Research Review Corner: May 2013

This review was prepared by Michael Haneline, DC, MPH, of Research Review Service.

This review was prepared by Michael Haneline, DC, MPH, of Research Review Service.

BACKGROUND INFORMATION
The primary symptom of acute coronary syndrome (ACS) is acute chest pain and this symptom accounts for about five per cent of all admissions to hospital emergency departments in Europe and the United States. Most patients with acute chest pain, however, do not actually have ACS (only 20 per cent – 25 per cent do); rather their symptoms stem from non-cardiac sources, such as the musculoskeletal or digestive systems. Sometimes no pain source is identified, resulting in the patient leaving the hospital with a diagnosis of undifferentiated chest pain. This often results in repeated emergency room consultations, representing a high cost exposure for health care systems.

The authors of this study have done previous work in this area which pointed to musculoskeletal disorders as a possible source of pain in patients with undifferentiated chest pain.¹ They previously carried out a nonrandomized clinical trial in which patients with musculoskeletal chest pain showed improvement while under chiropractic treatment. However, the study’s methodology did not permit them to draw strong conclusions about the value of chiropractic treatment to these patients. In addition, that study did not consider patients with acute chest pain.

The purpose of this study was to gauge the relative effectiveness of two conservative treatment approaches in patients with an acute episode of musculoskeletal chest pain. The treatment approaches included:

1. Chiropractic treatment, which included spinal manipulation
2.  Self-management (a minimal intervention).

PERTINENT RESULTS

• After 309 people consented to participate in the study, 115 of them met the inclusion criteria and were randomized to either the chiropractic treatment group (59 participants) or the self-management group (56 participants).
• There was a statistically significant reduction in the number of patients with “worst chest pain” when compared with baseline at four weeks, and similar improvements were observed between weeks four and 12. Both groups showed similar improvements, but none of the differences between the groups were statistically significant.
• Numeric changes in “worst chest pain” showed decreases in both groups at four and 12 weeks, although there was more of a reduction in the chiropractic treatment group. The differences between the groups were statistically significant at 12 weeks.
• There were significant reductions in the number of patients with “chest pain now” and “average chest pain” from baseline to four and 12 weeks, but there were no significant differences between the groups.
• There were significant reductions in thoracic spine pain at 12 weeks in the chiropractic treatment group, but not at four weeks. The self-management group exhibited only small insignificant improvements in thoracic spine pain at both time points. The chiropractic treatment group was significantly more improved than the self-management group at 12 weeks for this variable.
• There were decreases in neck pain at four and 12 weeks in both groups, although they were not statistically significant.
• There were significant decreases from baseline in shoulder-arm pain in both groups at four weeks, but the changes were only significant in the chiropractic treatment group at 12 weeks.
• Although not statistically significant, there was a larger reduction in “chest pain now”, “average chest pain”, and neck pain in the chiropractic treatment group at four weeks. Also at four weeks, patients in the self-management group noticed greater improvements in thoracic spine and shoulder-arm pain. Similarly, there were more pronounced, but still not statistically significant, differences between the groups at 12 weeks favoring the chiropractic treatment group.
• Patients in the chiropractic treatment group did significantly better regarding “perceived change in chest pain” at four weeks. These patients rated their chest pain as “better” or “much better” 82 per cent of the time, versus 60 per cent in the self-management group. Chest pain was rated as unchanged in seven per cent of the chiropractic treatment group, versus 32 per cent of the self-management group. The chiropractic treatment group still had the advantage at 12 weeks, but the differences between the groups were no longer statistically significant.
• Forty-four patients in the chiropractic treatment group (75 per cent) experienced adverse effects, which were all benign and short-lived. The most common adverse effects were increased local tenderness, headache and fatigue. No serious adverse effects were reported. Patients in the self-management group were not questioned about whether they experienced adverse effects.

CONCLUSIONS AND PRACTICAL APPLICATIONS
Patients with acute musculoskeletal chest pain improved when they were managed with either chiropractic treatment or self-management. Most of the differences between the groups favored the chiropractic group. However, not all of the differences were statistically significant.

Very little work has been done on chiropractic care for acute chest pain. The authors mentioned that this was the first randomized controlled trial to assess the effect of chiropractic treatment on acute musculoskeletal chest pain. Thus, their conclusion is sensible… that the study’s results suggest that chiropractic treatment might be useful, but further research is needed.

Practitioners may use this study to support evidence-based care for selected patients with chest pain who have been thoroughly screened for the presence of other possible causes. Patients should be advised that the evidence supporting chiropractic care for acute chest pain is preliminary and that they will be given a trial of chiropractic treatment for a predetermined period of time. Continued treatment would be conditional upon symptomatic improvement per standard outcome measures.

