Pain Med. 2018 (Sep 1); 19 (suppl_1): S54–S60 ~ FULL TEXT
Anthony J Lisi, DC, Kelsey L Corcoran, DC, Eric C DeRycke, MPH, Lori A Bastian, MD, MPH, William C Becker, MD, Sara N Edmond, PhD, Christine M Goertz, DC, PhD et al.
Pain Research, Informatics,
Multimorbidities and Education (PRIME) Center,
VA Connecticut Healthcare System,
West Haven, Connecticut.
OBJECTIVE: To examine patient sociodemographic and clinical characteristics associated with opioid use among Veterans of Operations Enduring Freedom/Iraqi Freedom/New Dawn (OEF/OIF/OND) who receive chiropractic care, and to explore the relationship between timing of a chiropractic visit and receipt of an opioid prescription.
METHODS: Cross-sectional analysis of administrative data on OEF/OIF/OND veterans who had at least one visit to a Veterans Affairs (VA) chiropractic clinic between 2004 and 2014. Opioid receipt was defined as at least one prescription within a window of 90 days before to 90 days after the index chiropractic clinic visit.
RESULTS: We identified 14,025 OEF/OIF/OND veterans with at least one chiropractic visit, and 4,396 (31.3%) of them also received one or more opioid prescriptions. Moderate/severe pain (odds ratio [OR] = 1.87, 95% confidence interval [CI] = 1.72-2.03), PTSD (OR = 1.55, 95% CI = 1.41-1.69), depression (OR = 1.40, 95% CI = 1.29-1.53), and current smoking (OR = 1.39, 95% CI = 1.26-1.52) were associated with a higher likelihood of receiving an opioid prescription. The percentage of veterans receiving opioid prescriptions was lower in each of the three 30-day time frames assessed after the index chiropractic visit than before.
CONCLUSIONS: Nearly one-third of OEF/OIF/OND veterans receiving VA chiropractic services also received an opioid prescription, yet the frequency of opioid prescriptions was lower after the index chiropractic visit than before. Further study is warranted to assess the relationship between opioid use and chiropractic care.
KEYWORDS: inter-rater reliability; ergonomics; work demands; observation
From the FULL TEXT Article:
Current clinical practice guidelines recommend specific
nonpharmacological therapies as front-line treatments
ahead of pharmacological treatment for the management
of low back pain , neck pain , and osteoarthritis of
the hip, knee, and hand. [3, 4] For military and veteran
populations, the recent joint Department of Health and
Human Services/Department of Defense/Department of
Veterans Affairs (VA) Pain Management Collaboratory
identified nonpharmacological approaches to pain management
as a national research priority.  For the VA in
particular, a 2016 VA Health Services Research and
Development State of the Art conference on nonpharmacological
treatments for pain recommended broader uptake
of a group of evidence-based nonpharmacological
therapies. A key set of the recommend therapies—spinal
manipulation, massage, acupuncture, exercise, and patient
education—are the core components of multimodal
chiropractic care in the VA.
The VA began providing chiropractic services on-site
at select medical facilities in 2004 and has expanded implementation
each year thereafter.  Apart from the potential
to reduce pain and improve function in patients
with musculoskeletal conditions, chiropractic care may
have an impact on opioid use in such patients. Prior
work has presented a negative correlation between chiropractic
use and opioid use in employer health plan, [7, 8]
workers’ compensation , and Medicare 
In recent years, the VA has seen initial success in reducing
opioid use. From 2012 to 2016, the number of
veterans receiving an opioid for any reason decreased
approximately 25%, and one component of the VA’s approach
has been expanding access to nonpharmacological
pain therapies. 
