Anthony Rosner, Ph.D.'s Response

Anthony Rosner, Ph.D.'s Response
to the Cherkin LBP Study

NEJM 1998 (Oct 8); 339 (15): 1021-1029

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:

Foundation for Chiropractic Education and Research

   PO Box 4689 Des Moines IA 50306-4689

For Immediate Release: October 14, 1998
Contact: Robin R. Merrifield

P.O. Box 9656
Seattle WA 98109
Phone/Fax: 800-343-0549

New England Journal of Medicine Publishes Study
on Chiropractic and Low Back Pain:
FCER's Director of Research Responds

FCER Director of Research Anthony Rosner, Ph.D., Addresses the New England Journal of Medicine Study on Low Back Pain

Des Moines, Iowa The Cherkin study that has just appeared in The New England Journal of Medicine (October 8, 1998 issue) and appears to have taken the media by storm is an inaccurate and unfortunate representation of the patients who normally seek chiropractic care for low back pain. It underscores the dangers of generalizing the results of randomized clinical trials which themselves represent a specialized application of therapies under restrictions that are not necessarily indicative of either the actual therapists or patients whom they see. Worse, its design flaws are so numerous and serious, as will be summarized below, that its validity is compromised to the point of misleading the reader from what is actually shown in the trial.

  • Validity of the intervention

One must be aware that several chiropractic techniques are applicable to the management of low back pain, some of which are low-force (Logan Basic Technique, Flexion-Distraction, use of a drop table, or traction). In this trial, only one high-velocity technique (side-posture) was applied and this may not be equally effective for all patients (particularly older people). Furthermore, important ancillary procedures that are intrinsic to the chiropractic visit appear to have been denied to patients; in particular, extension exercises were denied and patients most likely were not given any literature even though these two options might be considered part of a customary chiropractic regimen. The implication is that both these elements were only permitted in the other two arms (educational booklet and McKenzie method) of the trial reported. In short, chiropractic treatment in this particular trial appears to be only a pale shadow of the actual therapy administered to patients in the real world. The fact that back pain recurrences as reported by the authors were 50% by the end of the first year and 70% by the end of the second year confirms this point of view, not only for chiropractic but for the McKenzie physical therapy modality as well.

  • Characteristics of the Medical Booklet

What was the purpose and what were the details of the arm of the trial involving the educational booklet? One is left wondering what form of therapy this is supposed to represent in real life, and whether any attention (and of what kind) was given to the patient in addition to this literature. Finally, no details of any kind are provided as to the presentation and actual content of the booklet.

  • Lack of sufficient attention to patient expectations

No details are provided as to how patients were polled regarding their expectations of treatment, how the questioning was phrased, and whether the instrument was validated. The consequences of patient expectations have been given inadequate attention. Once patients were eligible to participate, how many refused to participate and for what reasons? The percentage of patients who had prior chiropractic care for low back pain appears to be substantially lower for those patients in the chiropractic arm (24%) than for either the McKenzie or medical booklet cohorts (35% and 40% respectively). Yet the authors themselves quote from another prominent investigation that "the British study found the benefits of chiropractic treatment to be most evident among patients who had previously been treated by chiropractors, a group presumably favorably inclined toward chiropractic care." Consequently, one can easily argue that the patients in the chiropractic cohort appear to be doomed to diminished outcomes.

  • Baseline characteristics

Baseline values regarding severity among the three groups tested appear to create a bias in the outcomes. First, the chiropractic group shows the highest tendency in percentages of patients who, due to low back pain and prior to their therapy, encounter (a) greater than one day of bed rest (35% vs 24% and 22% for the McKenzie and booklet groups respectively), (b) more than one day of work lost (39% vs 41% and 30% for the McKenzie and booklet group), and (c) greater than one day of restricted activity (72% vs 65% and 52% for the McKenzie and booklet cohorts).

Second, the initial bothersome and Roland-Morris disability scores of 4 and 7-8 are substantially below the respective values of 6-7 and 10 which are more frequently observed in trials involving significant low back pain. This means that any observed changes are compressed within an artificially narrow range and that statistical variations become more disruptive. The effect of both of these aberrations is to compromise the monitoring of back pain resolution.

  • Patient Compliance issues

Sufficient details regarding patient compliance are lacking. In addition, there would appear to be a wide variance between the percentage of patients therapists considered to be the level of compliance (55%) as opposed to what patients in at least the McKenzie groups have reported (78%). What were the levels recorded in both the chiropractic and booklet groups? How, when, and how often was the question posed to study subjects? Since compliance is closely linked to satisfaction and has a major bearing on outcomes, this issue cannot be ignored.

  • Lack of convincing or meaningful cost data

There is no way to draw a meaningful conclusion from the cost data as presented.

Requisite statistics regarding costs are totally ignored, such that one cannot assess whether costs follow a normal distribution or are skewed (and to different extents) in each of the three regarding modalities. Furthermore, it is incomprehensible that the HMO costs regarding laboratory services, medications, and radiology should constitute 50% of the chiropractic bill when the norm within the United States indicates that about 80% of chiropractic costs are borne within the therapist s office and 20% are allocated to external services while precisely the opposite distribution of percentages is observed in the offices of allopathic physicians.

