J Manipulative Physiol Ther. 2002 (Sep); 25 (7): 450–454 ~ FULL TEXT
Iben Axén, DC, Annika Rosenbaum, BAppSc (Chiro), Robert Röbech, MHSc (ClinBiomech),
Thomas Wren, DC, Charlotte Leboeuf-Yde, DC, MPH, PhD
Medical Research Unit
Ringkjøbing County, Denmark.
OBJECTIVE: To investigate whether 3 distinct patterns of reactions to chiropractic care predict early favorable treatment outcome in patients with persistent low back pain.
DESIGN AND SETTING: Multicenter, clinic-based prospective outcome study with standardized interview questionnaires conducted in private chiropractic practices in Sweden.
STUDY SUBJECTS: Previously compliant chiropractors were invited to participate in the study. A maximum of 20 consecutive patients (per chiropractor) who sought chiropractic care for low back pain with or without sciatica with a duration of more than 2 weeks at the time of consultation and for a minimum of 30 days total during the past year.
INTERVENTION: Chiropractic management as decided by the treating chiropractor.
OUTCOME AND PREDICTOR VARIABLES: Improvement was defined at the 4th visit as self-reported "definitely improved" (the best of 5 choices). The hypothesized most favorable prognostic group had immediate improvement reported on the 1st visit, reduced pain intensity reported on the 2nd visit, reduced disability reported on the 2nd visit, and a common reaction or no reaction reported on the 2nd visit. The hypothesized least favorable prognostic group had no immediate improvement on the 1st visit, no reduction of pain intensity on the 2nd visit, no reduced disability on the 2nd visit, and no reaction or an uncommon reaction reported on the 2nd visit. The hypothesized intermediate prognostic group included all patients who did not fit into the hypothesized most favorable or least favorable groups.
COVARIABLES: Age, sex, pain intensity during past 24 hours, description of disability, duration and pattern of pain during present attack, duration and pattern of pain during past 12 months.
ANALYSIS OF DATA: The 3 predictor-groups were cross-tabulated against the outcome variable and the other covariates.
RESULTS: Of the 115 patients in the most favorable prognostic group, 84% (95% confidence interval, 77-91) reported to be "definitely improved" by the 4th visit versus 63% (59-67) of the 384 patients in the intermediate prognostic group, and 30% (22-38) of the 116 patients in the least favorable prognostic group. No major interactions from the covariates could explain these results.
CONCLUSION: Among chiropractic patients with persistent low back pain, it is possible to predict which patients will report definite improvement early in the course of treatment.
Keywords: Low Back Pain, Chiropractic, Prognosis, Outcome, Positive Predictive Value
From the FULL TEXT Article:
Chiropractic management is commonly used in the treatment for low back pain (LBP).  Previous surveys have shown that almost all chiropractic patients receive spinal manipulation, often in conjunction with soft tissue therapy, advice, and/or exercise therapy. [1, 2] Spinal manipulation, however, is central for most chiropractors and is used as a method to normalize movement and diminish pain.
Although clinical experience shows this approach to be helpful, this is not always the case, and little is known about the predictors for treatment outcome. Therefore, chiropractors, probably partly subconsciously, develop their own experiential set of predictors. For example, most chiropractors probably expect a favorable prognosis in patients who report some improvement early in the course of treatment and a normal reaction to treatment such as moderately increased local pain or feeling tired for a couple of hours shortly after treatment. [2, 3]
LBP is difficult to study and treat. The natural course, cause, and pathophysiologic condition of LBP and the reasons for recovery/nonrecovery are only partially understood. Because of this, identifying clinically relevant subgroups in relation to therapeutic approach and prognostication is difficult. In Norway and Sweden, research groups are presently working to identify such subgroups. We decided to study the prediction of early recovery in patients with persistent LBP.
Based on clinical experience and intuition, a “good prognosis” patient response profile was defined,
consisting of the following factors:
immediate improvement on the first treatment and/or a common reaction (or none at all) after the first treatment, followed by self-reported improvement at the second visit.
Conversely, the “poor prognosis” patient response profile consisted of the following elements:
no immediate improvement at the first treatment and/or an uncommon reaction (or none at all) reported after the first treatment and no improvement reported at the second visit.
