ABSTRACT:Purpose and Study Design: Prospective cohort study to explore the clinical treatment effect of mechanical vs. manual manipulation for acute low back pain.Methods: 92 patients with a history of acute low back pain were recruited from three private chiropractic offices. Two of these offices utilized manual lumbar manipulation and one used mechanical instrument manipulation (Activator) as their primary modes of treatment. The chiropractors used a "treatment as usual" protocol with the participants for a maximum of eight visits or four weeks, which ever occurred first. Primary and secondary outcome measures were the differences in pain and Oswestry scores from baseline to four weeks, respectively. Results: Socio-demographic characteristics of the two cohorts at baseline were not found to show any significant differences between the groups except for age. The Activator cohort had a significantly higher utilization of adjunctive modalities and x-rays, with a mean number of office visits about twice that of the manual manipulation cohort at four weeks. The pain scores decreased in both groups with the manual manipulation group showing a slightly greater amount of pain reduction at four weeks, but this difference did not reach statistical significance after controlling for baseline pain. The manual manipulation group also showed a slightly greater reduction in Oswestry scores from baseline to four-weeks, but this difference was not statistically significant after adjusting for baseline Oswestry score.Conclusions: In this observational study of treatment-as-usual there was no significantly greater reduction in pain scores or Oswestry scores between the manipulation and Activator groups at four weeks. There were many differences between the Activator and manual manipulation groups with respect to treatment beliefs and expectations, modality usage, and frequency/duration of care, which are potential sources of confounding in the interpretation of these results. This study provides important pilot data and research issues for the design of a future randomized clinical trial that can control for these issues of confounding variables
