Development and validation of two brief versions of the Nurse Professional Competence (NPC) Scale: The NPC-6 and...

Several instruments for measuring nurse professional competence have been tested in different countries and shown to be both reliable and valid. However, there remains a lack of shorter, validated instruments suitable for use in different countries, in large-scale research settings and for longitudinally tracking trends and educational interventions.

The aim of this study was to develop and validate two shortened versions of the Nurse Professional Competence (NPC) Scale, comprising items across the six established competency factors.

A cross-sectional, methodological study design, with two secondary data analyses, was conducted.

Participants with NPC data were 612 Swedish registered nurses and 2135 Chinese registered nurses.

Items were selected from the 35-item scale (NPC-35) based on highest corrected item-total correlations, theoretical considerations, and discussions within the research group. Two versions were developed: a 6-item scale (NPC-6) and a 12-item scale (NPC-12). NPC-6 intended to be used only as a total score and NPC-12 to be used both as a total score and as factor scores. The psychometric properties of the shortened scales were evaluated by examining their associations with NPC-35, as well as their reliability and validity.

The Swedish and Chinese NPC-6 and -12 scales contained the same items and showed strong associations with the NPC-35 scale (r = 0.925-0.990), after removing overlapping items. Both versions had high internal consistency, with Cronbach's alpha and McDonald's omega values ranging from 0.86 to 0.98. Principal component analyses, using one factor/total scale, indicated that the Swedish and Chinese NPC-12 scales explained 55% and 81% of the variance, respectively, while the NPC-6 scales explained 60% and 82%, respectively. Tests of known-groups validity showed statistically significantly higher scores, NPC-6 and -12, among specialist nurses than non-specialist nurses. Confirmatory factor analyses of the NPC-12 confirmed the original factor structure with six competency factors.

The findings indicate that the NPC-6 is a psychometrically acceptable instrument in both countries and the NPC-12 in China when used among registered nurses. The Swedish NPC-12 explained only 55.3% of the variance in nurse professional competence when used as a total score and needs further testing. However, the six competency factors of the NPC-12 might be used instead, as indicated by factor analyses. NPC-6 is intended for total score use only, whereas NPC-12 can be scored using both total and factor scores. Additional psychometric testing is warranted to confirm structural stability, test-retest reliability, and sensitivity to change in different settings and samples.