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This study was based on the Knowledge-Attitude-Practice (KAP) framework and used a three-phase process to develop and psychometrically evaluate the Knowledge-Attitude-Practice Questionnaire for Health Professionals in Adult Functional Constipation Care (KAP-FC). The study was approved by the Ethics Committee of Nantong City Hospital (Approval No. NTLYLL2022087), and written informed consent was obtained from all participants before enrollment. Participants were informed that they could withdraw from the study at any time without consequence. All participants were assured that the questionnaire data would be used solely for research purposes and would be kept confidential.
Construction and development of the initial questionnaire
In the first phase, an initial item pool was developed through literature review, theoretical analysis, and qualitative interviews. The literature review focused on functional constipation, constipation-related nursing care, health education, patient assessment, treatment adherence, and the development of KAP-based questionnaires. On this basis, the research team drafted preliminary items covering three theoretical domains: knowledge, attitude, and practice. Semi-structured interviews were then conducted after appointments were arranged with the participants. Each interview lasted approximately 15–30 min and was conducted in a separate doctor’s or nurse’s office to ensure privacy and minimize interruptions.
Purposive sampling was then used to recruit eight healthcare experts from the gastroenterology and geriatrics departments at a tertiary hospital in Nantong for semi-structured interviews. The inclusion criteria were as follows: (1) at least 15 years of clinical experience in gastroenterology or geriatrics in a tertiary hospital; (2) a bachelor’s degree or above; (3) a senior professional title, or an intermediate professional title together with at least five years of provincial-level gastroenterology specialist nurse qualification; and (4) informed consent and voluntary participation in the study. Before the interview, the research team explained the study purpose, interview content, confidentiality requirements, and the participants’ right to withdraw.
The semi-structured interview guide included the following questions: (1) Are you familiar with the diagnostic criteria for FC? (2) Is FC common in your department? (3) How do you evaluate the ability of clinical nurses to provide FC care, and can this ability meet routine clinical needs? (4) What constipation-related knowledge should qualified nurses possess in clinical practice? (5) Do you have any further comments on the issues discussed above? (6) What role should clinical nurses play in the care of patients with FC, and what care measures should they implement?
Interviews were conducted by trained research team members. With participant consent, interviews were audio-recorded and transcribed verbatim. The research team reviewed the transcripts after each interview and continued recruitment until no new themes or item-relevant information emerged, indicating data saturation. The Colaizzi seven-step analysis method was used to extract themes and core items14. An initial questionnaire containing 30 items across the knowledge, attitude, and practice dimensions was then developed.
Scoring criteria were defined before the formal survey. In the knowledge dimension, single-choice items were scored from 1 to 3 points based on the response option, with higher scores indicating greater knowledge. For multiple-choice items, scores were calculated according to the proportion of correctly selected correct options using the following formula: Item score = 1 + 2 × (number of correctly selected correct options/total number of correct options). The calculated score was then converted according to the predefined questionnaire scoring table. The score was then assigned according to the predefined scoring table for the questionnaire. The total knowledge score was calculated by summing the scores of all knowledge items, with higher scores indicating a higher level of FC-related knowledge. For the attitude dimension, a 5-point Likert scale was used, ranging from 1 = strongly disagree to 5 = strongly agree, with total scores ranging from 6 to 30. For the practice dimension, a 5-point Likert scale was used, with responses ranging from 1 = never to 5 = always, and total scores from 10 to 50. Higher scores indicated more positive attitudes or more standardized practice.
Validation and evaluation of the questionnaire content
Sixteen interdisciplinary experts, including gastroenterologists, gastroenterology specialist nurses, and geriatric nursing experts, participated in two rounds of Delphi consultation. The inclusion criteria were as follows: (1) gastroenterology medical experts with more than 15 years of professional experience and either a senior professional title or a master’s degree or higher; gastroenterology nursing experts with a bachelor’s degree or higher and either a senior professional title or provincial-level specialist nurse qualification for at least five years; or geriatric medical or nursing experts with a bachelor’s degree or higher and a senior professional title; (2) familiarity with the Delphi technique; and (3) voluntary participation and willingness to complete the consultation process. In both rounds, the Delphi questionnaires were distributed separately, and all experts completed them independently and anonymously. The feedback and comments obtained from the first round were summarized by the research team and incorporated into the second-round questionnaire to guide further item revision and expert evaluation.
