Claustrophobia: a proxy for psychological distress in patients with back pain

Case-control study.

The aim of this study was to assess the levels of psychological distress in patients with back pain who expressed claustrophobia at the time of their magnetic resonance imaging (MRI) scan, compared with sex and age-matched normal controls who did not exhibit claustrophobia. The secondary aim was to document the level of disability and intervention rates in this group.

Psychosocial factors influence the outcomes of low back pain treatment with psychological distress being associated with poorer surgical outcomes in patients with low back pain. Up to 14% of patients experience claustrophobia during MRI scans requiring sedation to complete the scan. The effect of claustrophobia on back pain disability and outcomes has not been previously reported.

Twenty females and 13 males all requiring MRI scan under sedation for claustrophobia (group 1) were compared with an age and sex-matched cohort that had MRI scan without sedation (group 2). Both groups were drawn from a chronic back clinic. Average age in both groups was 54 years (range, 27 to 79 y). Both groups had standard conservative therapy, together with psychometric evaluation: Zung Depression Index and Modified Somatic Perception Questionnaire. Disability was measured by Oswestry Disability Index. Primary outcome measures were intervention rates (surgery, injections, and physiotherapy sessions) and prevalence of psychological distress.

Mean Zung Depression Index in group 1 was significantly higher than in group 2 (59.5 vs. 28.9, P<0.05) as was the mean Modified Somatic Perception Questionnaire score (13.3 vs. 9.2, P<0.05.) Prevalence of psychological distress was higher in group 1 (75.8% vs. 18.2%, P<0.05). Oswestry Disability Index was the same in both groups (50% vs. 48%). Group 1 had 13 interventions (13 patients=39.4%) compared with 26 in group 2 (26 patients=78.8%) (P< 0.05). Twenty-two patients (66.7%) in group 1 were discharged after their MRI scan with no intervention compared with 7 patients (21.2%) in group 2 (P<0.05).

Claustrophobic patients with back pain showed higher levels of depression than nonclaustrophobic patients, with a higher rate of psychological distress. Disability, however, was not higher. The majority of claustrophobic patients did not require surgical intervention. The reasons for this are unclear and require further investigation. Claustrophobia requiring sedation for MRI scans may be a proxy for psychological distress in these patients and psychometric testing is advised during assessment to help with surgical decision making.