COMMENTS AND RESPONSES Spinal Manipulation for

manipulation is not more effective than other active interventions for low back pain. Of interest, this conclusion contrasts with the au-thors ’ previous findings suggesting a benefit (2–4). Conclusions may vary across trials of spinal manipulation because researchers often fail to adequately consider the importance of classification. Using broad inclusion criteria results in a heterogeneous sample that may include many patients for whom no benefit is expected, thus masking the intervention’s true value. In their meta-analysis, Assendelft and col-leagues questioned the need for future clinical trials, an action that could perpetuate their negative findings. However, they paid little attention to identifying relevant subgroups despite their previous recommendations to do so (3, 4). The results of Assendelft and colleagues ’ study reinforce the importance of matching individual patients to interventions with a high probability of success. Clinicians can accurately identify patient