Development and validation of the Clinical Nursing Knowledge Questionnaire-15 (CNKQ-15) for assessing contraceptive knowledge among nurses

Background Deficiencies in contraceptive knowledge among healthcare professionals persist worldwide, while existing assessment tools lack rigorous psychometric validation and standardized interpretation. Given nurses’ central role in contraceptive counseling, a robust, profession-specific instrument is needed to accurately identify knowledge gaps and guide targeted training to improve clinical practice. Objective To develop and psychometrically validate the Contraception Nursing Knowledge Questionnaire (CNKQ-15) in order to provide a standardized tool for assessing contraceptive knowledge and identifying training needs among nursing professionals. Design A methodological study conducted in two phases: qualitative instrument development and cross-sectional psychometric evaluation. Setting(s) A nationwide study conducted in Spain between February and April 2025. Data collection was distributed digitally through the General Council of Nursing and provincial official nursing colleges. Participants A total of 1123 actively practicing nursing professionals (including generalist nurses and specialized nurses). Methods Content validity was assessed by a multidisciplinary expert panel using Aiken’s V index. Psychometric evaluation included item difficulty and discrimination analysis, known-groups discriminant validity (comparing specialists in Obstetrics and Gynecology with non-specialized nurses), and test-retest reliability evaluated in a subsample of 100 participants over a 14-day interval. Standardized cut-off points were also established. Results The final sample included 1123 nursing professionals, predominantly women (90.5%), with a mean age of 38.3 years (SD = 10.3). Most participants reported no specialization (58.2%), while 23.5% specialized in Obstetrics and Gynecology. The CNKQ-15 showed adequate item difficulty indices (0.30–0.94) and demonstrated strong discriminant validity, effectively distinguishing between professionals specialized in Obstetrics and Gynecology and those without specialization (mean scores 12.7 vs. 9.9; p < 0.001). Test–retest reliability was excellent, with an intraclass correlation coefficient of 0.85 (95% CI [0.77–0.91]). According to the established cut-off points, 48.3% of participants exhibited null or insufficient knowledge of contraception, 30.1% achieved only a minimal level, and fewer than one in five demonstrated good or very good knowledge. This proportion of inadequate knowledge increased to 59.3% among nurses without specialization in Obstetrics and Gynecology. Conclusions The CNKQ-15 shows adequate content validity, discriminant validity, and reliability. Its standardization allows the accurate identification of knowledge gaps among nursing professionals, including midwives, and offers a practical tool for evaluating contraceptive training and guiding targeted educational interventions. Social media abstract The newly validated CNKQ-15 robustly assesses contraceptive knowledge in nurses and midwives, identifying critical gaps. @cris90due