The Prediction of Clinical Outcome from Transurethral Microwave Thermotherapy by Pressure-Flow Analysis: A European Multicenter Study

A total of 100 patients treated with a single session of microwave thermotherapy at 4 European centers was stratified according to 2 different types of obstruction (constrictive and compressive) and compared to clinical outcome at 6 months. Patients had a Madsen-Iversen score of 8 or more, maximum flow rate of 15 ml. per second or less and residual urine volume of 300 ml. or less at entry. The change in Madsen-Iversen score was the same in the 2 groups. Maximum flow rate increased from 8.71 +/- 2.62 to 14.73 +/- 4.04 ml. per second in the constrictive group, and from 8.54 +/- 2.26 to 10.41 +/- 4.52 in the compressive group (p < or = 0.0001). Residual urine decreased from 96.00 +/- 72.85 to 40.34 +/- 56.33 ml. in the constrictive group and from 109.86 +/- 67.09 to 84.65 +/- 81.45 ml. in the compressive group (p < or = 0.0001). Success, as defined by an increase of 50% or more in maximum flow rate and Madsen-Iversen score, was noted in 68% of the constrictive but only 15% of the compressive groups (p < or = 0.0001 chi-square test for trend). Selection by pressure-flow criteria for patients being considered for thermotherapy should improve the overall clinical results.