The international prostate symptom score overestimates nocturia assessed by frequency-volume charts

We analyzed differences in nocturia, as estimated by the International Prostate Symptom Score and 7-day frequency-volume charts.

A total of 398 forms were collected from 500 consecutive urological outpatients willing to record a 7-day frequency-volume chart. All patients completed a general questionnaire, an International Prostate Symptom Score, and a bladder symptom and bother score. Missed recordings were indicated by a coded letter. Patients who lacked essential data, bedtimes or an International Prostate Symptom Score, or who recorded the frequency-volume chart for less than 5 days were excluded from study.

A total of 186 men and 115 women with a mean age of 56 years were evaluable. In 10.6% of patients no nocturia occurred. Of those with nocturia 70% and 34% experienced nocturia a mean of 1 or more and 2 or more times, respectively. In 43% of patients the International Prostate Symptom Score equaled calculated categorized nocturia while 50% had a higher International Prostate Symptom Score nocturia score than calculated nocturia. On univariate analysis the correlation of International Prostate Symptom Score question 7 with mean nocturia increased with frequency-volume chart duration (day 1 r = 0.52 to day 3 r = 0.63). On longer duration frequency-volume charts the correlation showed no further increase. Multivariate regression analysis revealed that the nocturia score was determined by mean nocturia in the frequency-volume chart, the nocturia bother score and patient age.

The International Prostate Symptom Score nocturia score overestimated nocturia in most patients, as derived from a 7-day frequency-volume chart. When scoring International Prostate Symptom Score nocturia question 7, patients included a degree of bother. The correlation of question 7 with mean nocturia increased with frequency-volume chart duration until day 3.