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Research Review By Dr. Jeff Muir©


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Date Posted:

February 2019

Study Title:

Association Between Utilization of Chiropractic Services for Treatment of Low Back Pain and Risk of Adverse Drug Events


Whedon JM, Toler AWJ, Goehl JM, Kazal LA

Author's Affiliations:

Health Services Research, Southern California University of Health Sciences, Whittier, California; Community and Family Medicine, Geisel School of Medicine, Dartmouth College, New Hampshire.

Publication Information:

Journal of Manipulative and Physiological Therapeutics 2018; 41: 383-388.

Background Information:

Adverse drug events (ADE) such as medication errors, adverse or allergic reactions and overdoses are injuries that result from prescription drug interventions. They generally result from misuse or overuse (1) and can cause increased rates of disability, hospitalization and even death. At rates of incidence of between 12.8-16.1%, ADEs represent a potentially significant concern among health care practitioners and patients alike.

While recent studies have found modest, short-term benefits for medications used to treat low back pain, including acetaminophen, non-steroidal anti-inflammatories (NSAIDs) and opioids, these types of medications are most commonly associated with the occurrence of ADEs (2-4). Acetaminophen is associated with toxic effects including hepatic and renal disease, gastrointestinal (GI) bleeding and increased myocardial infarction, stroke and hypertension risk (5). NSAIDs are classically associated with GI reactions (6) and risk of heart failure (7), while opioids are at the heart of the current healthcare crisis that has resulted in a 200% increase in opioid overdose occurrence since 2000 (8)!

Chiropractic care has been recommended as a first-line treatment for low back pain in evidence-based treatment guidelines (9) and systematic reviews (10). Chiropractic care may also lead to reductions in prescription drug use (11); however, the evidence in support of this hypothesis is sparse and conflicting. As a result, the authors sought to evaluate the association between utilization of chiropractic services and risk of ADEs in a population of patients suffering from low back pain. They hypothesized that those who received chiropractic services for low back pain (LBP) would have a lower likelihood of ADE compared to non-recipients.

Pertinent Results:

In over 19 000 patients (9810 chiropractic, 9343 non-recipients) from New Hampshire:
  • the risk of ADE was significantly lower in patients receiving chiropractic services (41/9810 or 0.4% of chiropractic patients, 44 ADEs total vs. 84/9343 or 0.9% of non-chiropractic patients, 94 ADEs total; OR 0.49, p = 0.002).
  • ADEs were nonspecific with regard to drug category in 84% of incidents that occurred among chiropractic recipients vs. 82% among non-recipients.
  • 16% of chiropractic nonrecipients were diagnosed with drug withdrawal, compared with 0 recipients of chiropractic services.
  • 2 nonrecipients sustained opioid poisoning as compared with 1 chiropractic recipient.
  • Common ADEs included dermatitis, allergy, induced mental disorder and poisoning.

Clinical Application & Conclusions:

The authors observed impressive differences between recipients of chiropractic care and nonrecipients with regard to the rate of adverse drug events (ADEs), with nonrecipients reporting ADEs at a significantly higher rate. No inferences could be made; however, regarding the ability of chiropractic care to lower the rate of ADEs, as the study was designed only to evaluate correlation and was not able to establish causal relationships. It remains possible that an unmeasured confounder may have been the underlying cause of the negative correlation between utilization of chiropractic services and occurrence of an ADE. With that in mind, the results are still promising and certainly warrant further investigation into the specifics of this association. The ability of chiropractic care (or any other conservative intervention) to reduce ADEs is certainly a strong argument for inclusion in treatment guidelines and recommendations, with clinical efficacy and cost-effectiveness also representing important factors for consideration.

Study Methods:

Data from the Department of Health and Human Services of the state of New Hampshire was evaluated, excluding Medicare and Medicaid databases. Eligible patients were between 18 and 99 years of age, enrolled in a health plan in both 2013 and 2014 with at least 2 clinical office visits within 90 days for a primary diagnosis of low back pain.

Multinomial logistic regression analysis was used to calculate the estimated probability of each participant to be in each cohort, using socio-demographic measures. Logistic regression was then used to compare recipients of chiropractic services to nonrecipients. A follow-up period of 12 months was used commencing from the index date. ADEs were identified based on the International Classification of Diseases (ICD) diagnosis code.

Study Strengths / Weaknesses:

  • Large sample size
  • Confounding factors accounted for via regression analysis prior to data analysis.
  • Study was designed only to evaluate correlation and cannot be used to evaluate causation (that is, whether chiropractic utilization directly results in fewer ADEs).
  • Factors such as onset, anatomic location and severity of pain were not included in regression analysis and may adversely influence outcomes.
  • ICD codes used to record ADEs were nonspecific regarding drug category, thus it is possible they were not caused by a drug used to treat low back pain.
  • An inability of the datasets to support cohort assembly prevented the authors from using their preferred methodology: to compared primary care alone with primary care plus chiropractic care.

Additional References:

  1. Wallace J, Paauw DS. Appropriate prescribing and important drug interactions in older adults. Med Clin North Am 2015; 99(2): 295-310.
  2. Taché SV, Sönnichsen A, Ashcroft DM. Prevalence of adverse drug events in ambulatory care: a systematic review. Ann Pharmacother 2011; 45(7-8): 977-989.
  3. Saedder EA, Brock B, Nielsen LP, Bonnerup DK, Lisby M. Identifying high-risk medication: a systematic literature review. Eur J Clin Pharmacol 2014; 70(6): 637-645.
  4. Sakuma M, Kanemoto Y, Furuse A, Bates DW, Morimoto T. Frequency and severity of adverse drug events by medication classes: the JADE study. J Patient Saf 2015; 13: 13.
  5. Roberts E, Delgado Nunes V, Buckner S, et al. Paracetamol: not as safe as we thought? A systematic literature review of observational studies. Ann Rheum Dis 2016; 75(3): 552-559.
  6. Machado GC, Maher CG, Ferreira PH, Day RO, Pinheiro MB, Ferreira ML. Non-steroidal anti-inflammatory drugs for spinal pain: a systematic review and meta-analysis. Ann Rheum Dis 2017; 76(7): 1269-1278.
  7. Bhala N, Emberson J, Merhi A, et al. Vascular and upper gastrointestinal effects of non-steroidal anti-inflammatory drugs: meta-analyses of individual participant data from randomised trials. Lancet 2013; 382(9894): 769-779.
  8. Rudd RA, Aleshire N, Zibbell JE, Gladden RM. Increases in drug and opioid overdose deaths – United States, 2000-2014. MMWR Morb Mortal Wkly Rep 2016; 64(50-51): 1378-1382.
  9. Rudd RA, Aleshire N, Zibbell JE, Gladden RM. Increases in drug and opioid overdose deaths – United States, 2000-2014. MMWR Morb Mortal Wkly Rep 2016; 64(50-51): 1378-1382.
  10. Paige NM, Miake-Lye IM, Booth MS, et al. Association of spinal manipulative therapy with clinical benefit and harm for acute low back pain: systematic review and meta-analysis. JAMA 2017; 317(14): 1451-1460.
  11. Rhee Y, Taitel MS, Walker DR, Lau DT. Narcotic drug use among patients with lower back pain in employer health plans: a retrospective analysis of risk factors and health care services. Clin Ther 2007; 29(suppl): 2603-2612.

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