OMT Associated With Reduced Analgesic Prescribing and Fewer Missed Work Days in Patients With Low Back Pain: An Observational Study

Methods

Data Source

The AOA-CAP is a Web-based primary care registry currently used in AOA-approved family medicine and internal medicine residencies. Residency programs randomly selected medical records of patients who received a diagnosis of low back pain (according to International Classification of Diseases, Ninth Revision) for abstraction. Although an informational packet was provided to residency programs in an effort to standardize the abstraction, there was no strict oversight of how residency directors randomized medical record selection. Medical record exclusion criteria included an age younger than 17 years and chronic low back pain of less than 12 weeks' duration that was occurring at the time of abstraction. Patient data were entered using a standard set of directions developed by the BOCER, which focused on process and outcome measures (Figure 1). The AOA Department of Research and BOCER recommended that 20 medical records be abstracted from each residency, which was intended to ensure an adequate sample for quality assessment. The AOA provided the data from the AOA-CAP.

Figure 1.

Abstraction tool used in the recording of outcomes from the American Osteopathic Association Clinical Assessment Program in family medicine residency. Abbreviations: ADL, activities of daily living; BMI, body mass index; Chiro, chiropractor; CT, computed tomography; DX, diagnosis; ID, identification number; LBP, low back pain; LE, lower extremity; Lum, lumbar; MRI, magnetic resonance imaging; Mus Relax, muscle relaxants; Myelo, myelography; Neuro, neurologist; Num Trigger, number of trigger point injections; Phys Med, physical medicine specialist; PMR, physical medicine and rehabilitation specialist; OMT, osteopathic manipulative treatment; Ortho, orthopedist; Pre, prescription; Prev, previous; Pro, proprioception; Ref, referral; Sacr, sacrum; Sed Rate, sedimentation rate; Surg, surgery; Thor, thorax; Trigger Pt Inj, trigger point injection; VAS, visual analog scale.

Results

A total of 1013 medical records from 27 family medicine residencies were abstracted and entered into the AOA-CAP low back pain module. Many residency directors submitted more than the recommended number of 20 medical records. Mean (standard deviation [SD]) age was 44.7 (15.9) years, and body mass index was 29.6 (8.1). Patients comprised 415 men (41.0%) and 598 women (59.0%) and had the following relevant comorbid conditions: neurologic disease (91 [9.0%]), spondylolisthesis (65 [6.4%]), and connective tissue disease (50 [4.9%]) (Table 1).

Table 2 depicts the baseline activities of daily living and the frequency of previous low back pain episodes. Of the 948 patients with available information, 546 patients (57.6%) had no limitations to daily activity, whereas 402 (42.4%) had at least some limitation. On review of 991 medical records, 338 patients (34.1%) had no history of acute low back pain, whereas 653 (65.9%) had at least 1 reported episode per year.

Table 3 depicts the 3 functions—the baseline sensory or proprioception, the motor, and the deep tendon reflex—of the patients. Of the 831 patients with available information, 729 (87.7%) had no sensory or proprioceptive deficit, and 102 (12.3%) had a deficit. Motor function was assessed as normal for 636 of 854 patients (74.5%), whereas 218 (25.5%) had a motor impairment. Normal ankle and knee reflexes were reported in 744 of 814 (91.4%) and 755 of 829 (89.0%) patients, respectively.

Of the patients who received at least 1 regional session of OMT for low back pain, 576 were treated in the lumbar region (56.9%), 411 (40.6%) in the thoracic spine, 440 (43.4%) in the sacrum/pelvis, 261 (25.8%) in the rib, and 256 (25.3%) in the lower extremity (Table 4). The 209 patients who received no OMT for low back pain are also shown adjacent to the average number of OMT sessions patients received for each body region.

To better compare data from the present study with that of the RCT by Andersson et al,¹⁴ we identified a cohort of 539 patients (Figure 2). Using this cohort, we compared data from patients receiving OMT with those who did not receive OMT (Table 5 and Table 6). We compared AOA-CAP patients who were treated with OMT alongside those who were not, noting the relationship between frequently prescribed medical treatments for low back pain and the likelihood that those patients received OMT. There is a statistically significant (P<.05) difference between patients who received or did not receive OMT and oral steroids (P=.0481), opioid (P=.0001), nonopioid analgesics (P=.0199), and spinal injections (P=.0052) (Table 5). Straight-leg raising (P=.0092), days off of work (P=.0001), and days with limited work duties (P=.0001) were all significantly different between patients who did and did not receive OMT (Table 6).

Figure 2.

Flowchart of how medical records of patients with low back pain (n=1013) from 27 family medicine residencies were segregated and compared with data from a randomized controlled study (RCT) by Andersson et al.¹⁴Abbreviation: ICD-9, International Classification of Diseases, Ninth Revision; LBP, low back pain.

By confining the present study to AOA-CAP data, we were able to screen the data of many more patients than Andersson et al¹⁴: 1013 patients vs 155 patients. Data from the present study aligned with those of Andersson et al¹⁴ as follows: there was no statistically significant difference in mean (SD) visual analog–scale scores for the OMT group vs the standard-care group (2.9 [2.2] vs 2.8 [2.0] and 3.2 [2.3] vs 2.6 [2.4], respectively), and both studies found decreased use of analgesics in the use of nonsteroidal medication (63% vs 72.7% [P=.019] and 24.3% vs 54.3% [P<.001], respectively).

