Lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH) typically respond well to medical therapy. While changes in total International Prostate Symptom Score (IPSS) are generally accepted as measurement for treatment response, IPSS storage and voiding subscores may not accurately reflect the influence of symptom improvement on patient bother and quality-of-life (QoL).
Structural equation modeling (SEM) was employed to evaluate physiologic inter-relationships measured by the IPSS storage subscore questions vs. IPSS voiding subscore questions, and to measure the magnitude of their effects on bother via BPH Impact Index (BII) and QoL (IPSS-QoL). Pooled data from 4 randomized controlled trials (tadalafil and placebo) in 1462 men with LUTS/BPH investigated the relationship of storage vs. voiding LUTS on BII and QoL.
The final structural equation model demonstrated sufficient fit to model interdependence of storage, voiding, bother, and QoL (Probability for Test of Close Fit <0.0001). Storage aspects had a 2-fold greater effect on voiding (0.61; P<0.0001) vs. voiding aspects on storage (0.28; P<0.0001). Direct effect of storage on bother was 2-fold greater than voiding (0.64 storage, 0.29 voiding; each P<0.0001). Bother directly impacted QoL by the largest magnitude (-0.83), largely driven by storage LUTS (P<0.0001).
Total IPSS is a reliable instrument to assess therapeutic response in LUTS/BPH; however, improvement of storage LUTS is mainly responsible for improvement of bother and QoL during treatment. Care should be taken when evaluating the accuracy of IPSS subscores as indicators of response to medical therapy.
The Journal of urology. 2016 Apr 19 [Epub ahead of print]
Kevin T McVary, Andrew Peterson, Craig F Donatucci, Simin Baygani, Carsten Henneges, Johannes Clouth, David Wong, Matthias Oelke
Department of Urology, Southern Illinois University, Springfield, Illinois, USA., Department of Surgery/Division of Urology, Duke University, Durham, North Carolina, USA., Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA. Electronic address: ., Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA., Lilly Deutschland GmbH, Bad Homburg, Germany., Lilly Deutschland GmbH, Bad Homburg, Germany., Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA., Department of Urology, Hannover Medical School, Hannover, Germany.