Data used for the present study derived from a larger prospective study designed to describe QoL and psychological well-being of breast cancer patients within a month from the cancer diagnosis, and one and two years after it. All participants were adult female breast cancer patients, had to understand the Italian language and signed the informed consent. In addition, a further inclusion criterion for the present study was to have been surgically treated for breast cancer one year before.
Procedure and materials
BIS was translated into Italian by back translation procedure: two Italian, English proficient, psychology researchers translated the BIS into Italian; then, the two Italian translations were compared and compiled into a single preliminary version; and finally re-translated into English by a professional translator. The final Italian version was achieved by revision of the preliminary one according to the results of the comparison of the original version of the scale and its re-translation into English from Italian.
The final Italian version of BIS is available as an (Additional file 1).
Italian BIS version was administered to participants together with the Hospital Anxiety and Depression scale (HADS, ), the Short Form 36 Health Survey Questionnaire (SF-36, ), and a form to collect socio-demographic and clinical data.
All participants received materials at home as the second step of a larger study, with the instruction to fill out and return them by mail (a pre-paid envelope was provided together with the study booklet) within 3 weeks.
The Institute Independent Ethics Committee gave its clearance to the study.
HADS is a self-report scale assessing anxious and depressive states of medical patients. It is made up of two factors, in which higher scores correspond to higher anxious and depressive states respectively. Validation data for Italian HADS version were provided by Annunziata et al. .
The SF-36 is a QoL measure consisting of 36 items and eight different QoL indices: Physical Functioning, Role-Physical Limitation, Bodily Pain, General Health, Vitality, Social Functioning, Role-Emotional Limitation, Mental Health. In each index, higher scores indicate better functioning in that domain. Validation for SF-36 Italian version was provided by Apolone et al. .
Socio-demographic and clinical data were self-reported and collected information on age, marital status, education, occupational status, and cancer treatments.
Feasibility of BIS was assessed by response rates and missing answers.
Response prevalence was defined as the frequency of positive ratings (score > 0) for each item, indicating some change in body image; 30% of positive ratings of the total sample in each item was used as criterion.
To assess the factor structure, a principal component analysis (PCA) was performed. Scree plots, the number of eigenvalues exceeding 1 and the percentage of explained variance were used in determining the number of extracted factors. Only items with factor loadings of 0.40 or above were retained.
Internal consistency was assessed using Cronbach’s Alpha; scores exceeding 0.70 have been considered acceptable .
The convergent/divergent validity was assessed by Spearman’s correlations with the subscales of the HADS and SF-36: rho < 0.30, 0.30 < rho < 0.45, 0.45 < rho < 0.60, and rho > 0.60 have been considered indices of a negligible, moderate, substantial, and high correlation, respectively .
The discriminant validity was assessed comparing BIS score according to the type of received surgery (quadrantectomy vs. mastectomy) through an independent sample t-test.
Descriptive statistics (mean, standard deviation, minimum, maximum) were calculated for the entire scale as well as for each item in this sample.
All analyses were performed on the subsample who had provided a complete BIS; an exception was made for feasibility which was assessed using all provided BIS.
In all analyses, p < 0.05 (2-tailed) was used for statistical significance. The Statistical Package for the Social Sciences (SPSS) was used to perform the analyses.