Development and Validation of a Safety Scale Perceived by the Witness of Prehospital Emergency Care.

OBJECTIVE: The aim of the study was to design and validate a new tool to measure the security perceived by witnesses of patient care and hospital transfers, after requesting urgent assistance via the "061" phone number.

METHODS: This is a descriptive observational, cross-sectional, design, and validation study of a scale conducted by telephone interview. Witnesses of urgent assistance and transfers by prehospital emergency medical services in the province of Cadiz, in the south of Spain, were the subjects of study. A questionnaire was designed after focus groups with patients, witnesses, and professionals. It consisted of 10 items, with Likert-type answers, and a range of 0 to 50 points. In addition to basic criteria (frequency of endorsement and ability to discriminate between groups), their validity (content and construct) and reliability (stability and homogeneity) were evaluated. Stability was evaluated by test-retest and homogeneity by means of two properties: internal consistency of items (corrected item-scale correlation coefficient) and internal consistency of the scale (Cronbach α coefficient).

RESULTS: A total of 849 questionnaires were obtained, with scores between 0 and 50 points, with an average of 47.31 (median of 50). The exploratory factor analysis detected a component that explained 61.1% of the total variance. The intraclass correlation coefficient was 0.933 with 95% confidence interval between 0.900 and 0.954. The corrected item-scale correlation coefficient was greater than 0.596, and the Cronbach α coefficient was 0.927 (95% confidence interval, 0.919-0.934).

CONCLUSIONS: The ESPT10 Witness Perceived Safety Scale is valid and reliable for quantifying the safety perception of witnesses of emergency assistance and transfers.