Study design, materials and methods
A prospective study was conducted in a tertiary urogynecology center which included all women with urinary symptoms who referred to us from April 2015 to March 2017. All women underwent a medical consultation by gynecologist using a standard consultation form and completed a validated Pelvic floor distress inventory (PFDI) questionnaires in Chinese  by herself in a separate area and urodynamic study were arranged for them afterwards. Item 19 of PFDI reports urge incontinence symptoms while item 20-23 report stress incontinence symptoms. Women with pelvic organ prolapse were excluded. They had a urine culture test to exclude urinary tract infection. All women were then arranged to have urodynamic study by using Laborie Urodynamics, Aquarius system, (Laborie, Canada) in a standard protocol. At the end of filling phase, women were seated for a pressure flow study and post-void residual measurement. A urodynamic diagnosis of urodynamic SUI, detrusor overactivity (DO) and mixed urinary incontinence was made according to the International Continence Society definition.
A correlation analysis was carried out between individual items on the PFDI questionnaire and UDS findings. Statistical analysis using the Kappa Measure of Agreement and chi-square test were performed with SPSS 22.0 software (SPSS, Inc, Chicago, IL). Ethics approval was obtained.
Total of 280 women were approached, 37 refused or being unable to answer the questionnaires, 102 were excluded due to co-existing pelvic organ prolapse, and subsequently 18 women did not turn up for urodynamic study, leaving 123 women who were included for analysis. The mean age of the women was 58.2 years old (SD 7.9) with median parity of 4 (2-4), and mean BMI of 24.9 kg / m2 (SD: 4.1). One hundred and eight women (87.8%) were post-menopausal and 106/123 (86.2%) were sexually inactive. All of them reported urinary symptoms with 40 / 123 (32.5%) of them reported stress incontinence, 15 / 123 (12.2%) with urge incontinence and 31 / 123 (25.2%) had mixed urinary incontinence and 37/123 (30.1%) were having other voiding problems. From urodynamic study, 51 / 123 (41.5%) were diagnosed with urodynamic stress incontinence and 5/123 (4.0%) were with detrusor overactivity. 4 / 123 (3.3%) of them had both stress incontinence and detrusor overactivity and 63 / 123 (51.2%) had no abnormality detected. We evaluated the relationship between stress incontinence questions 20-23 in PFDI and urodynamic stress incontinence ; also the relationship between urge incontinence question 19 in PFDI versus a urodynamic diagnosis of DO. The Kappa Measure of Agreement value was 0.45 (p<0.01) between reported symptoms of stress incontinence and urodynamic stress incontinence, while it was 0.20 (p=0.1) between symptoms of urge incontinence and detrusor overactivity. The sensitivity and specificity of symptoms of stress incontinence and urge incontinence with urodynamic stress incontinence and detrusor overactivity were calculated respectively. (Table 1)
Interpretation of results
Majority of women presented with urinary symptoms reported symptoms of stress incontinence. The SI symptoms had high sensitivity (92.6%) and positive predictive value (69.4%) to the diagnosis of urodynamic stress incontinence and with significant correlation. However, symptom of urge incontinence does not correlate significantly with urodynamic diagnosis of detrusor overactivity.