Dose-response for chiropractic care of chronic low back pain.
BACKGROUND CONTEXT
There have been no trials of optimal chiropractic care in terms of number of office visits for spinal manipulation and other therapeutic modalities.


PURPOSE
To conduct a pilot study to make preliminary identification of the effects of number of chiropractic treatment visits for manipulation with and without physical modalities (PM) on chronic low back pain and disability.


STUDY DESIGN/SETTING
Randomized controlled trial with a balanced 4x2 factorial design. Conducted in the faculty practice of a chiropractic college outpatient clinic.


PATIENT SAMPLE
Seventy-two patients with chronic, nonspecific low back pain of mechanical origin.


MAIN OUTCOME MEASURES
Von Korff pain and disability (100-point) scales.


METHODS
Patients were randomly allocated to visits (1, 2, 3 or 4 visits/week for 3 weeks) and to treatment regimen (spinal manipulation only or spinal manipulation with PM). All patients received high-velocity low-amplitude spinal manipulation. Half received one or two of the following PM at each visit: soft tissue therapy, hot packs, electrotherapy or ultrasound.


RESULTS
Pain intensity: At 4 weeks, there was a substantial linear effect of visits favoring a larger number of visits: 5.7 points per 3 visits (SE=2.3, p=.014). There was no effect of treatment regimen. At 12 weeks, the data suggested the potential for a similar effect of visits on patients receiving both manipulation and PM. Functional disability: At 4 weeks, a visits effect was noted (p=.018); the slope for group means was approximately 5 points per 3 visits. There were no group differences at 12 weeks.


CONCLUSIONS
There was a positive, clinically important effect of the number of chiropractic treatments for chronic low back pain on pain intensity and disability at 4 weeks. Relief was substantial for patients receiving care 3 to 4 times per week for 3 weeks.