Spine (Phila Pa 1976). 1995 (Apr 15); 20 (8): 948–955
Triano JJ, McGregor M, Hondras MA, Brennan PC.
Institute for Spine and Biomedical Research, Plano, Texas, USA.
At least two controlled clinical trials have addressed the question of placebo effect directly. [1-2] Using a stratified design, Hadler and Curtis  compared two forms of spinal manipulation: high velocity, low-amplitude thrusting procedures versus mobilization techniques. A single treatment intervention was administered randomly to patients suffering from acute low back pain. Patients were assessed by one physician and treated by the other. Physicians gave their time to both groups equally and included back educational material and assurance.
Triano and colleagues  studied treatment effects for patients with low back pain persisting longer than seven weeks. Subjects were randomly assigned to a back education program, high-velocity low-amplitude (HVLA) manipulation and sham/mimic treatment procedure groups for a series of 10 treatment sessions. Sessions were scripted to balance for physical contact, attention, and intervention frequency and duration. Sessions involved a consistent time commitment and direct one-on-one attention from the physician, either in the form of teaching about spine anatomy and function, or in assessment and delivery of the sham/HVLA procedures.
In both studies, all treatment groups showed improvement over time. However, the patients receiving thrusting procedures demonstrated significantly greater and more rapid rates of improvement from their symptoms and in their ability to function.
 Benefit of Spinal Manipulation as Adjunctive Therapy for Acute Low Back Pain: A Stratified Controlled Trial.
Spine (Phila Pa 1976). 1987 (Sep); 12 (7): 702-6.
 Manipulative Therapy Versus Education Programs in Chronic Low Back Pain.
Spine (Phila Pa 1976). 1995 (Apr 15); 20 (8): 948-55.
STUDY DESIGN: A randomized trial was conducted on a representative sample of patients with untreated low back pain lasting 7 weeks or longer, or having more than 6 episodes in 12 months.
OBJECTIVES: To contrast the effectiveness of manipulation, a manipulation mimic, and a back education program. Methodologic criticisms of earlier studies were addressed.
SUMMARY OF BACKGROUND DATA: Published meta-analyses suggest clinical benefit from manipulation for acute patients. Data are inconclusive for patients having symptoms for longer than 1 month.
METHODS: A total of 1267 consecutive patients were screened. Block randomization was used to assign 209 qualifying patients to treatment groups. Self-reported pain and activity tolerance served as primary outcome measures. Patients were assessed at enrollment, after 2 weeks of treatment, and again after 2 weeks without treatment. Multiple teams conducted recruitment, randomization, assessment, treatment, and data analysis independently without sharing information. Treatments were carefully described, monitored, and balanced for physician attention and physical contact effects.
RESULTS: A total of 81.3% of subjects completed the study. Confounding factors and missing data were identified in approximately 20% of those completing the final follow-up. Analysis of the remaining data was carried out. A strong time effect under treatment was observed. Greater improvement was noted in pain and activity tolerance in the manipulation group. Immediate benefit from pain relief continued to accrue after manipulation, even for the last encounter at the end of the 2-week treatment interval.
CONCLUSIONS: Time is a strong ally of the low back pain patient. In human terms, however, there appears to be clinical value to treatment according to a defined plan using manipulation even in low back pain exceeding 7 weeks' duration.
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