Overactive bladder (OAB) is symptomized by urinary urgency. It is usually accompanied by increased daytime urinary frequency or nocturia, with or without urinary incontinence (UI) [1]. The prevalence of OAB increases with age and in older adults, and lifestyle modifications should be simple and sustainable [2]. 
This study aimed to review and summarize available scientific evidence on the effect of modification of fluid and caffeine intake on OAB in community-dwelling people.

A systematic review of randomized controlled trials (RCTs) and uncontrolled studies was conducted to evaluate fluid or caffeine intake modification interventions on OAB in adults. 
Studies published up to February 2022 were searched using PubMed, Embase, CINAHL, Scopus, the Cochrane Library, KoreaMed, and RISS. The keywords used in the search were (OAB OR UI OR LUTS) AND (“fluid intake intervention” OR “caffeine intake management”).
The inclusion criteria for this study were as follows: RCT or quasi-experimental studies; studies with OAB patients with adults as participants; studies that performed conservative interventions, including fluid or caffeine intake modification, without using pharmaceutical drugs or surgery; and studies that reported the urgency, frequency, UI episodes or amount of urine leakage, nocturia, and quality of life (QoL) as outcome variables. The exclusion criteria were as follows: studies including people with UI after surgery and presently admitted to a health institution; studies including people with a urinary disorder as a symptom of another disease; and studies that included pharmacological, surgical, or orthopedic treatment.
Cochrane’s tool for assessing the risk of bias (ROB 2.0) was used to assess the methodological quality of the selected studies [3]. Two authors independently assessed and co-checked the results and reached an agreement through discussion if there were any disagreements or misunderstandings.
Because of the heterogeneity among the included studies, quantitative analyses combining the outcomes of different studies were not performed.

A total of 5,900 articles were identified through the database searches. Four thousand six hundred ninety-two articles, excluding duplicates, were screened by title, leaving 124 articles. Twelve articles were selected through abstract screening. After reviewing the full text of the 12 articles, seven articles were selected, and one article was discovered through a review-article’s citation. Finally, eight papers were included in the systematic review, and the data were narratively synthesized. Seven were RCTs, and one was a quasi-experimental study. Four studies had a high risk of bias, and the other four had a low risk of bias.
Urgency was assessed in four studies, and caffeine restriction was effective in significantly reducing it. Increasing fluid intake had no significant effect on urgency compared to the control or decreased fluid intake groups. Frequency was reported on in five studies. They found that caffeine reduction and decreased fluid intake were effective for reducing the frequency of symptoms. An increased fluid intake resulted in more frequent episodes. The number of UI episodes was assessed in six studies. Caffeine reduction resulted in fewer UI episodes, but there were no significant differences between the intervention and control groups. UI symptoms were also improved by modifying caffeine and fluid intake. Nocturia was evaluated in two studies. They found that the caffeine-reduction only group and the caffeine and fluid intake modification group were more effective at reducing nocturia than the control group. QoL was reported on in five studies with various measurements. Although all five studies showed improvement in QoL in the intervention group, only two reported statistically significant improvement by managing both fluid and caffeine consumption.

Caffeine restrictions should first be considered to manage OAB symptoms as all outcome variables improve as a result. Fluid management was also effective, and reducing fluid intake is more effective than increasing it. Where both caffeine and fluid intake were managed, a decrease in both was more effective at improving urgency, frequency, wetting episodes, and QoL, than increasing fluid intake.

While there were a limited number of studies, our systematic review demonstrated that modifying fluid and caffeine intake is effective in relieving OAB symptoms in adults. Therefore, when managing OAB symptoms, fluid and caffeine regulation should be included in the intervention. Additional research is needed to determine the long-term effects of increased or decreased fluid intake on OAB because most results are based only on short outcomes. Moreover, more related studies should be conducted to allow for a more comprehensive meta-analysis.

D'Ancona C, Haylen B, Oelke M, et al. The International Continence Society (ICS) report on the terminology for adult male lower urinary tract and pelvic floor symptoms and dysfunction. Neurourol Urodyn. 2019;38(2):433-477. doi:10.1002/nau.23897
Natalin R, Lorenzetti F, Dambros M. Management of OAB in those over age 65. Curr Urol Rep. 2013;14(5):379-385. doi:10.1007/s11934-013-0338-5
Higgins JP, Altman DG, Gøtzsche PC, et al. The Cochrane Collaboration's tool for assessing risk of bias in randomised trials. BMJ. 2011;343:d5928. Published 2011 Oct 18. doi:10.1136/bmj.d5928

Continence 2S2 (2022) 100429
DOI: 10.1016/j.cont.2022.100429