Factors associated with sedentary behaviour in breast cancer patients

Abstract

Aim: To explore which factors predict sedentary behaviour in breast cancer patients with low levels of physical activity. Methods: In this cross-sectional study, data from breast cancer patients who participated in the PAM (Physical Activity & Memory) study were used. Sedentary behaviour was measured with the ActiGraph accelerometer and defined as less than 100 counts per minute (CPM). Four variables (age, anxiety, depression and physical fatigue) were selected based on literature and entered into a binomial logistic regression with stepwise backward selection (p ≤ 0.15). The discriminative value of the final model was determined with the ROC curve and the performance of this model was assessed with calibration. Results: A total of 141 patients were included, with a mean age of 53 years old and a mean body mass index (BMI) of 28.8, of which 32 patients were sedentary. Statistical analyses led to a model that was statistically significant (p = 0.003) and explained 9.3% of the variance. Of the four variables, only physical fatigue scored with the MFI-20 was statistically significant; a higher score of physical fatigue was associated with an OR of 1.16 and thus an increased likelihood of becoming sedentary. The corresponding ROC curve had an AUC of 0.67, which is considered to be a poor level of discrimination. Calibration of the final model was good. Conclusion: The final model was deemed inadequate to properly distinguish between sedentary patients and patients with low levels of physical activity. Nonetheless, this finding adds to the existing body of knowledge concerning factors predicting a loss of physical activity in breast cancer patients. As several studies have shown that fatigue can be a barrier for physical activity but can also be reduced by it, longitudinal research would need to be done with a larger sample size to look into the causal relationship between physical fatigue and sedentary behaviour in breast cancer patients. Clinical Relevance: Based on this finding it is advised to monitor the physical activity levels of breast cancer patients who score higher for physical fatigue, in order to prevent or remedy sedentary behaviour as much as possible.