Bowel health significantly impacts quality of life, yet relevant screening tools remain scarce in rural Indian population. Existing patient reported outcome measure (PROM) like the Initial Measurement of Patient-Reported Pelvic Floor Complaints Tool Bowel Function Assessment Tool, Short Form (IMPACT-SF) (1), while validated internationally, lacks regional adaptation in Southern India. IMPACT-SF does not account for all criteria for constipation, local dialects, and neglected defecation-related behaviours. Therefore, this is the first study aimed to adapt and validate the design of IMPACT-SF for a rural area in Southern India, while expanding its scope to assess region-specific bowel habits and defecatory behaviours.

The modification and validation of design of IMPACT-SF is a cross-sectional observational study informed by the guidelines of International Society for Pharmacoeconomics and Outcomes Research (ISPOR) (2). Our objective in modifying IMPACT-SF was to evaluate patient’s perceptions of bowel function particularly, constipation by incorporating all relevant aspects related to defecatory habits. We adapted the IMPACT-SF questionnaire based on a thorough literature search regarding bowel habits, defecatory behaviours, and clinical experience of two pelvic floor physiotherapists. We added questions related to manual manoeuvres, use of laxatives as per Rome IV criteria for diagnosis of constipation, defecatory behaviour and self-perceived constipation. To begin with the validation process, we purposively chose 11 experts (3-gynaecologists, 3-colorectal surgeons, 1-gastroenterologist, 1-urogynecologist, 2-pelvic floor physiotherapists and, 1-statistician) and 5 female participants who had experienced constipation ( 2- homemakers, 1-clerk, 1-doctoral student,1- physician). They were provided with a cover letter, content validity document, and the modified IMPACT-SF questionnaire explaining why experts/ participants were invited to participate, along with clear and concise instructions on how to rate each item. The evaluation sheet included 5 inquiries: relevance, clarity, appropriateness, sentence formation, and comments/ suggestions. A five-point Likert scale was used where ratings 1, 2, and 3 were considered content invalid whereas ratings of 4 and 5 were considered content valid.

All content validity calculations commenced from the second evaluation of modified IMPACT-SF (15 questions). Experts and participants provided subjective comments about question framing and the questionnaire was refined accordingly. 12 questions had an item-level content validity index (I-CVI) =1.0 whereas the other 3 questions had I-CVI= 0.6. Scale-level content validity index (S-CVI) was calculated using the average of all I-CVI divided by 15 questions of modified IMPACT-SF. The average of all I-CVI was calculated as 0.925 for sentence formation whereas all other criteria had S-CVI= 0.99.

The results indicate that most items in the IMPACT-SF are deemed essential by experts and participants, with a high overall S-CVI of 0.925-0.99 suggesting high content validity. The three items with an I-CVI of 0.6 may require revision or further evaluation to enhance their relevance or clarity.

The study successfully modified and validated the design of IMPACT-SF questionnaire for a rural population in Southern India, addressing a significant gap in context-relevant screening tool for defecatory dysfunction. Further, the study will incorporate translation of the questionnaire to local language (Kannada) informed by the guidelines of Beaton et al. (3). The study contributes to improved screening accuracy and patient care in managing bowel dysfunction within rural Indian communities.

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Patrick DL, Burke LB, Gwaltney CJ, et al. Content validity--establishing and reporting the evidence in newly developed patient-reported outcomes (PRO) instruments for medical product evaluation: ISPOR PRO good research practices task force report: part 1--eliciting concepts for a new PRO instrument. Value Health. 2011;14(8):967-977. doi:10.1016/j.jval.2011.06.014
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