FROM: J Manipulative Physiol Ther. 2004 (Oct); 27 (8): 493–502 ~ FULL TEXT
Charlotte Leboeuf-Yde, DC, MPH, PhD, Arndt Grønstvedt, DDS, DC,
Jan Arve Borge, DC, Jakob Lothe, DC, Eli Magnesen, DC,
Øyvind Nilsson, DC, Gro Røsok, DC, Lars-Christian Stig, DC,
Kristian Larsen, PT, MPH
The Medical Research Unit in Ringkøbing County,
OBJECTIVE: To identify demographic and clinic-related predictors for successful outcome in patients with persistent low-back pain who received chiropractic treatment.
DESIGN: Prospective uncontrolled multicenter study with internal control groups.
SUBJECTS: Each of 115 Norwegian chiropractors, out of 205 invited, were asked to recruit 10 consecutive patients who had low-back pain for at least 2 weeks at the time of consultation and a minimum of 30 days altogether within the preceding year. In all, 875 patients were included at baseline. The response rates at the fourth visit and at 3 and 12 months were 799, 598, and 512, respectively.
METHODS: Baseline data were obtained through questionnaires administered to chiropractic patients and to their treating chiropractors; clinical information was obtained through questionnaires at the fourth visit from patients and chiropractors. Outcome was obtained from patients at the fourth visit. Mail surveys of patients were conducted after 3 and 12 months, and additional information was obtained from chiropractors at 12 months in relation to treatment history.
POTENTIAL PREDICTORS: Demography and information on past and present history, clinical findings, and prognosis.
OUTCOME VARIABLE: Number of low-back pain"free patients (defined as those with a maximum pain score of 1/10 and a maximum Oswestry score of 15/100).
DATA ANALYSIS: Positive predictive values and relative risks were calculated for each categorized predictor variable singly and in combination in relation to being low-back pain free at the 3 follow-up surveys.
RESULTS: Treatment outcome at the fourth visit was best predicted by a model containing the following 5 variables: sex, social benefit, severity of pain, duration of continuous pain at first consultation, and additional neck pain (odds ratios between 2.2 and 4.3). A similar profile was found at 3 months, but 2 different variables (relating to disability) were the final variables in relation to the 12-month status. These final models were best at predicting absence of treatment success. Being low-back pain free at the fourth visit was a strong predictor for being low-back pain free both at 3 months and 12 months, with relative risks of 3.0 (2.2-4.8) and 3.1 (1.5-6.5), respectively.
CONCLUSION: In patients with persistent low-back pain, it is possible to exclude from treatment those who are unlikely to become low-back pain free after chiropractic care and to do this before they have been examined clinically. Early recovery is a strong predictor for outcome up to 1 year later.
From the FULL TEXT Article:
The causes of low-back pain (LBP) are largely unknown. Therefore, a rational approach to both prevention and treatment is hindered. Many people with LBP suffer persistent or recurrent problems, [1, 2] but the circumstances surrounding the transition from simple, so-called acute LBP to persistent/recurrent LBP are unclear.
Chiropractors rely heavily on spinal manipulative therapy (SMT) in their treatment of back problems, mostly in conjunction with soft tissue therapy and different types of advice on exercise, ergonomic precautions, and lifestyle changes. Clinical studies have shown SMT to have a positive influence on the outcome for some patients with more persistent LBP.  The clinical experience is that some of these indeed improve with SMT for longer or shorter periods, whereas others appear to be SMT resistant. Unfortunately, it is not known which of the patients are most likely to benefit from the chiropractic approach. In other words, there are no known predictors for treatment outcome with SMT. We also do not know if there are any predictors for treatment outcome that are unique for SMT or if they are mere indicators of the natural course. Obviously, it would be a great advantage if predictive profiles for good and poor outcomes could be defined to allow a selective approach in the treatment of this patient group. Also, it would be useful to conduct comparative trials on homogeneous patient groups in relation to outcome patterns.
In this study, it was investigated if some specific demographic or clinical factors can predict treatment outcome in patients with persistent LBP who receive chiropractic treatment.
In a previous analysis of the same study sample, it was noted that most improvement, both when recorded as mean status for the whole cohort and as numbers of LBP-free individuals, followed a specific pattern, ie, that the largest increment was found early in the course to level out later in the study (Leboeuf-Yde, unpublished data). These findings are in line with those noted by others in relation to other types of therapy. [4-11] In addition, we found what appeared to be a considerable regression toward the mean effect,  as improvement of pain or disability was more common among those at baseline who were classified as severely affected, and worsening was more common among those who were mildly affected. Shifts in pain or disability scores should therefore be examined early, and they need to be substantial to be taken seriously in studies without an untreated control group. Because preliminary predictor analyses showed that even the most substantial changes in population mean values were modest, we decided to investigate the predictive value of various factors in relation to the numbers of "cured" patients at the fourth visit and again at 3 and 12 months. A predictive model was then tested for outcome at the fourth visit, at 3 months, and at 12 months, as was the prognostic value of early recovery. We expected to detect at least some clinical and/or demographic predictors for favorable treatment outcome at the fourth visit and fewer at subsequent points in time.
