Cross-cultural validity of the Individualised Care Scale - a Rasch model analysis.

AIMS AND OBJECTIVES: The aim of this study was to investigate, using Rasch model analysis, the measurement invariance of the item ratings of the Individualised Care Scale.

BACKGROUND: Evidence of reliability is needed in cross-cultural comparative studies. To be used in different cultures and languages, the items must function the same way.

DESIGN: A methodological and comparative design.

METHODS: Secondary analysis of data, gathered in 2005-2006 from a cross-cultural survey using the Individualised Care Scale from Finnish, Greek, Swedish and English predischarge hospitalised orthopaedic and trauma patients (n = 1093), was used. The Rasch model, which produces calibrations (item locations and rank) and item fit statistics, was computed using the Winstep program.

RESULTS: The rank of average Individualised Care Scale item calibrations (-2·26-1·52) followed a generally similar trend (Infit ≤ 1·3), but slight differences in the item rank by country were found and some item misfit was identified within the same items. There was some variation in the order and location of some Individualised Care Scale items for individual countries, but the overall pattern of item calibration was generally corresponding.

CONCLUSIONS: The Rasch model provided information about the appropriateness, sensitivity and item function in different cultures providing more in-depth information about the psychometric properties of the Individualised Care Scale instrument. Comparison of the four versions of the Individualised Care Scale - patient revealed general correspondence in the item calibration patterns although slight differences in the rank order of the items were found. Some items showed also a slight misfit. Based on these results, the phrasing and targeting of some items should be considered.

RELEVANCE TO CLINICAL PRACTICE: The Individualised Care Scale - Patient version can be used in cross-cultural studies for the measurement of patients' perceptions of individualised care. Information obtained with the use of the Individualised Care Scale in clinical nursing practice is important, and valid measures are needed in evaluating patients' assessment of individualised care, one indicator of care quality.