Changing Patterns in Evaluating and Treating Chronic Low Back Pain
The last 15 years of research has brought a change in the way patients with chronic low back pain (CLBP) are categorized and treated. In a landmark study back in 1994, a well-known physical therapist identified subgroups of low back pain patients. When treated based on their unique characteristics, more of these patients returned to work and reported less disability compared with patients in a standard treatment program.

That report set into motion a series of studies classifying low back pain patients based on a variety of factors. Some of these included fear of movement, intensity of pain, and self-efficacy (belief in oneself). Other areas investigated also included pain present during specific exercises and catastrophizing (believing the worst will happen).

In this study, patients were subgrouped based on their lifting patterns during a repetitive lifting task. This type of classification system is based on physical functioning of patients with CLBP.

Previous studies have shown differences in the way patients with CLBP lift compared to normal people (in other words, people who don't have back pain). The focus of this study was to look at patients with CLBP and see if there are subgroups of motion differences during lifting within the group.

The procedure used to put patients into subgroups was called the Hidden Markov Model. This model is a statistical tool the authors used to see if the CLBP group were different in ways other than lifting patterns used. Two groups were included: a control group (normal healthy adults) and a group of adults with moderate to severe back pain lasting more than three months. Most of the patients had back pain for years.

Everyone completed a series of tests to assess pain, psychosocial, cognitive, and functional abilities. Some of the items investigated included gait (walking) speed, ability to perform activities of daily living, response of partner or spouse to the patient's pain, and perceived level of disability.

Each person completed a questionnaire asking subjects to rate their own confidence (self-efficacy) in completing a repetitive lifting task. A physical therapist measured spinal flexion and extension motions.

Everyone was then tested on repeated lifting tasks using a BTE Work Simulator and a computerized Motion Analysis Model. These tools show changes in body angles over time for each lift. Other components of each lifting pattern also included body posture and force of the lift. Five lifting patterns were observed. These included the slow, low jerk lift, the squat starting lift, the fast, high jerk lift, the torso starting posture lift, and the two-segment lift. In the two-segment lift, the lower body moves faster than the upper body.

Two main subgroups were identified from this study: the guarded CLPB lifters and the high-performing CLBP lifters. Guarded refers to the fact that this group performed a slow, low jerk lifting pattern. High-performing lifters means they used four of the lifting patterns -- all but the slow, low jerk method.

Further analysis showed that the high-performing lifters had less pain, more self-confidence, and could complete more lifts than the guarded group. They were more likely to use the squat style of lifting compared to the control group. Most likely this pattern is taught in treatment programs these CLBP patients have been in over the years. The high-performing lifters were more like the normal control subjects in their lifting patterns. They had a higher degree of self-efficacy (confidence) than the guarded lifters.

The guarded group with the jerk lifting pattern reported more intense and more frequent pain than the patients in the high-performing lift group. The authors think the increased pain levels may be why they choose to use this pattern. Using a jerk lift helps minimize muscle force to lift the load. Instead, more muscle groups are contracting to work together to perform the lift.

The authors conclude that subgroups of CLBP patients can be found based on lifting patterns. This is an indication that physical function can be used as a classification scheme when evaluating and treating people with CLBP. Finding ways to help patients increase their confidence level and change their pain perception may be helpful. More research is needed to change our current methods of rehabilitating these patients.
Jill C. Slaboda, PhD, et al. Classifying Subgroups of Chronic Low Back Pain Patients Based on Lifting Patterns. In Archives of Physical Medicine and Rehabilitation. August 2008. Vol. 89. No. 8. Pp. 1542-1549.