Annelotte van Bommel

149 Quality of life after immediate breast reconstruction The questionnaire was tested and approved by a panel of patient representatives before distribution. Patients responded via PROFILES, an online secured web- based environment 20 , or received the questionnaire on paper on request. Statistical analysis First, clinical characteristics of respondents and non-respondents were analyzed. Baseline characteristics of the respondents were presented for patients treated with mastectomy and IBR and for those without IBR. BREAST-Q domain scores were calculated with the Q-Score scoring software system to transform the raw BREAST-Qdata. 19 The BREAST-Qoutcomes were compared between patients with mastectomy and IBR and patients without IBR. Sub-analyses were performed for the various reconstructive techniques. Chi-square tests were used for categorical data and Student’s T-tests were used for comparison of continuous BREAST-Q scores. Finally, a multivariate linear regression analysis was performed to investigate the impact of IBR on the different domain outcomes, adjusted for confounding factors. Factors included in the model were chosen on their possible relevance. Two-sided p-values <0.05 were considered statistically significant. All statistical analyses were performed using SPSS (SPSS for MAC Version 20.0; SPSS Inc., Chicago, Il). RESULTS Study population Questionnaires were sent to a total of 1218 patients: 502 who had undergone mastectomy with IBR and 716 who had not received IBR after mastectomy. The overall response rate was 46% (558/1218). No statistically significant differences between responders and non-responders were found for most patient characteristics, except that older patients and patients without IBR were slightly underrepresented in the respondent group compared to the non-respondent group ( Supplementary Table ). A total of forty-seven patients without IBRwere excluded; 25 patients because they had received delayed breast reconstruction and 22 patients who returned incomplete BREAST-Q modules (defined as completion of less than one outcome domain in one of the two modules), leading to 511 patients available for analyses. 8