Translation, cultural adaptation, reliability, and validity of the Persian version of the Constipation Severity Instrument.

Aim: The aim of this study was to translate and cross-culturally adapt the Constipation Severity Instrument (CSI) and assess its reliability and validity in the Iranian Persian language with chronic functional constipation.

Background: Chronic functional constipation is a common complaint characterized by a range of symptoms. The use of a validated tool adapted to the culture is an important part of the treatment process.

Methods: CSI was translated into Persian language according to Beaton's guidelines. One hundred and twenty-five patients with chronic functional constipation, according to ROME IV criteria, completed the questionnaires. Face validity was assessed in two qualitative and quantitative forms (impact score), internal consistency and test-retest reliability were assessed by Cronbach's alpha coefficient and intraclass correlation coefficient (ICC), respectively. Convergent validity was assessed by correlating the total scores of the CSI and the WCSS. The floor/ ceiling effects of the questionnaire were also assessed.

Results: The impact score of all questions was greater than 1.5. The Cronbach's alpha coefficient for the total score was 0.90 and the ICC was 0.90. The total score of the CSI was significantly correlated with the total score of the WCSS (Spearman's p=0.74). No floor/ceiling effects were found.

Conclusion: The Persian version of the CSI is a reliable and valid tool that can be used for psychometric evaluation. Clinicians can also benefit from this questionnaire when assessing treatment outcomes in Iranian patients.