Personality traits, pain duration and severity, functional impairment, and psychological distress in patients with persistent low back pain.

The relationships between psychological distress, pain duration, neuroticism, extraversion, pain severity, and functional impairment were examined in a large group of patients with persistent complaints of low back pain. We evaluated patients on a host of relevant variables before treatment and at 1 year and 2 years after treatment which permitted assessment of the stability of the relationships over time. We found that the levels of psychological distress reported by patients were not related to the duration of their complaint. Rather, levels of psychological distress are related to both aspects of the patients' personalities, and characteristics of their illness. Patients who scored high on neuroticism reported higher levels of psychological distress than patients who scored low on this trait. Similarly, patients who had more severe pain and were more functionally impaired also reported higher levels of psychological distress due to pain. The relative strengths of these relationships varied with treatment status. Before treatment, psychological distress and neuroticism were strongly related, but after treatment, the relationship was moderate. In contrast, the relationship of psychological distress to pain severity and functional impairment was significantly strengthened after treatment. We attributed this shift in the relative strengths of the relationships to change in the patient perception of their illness.