Context: Randomized controlled trials (RCTs) are considered the standard for establishing practice guidelines; however, they are expensive and time-consuming, and often the generalizability of the results is limited. Objectives: To conduct an observational study using the findings of the American Osteopathic Association's Clinical Assessment Program (AOA-CAP) low back pain module, and to compare these findings with those of a major back pain-related RCT to determine the validity and generalizability of this pseudoexperimental model. Methods: Data were abstracted from the AOA-CAP for Residencies platform from April 1, 2006, through October 5, 2007, with a diagnosis code consistent with low back pain. Process and outcome measures were compared after segregating a similar patient population to an RCT that compared "osteopathic spinal manipulation" with standard care. Results: A total of 1013 medical records were abstracted and entered into the AOACAP low back pain module. Mean (standard deviation [SD]) age was 44.7 (15.9) years, and body mass index was 29.6 (8.1). The eligible patients comprised 415 men (41.0%) and 598 women (59.0%), and common comorbid disease was found in 69 patients (6.8%). Activities of daily living were limited in 402 patients (42.4%), whereas 546 (57.6%) had no limitations. Previous exacerbations of low back pain occurred in 653 patients (65.9%). Most patients had no sensory or proprioception deficit (729 [87.7%]), and motor function was normal in 636 patients (74.5%). Normal ankle and knee reflexes were found in 744 of 814 (91.4%) and 755 of 829 (89.0%) patients, respectively. Osteopathic manipulative treatment (OMT) was performed on the lumbar spine (576 patients [56.9%]), thoracic spine (411 [40.6%]), sacrum/pelvis (440 [43.4%]), rib (261 [25.8%]), and lower extremity (256 [25.3%]). A segregated patient cohort (n=539) showed statistically significant differences between patients who received OMT and those who did not with the use of analgesics, steroids, spinal injections, straight-leg raising, and days off or limited work duties. Conclusion: The observational findings of the present study, which suggest that analgesic medication use is lower in patients who receive OMT, align with previous findings of RCTs and support the generalizability of these findings.