January 2007

Clinical meaningfulness of the chiropractic adjustment

Part II: Perspective of the scientific community

by Robert H. Blanks, PhD, President, Research and Clinical Science

This second in a series of four articles addresses the urgency of adopting an international chiropractic research agenda to establish a strong evidence‑based rationale for chiropractic and, in particular, for the original premise of chiropractic, the correction of vertebral subluxation.

The purpose of this series is to support the contention of Dr. Joseph C. Keating's hard‑hitting presentation, "The Challenge" in which he states that the important research goal is "to determine the clinical meaningfulness (or lack thereof) of subluxation‑syndrome."

He makes three assertions in that presentation: 1) "we've talked about it for more than a century," 2) "No one disputes the existence of subluxations" but 3) "The question has always been whether or not subluxations (or other segmental lesion) has health consequences (i.e., subluxation‑syndrome)."

These are important considerations and are particularly poignant because they come from a noted leader in the chiropractic research community and member of the Board of Directors of the National Institute of Chiropractic Research (NICR).

Dr. Keating's presentation goes on to describe the problem of defining "clinical meaningfulness," how to apply scientific methodology to evaluate subluxation‑syndrome in terms of clinical outcome measures such as assessments or change in any specific disease or "condition." Finally, he poses the question, "Who will do the research?"

Last month's article explored the importance of "clinical meaningfulness" in terms of improving the patient‑doctor relationship. This month will be an evaluation of this concept in terms of chiropractic interaction with the scientific community.

Clinical meaningfulness of VS

A concept either has clinical meaningfulness (the observed change or difference means something) or it does not have clinical meaningfulness ‑‑ the reported change or difference is not meaningful and should be ignored.

In chiropractic, the question isn't so much whether subluxations exist but whether it matters if they do. Are vertebral subluxations of importance and does correcting VS make a difference? If the answer is "yes," the concept of VS has clinical meaningfulness. However, if the answer is "no," then it becomes a moot point to discuss over coffee.

The challenge comes in trying to figure out how to determine the answer. The outcome criteria and levels for clinical meaningfulness are established empirically and differ across disciplines. The primary concern is to establish an operational definition that takes into account the opinions of all stakeholders, environmental factors, objectives of the research, etc.

Proposed RCS research agenda

The first task RCS (Research & Clinical Science) faced was to develop effective strategies for accumulating the appropriate level of clinical evidence needed to determine the clinical significance for subluxation correction.

Then, it had to develop research methodologies capable of convincing the scientific community and others about the usefulness of the data and the approaches taken.

The strategy required linking the criteria for detection, analyses and correction of VS with measurable changes in health, wellness and quality of life.

Before initiating any clinical study [1] chiropractic investigators need to address three questions:

1. What is the condition to be evaluated? At RCS, researchers are interested in the "condition" of vertebral subluxation, as described by the broadest and most readily accepted definition proposed by the Association of Chiropractic Colleges (ACC).

The ACC, made up of the presidents of the 19 chiropractic colleges and programs accredited by the Council of Chiropractic Education (CCE) in the United States and Canada, drafted the "Chiropractic Paradigm" which states, in part, that "Chiropractic is concerned with the preservation and restoration of health, and focuses particular attention on the subluxation. A subluxation is a complex of functional and/or structural and/or pathological articular changes that compromise neural integrity and may influence organ system function and general health."

2. What type of study design and outcome measures will be used and what is their level of development including validation? RCS is conducting clinical research in a practice‑based patient population and uses a variety of statistical measures to evaluate VS in relation to the host of covariates (independent variables).

That is to say, we evaluate VS using many of the common objective and subjective clinical measures found in chiropractic practices, including spinous/muscle tenderness, fixation, hyper/hypotonicity, posture, range of motion, X‑ray, EMG, thermography, algometry, etc.

We also use patient‑reported outcome measures including sociodemographic (age, sex, marital status, etc.) information and several quality‑of‑life (QOL) survey instruments that have proven effective in many medical research studies.

3. What are the study objectives? Although many people think this is as simple as "prove chiropractic works," the actual objectives are far more intricate than that.

