Patient perceived participation in decision making on their antipsychotic treatment: Evidence of validity and reliability of the COMRADE scale in a sample of schizophrenia spectrum disorders.

Objective: The aim of this paper is to provide evidence of the validity and reliability of the COMRADE scale (Combined Outcome Measure for Risk communication And treatment Decision making Effectiveness) in patients suffering from schizophrenia spectrum disorders.

Method: 150 patients recruited at five mental health centers were assessed using a cross-sectional study design. The COMRADE, WAIS-S (therapeutic alliance) and TSQM (satisfaction with medication) scales were used.

Results: Exploratory Factor Analysis identified three factors from the COMRADE (F1: "Risk communication"; F2: "Confidence in decision" and F3: "Knowledge of decisional balance") which explain 45.2, 8.5 and 6% of the variance, respectively. Statistically significant correlations were observed between the scores of the COMRADE subscales with the subscales of the WAI-S and the TSQM. The internal consistency observed for each of the factorial scores of the COMRADE were (Cronbach's alpha values) 0.90, 0.89 and 0.74, respectively.

Conclusion: The COMRADE scale offers appropriate psychometric properties for its use as a measure of perceived patient involvement in the shared decision making process in antipsychotic treatment.

Practice Implications: The use of the COMRADE measure in psychiatric clinical practice and in research studies provides an outcome measure of interventions from the shared decision making model.