Bladder diary measurements in asymptomatic males: frequency, volume per void, and 24-hr volume

To collect bladder diary frequency and volume measurements from asymptomatic males and to use these data to develop clinical reference values.

Computer processed three-day bladder diaries were collected from 92 males (median age: 46.2 years; range: 20.6-84.6 years) defined as "asymptomatic" by questionnaire. Minimum (V(min)), maximum (V(max)), and average (V(avg)) volume per void (Vol/Void), 24-hr frequency (F(24)), and 24-hr volume (V(24)) were studied. Relationships of Vol/Void and F(24) to age and V(24) and of V(24) to age were investigated by regression analysis.

V(max) and V(avg) increased as V(24) increased and decreased with increasing age (P < 0.0005). We found no significant relationship between V(min) and age, but V(min) increased with increasing V(24) (P < 0.0005). F(24) increased with increasing V(24) and increasing age (P < 0.0005). We found a concave downward, curvilinear relationship between age and V(24), which, while it did not reach statistical significance, was very similar in shape to age versus V(24) relationships found by other studies of larger datasets.

Our results suggest that reference values of F(24) and Vol/Void should be adjusted for their relationships to the patient's age and V(24). Regression equations expressing these relationships can be used to make these adjustments. From frequency histograms of residuals the difference between the patient's actual and expected reference measurement can be ranked within the reference population as a percentile. We illustrate this method by using our results to calculate age- and V(24)-adjusted 5% "normal limit" tables of F(24), V(avg), and V(max).