How should patients with an overactive bladder manipulate their fluid intake?

OBJECTIVE To assess how the symptoms of overactive bladder (OAB) syndrome in adults are affected by decreasing or increasing fluid input, and the effect of fluid manipulation on quality of life. PATIENTS AND METHODS Adults with symptoms of OAB were randomized in a two-group, prospective, cross-over trial following a 4-day screening period (to establish baseline values) using frequency/volume charts, if they had a mean of eight or more voids and one or more urgency and/or urgency incontinence episodes in 24-h. Patients were asked to either increase or decrease their fluid intake, from baseline, as follows: group 1, 4 days drinking 25% less than baseline, and 2 days normal, then 4 days at 50% less than baseline, and 2 days normal, then 4 days at 25% more than baseline, and 2 days normal, and then 4 days at 50% more than baseline. Group 2 did the reverse. The primary endpoint was the change in the frequency of unwanted events during a 24-h period. RESULTS In all, 67 patients were contacted, 40 recruited and 24 were eligible. There was a significant reduction in frequency, urgency and nocturia when patients decreased their fluid input by 25%. Increasing fluid input by 25% and 50% resulted in a worsening of daytime frequency. Overall there was no statistically significant improvement in quality of life but there was some subjective improvement in urgency and nocturia, as measured by a validated instrument, in the group that decreased their fluid input by 25%; approximate to 300 mL of daily fluid came from water-containing foods. CONCLUSIONS Fluid manipulation is a cheap, noninvasive and easy way to help control the symptoms of OAB. Patients have difficulty in either decreasing or increasing their fluid input by 50%. Patients can now be told to expect a significant improvement in urgency, frequency and nocturia episodes if they reduce their fluid input by 25%.