Construction of scales for the Center for Marital and Sexual Health (CMASH) Sexual Functioning Questionnaire.

The objective of this study was to identify a set of scales for summarizing the results of the Center for Marital and Sexual Health Sexual Functioning Questionnaire (CMASH SFQ). Scales for this instrument were constructed using patients' responses to the CMASH SFQ in a recent clinical trial of prostaglandin E1 (PGE1, alprostadil), an injectable vasodilator used to treat erectile dysfunction. A set of items was identified as a scale if they met predetermined standards of internal consistency, discriminant validity, and convergent validity. The reproducibility of the scales was then evaluated, and the extent to which the scales reliably measured change in treatment-related quality of life was assessed. Reliable and responsive scales for four domains related to sexual functioning were identified. Items in these scales were generally internally consistent; items in the scales and the scores for the scales generally satisfied criteria of discriminant validity; and the scales generally satisfied the standard for convergent validity. Evaluating patients' responses to the CMASH SFQ with scores for four reliable and responsive scales allows easier summarization of patients' sexual functioning and increases the statistical power of evaluations of the effects of interventions designed to improve sexual functioning.