Women overestimate daytime urinary frequency: the importance of the bladder diary.

PURPOSE: We determined whether women with urinary incontinence reliably report urinary frequency.
MATERIALS AND METHODS: We retrospectively reviewed the medical records of 1,136 women who underwent a suburethral sling operation from 1999 to 2007. A routine form was used to document medical history, urinary symptoms, physical examination and urodynamics. A total of 601 patients with a mean +/- SD age of 59.2 +/- 11.6 years (range 30 to 91) who completed a bladder diary were included in this study. Patients were categorized into 4 levels of urinary frequency, and medical histories and bladder diaries were compared. The Spearman correlation coefficient was used to determine the degree of agreement between histories and diaries.
RESULTS: According to the diaries 535 patients (89%) voided 4 to 10 times during the day and 527 (87.6%) voided no more than twice at night. Only 47% of the women were accurate about daytime frequency. On the other hand, 93% of the women were accurate about the nighttime estimation. Of the women 51% overestimated daytime frequency. Overestimation was marked, especially in patients who reported a daytime frequency of greater than 10 voids per day. There was weak correlation between daytime urinary frequency obtained from medical histories and the frequency recorded in diaries (r = 0.31, p = 0.011). However, nighttime urinary frequencies correlated highly (r = 0.79, p = 0.02). Overestimation rates were similar in patients with and without overactive bladder.
CONCLUSIONS: Our results suggest that half of patients tend to overestimate daytime urinary frequency. However, the accuracy rate of nighttime frequency is much higher. A bladder diary provides invaluable information about urinary frequency and it should be an integral part of the routine assessment in women with lower urinary tract symptoms.