Before each consultation round, the research team screened experts according to the predefined eligibility criteria and confirmed their professional background, years of experience, title, specialty, and willingness to participate. The consultation questionnaire asked experts to rate the importance of each item and provide qualitative comments on wording, clinical relevance, item clarity, and dimensional attribution. The expert participation rate, expert authority coefficient (Cr), coefficient of variation (CV), full-score rate, and Kendall’s coefficient of concordance were used to evaluate expert authority and consensus.
Items were retained when they met the following criteria: mean importance score ≥ 3.5, CV ≤ 0.25, and full-score rate ≥ 20%. Items that did not meet these criteria were revised or deleted after discussion by the research team, taking into account the experts’ qualitative comments and the item's theoretical relevance to FC nursing care. Items with unclear wording but adequate theoretical relevance were modified, whereas items with poor expert agreement, low importance, or conceptual overlap with other items were deleted or merged. After the two Delphi rounds, the questionnaire contained 30 items across the knowledge, attitude, and practice dimensions.
The revised questionnaire was then pre-tested. Stratified convenience sampling was used to recruit 30 registered clinical nurses from a tertiary hospital in Nantong, including 40% from gastroenterology, 40% from geriatrics, and 20% from other departments. The inclusion criteria were that participants be registered clinical nurses working in a tertiary hospital, provide informed consent, and be willing to participate. The exclusion criteria were nurses with 12 months or less of work experience, trainee nurses, pediatric nurses, and nurses with past or current mental health disorders. The survey was coordinated by the nursing department and conducted by trained research team members in each department. Participants completed the questionnaire 30 min after the departmental shift handover, and the research team provided standardized instructions for its completion. Thirty questionnaires were distributed and returned, yielding a 100% response rate. Participants reported no difficulty understanding the items, and the mean completion time was 8.5 ± 2.3 min. The pre-test showed good internal consistency, with a Cronbach’s α of 0.926, supporting the feasibility of the questionnaire for the formal survey.
Reliability and validity testing of the questionnaire
In October 2022, three tertiary hospitals in Nantong were randomly selected for the formal questionnaire survey. Stratified convenience sampling was used to recruit nurses from departments with a high frequency of FC-related care needs, including gastroenterology, neurology, cardiology, and geriatrics, as well as other clinical departments when eligible nurses were available. Within each selected department, eligible nurses were invited by trained research team members after coordination with the nursing department. The inclusion and exclusion criteria were the same as those used in the pre-test.
A total of 491 questionnaires were collected. After excluding 25 invalid questionnaires, 466 valid questionnaires were included in the final analysis, giving an effective response rate of 94.9%. The final sample included 71 nurses from gastroenterology or gastrointestinal disease-related departments and 395 nurses from other departments.
Questionnaires were administered through both online and paper-based routes. For the online survey, the questionnaire link was distributed through the hospital OA system using a Chinese online questionnaire survey platform. Each IP address was allowed to submit the questionnaire only once to reduce duplicate responses, and the acceptable response time was set at 3 to 15 min based on the pre-test completion time. Responses outside the predefined time range or with obvious invalid response patterns were automatically flagged. For the paper-based survey, questionnaires were distributed after morning departmental meetings and collected on-site. Research team members checked the completeness of paper questionnaires immediately after collection. Questionnaires with missing key information, incomplete item responses that prevented score calculation, duplicate submissions, or invalid response patterns were excluded from analysis. For analyzable questionnaires with minor missing information in non-key demographic variables, the available valid item responses were retained for analysis.
Standardized expert and participant selection
Eligibility criteria were established before the semi-structured interviews, Delphi expert consultations, pre-test, and formal survey. For the interview and Delphi phases, experts were screened according to specialty, years of professional experience, educational background, professional title, specialist qualification, familiarity with the Delphi method, and willingness to participate. For the nurse pre-test and formal survey, participants were screened according to registration status, clinical work experience, department, informed consent, and exclusion criteria. This process was used to ensure the professional relevance of expert input and the eligibility of survey participants.