STUDY METHODS, STRENGTHS AND WEAKNESSES
This was a prospective, randomized trial that took place in an emergency cardiology department at a 1000-bed, university hospital in Denmark, as well as at four nearby chiropractic clinics. Participants were selected from patients who presented at the emergency unit with acute chest pain and underwent the routine diagnostic procedures for ACS (e.g., electrocardiogram, creatine kinase MB (mass) levels on admission and six to nine hours later, and troponin T-levels at least six hours after the worst symptoms) and all tests were found to be within normal ranges. The participants were asked whether they wanted to participate after they were discharged from the unit.

Participants were eligible for the study if they met the following inclusion criteria:

• no diagnosis of ACS or another cardiac or medical diagnosis,
• aged 18 to 75 years,
• primary complaint of acute chest pain for less than seven days,
• ACS ruled out via the study’s diagnostic procedures,
• no significant comorbidity or contraindications for spinal manipulative therapy,
• a resident of the local county, and
• able to read and understand Danish.

Exclusion criteria were as follows: previous ACS, prior percutaneous coronary intervention or coronary artery bypass grafting, inflammatory joint disease, insulin-dependent diabetes, fibromyalgia, malignant disease, major osseous anomaly, osteoporosis, apoplexy or dementia, inability to cooperate, and pregnancy.

A diagnosis of musculoskeletal chest pain was determined at the initial visit using a case history and a clinical health examination that involved manual examination of the spine and chest wall.

Participants were randomized to receive either chiropractic treatment, provided by one of 8 experienced chiropractors, or self-management.

• Each of the chiropractors provided an individual treatment strategy that was chosen by the chiropractor which had to include thoracic and/or cervical spine high-velocity, low-amplitude manipulation. At the treating clinicians’ discretion, Joint mobilization, soft tissue techniques, stretching, stabilizing or strengthening exercises, heat or cold treatment, and advice could be included.
• Participants in the self-management group were provided a 15-minute consultation with the study clinician which consisted of reassurance and advice directed toward promoting self-management, including instructions about posture and home exercises aimed at increasing spinal movement or muscle stretch.

Participants from both groups were asked to complete self-report questionnaires at 4 and 12 weeks post-randomization, and for those in the chiropractic group, also after their final chiropractic treatment session. The in-office questionnaires were immediately placed in sealed envelopes to ensure anonymity.

The following were the primary outcome measures used in the study:

1. Change in pain intensity from baseline to follow-up on an 11-point numeric rating scale. Patients were asked to “Rate your worst chest pain during the last seven days”.
2. Self-perceived change in chest pain at follow-up using a 7-point ordinal scale with response categories ranging from “much worse” to “much better.” Patients were asked “How is your chest pain now compared with what it was before you received treatment in this study?”

Several secondary outcome measures were used, including the SF-36 Health Survey, 5 measures of change in pain intensity (“chest pain now,” “average chest pain,” “thoracic spine pain,” “neck pain,” and “shoulder-arm pain” reported as average intensities during the previous week), self-perceived change in general health, and self-perceived effect of treatment.

Strengths & Weaknesses:
The patients who received chiropractic care were seen by clinicians on multiple occasions and had hands-on treatment, whereas the patients in the self-management group were only seen once and essentially treated themselves. This disparity may have resulted in an advantage to those in the chiropractic treatment group because they received more attention (Hawthorne effect). They also experienced physical interventions which may have brought about a more powerful placebo effect.³

Some of the improvements that were observed were likely the result of natural history. Since a non-treatment group was not included in the study, that amount is not known.

There is no criterion standard that can be used to diagnose musculoskeletal chest pain; rather it is a diagnosis which comes about mainly by the exclusion of other potential causes. It is a clinical diagnosis that is difficult to confirm and is subject to inter-observer variation. Thus, musculoskeletal chest pain may not have been the sole cause of chest pain in all of the included patients. Patients who did not actually have the condition would therefore be much less likely to respond to the study intervention.

ADDITIONAL REFERENCES

1. Stochkendahl MJ, Christensen HW. Chest pain in focal musculoskeletal disorders. Med Clin North Am 2010; 94: 259-73.
2. Christensen HW, Vach W, Gichangi A, Manniche C, Haghfelt T, Høilund-Carlsen PF. Manual therapy for patients with stable angina pectoris: a nonrandomized open prospective trial. J Manipulative Physiol Ther 2005; 28: 654-61.
3. Kaptchuk T et al. Sham device v inert pill: randomised controlled trial of two placebo treatments. BMJ 2006; 332: 391-397.

In addition to practising full time in Toronto, Dr. Shawn Thistle is founder and president of Research Review Service Inc., an online, subscription-based service designed to help busy practitioners integrate current, relevant scientific evidence into their practice (www.researchreviewservice.com). Shawn also recently launched The Epicurean Scholar, which offers continuing education seminars combined with gourmet food and wine events (www.epicureanscholar.com).  Dr. Thistle graduated from CMCC (where he lectures in the Orthopedics Department) and holds an Honours Degree in Kinesiology from McMaster University. He also holds a certificate in Contemporary Medical Acupuncture from McMaster University, and is a Certified Active Release Techniques (ART®) Provider and Functional Range Release®/Functional Anatomical Palpation® instructor and provider.