The perceived personal control (PPC) questionnaire as an outcome of genetic counseling: reliability and validity of the instrument.

The perceived personal control (PPC) questionnaire was developed by Berkenstadt and colleagues as an outcome measure for the evaluation of the process of genetic counseling. The present study aimed to further assess the psychometric properties of a Dutch version of the instrument. Data were used from two samples. A reproductive genetic counseling sample (n = 140), which included pregnant and non-pregnant women, and a cancer genetic counseling sample (n = 181), also consisting of women only. Counselees completed questionnaires before and following their first consultation. Besides the PPC these questionnaires addressed counselees' degree of concern, risk perception and satisfaction with the consultation. The following psychometric properties were assessed: acceptability, internal consistency, dimensionality, and validity. The instrument was well accepted as indicated by few missing items. The internal consistency was good for the total PPC (Cronbach's alpha: 0.79-0.81), reasonable for the original subscales of 'decisional' and 'behavioral control' (>0.60), but unacceptable for the subscale of 'cognitive control' (<0.60). The original three-factor solution was not confirmed; a one-factor solution proved most stable. Significant differences between pre- and post-counseling PPC scores support the PPC's construct validity. Concurrent validity was confirmed by positive associations with counselees' satisfaction although non-significant (concern) and unexpected (risk perception) results were also found. When used as a one-dimensional scale, the PPC has its value as an outcome measure in research addressing genetic counseling. However, the instrument's validity needs to be further assessed.