Lowering fluid intake improves OAB symptoms
In many patients with overactive bladder (OAB), initial management can be with simple conservative measures, such as lifestyle adaptation (for example fluid restriction, weight loss and emptying the bladder before activity), pelvic floor exercises and bladder retraining. However, for measures such as fluid restriction to work, the recommended change has to be both achievable and effective.
A study has found that decreasing fluid intake by 25% per day significantly improves symptoms.
The study recruited 24 men and women aged >18 years with OAB. After a screening period to determine baseline drinking habits, the participants were randomised in a two-group prospective crossover trial of fluid manipulation. Patients were asked to either increase or decrease their fluid intake, from baseline, as follows: group one, four days drinking 25% less than baseline, and two days normal, then four days at 50% less than baseline, and two days normal, then four days at 25% more than baseline, and two days normal, and then four days at 50% more than baseline. Group two did the reverse.
At the end of the trial, patients were asked to complete a quality of life questionnaire.
The study found that patients were able to reduce their fluid intake by 25% but when asked to reduce their intake by 50% the group only managed a 32% reduction. Similarly, the patients struggled with increasing their fluid intake.
Reduction of fluid intake by 25% led to significant decreases in daytime frequency (23%, P= <0.001) and urgency (34%, P= 0.004). There was a significant decrease in nocturia, although this was small (7%, P=<0.001) and probably not clinically significant. Some items on a urinary quality of life questionnaire also showed significant improvement.
Eighty-three per cent of patients said the 25% reduction period was the most helpful.
This study is limited by its sample size but suggests that simple and manageable decreases in fluid intake can make a significant difference to patients with OAB. When fluid manipulation is combined with other conservative measures, it may be possible for many patients with milder symptoms to avoid drug therapy.
However, fluid manipulation did not seem to affect the severity of nocturia. Drug therapy may be required at an earlier stage for patients who are bothered by this symptom, particularly given the well recognised impact of nocturia on quality of life.
Hashim H, Abrams P. How should patients with an overactive bladder manipulate their fluid intake? BJU Int 2008 doi:10.1111/j.1464-410X.2008.07463.xReviewer
Dr Jonathan Rees
GPwSI Urology, Bristol