To provide further insights into the mysteries of the clinical course of LBP, we report the predictive values of 44 clinic-related and 6 demographic baseline variables, singly and in combination. These were all collected because the research team considered them to be of clinical relevance in relation to treatment outcome. Our results, however, indicate that very few of these items have a predictive value either on their own or in combination with others. Interestingly, this is the case for all the clinical examination findings. Thus, for example, pain radiating into the leg, possible nerve root signs, pain on cough, antalgic scoliosis, absence of painful movements, or the presence of painful lumbar movements did not predict outcome. Burton et al  concluded in a similar study of acute and subchronic low back trouble that clinical factors have little explanatory value but that psychologic information is better at predicting the 1-year outcome in osteopathic practice. Interestingly, Nyiendo et al  noted that a low psychosocial score was not predictive for the 1-year outcome for chiropractic patients with chronic LBP, whereas it was a predictor for negative outcome in medical patients. Nonetheless, they also found more nonclinical than clinical factors to be associated with outcome in both chiropractic and medial patients.
According to our study, assuming a cutoff probability of 50% of the disease, it is possible to identify a specific group of patients of which 99% are likely not to become LBP free with chiropractic care at the fourth visit on the basis of 5 variables. These are 2 demographic variables (women, some sort of social benefit) and 3 anamnesis variables (moderate or severe pain, continuous pain for at least 6 months at the first consultation, and persistent neck pain in the past year). Contrary to what one may expect, the social benefit variable was no longer part of the model for 3 months, but the other variables remained significant. These similarities indicate that the predictive items found for the fourth visit and at 3 months follow-up relate to a single issue, possibly that of the LBP episode. At 12 months, however, only 2 variables remained in the final model and they were completely different from those earlier in the course (moderate/severe disability as measured with the revised Oswestry questionnaire and reduced daily activities because of LBP in the past year). This indicates that completely different aspects are brought into play in relation to the long-term LBP disease.
Importantly, status at the fourth visit was a strong predictor for the outcome at 3 and 12 months. In fact, the number of LBP-free individuals at 3 months was 65% (61 of 94) for those who were LBP free at the fourth visit versus 22% (110 of 504) for those who were not and 20% (17 of 83) versus 6.5% (28 of 429) at 12 months. Also, a larger number of visits were not associated with a future LBP-free status. In other words, a positive treatment outcome is apparent early in the course of care and a lack of the same is not remedied during the remainder of the treatment program.
Little is known in this area. As our team started from square one, it is, of course, possible that different findings would have been obtained with another study design, such as a different cut point for the definition of improvement in relation to pain and disability and other periods for follow-up. Although the 2 instruments used in our study to measure pain and disability to determine outcome are considered valid, our predictor variables have not been validated. However, this is hardly feasible; some questions must be considered on the basis of their face validity and user friendliness. Nevertheless, the outcome of this study might have been different had the predictor variables been defined or categorized differently.
Whether our findings can be transferred to other patient populations can also be debated. Low response rates can threaten the ability to generalize a study. In the present study, it appears unlikely that dropout subjects were biased in relation to the predictor variables, although it is possible that they were biased in relation to outcome. If in what way, and to what degree this may have affected the results is impossible to say. It is also possible that those chiropractors who chose to participate in the study were different from those who did not participate. Such differences could result in atypical patients, clinic behavior, and treatment outcomes. On the other hand, the typical randomized clinical trial is probably even more likely to result in such differences because participation in studies of that type often encourages even more rigorous clinician and patient selection in addition to the treatment provided that is more likely to be state of the art. Practice-based studies, as presented in this report, are therefore better at including more common clinicians, patients, and treatment approaches, which provide a more realistic picture of the clinical world. Other strengths of our study are that a large number of variables and interactions were tested, the choice of variables emanated from experienced clinicians, and the rationale for the analyses is well explained.
It would now be interesting to test whether our results represent a profile typical to chiropractic treatment or if they are a mere reflection of circumstances surrounding the natural course. However, this requires the inclusion of a nontreated control group or a control group treated with a method known to result in no positive effect whatsoever.
Also, the concepts of the LBP episode versus the LBP disease merit further consideration in contrast to the usual but, in our opinion, clinically irrelevant distinction between acute and chronic LBP.
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