Psychological factors in the treatment of back pain by spinal manipulation.

Ninety patients with low back pain completed a short form of the Minnesota Multiphasic Personality Inventory (MMPI) and, subsequently, received spinal manipulative therapy. Most (84%) of the patients reported immediate relief following manipulation but the extent of that relief was not correlated with any psychological measure. However, several days after treatment, the percentage of patients reporting improvement was much lower (55%) and lack of improvement was associated with elevated scores on hypochondriasis (Hs), and functional low back pain (Lb). Unimproved patients also tended to report longer durations of back pain prior to treatment. Multiple regression analyses indicated that pain duration and the psychological factors were independent predictors of the response to treatment. It is suggested that, although a single manipulative treatment will often relieve the immediate cause of back pain, underlying psychosomatic factors may predispose the condition to recur.