Herman PM, et al. - In the descriptive analyses using 12 large study datasets, authors investigated if chronic pain impact levels could be classified in chronic low-back pain clinical trial samples and also to examine the baseline patient mix across studies with evaluation of the construct validity of high-impact chronic pain. They noted excellent predictive power of the logistic models to recognize those with high-impact chronic pain. The baseline mix of patients fluctuated extensively, however, studies were all of the chronic low-back pain cases. They found similar utilities, and productivity for those with high-impact chronic pain and worsened with an incline in chronic pain impact across all datasets.