Abstract
OBJECTIVES: To validate the patient-reported measure of Social Support Perceived by Patients Scale-Nurses (SuPP-N). DESIGN/SETTING: A secondary data analysis based on a cross-sectional breast cancer patient survey in 83 German hospitals. Patients were asked to give written informed consent before they were discharged. If they agreed to participate, the questionnaire was sent via mail to their home address after discharge. PARTICIPANTS: Of 5583 eligible patients, 4841 consented to participate in the study and 4217 returned completed questionnaires (response rate: 75.5 %). For the data analysis n=3954 respondents were included. On average, participants were 60 years old and mostly in cancer stages I and II. PRIMARY AND SECONDARY OUTCOME MEASURES: Perceived social support was assessed with a three-item patient-reported scale (SuPP-N). Convergent validity and criterion-related validity were tested using the following constructs: trust in nurses, trust in the treatment team (Wake Forest Physician Trust Scale, adapted), quality of life (European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire), processes organisation, availability of nurses. RESULTS: The structural equation model (SEM) assuming a one-dimensional structure of the instrument showed acceptable goodness of fit (root mean square error of approximation=0.04, Comparative Fit Index=0.96 and Tucker-Lewis Index=0.96; factor loadings ≥0.83). Hypothesis-consistent correlations with trust in nurses (beta=0.615; p<0.01) and trust in the treatment team (beta=0.264; p<0.01) proved convergent validity. Criterion-related validity was proved by its association with patients' quality of life (beta=-0.138; p<0.01), processes organisation (beta=-0.107; p<0.01) and the availability of nurses (beta=0.654; p<0.01). CONCLUSION: The results of the SEM identify potential important factors to foster social support by nurses in cancer care. In patient surveys, the SuPP-N can be used efficiently to measure patient-reported social support provided by nurses. The use of the scale can contribute to gain a better understanding of the relevance of social support provided by nurses for patients and to detect possible deficits and derive measures with the aim of improving the patient-nurse interaction.