A prospective analysis of stress and fatigue in recurrent low back pain

The purpose of the present study was to determine whether patients with recurrent low back pain display a different pattern of mood fluctuations across days than matched healthy controls and whether these mood states are related to pain occurrence and/or magnitude using a prospective design. The questions addressed are whether mood states prior to a pain episode are associated with the episode or whether mood relates to pain as a secondary reaction. Similarly, the relationship between mood state recorded prior to, during or following pain and magnitude of pain experienced was investigated. Thirty-three ambulatory chronic low back pain patients and an equivalent group of asymptomatic controls matched for age, sex, socioeconomic status, and reported activity level monitored mood state (anxiety, tension, depression, anger, vigor, fatigue, confusion) and pain before breakfast, at 4 p.m. and at bedtime for 14 consecutive days. Groups were successfully matched. Analyses revealed significantly higher levels of tension, anxiety and fatigue and lower levels of vigor in the pain cases. No mood state was predictive of pain onset but fatigue was associated with pain 24 h following pain, indicating fatigue as secondary to pain. While mood state recorded prior to or following pain was unable to predict magnitude of pain, fatigue was associated with the level of pain experienced during the pain episode itself. The findings reveal a pattern of anxiety, tension and fatigue where fatigue is associated with increased pain during the pain episode and is increased 24 h following pain. This fatigue-pain relationship is superimposed upon a continuous elevation of anxiety and tension. These findings suggest the importance of pain management efforts directed at decreasing patients' fatigue levels, and increasing functional endurance while simultaneously reducing anxiety. The results also question the role of negative mood states in the initiation or exacerbation of pain and highlights the influence of physical mood states such as fatigue on pain in low back pain.