As the conversation around the US opioid crisis continues, with claims that more than 115 people in the US die every day after overdosing on opioids, a new study has examined whether there could be any link between chiropractic care and the risk of adverse drug events (ADE’s). While a topic such as this is loaded with possibilities that no single paper could rule out, the study did reveal that adverse drug reactions were 51% lower for the cohort studied. Now that is something that certainly warrants further investigation.
As you can imagine, it was a complicated research question to answer. The process saw researchers create a retrospective cohort study, sourcing all payer claims (from private and public third party payers) administered by the Department of Health and Human Services in New Hampshire, USA . Their sample was significant: New Hampshire Residents aged 18-99 years old, enrolled in a health plan in 2013 and 14 with at least 2 clinic visits within 90 days for a diagnosis of low back pain.
This amounted to a sample group of more than 19,000, and the group was almost evenly divided between recipients and nonrecipients of chiropractic services. Researchers remarked:
“The cohorts did not differ by sex, but they did differ by age category, with a larger portion of young adults among chiropractic recipients. The cohorts also differed by health status; as measured by Charlson comorbidity score, nonrecipients had significantly inferior health status .”
While the researchers adjusted for this in their modelling, there were a number of limitations to the study. Among them were:
- the patients self-selection of care pathways
- unknown factors such as the onset, location and intensity of pain
- the retrospective and self-reported nature of the study
- inability to establish causation, just correlation
Regardless of those questions, and despite the fact that the study was constrained to the low back pain model of chiropractic, the study found a 51% reduction in risk of ADE’s for chiropractic-service recipients.
“Among 9810 recipients of chiropractic services, 41 participants (0.4%) experienced 44 ADEs. Among 9 343 non-recipients, 84 participants (0.9%) experienced 94 ADEs. The adjusted likelihood of an ADE occurring in an outpatient setting within 12 months was 51% lower among recipients of chiropractic services as compared to nonrecipients (OR 0.49; P = .0002). The ADEs were nonspecific with regard to drug category in 84% of incidents that occurred among recipients of chiropractic services and in 82% of incidents that occurred among nonrecipients. ”
The study uncovered 44 ADE’s in chiropractic recipients, and 94 ADE’s in nonrecipients. There were some ADE’s that occurred in both sample groups, despite the number of events in the chiropractic recipient group being lower. These included drug induced dermatitis, allergies, drug induced mental disorders, and poisoning. There were also a number of ADE’s that occurred only in the nonrecipient group. These included withdrawals, drug induced neuropathy and poisoning specifically from antidepressants, aromatic analgesics, hypnotics, anticoagulants, heroin and opium.
This study, whilst it does perhaps leave us with more questions than answers, suggests that “utilization of chiropractic care may be associated with reduced risk of ADE’s.” No causal relationship has been established, and this in itself is fodder for future work. The researchers suggested that future work include larger databases, longer time periods and more sensitive methods of identifying ADE’s.
So where does this leave us?
This piece of research places yet another question-mark over the effectiveness of some drugs to treat low back pain, whilst simultaneously suggesting that chiropractic care is a positive thing for sufferers. (Cue our collective surprise.) While the research on chiropractic and low back pain has been out for a long time, the line of investigation providing some critique of NSAIDs (nonsteroidal anti-inflammatory drugs) seems to be in its infancy.
Among the most recent contributions was an Australian study finding that non-steroidal anti-inflammatory drugs are “only a little better than placebo” for back pain. In the study, published in the Annals of the Rheumatic Diseases, the authors stated:
“We provide sound evidence that NSAIDs are effective, but do not offer clinically important benefits for spinal pain above those attributable to placebo, given overall pooled estimated differences were <10 points. This is crucially important because we now know paracetamol is ineffective, and opioids only offer small benefits for spinal pain. Thus, given our results and evidence from these recent high-quality meta-analyses, it seems that there are no analgesics with clinically important effects over placebo for spinal pain.”
This research followed a 2016 study with nearly 8,000 participants that found opioids were “often ineffective for back pain .” It was a meta-analysis that collated placebo-controlled RCT’s, thus providing a systematic analysis on the practice of prescribing drugs for back pain. The authors of that study concluded:
“For people with chronic low back pain who tolerate the medicine, opioid analgesics provide modest short-term pain relief, but the effect is not likely to be clinically important within guideline recommended doses. Evidence on long-term efficacy is lacking. The efficacy of opioid analgesics in acute low back pain is unknown .”
The study landed just months after a research paper presented to the European League Against Rheumatis, found that NSAIDs could inhibit ovulation after just ten days . This study, unsurprisingly, cast a critical light on the potential effects of long-term NSAID use on fertility.
Meanwhile, a 2018 study compared US military personnel who just used usual medical care for their back pain with those who used medical care plus chiropractic. It found that the latter had better results, and less pain and disability . While this study, along with the latest study on chiropractic care and adverse drug reactions, looks through the limited lens of the low back pain model for chiropractic, they still suggest something we know to be true – if you have low back pain, consider a chiropractor before you consider long term drug use.
 Staff Writer (2018), “Opioid Overdose Crisis” National Institute on Drug Abuse, https://www.drugabuse.gov/drugs-abuse/opioids/opioid-overdose-crisis retrieved 5 August 18
 Whedon J, Toler A, Goehl J, Kazal L (2018), “Association Between Utilization of Chiropractic Services for Treatment of Low Back Pain and Risk of Adverse Drug Events,” Journal of Manipulative and Physiological Therapeutics, Vol. 41, Issue 5, June 2018, pp. 383-388 https://www.sciencedirect.com/science/article/pii/S0161475417301367 retrieved 5 August 18
 Machado GC, Maher CG, Ferreira PH, et al “Non-steroidal anti-inflammatory drugs for spinal pain: a systematic review and meta-analysis,” Annals of the Rheumatic Diseases, Published Online First: 02 February 2017. doi: 10.1136/annrheumdis-2016-210597
 Shaheed, CA, Maher, CG, Williams, KA, Day, R, McLachlan A (2016), “Efficacy, Tolerability, and Dose-Dependant Effects of Opioid Analgesics for Low Back Pain: A Systematic Review and Meta-Analysis,” JAMA Intern Med. Published online May 23, 2016. doi:10.1001/jamainternmed.2016.1251
 EULAR Press Office, 2015 “Non-steroidal anti-inflammatory drugs inhibit ovulation after just 0 days,’ Eureka Alert, http://www.eurekalert.org/pub_releases/2015-06/elar-nad061015.php retrieved 21 August 2015
 Goertz C, Longg C, Vining R, Pohlman K, Wlater J and Coulter I (2018) “Effect of Usual Medical Care Plus Chiropractic Care vs Usual Medical Care Alone on Pain and Disability Among US Service Members with Low Back Pain,” JAMA Network Open, 208;1(1): DOI:10.1001/jamanetworkopen.2018.0105