DOI: 10.5061/dryad.v6wwpzh4b
title: Converting between the International Prostate Symptom Score (IPSS) and the Expanded Prostate Cancer Index Composite (EPIC) urinary subscales: modeling and external validation

description: Background: Prostate-related quality of life can be assessed with a
 variety of different questionnaires. The 50-item Expanded Prostate Cancer
 Index Composite (EPIC) and the International Prostate Symptom Score (IPSS)
 are two widely used options. The goal of this study was, therefore, to
 develop and validate a model that is able to convert between the EPIC and
 the IPSS to enable comparisons across different studies. 
 Methods: Three hundred forty-seven consecutive patients who had previously
 received radiotherapy and surgery for prostate cancer at two institutions
 in Switzerland and Germany were contacted via mail and instructed to
 complete both questionnaires. The Swiss cohort was used to train and
 internally validate different machine learning models using fourfold
 cross-validation. The German cohort was used for external validation.
 Results: Converting between the EPIC Urinary Irritative/Obstructive
 subscale and the IPSS using linear regressions resulted in mean absolute
 errors (MAEs) of 3.88 and 6.12, which is below the respective previously
 published minimal important differences (MIDs) of 5.2 and 10 points.
 Converting between the EPIC Urinary Summary and the IPSS was less accurate
 with MAEs of 5.13 and 10.45, similar to the MIDs. More complex model
 architectures did not result in improved performance in this study. The
 study was limited to the German versions of the respective questionnaires.
 Conclusions: Linear regressions can be used to convert between the IPSS
 and the EPIC Urinary subscales. While the equations obtained in this study
 can be used to compare results across clinical trials, they should not be
 used to inform clinical decision-making in individual patients. Trial
 registration This study was retrospectively registered on
 clinicaltrials.gov on January 14th, 2022, under the registration number
 NCT05192876.
description: # Converting between the International Prostate Symptom Score (IPSS) and
 the Expanded Prostate Cancer Index Composite (EPIC) urinary subscales:
 modeling and external validation
 [https://doi.org/10.5061/dryad.v6wwpzh4b](https://doi.org/10.5061/dryad.v6wwpzh4b) The study was conducted in radiation oncology departments at two institutions, the Cantonal Hospital Winterthur in Switzerland and the Ruppiner Kliniken GmbH in Germany. Three hundred and forty-seven consecutive patients who had received radiation therapy for prostate cancer in the post-operative setting at our institutions between 2010 and 2020 were identified and received the German versions of the EPIC and IPSS questionnaires in August 2020, unless a date of death had been documented in our electronic health records. Patients completed the questionnaires based on their current quality of life and symptom burden. We received responses from 208 patients. Of these responses, 175 had no missing values for any of the quality of life questionnaires and a signed informed consent. Responses to the questionnaires were collected and anonymized. ## Description of the data and file structure Each row in the table represents a patient and their response. For each patient, there are the following columns: * Hospital: Which hospital treated the patient (KSW = Cantonal Hospital Winterthur, UKRB = Ruppiner Kliniken GmbH). * EPIC_1: The response to the EPIC question "Over the past 4 weeks, how often have you leaked urine?". Possible answers: More than once a day (1), About once a day (2), More than once a week (3), About once a week (4), Rarely or never (5). * EPIC_2: The response to the EPIC question "Over the past 4 weeks, how often have you urinated blood?". Possible answers: More than once a day (1), About once a day (2), More than once a week (3), About once a week (4), Rarely or never (5). * EPIC_3: The response to the EPIC question "Over the past 4 weeks, how often have you had pain or burning with urination?". Possible answers: More than once a day (1), About once a day (2), More than once a week (3), About once a week (4), Rarely or never (5). * EPIC_4: The response to the EPIC question "Which of the following best describes your urinary control during the last 4 weeks?". Possible answers: No urinary control whatsoever (1), Frequent dribbling (2), Occasional dribbling (3), Total control (4). * EPIC_5: The response to the EPIC question "How many pads or adult diapers per day did you usually use to control leakage during the last 4 weeks?". Possible answers: None (0), 1 pad per day (1), 2 pads per day (2), 3 or more pads per day (3). * EPIC_6a: The