Danish version of the National Institutes of Health–Chronic Prostatitis Symptom Index (NIH-CPSI) questionnaire: a linguistic translation, cross-cultural adaptation and test–re-test reliability study

Abstract

Objective: To translate and cross-culturally adapt the National Institutes of Health–Chronic Prostatitis Symptom Index (NIH-CPSI) into Danish and assess the reliability of the translated version.

Methods: The NIH-CPSI was translated into Danish by a formalized translation procedure. Study participants suffering from Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS) were recruited from a CP/CPPS newsletter email-list. The translated questionnaire was tested for face validity by interviewing men (n = 7) suffering from CP/CPPS. Relative reliability (interclass correlations coefficient, ICC) and absolute reliability (minimal detectable change, MDC; and standard error of measurement, SEM) were assessed on an electronic version of the Danish NIH-CPSI, including a general response assessment of symptom stability at the second assessment.

Results: One hundred and twenty-nine men volunteered for the test–re-test study, 43 did not fit the eligibility criteria or had incomplete tests and 27 were excluded due to symptom changes between test and re-test, leaving 59 participants for the reliability study. The relative reliability for the total NIH-CPSI score was found to be an excellent ICC of 0.93 (95% CI = 0.91–0.96). The absolute reliability for the total NIH-CPSI score revealed an MDC of 5.0 and a SEM of 1.8, corresponding to 12% and 4%, respectively, of the maximal obtainable NIH-CPSI score.

Conclusion: The NIH-CPSI questionnaire was successfully translated and cross-culturally adapted into a Danish version. An electronic version of the Danish NIH-CPSI showed excellent reliability. The questionnaire is suitable for use as an outcome measure in research studies and may also be a useful tool in the clinical setting.

Keywords:

• Pelvic pain
• chronic prostatitis: questionnaire
• reliability
• NIH-CPSI

Acknowledgements

We would like to thank the authors of the original NIH-CPSI Mark Litwin and J. Curtis Nickel; the translators Michael Thinggaard, Gordon Roberts and Lisa Hansson and the Danish language specialist Tina Jensen for help during the translation procedure. We would also like to thank all the men participating in the study.

Disclosure statement

No potential conflict of interest was reported by the authors.