Psychometric evaluation of the Indonesian version of the confidence scale among primary healthcare nurses in dengue-related prevention practice

BACKGROUND: Confidence may influence nurses' clinical practice. In dengue-endemic countries such as Indonesia, dengue infection prevention represents a core component of dengue-related practice among primary healthcare (PHC) nurses. However, validated Indonesian instruments for assessing nurses' confidence in dengue-related prevention practice are limited. Therefore, this study aimed to translate and evaluate the psychometric properties of the Indonesian version of a Confidence Scale (C-Scale-I). METHODS: A cross-sectional study was conducted between May and August 2024 among nurses working in PHC units across Indonesia. The original C-Scale was adapted into Indonesian using a six-step cross-cultural process, including forward translation, synthesis, backward translation, expert review, pretesting, and instrument appraisal. Psychometric evaluation included face and content validity, construct validity using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), measurement invariance, known-groups validity, concurrent validity, internal consistency, and test-retest reliability. RESULTS: A total of 458 nurses from 85 PHC units participated. Pretesting among 30 nurses indicated acceptable face validity. Content validity was also acceptable based on evaluation by eight experts. EFA supported a single-factor structure explaining 74.13% of the total variance. CFA confirmed the one-factor model with acceptable fit indices, with factor loadings ranging from 0.79 to 0.86. Measurement invariance across education levels was supported based on ΔCFI and ΔSRMR criteria. Known-groups validity was indicated by higher C-Scale-I scores among nurses familiar with national dengue guidelines compared with those who were not. Concurrent validity showed a positive correlation with the Visual Analogue Confidence Scale. The scale had acceptable internal consistency (Cronbach's α = 0.92; McDonald's ω = 0.92) and test-retest reliability over a two-week interval (intraclass correlation coefficient = 0.74, 95% CI 0.52-0.86). CONCLUSIONS: The C-Scale-I demonstrates acceptable validity and reliability for assessing confidence in dengue-related prevention practice among PHC nurses. This tool may assist nursing leaders and educators in identifying confidence gaps and strengthening continuing education initiatives related to dengue prevention in PHC settings. Further studies are needed to evaluate additional psychometric properties, such as responsiveness to change, discriminant validity, and predictive validity, and to examine its applicability in other nursing populations and contexts.