Research Review By Dr. Jeff Muir©

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Date Posted:

June 2022

Study Title:

Association between chiropractic care and use of prescription opioids among older medicare beneficiaries with spinal pain: a retrospective observational study

Authors:

Whedon JM, Uptmor S, Toler AW, Bezdjian S, MacKenzie TA & Kazal LA

Author's Affiliations:

Southern California University of Health Sciences, Whittier, CA; Arizona Personal Injury Centers, Phoenix, AZ; Geisel School of Medicine at Dartmouth, Hanover, NH, USA

Publication Information:

Chiropractic & Manual Therapies 2022; 30: 5.

Background Information:

Back pain is currently the most common condition for which opioids are prescribed (1), with opioid use among the Medicare population increasing to a point where, between 2007 and 2016, up to 14% of Medicare beneficiaries aged 65 and older were prescribed opioids (2). This fact is compounded in this population by the common presence of comorbidities and significant polypharmacy concerns (3). The rate of death related to opioid use in this population increased in 2018, contrary to opioid death rates in a younger population, which have been decreasing (4).

Chiropractic care remains a mainstay non-pharmacological therapy for back and spinal pain, with several studies demonstrating both a reduced risk of adverse drug events (5) and, in a large observational study, an association between the use of chiropractic care and a decreased use of opioids (6).

The relationship between chiropractic care and opioid use has been well demonstrated in Medicare populations under age 65 (7), but the evidence in a population over age 65 is wanting. Therefore, the purpose of this study was to evaluate the impact of chiropractic utilization on the use of prescription opioids in Medicare beneficiaries aged 65 and over.

Pertinent Results:

55 949 subjects were included in the study, of which 9356 (~17%) were chiropractic care recipients, leaving 46 593 as non-recipients. Demographically, chiropractic recipients were more likely aged 65-74, were more likely female (2:1 ratio vs. males), were more likely white (vs. black or other ethnic minorities) and were more likely to have a “category 2” diagnosis (vs. category 1 [more favourable prognosis] or category 3 [less favourable]).

The adjusted risk of filling an opioid prescription within 365 days of the first office visit was 56% lower in chiropractic care recipients ([hazard ratio] HR 0.44; 95% CI [confidence interval]: 0.40–0.49). This remained so throughout the study period, with a narrow range of HRs from a minimum of 0.39 to a maximum of 0.45. When analyzed geographically, statistically significant results were noted in only 16 states and no discernible national pattern in the United States was observed, although the highest HRs (and therefore the lowest risk reduction) were noted in southern states, where chiropractic service utilization is relatively low (8).

When the timing of chiropractic treatment was evaluated (early, delayed or late), the greatest proportion of those avoiding filling an opioid prescription were early recipients (87% of cohort), who were 62% less likely to fill a prescription than non-recipients (HR 0.38; 95% CI: 0.34–0.42). No significant differences between recipients and non-recipients were noted in delayed or late recipients. Survival analysis indicated that the benefit of chiropractic care (i.e. not filling an opioid prescription) was maintained consistently up to 365 days following diagnosis.

Clinical Application & Conclusions:

The authors concluded that older Medicare patients with spinal or back pain who sought care from both a chiropractor and a primary care physician had less than half of the risk of non-chiropractic recipients for filling an opioid prescription. This association was most pronounced in patients seeking chiropractic care in the first 30 days following diagnosis.

EDITOR’S COMMENT: This is yet another study from this author group (we have reviewed others) demonstrating the value of chiropractic care in the management of low back and spinal pain in older adults. Avoiding an opioid prescription in even a small proportion of older patients with spinal pain, apart from benefitting the individuals greatly, could impart huge savings in the healthcare system in general as the downstream negative consequences of opioid use could be avoided.

Study Methods:

Study Population:
Patients who received Medicare benefits between 2012 and 2016, aged 65-99 years, who saw a chiropractor and primary care physician for a primary diagnosis of spinal pain were included in the study. Patients with pathological pain related to diagnoses such as cancer or those receiving hospice care were excluded.

Eligible patients were categorized as recipients of chiropractic care or non-recipients, based on whether chiropractic care had been accessed within 120 days of cohort inclusion. Recipients were further categorized as having accessed their care early (within 30 days of diagnosis), delayed (31-90 days from diagnosis) or late (91-120 days from diagnosis).

Outcome Measures and Statistical Analysis:
The primary outcome of interest was incidence of opioid prescription fill. Cox proportional hazard modelling was used to evaluate the risk of opioid prescription fill within 365 days of diagnosis. Demographic statistics were controlled for in each study group, as was the patients’ propensity to utilize chiropractic care, using inverse probability weighting (9). Hazard ratios were also compared by state to evaluate potential geographic patterns.

Study Strengths / Weaknesses:

Strengths:
  • Large sample size using the Medicare database.
  • Well-designed control methods limited potential sources of bias in data collection.
  • This was a unique and important study on an older patient population – one that will seek chiropractic care more frequently as the population ages.
Weaknesses:
  • Lack of Part C claims data may have introduced selection bias (Part C includes private, expanded coverage).
  • Spinal manipulation is the only chiropractic treatment billed under Medicare, excluding other treatments – this may have limited the accuracy of this data in terms of other treatments chiropractors may have provided.
  • Opioid prescription may have been confounded by other indications (this is an issue in all studies like this)

Additional References:

  1. Hudson TJ, Edlund MJ, Steffick DE, Tripathi SP, Sullivan MD. Epidemiology of regular prescribed opioid use: results from a national, population based survey. J Pain Symptom Manage 2008; 36: 280–8.
  2. Jeffery MM, Hooten WM, Henk HJ, et al. Trends in opioid use in commercially insured and Medicare Advantage populations in 2007–16: retrospective cohort study. BMJ 2018; 362: k2833.
  3. Corsonello A, Pedone C, Incalzi RA. Age-related pharmacokinetic and pharmacodynamic changes and related risk of adverse drug reactions. Curr Med Chem 2010; 17: 571–84.
  4. Wilson N, Kariisa M, Seth P, Smith Ht, Davis NL. Drug and Opioid-Involved Overdose Deaths - United States, 2017–2018. MMWR Morb Mortal Wkly Rep 2020; 69: 290–7.
  5. Whedon J, Toler AWJ, Goehl J, Kazal L. Association between utilization of chiropractic care for low back pain and risk of adverse drug events. J Manipulative Physiol Ther 2018; 41(5): 383–8.
  6. Corcoran KL, Bastian LA, Gunderson CG, Steffens C, Brackett A, Lisi AJ. Association between chiropractic use and opioid receipt among patients with spinal pain: a systematic review and meta-analysis. Pain Med 2020; 21: e139–45.
  7. Weeks WB, Goertz CM. Cross-sectional analysis of per capita supply of doctors of chiropractic and opioid use in younger medicare beneficiaries. J Manipulative Physiol Ther 2016; 39: 263–6.
  8. Whedon JM, Song Y, Davis MA. Trends in the use and cost of chiropractic spinal manipulation under Medicare Part B. Spine J 2013; 13: 1449–54.
  9. Weeks WB, Tosteson TD, Whedon JM, et al. Comparing propensity score methods for creating comparable cohorts of chiropractic users and nonusers in older, multiply comorbid medicare patients with chronic low back pain. J Manipulative Physiol Ther 2015; 38: 620–8.