First, RCS will evaluate a large population of individuals who have never had chiropractic care and compare their data to that of patients undergoing regular subluxation‑centered care.

In so doing, we hope to develop a statistical "predictive model" that will link VS to specific clinical indicators as well as to patient‑reported outcome measures including symptom relief and QOL surveys.

That way, vertebral subluxations can be defined not by a single indicator (findings on an X‑ray or presence of pain), but by multiple indicators likely to span biological, psychological and social factors. This has already been done for some medical conditions, such as metabolic syndrome [2] and temporal mandibular disorder [3].

Then, from this large database, RCS will evaluate the health and wellness benefits of chiropractic, its frequency of use among patients worldwide, and track any changes while under care.

Groups receiving chiropractic care will be compared to groups not receiving chiropractic. Clinical meaningfulness will be extracted from difference scores (the difference between scores on the dependent variable at two different times) in the clinical measures, self‑reported QOL and other patient‑centered measures. This will permit us to determine what clinically meaningful minimum difference for a particular scale represents.

There are several options in determining clinical significance, [4] but each requires ascertaining the size of the difference between all outcome measures, and then validating clinical outcome measures against patient‑reported measures. This includes patients' global rating of change, [5,6] and other patient‑centered alternatives [7,8] including satisfaction with care. [9]

While it is a complex process, the results can be staggering.

In an earlier study of 2,818 patients undergoing chiropractic (Network Spinal Analysis) for wellness objectives, a QOL instrument demonstrated statistically significant changes in patient self‑reported QOL across all domains measured.

According to the published research report, "These benefits are evident from as early as 1‑3 months under care, and appear to show continuing clinical improvements in the duration of care intervals studied, with no indication of a maximum clinical benefit." [10]

The limitation of this study was its retrospective design and absence of a control group. Difference scores in our earlier study were obtained using a novel retrospective recall method by comparing the patients responses to the QOL questionnaire "presently" vs. "before starting care."

Preliminary analysis of ongoing RCS prospective study

This general QOL instrument has been incorporated into the RCS assessment program, and is being used to track patient outcome measures across the hundreds of offices currently serving as authorized RCS research sites.

The QOL information has been translated into a single numerical score, the "Vitality Wellness Index" (VWI). That number is compared to the patient's previous value or values, across a large population of chiropractic patients, and relative to the control group of research volunteers who have never received chiropractic care.

Although the first RCS study is still in progress, a snapshot of these data help to illustrate the advantage of the research approaches taken.

Over a three‑month period during the first year of the research protocol (May 21, 2006 to Aug. 30, 2006) a total of 787 research subjects took the on‑line quality of life survey and completed the other sociodemographic assessments.

Of these, 523 were patients undergoing care in 63 participating offices and 264 were research volunteers who had never had chiropractic care. The age, sex, marital status and other sociodemographics on the two populations were comparable, thereby allowing a comparison.

The VWI scores were significantly higher for patients than non‑patients by an average of 20%. A ratio of this difference to the variability of the controls is defined as the clinical effect size (CES). The CES for the overall VWI was 0.6 corresponding to a moderate, but clinically meaningful effect. [11]

Another helpful measure of clinical effectiveness is the percentage of patients achieving a minimal clinically important difference. In this case, the three levels of effect size were defined as "small" (CES = 0.2), "moderate" (CES = 0.5) or "large" (CES > 0.8) clinical effect size.

These results are quite revealing. Of the 523 patients examined, 67% achieved difference scores corresponding to a small effect size; 57% a moderate effect size; and 43% of the overall group achieved a large clinical effect corresponding to a change of four‑fifth of a standard deviation from baseline control levels.

The magnitude of these difference scores are comparable to those measured in the earlier study of patients undergoing Network Spinal Analysis, thus confirming the association between subluxation‑centered care and improved self‑reported quality of life scores.

However, the use of a control group in the RCS study (i.e., individuals who have never had chiropractic care), advances the cause‑effect relationship between chiropractic and positive QOL changes and anticipates the next step in proving causality.

Moreover, while the VWI shows a significant 20% improvement overall, the average difference scores for the subscales comprising the VWI are even more illuminating.

