Creation and validation of a bladder dysfunction symptom score for HTLV-1-associated myelopathy/tropical spastic paraparesis
Authors: Yamakawa Natsuko , Yagishita Naoko , Matsuo Tomohiro , Yamauchi Junji , Ueno Takahiko , Inoue Eisuke , Takata Ayako , Nagasaka Misako , Araya Natsumi , Hasegawa Daisuke , Coler-Reilly Ariella , Tsutsumi Shuntaro , Sato Tomoo , Araujo Abelardo , Casseb Jorge , Gotuzzo Eduardo , Jacobson Steven , Martin Fabiola , Puccioni-Sohler Marzia , Taylor Graham P. , Yamano Yoshihisa ,   the Japan Clinical Research Group on HAM/TSP, Nakayama Takeo , Kamei Satoshi , Kira Jun-ichi , Watanabe Toshiki , Kohriyama Tatsuo , Okayama Akihiko , Kawakami Atsushi , Yuzawa Kenji , Nakagawa Masanori , Nakamura Tatsufumi , Kubota Ryuji , Matsuura Eiji , Kamoi Koju , Nakajima Takashi , Murai Hiroyuki , Uchimaru Kaoru , Tsuboi Yoshio , Namihira Yukihiro , Ishihara Satoshi , Niino Masaaki , Nagai Masahiro , Umekita Kunihiko , Takenouchi Norihiro , Matsuzaki Toshio , Hokezu Youichi , Nakamura Hideki , Matsushita Takuya , Morio Yuji , Yonezawa Hisashi , Tokashiki Takashi , Tamaki Keiko , Sakima Hirokuni , Yagishita Naoko , Matsuo Tomohiro , Yamauchi Junji , Inoue Eisuke , Takata Ayako , Araya Natsumi , Hasegawa Daisuke , Sato Tomoo , Yamano Yoshihisa 
Published: July 2020

Abstract
Background
Urinary dysfunction is one of the main features of human T-cell leukemia virus type 1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). However, a comprehensive assessment of the severity is difficult because a standardized assessment measure is unavailable. Therefore, this study aimed to develop a novel symptom score for the assessment of urinary dysfunction in HAM/TSP. We interviewed 449 patients with HAM/TSP using four internationally validated questionnaires for assessment of urinary symptoms (27 question items in total): the International Prostate Symptom Score; the International Consultation on Incontinence Questionnaire-Short Form; the Overactive Bladder Symptom Score; and the Nocturia Quality-of-Life questionnaire. We developed a symptom score based on the data of 322 patients who did not use urinary catheters by selecting question items from questionnaires focused on descriptive statistics, correlation analysis, and exploratory factor analysis. The score distribution, reliability, and validity of the developed score were evaluated.

Results
First, 16 questions related to quality of life, situations, or subjective assessment were omitted from the 27 questions. Exploratory factor analysis revealed that the remaining 11 questions pertained to three factors: frequent urination, urinary incontinence, and voiding symptoms. Three questions, which had similar questions with larger factor loading, were deleted. Finally, we selected eight question items for inclusion in the novel score. The score distribution exhibited no ceiling or floor effect. The Cronbach’s alpha (0.737) demonstrated reliable internal consistency. The new score comprised two subscales with acceptable factorial validity (inter-factor correlation coefficient, 0.322): storage symptoms (frequent urination plus urinary incontinence) and voiding symptoms. The correlation between each item and the subscales suggested acceptable construct validity.

Conclusions
We developed a novel score, the HAM/TSP-Bladder Dysfunction Symptom Score, and demonstrated its reliability and validity. The applicability of this score to patients using catheters should be examined in future research.