Development and validation of parallel short forms PaSA-cardio for the assessment of general anxiety in cardiovascular rehabilitation patients using Rasch analysis.

OBJECTIVE

To develop and validate parallel short forms for the assessment of general anxiety in cardiovascular rehabilitation patients, that facilitate repeated measurement over time without contamination from residual practice effect variance.

DESIGN

Development of the parallel short forms using Rasch analysis. Validation study.

SETTING

Cardiac rehabilitation centres in Germany.

SUBJECTS: Cardiovascular rehabilitation patients.

INTERVENTIONS: Not applicable.

MAIN MEASURES: Parallel short forms PaSA-cardio, Hospital Anxiety and Depression Scale, Short Form Health Survey SF-12 and Structured Clinical Interview for DSM-IV Axis I Disorders.

RESULTS

Each version of the parallel short forms (PaSA-cardio-I and PaSA-cardio-II) comprises ten items. The two forms fitted to the Rasch model with a non-significant item-trait interaction (PaSA-cardio-I: chi-square = 39.49, degrees of freedom = 30, probability = 0.12; PaSA-cardio-II: chi-square = 26.56, degrees of freedom = 30, probability = 0.65). Person-separation reliability was 0.75/0.76. Unidimensionality could be verified. Correlation between the two models was 0.94 and 0.95, and correlations with the underlying item bank were 0.95 and 0.93. Validity could be confirmed. The area under the curve was between 0.88 and 0.97 for PaSA-cardio-I and between 0.92 and 0.95 for PaSA-cardio-II.

CONCLUSIONS

Assessment of general anxiety in cardiovascular rehabilitation patients with the PaSA-cardio was valid, economical and accurate. The two forms of the PaSA-cardio are equivalent and allow retest without contamination from residual practice effect variance.