response to the EPIC question "How big a problem, if any, has each of the following been for you during the last 4 weeks - Dripping or leaking urine?" Possible answers: No problem (0), Very Small Problem (1), Small Problem (2), Moderate Problem (3), Big Problem (4). * EPIC_6b: The response to the EPIC question "How big a problem, if any, has each of the following been for you during the last 4 weeks - Pain or burning on urination?" Possible answers: No problem (0), Very Small Problem (1), Small Problem (2), Moderate Problem (3), Big Problem (4). * EPIC_6c: The response to the EPIC question "How big a problem, if any, has each of the following been for you during the last 4 weeks - Bleeding with urination?" Possible answers: No problem (0), Very Small Problem (1), Small Problem (2), Moderate Problem (3), Big Problem (4). * EPIC_6d: The response to the EPIC question "How big a problem, if any, has each of the following been for you during the last 4 weeks - Weak urine stream or incomplete emptying?" Possible answers: No problem (0), Very Small Problem (1), Small Problem (2), Moderate Problem (3), Big Problem (4). * EPIC_6e: The response to the EPIC question "How big a problem, if any, has each of the following been for you during the last 4 weeks - Waking up to urinate?" Possible answers: No problem (0), Very Small Problem (1), Small Problem (2), Moderate Problem (3), Big Problem (4). * EPIC_6f: The response to the EPIC question "How big a problem, if any, has each of the following been for you during the last 4 weeks - Need to urinate frequently during the day?" Possible answers: No problem (0), Very Small Problem (1), Small Problem (2), Moderate Problem (3), Big Problem (4). * Urinary_Summary: The Urinary Summary domain of the EPIC. * Urinary_Function: The Urinary Function domain of the EPIC. * Urinary_Bother: The Urinary Bother domain of the EPIC. * Urinary_Incontinence: The Urinary Incontinence domain of the EPIC. * Urinary_Irritative_Obstructive: The Urinary Irritative/Obstructive domain of the EPIC * IPSS_1: The answer to the IPSS question "Over the past month, how often have you had a sensation of not emptying your bladder completely after you finish urinating?" Possible answers: Not at all (0), Less than 1 time in 5 (1), Less than half the time (2), About half the time (3), More than half the time (4), Almost always (5). * IPSS_2: The answer to the IPSS question "Over the past month, how often have you had to urinate again less than two hours after you have finished urinating?" Possible answers: Not at all (0), Less than 1 time in 5 (1), Less than half the time (2), About half the time (3), More than half the time (4), Almost always (5). * IPSS_3: The answer to the IPSS question "Over the past month, how often have you found you stopped and started again several times when you urinated?" Possible answers: Not at all (0), Less than 1 time in 5 (1), Less than half the time (2), About half the time (3), More than half the time (4), Almost always (5). * IPSS_4: The answer to the IPSS question "Over the past month, how often have you found it difficult to postpone urination?" Possible answers: Not at all (0), Less than 1 time in 5 (1), Less than half the time (2), About half the time (3), More than half the time (4), Almost always (5). * IPSS_5: The answer to the IPSS question "Over the last month, how often have you had a weak urinary stream?" Possible answers: Not at all (0), Less than 1 time in 5 (1), Less than half the time (2), About half the time (3), More than half the time (4), Almost always (5). * IPSS_6: The answer to the IPSS question "Over the past month, how often have you had to push or strain to begin urination?" Possible answers: Not at all (0), Less than 1 time in 5 (1), Less than half the time (2), About half the time (3), More than half the time (4), Almost always (5). * IPSS_7: The answer to the IPSS question "Over the past month how many times did you most typically get up each night to urinate from the time you went to bed until the time you got up in the morning?" Possible answers: Not at all (0), Less than 1 time in 5 (1), Less than half the time (2), About half the time (3), More than half the time (4), Almost always (5). * IPSS_Total: The sum of the answers to the IPSS questions. ## Sharing/Access information The data is also available from a github repository  * [https://github.com/windisch-paul/EPIC-IPSS-converter](https://github.com/windisch-paul/metastatic_vs_local) ## Code/Software The python script that was used to train the models referenced in the associated publication is available as "EPIC_IPSS_analysis.ipynb" from the repository ([https://github.com/windisch-paul/EPIC-IPSS-converter](https://github.com/windisch-paul/EPIC-IPSS-converter)).