Lack of energy: an important and distinct component of HIV-related fatigue and daytime function.

CONTEXT: Fatigue is a prevalent symptom among adults living with HIV. There is increasing evidence that fatigue and energy are related, yet distinct constructs. Although HIV-related fatigue has been well studied, little is known about perceived energy and how it relates to fatigue, individual characteristics, and other symptoms.
OBJECTIVES: To describe the experience of perceived energy in adults with HIV and evaluate its relationship to demographic and clinical characteristics as well as symptoms of fatigue, sleep disturbance, anxiety, depression, and daytime function.
METHODS: The design was descriptive, comparative, and correlational. The sample of 318 adults with HIV completed a demographic questionnaire; the Memorial Symptom Assessment Scale; and measures of fatigue, sleep disturbance, anxiety, depressive symptoms, and daytime function. Medical records were reviewed for disease and treatment data. Participants who reported a lack of energy were compared with those who did not on demographic, clinical, and symptom variables. Regression models of perceived energy and its interference with daytime function also were evaluated.
RESULTS: Perceived lack of energy was highly prevalent (65%) and more strongly related to interference with daytime function than more general measures of fatigue severity, even when controlling for other characteristics and symptoms. Like other aspects of fatigue, lack of energy was associated with sleep disturbance, anxiety, and depressive symptoms. Lack of energy was more strongly related to morning fatigue than to evening fatigue.
CONCLUSION: Lack of energy interferes with daytime function and is not just the inverse of fatigue but a distinct perception that differs from fatigue.