The Relationship between Objective Frequency–Volume Chart Data and the I-PSS in Men with Lower Urinary Tract Symptoms

ObjectiveThe International Prostate Symptom Score (I-PSS) is considered a benchmark in defining the severity of lower urinary tract symptoms (LUTS). However, its relationship with variables of the frequency–volume (FV) chart, an objective measure of LUTS, is not well understood. We analyzed this relationship between the I-PSS and FV chart variables in men with LUTS.MethodsPatients referred for the investigation of uncomplicated LUTS completed an I-PSS and a 3-d FV chart. Correlation coefficients were used to describe the relationship between total I-PSS and its components with the FV variables. The distributions of FV variable scores within the categories of I-PSS severity were also examined. The effect of patient's quality of life score on I-PSS and FV variables was analyzed using regression.ResultsA total of 104 patients completed both the I-PSS and FV chart. The association between FV variables and I-PSS scores was generally weak, with 24-h frequency being the strongest (r = 0.43) and with considerable overlap within each severity category. There was weak association between the I-PSS for nocturia and urgency and their FV counterparts. The number of self-reported nocturnal voids tended to be overestimated. These discrepancies were partly explained by the patient's quality of life rating, which reduced the level of variation between I-PSS score and FV variables and accounted for some of the overestimation.ConclusionWeak associations were found between the self-rated I-PSS scores and FV measures of voiding, suggesting that the accurate assessment of LUTS requires self-reported measures of symptoms and objective measures of voiding behaviour. Significant differences between the two types of data might be explained by perceived quality of life.