Decision-related outcomes
Table 
Decision-related outcomes at baseline (t0), three (t1) and six months (t2) after study inclusionStatistical significance for any score: 2-sided Mann-Whitney-U-Test; except #: 1-sided according to study protocol [At t0, 53.5% of the total group (IG and CG) classified themselves as undecided. This applied to more women aged 18–40 years than women aged > 40 years (61.4% vs. 43.1%; p = 0.000). Of those who reported choosing at least one preventive option, 26.6% had chosen one of the two risk-reducing surgeries (risk-reducing mastectomy (RRM) only or RRBSO only), 15.1% opted for both surgical options (RRM plus RRBSO), and 4.8% opted for IBS/IBSA only. At t0, IG and CG showed comparable decision status regarding all options. During follow-up (t1, t2), the proportion of undecided women continued to decrease, comparably in IG and CG, with no more significant differences between age groups. At t1, there was a non-significant trend for more women in the IG to choose RRM plus RRBSO, and more women in the CG to choose IBS/IBSA plus RRBSO. This trend strengthened at t2, when statistically significantly more women in the IG chose RRM plus RRBSO than in the CG. For all other options, IG and CG showed no statistically significant differences at t1 and t2.The DRS for the three options displayed a Cronbach’s alpha between 0.74 and 0.83. Overall, decision regret with regard to each of the three preventive options was low, with mean scores in the lower decile of the score range for the total group, the IG, and the CG. There were no statistically significant differences between IG and CG. Women aged 18–40 years were significantly less likely than women aged > 40 years to regret the decision to have RRM (7.9 vs. 18.7; p = 0.000).