The IUSS questionnaire was developed by Nixon et al. [8]. The UPS questionnaire was developed by Cardozo et al. [9]. The USS was developed by Chung et al. [10] by modifying the IUSS. The PPIUS was developed by Cartwright et al. [11].

This study was approved by the Institutional Review Board of the Seoul Metropolitan Government - Seoul National University Boramae Medical Center (approval number: 26-2016-60). A linguistic validation procedure was implemented to obtain translated Korean versions of the IUSS, UPS, USS, and PPIUS questionnaires that should be conceptually equivalent to the original questionnaires. The procedure of translation and linguistic validation was performed following a well-established process that consisted of forward translation, reconciliation, back-translation, cognitive debriefing, and proofreading, as described in previous investigations [12-14].

In each step of the process, all translators and a panel consisting of 2 Korean experts (SJO and SYC) commented on the difficulty and naturalness of the translations and alternative translation options.

The panel contacted all copyright holders of each questionnaire, and requested and acquired permission to translate and utilize a Korean version of each questionnaire.

Two trained bilingual translators independently translated the original version of each questionnaires into conceptually equivalent Korean phrasing (version 1.0a and 1.0b). The translators did not have a medical license, and they were forbidden to contact each other.

The 2 independently translated versions were compared by the panel, including both independent translators, and were reconciled considering delicate cultural differences and linguistic nuances into a single new version (version 1.1).

A third bilingual translator received the reconciled Korean version of each questionnaire (version 1.1), and back-translated it into English. The back-translated English version of each questionnaire was compared with the original English version. The panel, including all translators, discussed the translations and made changes (version 1.2).

The questionnaires (version 1.2) were given to 5 Korean-speaking patients with OAB with different educational backgrounds. They were asked whether the questionnaires were understandable, clear, and intuitive. After the interview, the panel discussed the patients’ responses, and agreed on a new version (version 1.3).

Version 1.3 was proofread by the panel to check for grammatical problems and availability for evaluating OAB (version 1.4).

As shown in Table 1, all items of the IUSS, USS, PPIUS, and UPS questionnaires were translated into Korean by 2 independent translators. The transcriptions given below of the Korean text of the translated questionnaires follow the official Revised Romanization of Korean system developed by the National Academy of the Korean Language.

The name of the IUSS questionnaire was translated as Indevus yojeolbakseongui simgak jisu. The word “urgency” was translated as gingeup and gingeupseong (“emergent”) by translators 1 and 2, respectively, but the panel agreed on yojeolbakseong as alternative option that appropriately conveyed the medical nuance of this term. “Degree of urgency is meant to describe your urge to urinate” in the original text was translated as yojeolbakseongui jeongdoneun gwihaui sobyeon maryeoumui jeolbakameul pyohyeonhamnida. The phrase “urge to urinate” was translated as sobyeon yokgu by translator 1 and sobyeon maryeoum by translator 2, and the panel agreed on sobyeon maryeoum as a more familiar expression. “Sometimes you may feel a very strong urge to urinate, and at other times, you may feel a milder urge prior to the onset of a toilet void” in the original text was translated as gwihaga sobyeoneul bogi jikjeone, ttaeroneun sobyeon maryeoumeul maeu ganghage neukkil ttaedo isseuna, geu oeeneun, sobyeon maryeoumi yakal ttaedo itseumnida. The panel agreed on the general tone of the sentence as rendered by translator 1, as it was a more honorific form.

“Rate this feeling by circling 0, 1, 2, or 3, defined as:” in the original text was translated as daeumgwa gateun seolmyeonge ttara 0, 1, 2, 3 euro pyogihayeo neukkimeul pyeonggahayeo juseyo. “0: NONE-no urgency” in the original text was translated as 0: eopseum- jeolbakaji aneum. “1: MILD-awareness of urgency, but is easily tolerated and you can continue with your usual activity or tasks” in the original text was translated as 1: yakam-jeolbakameul uisikal su isseuna, gwihaui hwaldonggwa eommureul jisokal su isseul jeongdoro swipge chameul su isseum. “2: MODERATE-enough urgency discomfort that interferes with or shortens your usual activity or tasks.” in the original text was translated as 2: botong- jeolbakameuro inhae ilsangjeogin hwaldonggwa eommue banghaega doel jeongdoui bulpyeonhameul neukkim. “3: SEVERE: extreme urgency discomfort that abruptly stops all activity or tasks” in the original text was translated as 3: simgakam- jeolbakameuro inhae modeun hwaldonggwa eommuga gapjakseureopge jungdandoel jeongdoro bulpyeonhameul neukkim. The panel agreed on an alternative option for the proper translation of “abruptly.”