Comment

Our findings revealed that OMT was associated with reduced use of all analgesic medications and nonopioid analgesics, as well as an association with reduced missed or restricted-duty days at work. Our study found no statistically significant difference for the use of muscle relaxants between the OMT group and the standard-care group. The OMT-treated group showed improvements in straight-leg raising. Andersson et al¹⁴ reported that there was a significant reduction in nonsteroidal anti-inflammatory drug and muscle relaxant use in patients receiving OMT. However, Andersson et al¹⁴ found no significant difference in straight-leg raising between the first and final visit and at the final visit. The commonly used outcome of pain reduction as measured by visual analog score was not significantly different between OMT and conventional treatment in the present study. These findings are consistent with those of Andersson et al,¹⁴ which showed no statistically significant difference in visual analog scale score between the first and final visit.

Moreover, back pain is often a disease of chronic pain altering the acute peripheral pain to supraspinal central nervous system pain. Henry et al¹⁵ reviewed numerous studies that showed functional and morphologic changes associated with chronic back pain. The reorganization of sensory pain perception suggests that the standard of the visual analog score may be insensitive to the potential improvement associated with the application of OMT. Supraspinal central pain responds less well to opioid analgesia compared with peripheral pain.¹⁶ Taken together, the findings of the present study and those of Andersson et al suggest that traditional primary endpoints, such as pain perception, may not reveal significant advantages of OMT for low back pain. Indeed, more studies need to be conducted to test whether the benefits of OMT as a treatment modality for low back pain can be confirmed by means of more unconventional measures, such as medication use, medication compliance, hospital admission times, and employee absenteeism.

We must note the potentially confounding effect of analgesic medications. If the patients who received OMT used less medication, then it could be reasonable to infer that those patients were in less pain, thus needing to take less medication. However, the group that did not receive OMT had similar pain scores but used more analgesic medication, leading to the possibility that if both groups had similar pain medication use, there would have been a significant difference in the pain scores. An RCT designed to test this theory may not be ethically feasible because the dosage of medication would need to be standardized between both groups. This process would entail medicating patients who did not need it, denying medication to those who did, or withdrawing patients from the study if their need for medication became too great. Thus, an experimental model other than an RCT would likely be required to obtain more data on this question.

The use of a patient registry to compare clinical practice outcomes with those of an RCT is a novel approach. Although both studies come to the same conclusion, they use very different methodologies, with large differences in generalizability and inference. The RCT by Andersson et al¹⁴ started with 1193 patients; exclusion criteria, pain issues, lack of consent, medical problems, withdrawals, and loss to follow-up reduced the number for randomization to 155. The AOA-CAP study started with 1013 patients, and this number was reduced to 539 by applying exclusion criteria similar to those used in the RCT. With such a large loss of patients from the cohort in the RCT, the generalizability of the findings to large populations is suspect. Although fewer patients met the exclusion criteria in the present study (41.7% vs 87% in the RCT), the challenge in interpreting the findings from the AOA-CAP study is due to the selection bias that may exist in patients chosen for intervention. Although the instructions asked the residency program contact person to randomly select patients who had a diagnosis of low back pain, it was possible that programs selected patients who had the best outcome or who were chosen to highlight some other aspect of their care, such as fulfilling a quota to perform OMT on a certain number of patients.

The 2013 Patient-Centered Outcomes Research Institute methodology report¹⁷ stated that “well-designed observational studies have been extremely valuable as a complement to RCTs, helping to determine under what circumstances and to which patients the findings of RCTs apply.” Using a patient registry system such as the AOA-CAP provides an opportunity for observational studies to be performed for several purposes: (1) to validate/confirm the results of an RCT, (2) to evaluate the manner in which the results of RCTs are being translated into patient care, and (3) to generate new research questions. However, as with all study designs, observational, registry-based studies have their weaknesses—namely, with data quality and bias, especially selection bias. The strengths of a registry-based study are that some questions may be answered quickly because the data have already been gathered and that there is a greater likelihood that the findings will be more broadly applicable because registries are based on real-world clinical practice.

Combining the PBRN study design with a relatively low-risk intervention, such as OMT, in a way that improves clinical outcomes is an excellent example of applying the evidence from an RCT to improve patient care and simultaneously increasing, and hopefully clarifying, the evidence in the literature about traditionally osteopathic-type interventions. A PBRN would also allow researchers to observe the effects of OMT through evaluating alternative outcome measures, in this case by the decreased use of medications and decreased numbers of lost or modified-duty work days. Osteopathic physicians should support the development of a PBRN, which would provide clinicians an opportunity to study the efficacy of OMT in a more cost- and time-efficient manner.

Conclusion

Our findings suggest that analgesic medication use is lower in patients who receive OMT, which aligns with previous findings of an RCT and supports the generalizability of these findings. In light of the cost and time savings of the present observational study design, PBRN studies may be particularly useful as we move into an era of cost-effective, evidence-based medicine.