosis and prior to RALP.
Statistics
Linear regression was used to assess correlation between sagittal and coronal measurements of MUL. To assess the association of MUL with continence at baseline and separately at 12 months post RALP, a logistic regression model was used. Continence was deemed to be and EPIC-26 score of 100 before treatment, and incontinence a score less than 100. A linear model was used to assess change in continence between baseline and 12 months post treatment. To assess continence from 3–12 months a mixed effect linear model was used. A further logistic regression model was used to assess return to baseline continence in the subset of men who were continent prior to surgery. Statistical analysis was performed in R and p < 0.05 considered to be statistically significant.
Ethics
This study uses data collected retrospectively as part of the South Australian Prostate Cancer Clinical Outcomes Collaborative Database. The database has been reviewed and approved by the Southern Adelaide Human Research Ethics Committee (307.14). The database informs participants about the study, and uses an approved opt-out consent process. Informed consent was obtained from all individual participants included in the study (through the opt-out mechanism). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (Southern Adelaide Human Research Ethics Committee (307.14)) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.