Re-categorisation of male lower urinary tract symptoms based on the international prostate symptom score questionnaire

AIMS

The purpose of this study was to develop a new sub-classification system for male lower urinary tract symptoms (LUTS)-mild, moderate and severe-using the conventional International Prostate Symptoms Score (I-PSS).

METHODS

From October 2007 to March 2012, a total of 2234 male patients (≥ 50 years old) presenting with LUTS were enrolled in this study. Patients were sorted according to their I-PSS (ranging from 1 to 35 points) and divided into three groups based on their quality of life (QoL) score. A chi-square automatic interaction detection (CHAID) algorithm, based on adjusted significance testing, was used. The Kappa coefficient was calculated for the agreement of original and new categorisation.

RESULTS

Mean total I-PSS and QoL scores were 11.0 and 2.9 respectively. According to the original classification, 838 patients (38.6%) had mild, 1053 (48.5%) had moderate and 282 (13.0%) had severe symptoms. After the CHAID algorithm was applied, the scores were re-categorised as 'mild' (1-6 points), 'moderate' (7-21 points) and 'severe' (22-35 points). The overall model was able to correctly predict whether an I-PSS was associated with mild, moderate or severe symptoms, with 70.1% accuracy. According to this new classification, 704 patients (32.4%) were shown to have mild, 1255 (57.8%) to have moderate and 214 (9.8%) to have severe LUTS. The agreement of conventional and new categorisation is very strong (Kappa coefficient = 0.84).

CONCLUSIONS

Conventional categorisation of LUTS by I-PSS needs to be updated and the category of moderate LUTS should be broadened.