The name of the UPS questionnaire was translated as yojeolbakseong inji jisu. “The patient is asked to describe his/her typical experience when he/she feels the desire to urinate” in the original text was translated as hwanjabunege sobyeon maryeoul ttae ilsangjeogeuro neukkineun gyeongheomeul seolmyeonghadorok hamnida. The panel agreed to translate “typical” as ilsangjeogeuro neukkineun (“routinely felt”), as it is a familiar expression.

“The response options are” in the original text was translated as seontaekangmogeun daeumgwa gateum. “1. I am usually not able to hold urine” in the original text was translated as 1. naneun juro sobyeoneul chameul su eopda. “2. I am usually able to hold urine until I reach the toilet if I go immediately” in the original text was translated as 2. naneun juro hwajangsireul jeuksi gandamyeon sobyeoneul chameul su itda. “3. I am usually able to finish what I am doing before going to the toilet” in the original text was translated as 3. naneun juro hwajangsil gagi jeone naega hadeon ireul kkeunnael su itda.

The name of the USS questionnaire was translated as yojeolbakseong simgak jisu (hogeun jeongdo) seolmunji. “How do you feel before each void?” in the original text was translated as gwihaneun maebeon sobyeoneul bogijeone eotteoke neukkisimnikka? The word “void” was translated as sobyeoneul bogi (“relieve oneself ”) by translator 1 and sobyeoneul biul (“empty”) by translator 2, and the panel agreed on sobyeoneul bogi as it is a more precise and familiar expression than sobyeoneul biul. “Please record the score that best describes how you feel before voiding” in the original text was translated as sobyeoneul bogi jeon gwihaui sangtaereul gajang jal pyohyeonhaneun hangmoge (jeomsureul) pyogihaseyo. The word “best describe” was translated as gajang jal banyeonghaneun (“best reflect”) by translator 1 and gajang jal myosahan (“best portray”) by translator 2, and the panel agreed on gajang jal pyohyeonhaneun (“best express”).

“Record at each voiding in the diary according to the following descriptions” in the original text was translated as araee seolmyeonge ttara baenyoilgie sobyeoneul biul ttaemada girokaejuseyo. The panel agreed on translating “the diary” as baenyoilgie, as it is a widely accepted translation of “voiding diary.” “0. No feeling of urgency: I can continue activities until I choose to use the bathroom” in the original text was translated as 0. yojeolbakseong eopseum: naneun hwajangsireul sayonghaneun geoseul gyeoljeonghagi jeonkkaji hadeon hwaldongeul jisokal su isseum. The panel determined that the translation of “choose to use the bathroom” as hwajangsireul sayonghaneun geoseul gyeoljeonghagi was appropriate, but was an awkward expression that required feedback. “1. Mild feeling of urgency: I can feel the need to urinate, but it is easily tolerated. I can finish my activity or task before going to the bathroom” in the original text was translated as 1. yakan jeongdoui yojeolbakseong: naneun sobyeon maryeoumeul neukkil su isseuna, swipge chameul su isseum. hwajangsil gagijeone hwaldonggwa eommureul mamurihal su isseum. The phrase “easily tolerated” was translated as swipge tongjehal su itda (“easily controlled”) by translator 1 and gyeondil su itda (“tolerated”) by translator 2, and the panel agreed on swipge chameul su isseum (“easily bearable”). “2. Moderate feeling of urgency: The sensation of urgency causes a compelling desire to void. I need to stop my activity or task and go to the bathroom” in the original text was translated as 2: junggan jeongdoui yojeolbakseong naneun yojeolbakseongeuro inhae sobyeoneul bogoja haneun yokgureul ganghage neukkim: eommuwa hwaldongeul jungdanhago hwajangsireul gal piryoga isseum. The panel determined that the translation of “sensation of urgency” as yojeolbakseong (“urgency”) did not reflect the meaning of “sensation.” “3. Severe feeling of urgency: The sensation of urgency causes a compelling desire to void. I have difficulty holding urine. I have to my stop activity or task to avoid a wetting accident and hurry to the bathroom” in the original text was translated as 3. simgakan jeongdoui yojeolbakseong: naneun yojeolbakseongeuro inhae sobyeoneul bogoja haneun yokgureul ganghage neukkim. sobyeoneul chamneunge eoryeoum. sobyeoneul jiriji anki wihae eommuwa hwaldongeul jungdanhago geupage hwajangsireul gal piryoga isseum. The phrase “a wetting accident” was translated as sobyeon silsu (“voiding accident”) by translator 1 and sobyeoni naoneun geot (“voiding”) by translator 2, and the panel agreed on sobyeoneul jiriji (“wetting”) as it is common translation of “wetting” or “incontinence.” “4. Unable to hold urine: The urine leaks from my bladder and I have a wetting accident before arriving at the bathroom” in the original text was translated as 4. sobyeoneul chameul su eopseum: naneun hwajangsire dochakagi jeone (banggwangeseo sobyeoni yuchuldoego) sobyeoneul jiryeo oseul jeoksinda. The panel agreed on the non-literal translation of “have a wetting accident” as sobyeoneul jiryeo oseul jeoksinda (“get one’s clothes wet”), as it is a widely used idiom.