  • Patient exclusion

The grounds for exclusion and symptoms of sciatica were not provided. In addition, patients attitudes towards provider groups should have been assessed for inclusion in the trial as these would have significant impact upon both their compliance and outcomes.

In summary, the study is a poor representation of therapies as applied to the live patient in the physician s office. If left unanswered, these inquiries would appear to be of sufficient import as to render the data seriously compromised and the study as a whole unreliable. It would be a grievous error at this point to accept the study as Gospel and the authors are invited to respond.

The Foundation for Chiropractic Education and Research (FCER) is the largest not-for-profit chiropractic organization devoted solely to the funding and distribution of chiropractic research. For more information on FCER, please call (800)637-6244.



Foundation for Chiropractic Education and Research

PO Box 4689 Des Moines IA 50306-4689


For Immediate Release: October 14, 1998 Contact: Robin R. Merrifield

P.O. Box 9656

Seattle WA 98109

Phone/Fax: 800-343-0549


New England Journal of Medicine Publishes Study on Chiropractic and Asthma: FCER s Director of Research Responds


Des Moines, Iowa The publication of "A Comparison of Active and Simulated Chiropractic Manipulation as Adjunctive Treatment for Childhood Asthma" in The New England Journal of Medicine, prompted the following response from Anthony L. Rosner, Ph.D., the Director of Research for the Foundation for Chiropractic Education and Research (FCER).

A casual reading of the Balon and Aker study, published in the October 8, 1998 issue of The New England Journal of Medicine suggests that chiropractic spinal manipulation provides no benefit to patients. What is overlooked are the facts that the design of the study is such that the outcome is all but guaranteed in advance and the benefits of chiropractic manipulation in the management of asthma (suggested in several previously published case studies and clinical trials) are obscured and therefore judged to be nonexistent. At a time when public interest in the application of alternative medicine is rising, it is regrettable that a study with such deep flaws should have found its way to the lead position in such a prominent journal. Major deficiencies of the study are summarized as follows:

  • Lack of validity of the sham procedure

With over 20 commonly used techniques and over 100 procedures overall described for chiropractic, there is a great deal of controversy as to what constitutes a proper sham or mimic treatment. Furthermore, with applications to no less than three regions of the patient (gluteal, scapular, and cranial), there is high probability that the sham procedure is invasive and overlaps to a large extent with the maneuvers chosen for the actual manipulation. The problem is compounded by the fact that nearly a dozen chiropractors had to be trained to perform such a procedure with no indication of standardization. The effect of all of this is to minimize or obscure the therapeutic effect that might be observed in an actual adjustment.

  • Masking of possible effects by medication

The fact that all patients have been medicated may be necessary from an ethical point of view, but it would be expected to mask the beneficial effects that might have been observed from spinal manipulation. The reader must be cognizant of the fact that the trial reports no benefits in addition to standard medication.

  • Vagueness of interaction with the patient

The nature of personal interaction with the patient is ill-defined at best, dubious at worst. No indication is given as to how the practitioner (such as might be seen in the clinic) interacts with the patient except to administer a satisfaction questionnaire. This leads to additional intrigues as it is by no means clear how eligible patients as young as 7 years of age are to answer questions pertaining to "feeling at ease, the skill and the ability of the chiropractor, and overall quality of care."

  • Improvements over baseline values in both treatments

The fact that there were significant improvements by intervening with the patients is demonstrated by the declines at 2 months and 4 months of both daytime symptom scores and the number of puffs per day of a beta-antagonist, in addition to small increases in peak expiratory flow rates and pediatric quality of life scores in both groups. Such is to suggest that even in this trial there was significant improvement in the patients enrolled. What is not clear is which form(s) of intervention (global and/or manual) elicited responses and not that contact with the patient in the chiropractor s office under customary clinical conditions fails to provide additional benefits in addition to medication in the management of childhood asthma. It is simply an outmoded concept to assume that simply the presence or absence of cavitation constitutes the difference between chiropractic and no treatment.

  • Lack of complete representation of global symptoms

Given the fact that the human diurnal cycle lasts for 24 hours, I am surprised by the lack of data representing nighttime symptoms. In effect, we have been shown only half the picture in this study.

This presentation reflects the challenges and problems of properly designing a clinical trial that involves more than simply ingesting medications that can fully mask the other forms of treatment. Practitioners cannot be blinded in the application of manual therapies, with the result that the authors have relied upon the patients incorrect answers to validate their ignorance of the type of treatment applied despite the fact that nuances of emotion or expectations of the therapist would be expected to be conveyed to the patient.

What is needed is far more sensitivity to the actual nature of asthma. Since it is exacerbated by stress by a plausible mechanism, one would hope in the future to measure suitable indicators of stress (such as cortisol levels) in assessing the outcomes of asthma treatments. The chiropractor remains an ideal candidate for the evaluation of such procedures, and it is hoped that the current trial appearing in The New England Journal of Medicine will not be in any way a deterrent to much-needed future research.



                  © 19952024 ~ The Chiropractic Resource Organization ~ All Rights Reserved