The impact of stressful life events on exacerbation of chronic low-back pain

Abstract

The impact of stressful life events on the development and onset of chronicity of low-back pain is not yet fully understood. Sixty-four consecutive patients with chronic low-back pain treated at the orthopedic out-patient unit of the Innsbruck University Hospital were investigated with regard to stressful life events. Patients were classified into two groups: one group consisting of patients whose pain had an organic etiology (n=16), and another group consisting of those with pain of uncertain origin (idiopathic group, n=48). A method combining a semistructured interview with a self-assessment of the severity of stress caused by life events was employed for assessing the impact of such events on chronic low-back pain. In comparison to the patient group having organic causes of pain, the idiopathic group showed significantly more patients having at least one highly stressful event preceding the last substantial aggravation of pain (p=0.028). The latter group experienced significantly more exhaustion (p=0.016) and significantly more difficulties in active coping (p=0.011) when confronted with stressful life events. Stressful life events that arouse feelings of helplessness may contribute to the development of chronic idiopathic low-back pain. Our results emphasize the importance of investigating the subjective meaning and appraisal of stressful life events, taking into consideration both individual predisposition and psychosocial resources available to the patient. Finally, it is also important that the attending physician be aware of any life event that is particularly stressful for the patient so that psychosocial help be made available at the appropriate time.

Introduction

Approximately 80% of the general population suffers from low-back pain at least once in their lives [1]. If pain becomes chronic (lasting longer than 6 months), it causes severe problems for patients and orthopedists alike. Often no organic cause of the pain can be found [2]. Depression [3], pain-prone behavior [4], and stressful life events may trigger idiopathic chronic pain. Although life event research has boomed in the last 30 years, and a relationship between stressful life events on the one hand and functional abdominal pain [5]and idiopathic headache [6]on the other has been shown to exist, the relationship between stressful events and chronic low-back pain has not been adequately investigated. Growing evidence in life-event research has shown that particularly stressful events that cause severe distress may have some impact on the course of illness 7, 8, 9.

In the last 16 years only a few clinical studies have been published on the impact of stressful life events on low-back pain 10, 11, 12, 13. In addition, only one of these studies investigated patients with chronic low-back pain [13], possibly because of the difficulty of accurately dating the onset of pain, which is a prerequisite for investigating the relationship between stressful life events and chronic pain. The results of the studies just referenced are controversial, and methodological differences make comparisons difficult; Feuerstein et al. [13]and Leavitt et al. [10]used the Social Readjustment Rating Scale (SRRS) [14]in their studies of patients with back pain. They gathered data on life events that occurred before the patient visited the clinic instead of on those before the onset or exacerbation of pain. The importance of accurate dating of onset of illness and the occurrence of life events has been shown by Craufurd et al. [12], who used the Life Events and Difficulties Schedule (LEDS). They did not find any difference between patients with idiopathic causes and those with organic causes of pain before clinic attendance, but the former group showed significantly more stressful life events than the latter before the onset of pain. Unlike the LEDS, the SRRS includes items such as “major change in sleeping habits” or “change in social activities,” events that may be consequences of chronic pain. Thus, the aforementioned studies using the SRRS or similar questionnaires may confuse cause and consequence of pain. Jensen [11]used a semistructured interview based on a questionnaire by Theorell et al. [14], which also includes items such as “changes in social activities” and “major changes in sexual habits.” He too, gathered information on life events before patients' visit to the hospital instead of concentrating on those events that occurred before the onset or exacerbation of pain.

Dohrenwend and Dohrenwend [16], Katschnig [17], and Vossel [18]emphasized the importance of individual predisposition (e.g., locus of control) and psychosocial resources (such as social support) of a person at the time the life event occurred. In addition, Brown [7]points out the need to deal with specific aspects of meaning of an event and to move beyond general stress measurement in life-event research. None of the aforementioned studies dealing with back pain took these important considerations into account.

Our study is aimed at examining stressful life events in patients with idiopathic chronic low-back pain, taking into account the individual's predisposition and the psychosocial resources available at the time of the occurrence of the life event. Second, we tried to determine whether, among life events in general, events implying loss had any special impact on exacerbating chronic low-back pain. Patients with chronic low-back pain of uncertain origin were compared with subjects suffering from low-back pain with a well-defined organic cause.