A total of 304 Patients, 178 females and 126 males, were enrolled and presented for 540 clinic visits. Mean age at enrollment was 58±17 years. Response rates were 93% (500/540) for the IPSS, 91% (490/540) for the ICIQ symptom scores, and 64% (343/540) for the ICIQ bother scores.
Regression model for effects of gender on LUTS
A logistic regression model by gender, adjusted for age (Figure 1), demonstrated a greater number of women with urgency using both instruments (IPSS OR 2.27, 95% CI 1.55-3.33; ICIQ OR 2.25, 95% CI 1.42-3.56). Women reported more voiding symptoms than men, including straining (IPSS OR 1.70, 95% CI 1.10-2.62; ICIQ OR 1.79, 95% CI 1.04-3.06). Incontinence, too, was reported more by women then by men (ICIQ stress urinary incontinence (UI) OR 6.14, 95% CI 2.55-14.77; ICIQ unaware UI OR 2.18, 95% CI 1.03-4.62; ICIQ sleep UI OR 1.99, 95% CI 1.02-3.90; ICIQ urge UI OR 1.94, 95% CI 1.16-3.26).
Principal Component Analysis
For female patients, unsupervised PCA identified 2 principal components of IPSS, explaining 53% and 16% of the overall variance, and 3 principal components of the ICIQ-FLUTS questionnaire, accounting for 35%, 23%, and 11% of data variance.
After varimax rotation, factor 1 in the IPSS received the most contribution from questions regarding incomplete emptying, intermittent stream, weak stream, and straining to urinate, and determined to be a voiding-phase symptom component. Factor 2 in IPSS was contributed by daytime frequency, urgency, and nocturia, and deemed to represent storage-phase symptoms.
The 3 ICIQ-FLUTS principal components were concluded to represent: i. incontinence (contributed by urge incontinence, stress incontinence, frequency of incontinence, unaware incontinence, and sleep incontinence); ii. voiding symptoms and pain (hesitancy, straining, intermittency, and pain related to the bladder); and iii. storage phase symptoms (nocturia, urgency, and daytime frequency).
In a similar manner, unsupervised PCA detected 2 principal components for male IPSS and 3 principal components for ICIQ-MLUTS. IPSS components corresponded to voiding and storage symptom domains, while ICIQ-MLUTS components represented: i. incontinence (urge, stress, unaware, sleep, and post-void incontinence; and a lower yet worth-mentioning contribution from urgency); ii. voiding (hesitancy, straining, weak stream, intermittency, incomplete emptying); and iii. storage-phase symptoms (urgency, daytime frequency, and nocturia).
Principal Component Logistic regression
In females, maximum likelihood estimates for the effect of LUTS domains on QoL were significant for all components of the ICIQ-FLUTS (incontinence p<0.0001, voiding p<0.0001, storage p=0.008) and for the storage component of the IPSS (p=0.004). In males, maximum likelihood estimates were significant for the incontinence (p=0.024) and storage (p=0.027) components of the ICIQ MLUTS, as well as the voiding (p=0.018) and storage (p=0.006) components of the IPSS.
Given the significant effect of urinary incontinence on QoL, we plotted the predicted probabilities of each level of LUTS-related QoL using the incontinence principal component scores, while holding the other principal components constant. This identified the inflection point of QoL reporting probabilities. Females with positive incontinence scores had higher probabilities of reporting IPSS QoL of 5 (unhappy) or 6 (terrible), while in males, positive incontinence scores were related to a higher probability of IPSS QoL 4, 5 or 6 (mostly dissatisfied, unhappy, or terrible) (Figure 2).