This study appears to be the first attempt thus far to define predictors of treatment outcome in a specific population of patients with LBP who are submitting to chiropractic treatment. Studies of this type are simple to perform yet provide useful information in an area that is characterized by almost complete ignorance.
To our delight, we found that the data actually matched the clinical experience. However, the following points must be considered when interpreting these findings. In this study, we used a convenience sample of chiropractors because the research team was too small to make it possible to keep close contact throughout the study period with all 110 chiropractic colleagues in Sweden. This decision was made on the assumption that patients' recovery pattern would not be linked to their chiropractors' ability to return questionnaires. It is, of course, possible that nonparticipation in research projects is associated with lower interest in professional matters, and hence possibly a substandard clinical performance. However, the Swedish chiropractic profession is still sufficiently small to make it possible to keep track of any substandard or clinically deviant performers. The research team thought these cases were too few to seriously affect the study results.
In research situations, it is preferable to use previously validated questionnaires to measure pain and disability. However, in studies of this type, this is hardly possible.
First, simplicity and speed are essential for good compliance, making it impossible to use large questionnaires.
Second, the survey instrument was based on the research practitioners' own experience of useful questions to ask in their clinics. No existing validated questionnaire covered these questions.
Third, in clinical practice, specific and clinically useful questions that cannot be validated or tested for reproducibility because they are used on so many different patient populations by so many practitioners are often asked.
These measures of validity would be useless in the real world. How is it possible, for example, to prevent observer drift although good reproducibility can be shown to exist between 2 specific practitioners? Is it feasible to assume that practitioners can become certified to ask whether patients have had a painful reaction since last treatment and that this certification will be renewed at regular intervals?
Obviously, in a study in which follow-up data were collected by the treating practitioner, there will be a tendency for predominantly good results. The patient may provide polite responses indicating improvement, and the clinician may interpret vague answers in a predominantly positive manner.
Nevertheless, this is the everyday clinical situation. The patient-clinician interaction is based on the assumption that the patient wants to get well and that the clinician can help with this. Even so, all practitioners are familiar with the substandard treatment outcome: patients who get worse or do not improve. To avoid most polite reports of improvement, only the most stringent definition of improvement (ie, “definitely improved”) was tolerated in this study, as most experienced practitioners likely learn in their daily practice. In addition, the purpose of this study was not to measure treatment outcome but to compare different rates of treatment outcome in different prognostic groups. We expect that any obsequiousness bias would be divided equally among the 3 prognostic groups.
The combination of immediate improvement of symptoms interjected by a painful reaction can perhaps be seen as a physiologic prognostic factor for this type of subpopulation. Conversely, it could be argued that patients with a particularly positive outlook on life or with more positive expectations regarding the treatment outcome would be positive throughout the study, after the first visit, and at the fourth visit. However, our analysis of subgroups revealed that patients in the most favorable and intermediate prognostic groups were similar to patients in the least favorable prognostic group by type of pain and disability at baseline. The reporting of unpleasant side effects was also nearly identical in the most favorable and least favorable prognostic groups. This would not be the case if this prognostic profile were a pure reflection of patients' positive or negative attitudes in general.
It is also possible that patients with a recurring variant of LBP may appear to recover quickly because of the cyclic nature of their disease. However, subgroup analysis showed that the presence of intermittent LBP was similar in the 3 prognostic groups.
To learn more about the mechanisms of improvement, studying other therapies such as acupuncture, mobilization, and exercise therapy would be interesting to see if the pattern is the same. Another important aspect that needs to be studied is whether early “definite improvement” is a predictor for long-term improvement or has no consequence for the long-term prognosis.
According to our study results, there are 3 distinct subgroups of patients with persistent LBP
Those who react positively directly on treatment and who report a common reaction or no unpleasant reaction. Most (77% to 91%) of these patients report considerable improvement by the 4th visit
Those who report no early improvement and no uncommon unpleasant reaction or an uncommon unpleasant reaction directly on treatment. Only few (22% to 38%) of these patients report considerable improvement by the 4th visit
Those with a mixed pattern. Of these patients, 58% to 68% report improvement by the 4th visit
Determining whether these subgroup profiles can be used to define indications for spinal manipulative therapy is important.