Prostate cancer-specific anxiety in Dutch patients on active surveillance: validation of the memorial anxiety scale for prostate cancer

Men with prostate cancer (PC) may show specific disease-related anxiety. We evaluated the psychometric properties of the Dutch adaptation of the Memorial Anxiety Scale for Prostate Cancer (MAX-PC). The MAX-PC was translated using standardized forward-backward procedures. Patients (N = 150) on active surveillance, a strategy of initially withholding active therapy, for recently diagnosed early PC were mailed a questionnaire. Internal consistency was estimated using Cronbach's alpha. The scale structure was analyzed using confirmatory factor analysis (CFA). Construct validity was evaluated by Pearson's correlations between MAX-PC scores and scores on decisional conflict (DCS), generic anxiety (STAI), depression (CES-D), and general mental health (SF-12 MCS). Data from 129 respondents were used (response rate 86%). Cronbach's alpha for the total score and the three subscales were 0.77, 0.91, 0.64, and 0.85, respectively. CFA largely confirmed the three-factor structure as used in the original publication (model fit: chi(2) 149, P = 0.051). The patterns of directions and sizes of the correlations (r = 0.36-0.66) between MAX-PC scale scores and the other variables were in accordance with a priori hypotheses, except for the prostate-specific antigen anxiety subscale. The relatively poor performance of this scale in the original version was replicated. The structure and validity of the MAX-PC to quantify PC-specific anxiety were largely confirmed in Dutch patients.