Design: This study observed a single cohort of low back pain patients undergoing chiropractic treatment in a chiropractic outpatient clinic.
Methods: Patients completed the Bournemouth Questionnaire (BQ) at baseline, the following four visits and at 6 months. Conventional approaches to outcome analysis were used to compute within subject changes in BQ scores. In addition to this, both reliable change and clinically significant change was calculated, which provided a method to categorise patients into one of four groups:(i) clinically significant improvement;(ii) reliable improvement that was not clinically significant;(iii) no change; and(iv) reliable deterioration. The results of both analysis approaches were compared.
Results: Using simple change scores based on continuous data, analysis of the entire sample, and acute (<7 weeks) and chronic (>7 weeks) sub-groups, there was a highly statistically significant change in total BQ scores at all time intervals (p < 0.001). When analysed using cut-offs for reliable and clinically significant change however, the findings were less impressive. At visit 4, 61.5% of acute patients had clinically improved compared with 27.7% of chronic patients. At 6 months, these proportions were 64.4% and 51.0% respectively.
Conclusions: Conventional approaches based only on statistical investigation of change scores may over-estimate what patients report during treatment and bear little resemblance to patient outcomes in terms of reliable and clinically significant improvement.
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