[Reduction in pain intensity after treatment for chronic back pain. When is it clinically meaningful?]

The aim of this study was to evaluate how much change in pain intensity is necessary to discriminate between good, bad or no treatment outcome from the patient's point of view after therapy for chronic back pain.

A total of 153 patients with chronic back pain were admitted to a 3 week multimodal treatment program including functional restoration and cognitive behavioral support (outpatient). Pain intensity was measured at the beginning of treatment and 6 months after discharge using a visual analogue scale (VAS). At this time, patients had to evaluate their back pain compared to the beginning of treatment as of better, equal or worse (global self-assessment).

Six months after therapy, 48% of the patients assessed their back pain as better, 28% reported no change and 14% stated that their pain was worse. Mean pain reduction among the patients who assessed themselves as better was 25 points, while those who stated that their pain was worse had an average of 9 points more (VAS).

Patients' global self-assessment is a valid parameter to determine the outcome after treatment of chronic back pain. A clinically meaningful pain reduction can be assumed if there is at least a 25/100 point reduction (VAS), while a worsening of pain is already found to be important when there is a rise of 9/100 points.