A longitudinal study of depression, fatigue, and sleep disturbances as a symptom cluster in women with breast cancer

Abstract

Context: Depression, fatigue, and sleep disturbances have been identified as a symptom cluster among breast cancer patients. However, few longitudinal studies have examined the temporal relations between these symptoms surrounding diagnosis and treatment.

Objectives: The present study investigated the co-occurrence of and interrelations between nonsomatic depressive symptoms, fatigue, and sleep disturbances in breast cancer patients at three time points: before, after, and six to eight months following adjuvant chemotherapy treatment.

Methods: Separate samples of premenopausal (n = 67) and postmenopausal (n = 67) breast cancer patients completed self-report measures of depression, fatigue, and sleep disturbances at all three time points. Path analysis was used to explore within- and cross-symptom paths across time.

Results: Depression, fatigue, and sleep disturbances were correlated within each time point. Continuity paths, whereby prior levels of symptom severity tended to predict subsequent severity of the same symptom at the subsequent time point, were significant in both samples, except for depression in the premenopausal sample. Instead, significant cross-symptom paths emerged whereby baseline fatigue predicted postchemotherapy depression, and postchemotherapy fatigue predicted depression at follow-up in the premenopausal patients. No significant cross-symptom paths emerged for the postmenopausal sample.

Conclusion: Findings supported the notion that depression, fatigue, and sleep disturbances manifest as a symptom cluster. Fatigue may precede nonsomatic symptoms of depression among premenopausal breast cancer patients and represents a potential intervention target.

Keywords: Cancer; depression; fatigue; oncology; sleep disturbance; symptom cluster.

Fig. 1

Saturated model of within- and cross-symptom temporal relations in breast cancer patients. Note: Between symptom correlations at T2, and T1–T3 within- and cross-symptom paths are not depicted in order to keep the figure legible.

Fig. 2

Model 1: Depression, fatigue, and sleep disturbances in the postmenopausal sample. Note: Only statistically significant pathways are displayed in the model. **P ≤ 0.01, ***P ≤ 0.001. Refer to Table 3 for model statistics.

Fig. 3

Model 2: Depression, fatigue, and sleep disturbances in the premenopausal sample. Note: Only statistically significant pathways are displayed in the model. **P ≤ 0.01, ***P ≤ 0.001. Refer to Table 3 for model statistics.