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

We determined whether women with urinary incontinence reliably report urinary frequency.

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.

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.

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.