Sample and methods of data collection
This study is part of a randomised controlled trial evaluating a psycho-educational intervention to reduce patients’ CRF [18]. Recruitment took place in outpatient clinics at a university-based cancer centre in south-east Norway. This study is a cross-sectional descriptive study and includes baseline data from all patients before randomisation. At baseline the patients had received surgery, completed chemotherapy, were about to receive their final radiation therapy treatments (daily treatment number 25) and/or were in the first of five years of hormone therapy. To be included in the study, the women had to be undergoing active curative treatment for breast cancer stage I or II. In addition, as this was an intervention study for CRF, the women had to report a fatigue score of ≥ 2.5 on the numeric rating scale (NRS) (0–10 point variation). Eligible patients were ≥ 18 years of age, were able to read, write and understand Norwegian, and gave written informed consent. Eligible patients were approached in the outpatient clinics by the staff nurses. The women completed the self-reporting questionnaires at home and posted them back to the investigator [18]. There was no need to apply for license for any of the survey instruments used in this study.
Instruments
Demographic and treatment characteristics
For demographic data, the patients reported their year of birth (year born), marital status (single, married/live-in partner, divorced, widow/widower or separated); living arrangements (living alone, living with spouse/partner, living with siblings, living with family/relatives, living with children/children-in-law, living with parents, living in an institution or living with others); educational level (primary school, secondary school, high school, university college or university); work situation (paid employment, self-employed, full-time home maker, student/military service, unemployed/laid off, on disability benefit or retired); type of breast surgery (removed lump in breast or whole breast) and treatment (chemotherapy, radiation, hormonal treatment or other).
Fatigue
Fatigue was measured using the fatigue questionnaire (FQ) which is translated into Norwegian [19]. The questionnaire consists of 11 questions, seven of which measure physical fatigue (PF) and four of which measure mental fatigue (MF). The questions have four response alternatives on a scale from 0 (less than usual) to 3 (much more than usual). The questions give a total score from 0 to 33 points, where a high score indicates more fatigue (total fatigue = TF). For physical fatigue (PF), the total score is reported on a scale from 1 to 21, and for MF from 0 to 12. FQ has good reliability and validity, and the questionnaire is used in Norwegian and in international studies [18,19,20]. This study has Cronbach’s alpha value for TF = 0.9, PF = 0.8 and MF = 0.8.
Social support
Social support is measured using the Norwegian version of SPS [21]. Six provisions were initially measured but, after revision, ʻguidance’ and ʻreliable alliance’ were removed due to intercorrelation [17, 22, 23]. The questionnaire therefore consists of 16 items with four items for each provision: ʻattachment’, ʻsocial integration’, ʻreassurance of worth’ and ʻnurturance’. The items have four response alternatives on a scale from 1 (strongly agree) to 4 (strongly disagree). Negative items yield the opposite point score. The total score can range from 16 to 64, where a high score indicates a greater level of social support. For the four provisions, the total score is reported on a scale from 4 to 16 [21]. The questionnaire is used in both Norwegian and international studies, and reports good reliability and validity [17, 21, 24]. This study has a Cronbach’s alpha value for total SPS score = 0.8; ʻattachment’ = 0.7, ʻsocial integration’ = 0.7, ʻreassurance of worth’ = 0.7 and ʻnurturance’ = 0.7.
Comorbidity
The self-administered comorbidity questionnaire (SCQ), translated into Norwegian, consists of 13 common medical conditions simplified into a language that can be understood without prior medical knowledge [25]. Patients indicated whether they had the condition; whether they received treatment for it (proxy for disease severity), and whether it limited their activities (indication of functional limitations). The patient can receive a maximum of three points for each condition. The total SCQ score ranges from 0 to 39. The SCQ has well established validity and reliability [26, 27].
Statistical analyses
Descriptive statistics were used to describe demographic and treatment characteristics. Categorical variables are presented as counts with percentages. The continuous variables are presented with mean and standard deviation (SD) or with median and minimum and maximum values. The various demographic and treatment-related variables were dichotomised before further analyses. Univariate regression analysis was performed to find possible association between fatigue and social support, and a possible association between social support and demographic and treatment-related variables. As the variables living arrangement and marital status were strongly correlated with each other (p ≤ 0.05), only living arrangement was included in the regression analysis to avoid multicollinearity. The variables that were statistically significant in univariate analyses were further included in the multivariate regression analysis. p values < 0.05 were considered statistically significant. The statistics programme SPSS Statistics 23 for Windows was used to perform the analyses [28].
