Comprehension and construct validity of the Visual Prostate Symptom Score (VPSS) by men with obstructive lower urinary tract symptoms in rural Africa

Abstract

Introduction: The Visual Prostate Symptom Score (VPSS) is an image-based interpretation of the International Prostate Symptom Score (IPSS) intended to quantify frequency, nocturia, weak stream, and quality of life (QoL) in a literacy-independent manner. Methods: Ugandan men presenting with lower urinary tract symptons (LUTS) to a rural clinic completed VPSS and IPSS independently and then with assistance. They verbally interpreted VPSS images, rated question usefulness, and suggested improvements. Responses between word-based and image-based measures were compared (Student’s T, Fisher’s exact, and Spearman’s correlation tests). Results: One hundred thirty-two scores from 33 men (mean age: 61 years, range 28‒93; education: no schooling 20%, grades 1‒4 62%, 5‒7 9%, 8‒12 9%). Correlation between IPSS and VPSS scores was positive (r=0.70), as was that between the individual irritative, obstructive, and QoL questions. Independent of education, the weak stream image was best-recognized. Likert scale measures indicated this was the most useful image, followed by daytime frequency. Nocturia and QoL images were rated as less clear, with explanation required before most understood that QoL facial expression images reflected overall LUTS impact. Improvements suggested included: increased image size for frequency and nocturia pictograms, increased black/white contrast for nocturia, and addition of an image to allow reporting of urgency. Conclusions: In a population with little formal education, there was positive correlation between IPSS and VPSS, with inherent recognition best for weak stream and worst for QoL images. Increased image clarity and an additional image for urgency will enhance the global utility of the VPSS for men to report symptoms of LUTS.