Validity and Reliability of ICIQ-FLUTS LF in Thai Version and Correlation With IPSS

Incontinence Questionnaire - Female Lower Urinary Tract Symptoms Long Form (ICIQ-FLUTS-LF) was divided into 6 subgroups of symptoms measurement, which were storage, voiding, incontinence, bladder pain, post micturition, and ability to stop voiding. The construct validity was determined by comparing the ICIQ-FLUTS LF scores of the target group with the ICIQ-FLUTS LF scores of the control group. The comparisons were performed using the Wilcoxon signed-rank test.

The internal consistency (a parameter that verifies correlations between items within a subscale of the questionnaire) was assessed by using Cronbach's alpha coefficients. The assessment was done in each subscale of the questionnaire. If Cronbach's alpha coefficients were between 0.7 and 0.95, the instrument was considered to have good internal consistency.

The test-retest reliability (a property of producing repeated measurements that are consistent) was verified by having the participants of the target group answer the questionnaire twice with an interval of 2 weeks between the evaluations. We calculated test-retest reliability by using weighted kappa (κ).

The convergent validity (how closely a test is related to other tests that measure the same or similar constructs) was determined by comparing the ICIQ-FLUTS LF scores of the target group with a known validated questionnaire. In this study we used the International Prostate Symptom Score (IPSS) as the comparison test. The comparisons were performed using Pearson's correlation.