The name of the PPIUS questionnaire was translated as yojeolbakseong jisuui gangdoe daehan hwanjaui inji. “0. No urgency, I felt no need to empty my bladder, but did so for other reasons” in the original text was translated as 0. jeolbakaji aneum, banggwangeul biwoya handaneun piryoseongeul neukkiji anchiman dareun iyuro geureoke handa. “1. Mild urgency, I could postpone voiding as long as necessary, without fear of wetting myself” in the original text was translated as 1. yakan jeongdoui yojeolbakseong, sobyeoneul jirineun geose daehan geokjeong eopsi piryohan mankeum oraetdongan sobyeoneul chameul su itda. “2. Moderate urgency, I could postpone voiding for a short while, without fear of wetting myself” in the original text was translated as 2. junggan jeongdoui yojeolbakseong, sobyeoneul jirineun geose daehan geokjeong eopsi jamkkan dongan sobyeoneul chameul su itda. “3. Severe urgency, I could not postpone voiding, but had to rush to the toilet in order not to wet myself” in the original text was translated as 3. simgakan jeongdoui yojeolbakseong, sobyeoneul chameul su eopseo sobyeoneul jiriji anki wihae hwajangsillo dallyeogaya handa. “4. Urge incontinence, I leaked before arriving to the toilet” in the original text was translated as 4. jeolbakseong yosilgeum, hwajangsire dochakagi jeone sobyeoneul jirinda. The word “incontinence” was translated as sobyeon yuchul (“urine leak”) by translator 1 and yosilgeum (“incontinence”) by translator 2, and the panel agreed on yosilgeum as it is a medical term that is widely understood.

As shown in Table 2, all items of the OAB questionnaires that were reconciled by the panel were reverse-translated, and the panel then discussed the differences between the back-translated versions and original versions, as described below.

The panel discussed the differences between the translations of “enough urgency discomfort that interferes with or shortens” in the original version and “You feel enough discomfort that it interferes with” in the reconciled version. The panel ultimately agreed to omit “shortens” because the translation could fully convey the message through only “interferes with.”

The panel discussed the differences between translations of “the desire to urinate” in the original version and “urge to urinate” in the reconciled version. The panel finally agreed on the translation sobyeoneul bogosipeul ttae as the best expression of the phrase “the desire.”

The panel discussed the differences between translations of “until I choose to use the bathroom” in the original version and “before I decided to go to the toilet” in the reconciled version in terms of the nuances of the translation. The panel finally agreed on the translation hwajangsireul sayonghaeyagetdago maeummeokgi jeonkkaji, as it is a more familiar and communicative expression.

The panel had no disagreements with the back-translation of the PPIUS, given the translation process of the above questionnaires.

The revised version of the translations after forward and reverse translation were tested by 5 patients with OAB (3 men and 2 women; age range, 30–70 years) who had received medical therapy, including anticholinergics. Their levels of education ranged from high school to university. All patients completed the translated questionnaires within 8 minutes. The patients stated that the items of questionnaires were generally easy to understand.

One patient reported that there was a discrepancy among the questionnaires in terms of whether they phrased the items as referring to “patient” or “you,” and stated that this difference was not harmonious. In the IUSS and USS questionnaires, “you” was translated as gwiha (a polite expression for “you”), while in the USS, “patient” was translated as hwanjabun (a polite expression for “patient”). The panel discussed this difference, but decided to keep those terms in consideration of the original text. Another patient reported that in the USS questionnaire, the description of an item was so long that the meaning of the sentence was lost in the middle. The panel discussed the patient’s feedback and agreed that the sentence was long and distracting. Therefore, the panel decided to emphasize the main words by underlining them. Furthermore, the panel proofread the all four questionnaires and agreed to unify the translation of “urgency” as yojeolbak rather than yojeolbakseong, as yojeolbak is a briefer and clearer expression.

Finally, the panel revised the translations by consistently organizing the expressions, especially honorific forms, in the questionnaires. The final versions are shown in Fig. 1.