Of the four measured factors, "life enjoyment" showed the smallest increase (10%) for those under care. The difference scores in physical symptoms (physical state) improved 15%, mental‑emotional state improved 21%, and stress indicators improved by an overwhelming 34% with care.

Although preliminary, these results are very encouraging. Data collection will proceed over the next 18 months to obtain sufficient subjects to control for the host of clinical (clinical indicators, instrumentation), patient‑centered (QOL, patient satisfaction and disease/condition inventory, etc.) and sociodemographic (age, sex, marital status, occupation, etc.) variables before developing the predictive model linking vertebral subluxation with positive health, wellness and quality of life changes.

The researchers at RCS are confident that this large‑scale, statistically controlled, epidemiological study will provide the first important evidence for the clinical meaningfulness of VS.

Subsequent research, including case‑controlled and time‑series design, and randomized clinical trials, will follow in an effort to advance the level of scientific proof linking VS with health, wellness and quality of life outcomes.

More importantly, perhaps, the proposed research program makes it unnecessary to address specific diseases or conditions to test the causal link between subluxation‑correction and health. This allows the practitioner, as trained in the chiropractic colleges, to continue a responsible clinical approach, i.e., the detection, analyses and correction of subluxation, and not be forced to diagnose and treat diseases.

The research program will provide a scientifically valid approach to determine the clinical meaningfulness linking subluxation‑correction with general health, wellness and quality of life.

The next article in this series will address several strategies to apply the growing evidence‑based rationale underlying subluxation‑centered chiropractic to influence professional standards, clinical practice guidelines, and more favorable treatment by public and private third‑party payers.

References

1. Symonds T, Berzon R, Marquis P, Rummans TA. "The Clinical Significance of Quality‑of‑Life Results: Practical Considerations for Specific Audiences." Clinical Significance Consensus Meeting Group. Methods to explain the clinical significance of health status measures. Mayo Clin Proc. 2002;77:572‑583.

4. Guyatt GH, Osoba D, Wu AW, Wyrwich KW, Norman GR. Clinical Significance Consensus Meeting Group. Methods to explain the clinical significance of health status measures. Mayo Clin Proc. 2002;77;371‑383.

5. Jaeschke R, Guyatt GH, Keller J, Singer J. "Interpreting changes in quality‑of‑life score in N of 1 randomized trials." Control Clin Trials. 1991;12(4, suppl.):226S‑233S.

6. Juniper EF, Guyatt GH, Willan A, Griffith LE. "Determining a minimal important change in a disease‑specific quality of life." Questionnaire. J Clin Epidemiol. 1994;47;81‑87.

7. Wyrwick KW, Tierney WM, Wolinsky FD. "Further evidence supporting an SEM‑based criterion for identifying meaningful intraindividual changes in health‑related quality of life." J Clin Epidemiol. 1999;52;861‑873.

8. Patrick DL, Chiang YP. "Measurement of health outcomes in treatment effectiveness evaluations; conceptual and methodological challenges." Med Care. 2000;38(9, suppl.): II14‑II25.

9. Stucki G, Liang MH, Fossel AH, Katz JN. "Relative responsiveness of condition‑specific and generic health status measures in degenerative lumbar spinal stenosis." J Clin Epidemiol. 1995;48:1369‑1378.

10. Blanks RHI, Schuster TL, Dobson M. "A retrospective assessment of Network Care using a survey of self‑rated health, wellness and quality of life." J Vert Sub Res. 1997,Vol 1 (4):15‑31.

11. Cohen J. "Statistical power analysis for the behavioral sciences." New York: Academic Press, 1977;8.

(RCS co‑founder and President Dr. Robert Blanks is Professor in the Department of Biomedical Sciences at Florida Atlantic University and a past Professor of Anatomy and Neurobiology at the University of California, Irvine. Prior to this he spent two years at the Max Planck Institute for Brain Research in Frankfurt, Germany and two years in the Department of Anatomy at Harvard Medical School. Dr. Blanks is on the Advisory Board of the International Spinal Health Institute, is a Board Member of the Council on Chiropractic Practice and is actively involved in chiropractic research. To learn more about health outcomes research and RCS, call 800‑909‑1354 or 480‑303‑1694.)