Recall bias, pain, depression and cost in back pain patients

To investigate the relationship between recall bias for pain stimuli in chronic low back pain patients and the cost of managing their back pain in primary care.

A retrospective cross-sectional investigation.

A sample of 63 low back pain patients were interviewed in a primary care setting. Information was gathered on their pain intensity, disability ratings, depression, anxiety, and duration of pain. They were also presented with a surprise recall test for pain descriptors. The cost of each patient's treatment specifically for back pain in the previous 12 months was calculated. The relationship between the cost of back pain treatment and the scores from the interview were calculated first for total cost, and then for the breakdown of individual cost items.

Results indicated that recall bias for pain stimuli were significantly related to total cost (R2 = 8%). A detailed analysis revealed that pain intensity was related to the number of appointments with the general practitioners; depression scores related to the number of appointments with the in-house osteopaths; and recall bias for pain stimuli related to referrals to external experts (out-patients). A minority of patients high on recall bias was found to account for a disproportionate amount of the cost.

Although no causal path can be deduced from the findings, the study provides a novel approach to measuring psychological factors in back pain in reference to health care utilization. It is limited by its retrospective design, and should be followed by prospective studies to understand fully the relationship between cognitive bias and utilization of health services.