Correlation between the International Prostatic Symptom Score and a pressure-flow study in the evaluation of symptomatic benign prostatic hyperplasia

Abstract

Purpose: We examined the relationship between the International Prostatic Symptom Score (I-PSS) and the occurrence of bladder outlet obstruction caused by benign prostatic hyperplasia (BPH).

Materials and methods: The American Urological Association developed a questionnaire to quantify the severity of symptoms resulting from BPH. A further question relating the impact of BPH to the quality of life was subsequently added. This questionnaire has been adopted by the World Health Organization and is known as the I-PSS. There are 4 questions related to obstructive symptoms and 3 related to irritative symptoms. Scores of 0 to 7, 8 to 19 and 20 to 35 represent mild, moderate and severe symptoms, respectively. During an 18-month interval the I-PSS questionnaire was administered to 258 patients 50 to 81 years old (mean age 63 years) with BPH. A pressure-flow study was used to determine the presence of bladder outlet obstruction in 227 patients. Based on the scores, the patients were divided into 31 with mild, 116 with moderate and 111 with severe obstruction. The pressure-flow study was not conducted on patients with a mild symptom score.

Results: Of the patients with a severe symptom score 92 (82.9%) had bladder outlet obstruction, compared to 62 (53.4%) with a moderate symptom score. Statistical analysis (Pearson chi-square test) showed that there was a significant positive correlation between the symptoms and the presence of bladder outlet obstruction. Thus, when the I-PSS was greater than 28, the probability of bladder outlet obstruction was more than 0.91. Stratification of the results according to the obstructive (0 to 20) and irritative (0 to 15) symptoms of the I-PSS yielded a significant positive correlation between obstructive symptoms and the presence of bladder outlet obstruction. Thus, when the obstructive symptom score was greater than 15, the probability of bladder outlet obstruction was greater than 0.91.

Conclusions: When the total I-PSS is greater than 28 or the obstructive symptom score is greater than 15, a pressure-flow study must be avoided.