In the next instalment of my Research Review Series for MedBridge Education, we discuss a recent randomized controlled study investigating the validity of a clinical prediction rule for identifying patients with low back pain likely to respond favoribly to a spinal stabilization program.
Randomized Controlled Trial.
One hundred five patients diagnosed with LBP and referred to physical therapy at 1 of 5 outpatient clinics of Clalit Health Services in the Tel-Aviv metropolitan area, Israel, were recruited for this study. Of these 105 patients, 40 were positive on the Stabilization CPR and 65 were negative. The most evident difference between baseline differences of groups was age, with those in the stabilization group being significantly younger (one of the items of the CPR is < 40 years old).
Inclusion Criteria: 18 to 60 years of age, primary complaint of LBP with or without associated leg symptoms (pain, paresthesia), and had a minimum score of 24% on the Hebrew version of the modified Oswestry Disability Index (MODI) outcome measure.
Exclusion Criteria: History indicating any red flags (malignancy, infection, spine fracture, cauda equina syndrome), 2 or more signs suggesting lumbar nerve root compression (decreased deep tendon reflexes, myotomal weakness, decreased sensation in a dermatomal distribution, or a positive SLR, crossed SLR, or femoral nerve stretch test), history of corticosteroid use, osteoporosis, or rheumatoid arthritis. Additionally, patients were excluded if they were pregnant, received chiropractic or physical therapy care for LBP in the preceding 6 months, could not read or write in the Hebrew language, or had a pending legal proceeding associated with their LBP.
Outcome Measures: Hebrew version of the modified Oswestry Disability Index (MODI) and Numerical Pain Rating Scale (NPRS).
Randomization: Based on a computer-generated list of random numbers, which was then stratified by CPR status to ensure that adequate numbers of patients with a positive and a negative CPR status would be included in each intervention group.
Evaluation: A physical examination was conducted that included a neurological screen to rule out lumbar nerve root compression. Next, lumbar active motion was evaluated, during which the presence of aberrant movement, as defined by Hicks et al, was determined. Bilateral SLR range of motion, segmental mobility of the lumbar spine, and the prone instability testing was then also conducted. The patients’ status on the CPR (positive or negative) was established based on the findings of the physical examination.
Interventions: Patients in both the Lumbar Stabilization Exercise group (LSE Group) and Manual Therapy group (MT) received 11 treatments over an 8 week period and a 12 visit, which consisted of solely a re-evaluation. The LSE group was first educated on the function and common impairments related to the lumbar stabilizing musculature, they were then taught to perform an isolated contraction of the transversus abdominis and lumbar multifidus through an abdominal drawing-in maneuver (ADIM) in the quadruped, standing, and supine positions. Once the patient could successfully perform these actions, the demands on the musculature were increased by the addition of various upper and lower extremity movements. Finally, during the seventh session, functional movements were added to their program. Those patients randomized to the MT group received several thrust and non-thrust mobilization techniques to their lumbar spine in addition to manual stretching of several hip and thigh muscle groups. Each treatment session included up to three manual techniques (one of which had to be a thrust technique). With regards to exercise, those in the MT group performed active range of motion and self-stretching exercises, but did not perform isolated spinal stabilization exercises. All variations and progressions of exercises and manual therapy techniques can be seen in the appendix of the research report.
With regards to MODI, clinical significance could not be determined after 2-way interaction between treatment group and CPR status was calculated (p = 0.17). That being said, individuals who were positive on the CPR did demonstrate less disability at the end of the study compared to those who were negative (p = 0.02). Furthermore, amongst patients who were positive on the CPR, those who received LSE also demonstrated less disability following treatment compared to those who received MT. When the authors introduced a modified CPR, which consisted of positive prone instability test and presence aberrant movement, they did find a significant interaction with treatment for final MODI. Those positive on the modified CPR demonstrated superior outcomes compared to the group as a whole and also showed improved outcomes when receiving LSE compared to MT (p = 0.005).
The most prevalent limitations include an inadequate sample size, which resulted in a limited overall power of the findings as well as the retrospective nature of some of the findings (i.e. modified CPR). Additionally, this study had a high drop-out rate for a study of its size with an overall drop-out rate of 22.8% (33% in the LSE group and 14% in the MT group). The lower dropout rate in the MT group could potentially be due to an attention affect due to the manual contact required for the interventions within this group compared to the LSE group. Additionally, while short-term results are important, understanding the long-term implications of either MT or LSE is of greater importance. This study only included an 8 week follow-up and it would be beneficial to see the long-term implications with a 6 or 12 month follow-up to gauge the overall effectiveness of the CPR and associated interventions. Finally, it should be noted that status on CPR was determined prior to group determination, which introduces an additional level of bias. Future studies should look at results with CPR determination post priori or following allocation to groups.
Manual therapy and spinal stabilization are two very common interventions utilized by physical therapists when treating low back pain. As manual therapy is common amongst clinicians and generally considered an effective treatment option, it provides an excellent reference value in the validation of the stabilization CPR. Unfortunately, the utility of the CPR as it was constructed could not be validated based on the findings of this study. Several factors could have played into this discrepancy including attention effect by those in the MT group, small sample size, and large dropout percentage. While the original CPR could not be validated, retrospectively an abbreviated CPR was identified and ‘validated’ based on the findings of the 2-way interaction between treatment group and modified CPR status. So, while this study seems like a knock to the current lumbar stabilization CPR, the study design and execution of the study cannot allow the CPR to be disregarded as all of the aforementioned limitations may have played a significant role in the study’s results. Additionally, the creation of an abridged CPR may have more value to clinicians long-term as it provided superior results and requires less factors to be evaluated by the clinician. However, the results must be taken with a grain of salt as a prospective evaluation of the modified CPR must be conducted in order to determine its utility. Clinical prediction rules and the effectiveness of spinal stabilization are polarizing issues within the physical therapy community and this study debatably provides support to the use of spinal stabilization and indicates that future research is needed to clear up the murkiness of the current stabilization CPR. When treating the lumbar spine, no treatment should be provided with every patient and Chad Cook, PT, PhD, FAAOMPT goes into great detail in his course, “Evidence-Based Treatment of the Lumbar Spine”, with regards to the use of spinal stabilization within the Treatment-Based Classification system.
Rabin A, Shashua A, Pizem K, Dickstein R, Dar G. A Clinical Prediction Rule to Identify Patients With Low Back Pain Who Are Likely to Experience Short-Term Success Following Lumbar Stabilization Exercises: A Randomized Controlled Validation Study. Journal of Orthopaedic & Sports Physical Therapy. 2014; 44(1): 6–18, B1–13.