Psychometric properties and moderated mediation analysis of the ICIQ-NQOL in Chinese primary care patients with nocturia.

BACKGROUND

Many individuals consider nocturia a significant nuisance, leading to a reduced health-related quality of life (HRQOL). However, there has been a lack of psychometrically sound patient-reported outcome measures to assess the impact of nocturia on patients in Chinese contexts. This study aimed to translate, culturally adapt, and validate the International Consultation on Incontinence Questionnaire Nocturia Quality of Life Module (ICIQ-NQOL) for use among primary care patients in Hong Kong, China. Additionally, it sought to investigate the mechanisms that link nocturia and sleep quality with HRQOL by employing moderated mediation analysis.

METHODS

The traditional Chinese version of the ICIQ-NQOL was developed through iterative translations, cognitive debriefing interviews, and panel reviews. The psychometric evaluation included assessments of factor structure, convergent validity, concurrent validity, known-group validity, internal consistency, test-retest reliability and responsiveness. Study instruments included the ICIQ-NQOL, International Prostate Symptom Score (IPSS), Pittsburgh Sleep Quality Index (PSQI), and a modified Incontinence Impact Questionnaire-Short Form (IIQ-7).

RESULTS

A total of 419 primary care patients were recruited from general outpatient clinics, among whom 228 experiencing an average of two or more nocturia episodes per night over the past four weeks. Confirmatory factor analysis supported the two-factor structure of the ICIQ-NQOL. Concurrent validity was confirmed by moderate correlations between the IIQ-7 total score and the total score as well as two domain scores of the ICIQ-NQOL (r ranging from 0.43 to 0.49, all p < 0.001). The ICIQ-NQOL also had moderate correlations with the IPSS total symptom score (r ranging from 0.40 to 0.48, all p < 0.001). Convergent validity was supported by moderate correlations between the global PSQI score and the total score as well as two domain scores of the ICIQ-NQOL (r ranging from 0.42 to 0.52, all p < 0.001). Known-group comparisons showed that the ICIQ-NQOL could differentiate between patients with and without nocturia in terms of sleep/energy domain score (p < 0.001), bother/concern domain score (p < 0.001), and total score (p < 0.001), each demonstrating a moderate Cohen's d effect size. Item-total correlations corrected for overlap exceeded 0.4, and Cronbach's alpha coefficients were greater than 0.7. Test-retest reliability was confirmed with intraclass correlation coefficients exceeding 0.7 among patients reporting no change in their nocturia symptoms at a 2-week follow-up. Regarding responsiveness, the Cohen's d effect sizes for differences in domain and total scores between the baseline and 2-week follow-up assessments were greater than 0.3 among patients showing improvement in nocturia. Our moderated mediation analysis indicated that sleep quality significantly moderated the impact of nocturia on HRQOL, with a notably stronger indirect effect among females compared to males.

CONCLUSIONS

The ICIQ-NQOL is a reliable and valid instrument for assessing the HRQOL in primary care patients suffering from nocturia. The findings advocate for gender-specific approaches in the management and treatment of nocturia to optimize HRQOL.