Standardized data collection
Before formal data collection, standardized training was provided for all research personnel. A 10-minute instructional video on questionnaire completion was prepared, and five postgraduate nursing students were trained as quality-control personnel. They used unified instructions to explain the survey's purpose, completion requirements, and precautions, thereby reducing interpretation bias.
Two data collection routes were used to improve response coverage and data quality. Online questionnaires were distributed through the hospital OA system using a link to the questionnaire platform (n = 379). To reduce duplicate submissions, each IP address was permitted to submit the questionnaire only once. During data collection, duplicate questionnaires were identified based on repeated IP addresses, repeated submission records, or obvious overlap in participant information and were excluded from the analysis. Based on the pre-survey completion time, the acceptable response-time range was set to 3–15 min, and questionnaires outside this range or with obvious invalid response patterns were automatically flagged by the system. Paper questionnaires were distributed after departmental morning meetings (n = 112), collected onsite immediately upon completion, and checked by the research team for completeness. Incomplete responses were identified by missing key demographic information, unanswered questionnaire items that prevented score calculation, or incomplete item responses across the knowledge, attitude, or practice dimensions. Questionnaires with duplicate submissions, incomplete key information, invalid response patterns, or responses that did not meet the predefined quality-control criteria were excluded from the final analysis.
Sample size calculation
The sample size was determined based on the principle that it should be at least 10 times the number of questionnaire items. The initial questionnaire contained 30 items across three dimensions; therefore, at least 300 participants were required. In the formal survey, 466 valid questionnaires were collected, exceeding the minimum required sample size by 55.33% and meeting the requirements for psychometric analysis.
Statistical methods
Statistical analysis was performed using SPSS version 23.0. Expert consultation reliability was evaluated using the expert participation rate, expert authority coefficient (Cr), coefficient of variation, and Kendall’s coefficient of concordance. Categorical variables were presented as frequencies and percentages, and continuous variables were presented as mean ± standard deviation.
For item analysis, the critical ratio method and the item-total correlation method were used15. In the critical ratio method, the total questionnaire scores were ranked from high to low, with the top 27% classified as the high-score group and the bottom 27% as the low-score group. Independent-sample t-tests were then used to compare item scores between the two groups. Items with non-significant between-group differences (P > 0.05) or a critical ratio < 3.0 were considered for deletion. In the item-total correlation method, Pearson product-moment correlation coefficients were calculated between each item and the total questionnaire score, and items with correlation coefficients < 0.30 were considered for deletion.
Validity was evaluated using structural validity and content validity. For structural validity, exploratory factor analysis (EFA) was performed. The suitability of the data for factor analysis was assessed using the Kaiser-Meyer-Olkin (KMO) test and Bartlett’s test of sphericity. In this study, Bartlett’s test of sphericity was significant (P < 0.001), and the KMO value was 0.881, indicating that the data were suitable for factor analysis16. Principal component analysis with Kaiser-normalized varimax rotation was then used to extract factors. Common factors were retained based on eigenvalues > 1 and visual inspection of the scree plot. A cumulative variance contribution rate > 40%, item factor loadings > 0.40, and absence of cross-loadings were considered acceptable17. For content validity, six experts with experience in gastroenterology or gastrointestinal disease care and familiarity with questionnaire development were invited to evaluate the questionnaire. Each item was assessed using a four-point Likert-scale relevance, and the content validity index (CVI) was calculated. An item-level CVI > 0.780 and a scale-level CVI > 0.600 were considered to indicate acceptable content validity18.
Reliability was evaluated using Cronbach’s α, split-half reliability, and test-retest reliability. Cronbach’s α > 0.700 was considered acceptable, and values between 0.800 and 0.900 indicated good internal consistency. Split-half reliability > 0.700 was considered acceptable19. For test-retest reliability, 47 nurses were randomly selected from the 466 participants and completed the questionnaire again after a two-week interval. Stability over time was assessed using the intraclass correlation coefficient based on a two-way mixed-effects model with absolute agreement.