Little is known about the use of opioids specifically
among chiropractic patients in the VA. A case series
found that 39% of veterans of Operations Enduring
Freedom/Iraqi Freedom/New Dawn (OEF/OIF/OND) receiving
care at one VA chiropractic clinic had received
opioid therapy before initiating chiropractic treatment
for the same condition.  As reduction in opioid use
remains a national priority, a better understanding of the
relationship between opioid use and chiropractic services
is needed to inform research and policy efforts aimed to
assess and/or optimize the delivery of chiropractic care in
The purpose of this study was to assess patient sociodemographic
and clinical characteristics associated with
opioid use among OEF/OIF/OND veterans who receive
VA chiropractic care and to explore the relationship between
timing of a chiropractic visit and receipt of an opioid
prescription. It was hypothesized that rates of opioid
use would be higher before and lower after an initial chiropractic
This work is a cross-sectional analysis of VA administrative
data. The study population is the OEF/OIF/OND
roster, provided to the VA by the Department of Defense
Manpower Data Center’s (DMDC’s) Contingency
Tracking System. The roster is a list of veterans who separated
from OEF/OIF/OND military service and enrolled
in VA health care between October 1, 2001, and
September 30, 2014. Our analyses included only veterans
with one or more VA chiropractic visits starting in 2004,
the year that the VA began providing these services. The
study was approved by the institutional review board of
the VA Connecticut Healthcare System.
The DMDC roster includes information on veterans’ gender,
race/ethnicity, date of birth, date of last deployment,
branch of service (Army, Navy, Air Force, or Marine
Corps), component (National Guard, Reserve, or active
duty), and rank (officer, including warrant officer, or enlisted).
All roster data were current at the time of separation
from military service. Data on eligible veterans were
linked to VA administrative and clinical data contained
within the Corporate Data Warehouse (CDW). These
databases provide a record of inpatient and outpatient
health care encounters including patient demographics,
clinic visits, medication prescriptions, and other health
Variable of Interest: Opioid Receipt
We defined opioid receipt as at least one filled prescription
for opioids in the VA within a window of 90 days
before to 90 days after the index chiropractic clinic visit.
Opioid medications included formulations from the
CN101 VA drug class such as butorphanol, codeine,
dihydrocodeine, fentanyl, hydrocodone, hydromorphone,
levorphanol, meperidine, morphine, nalbuphine,
opium, oxycodone, oxymorphone, pentazocine, propoxyphene,
and tapentadol. Buprenorphine and methadone
were excluded as they are predominantly used to
treat opioid use disorder. Although in some cases methadone
may have been used to manage pain, we decided to
exclude it so that we did not capture cases in which it
was being used for substance use disorder in the absence
Demographic variables including age, gender, and race/
ethnicity (i.e., black, Hispanic, other/unknown, white)
Veterans presenting to VA clinics are screened for the
presence and intensity of pain using a 0–10 numerical
rating scale (NRS). Veterans are asked to “rate your current
pain on a 0 (no pain) to 10 (worst pain imaginable)”
scale, and the response is recorded in a data field in the
electronic health record (EHR). We selected the highest
current pain intensity (within+/–90 days of the index
chiropractic visit). The highest score was chosen rather
than an average of multiple scores to maximize subject
data capture in instances when only one pain score was
recorded. Pain intensity was categorized as none or mild
(0–3) and moderate or severe (4–10). 
Mental Health Conditions
The Agency for Healthcare Research and Quality’s
Clinical Classifications Software International
Classification of Disease (ICD-9) codes were used to
identify mental health conditions.  We examined the
following conditions based on their relatively high prevalence
in veteran populations and their frequent comorbidity
with painful conditions: mood disorders (i.e.,
major depressive disorder, depressive disorder not otherwise
specified, dysthymia, bipolar disorder); post-traumatic
stress disorder (PTSD); substance use disorders,
including alcohol or drug use; and traumatic brain injury
(TBI). ICD-9 codes for mental health conditions were
collected if they appeared at any time in the veteran’s VA
Body Mass Index
Body mass index (BMI; kg/m2) was extracted+/–90 days
from chiropractic consultation using the height and
weight recorded in the EHR. Using standard classification,
veterans were categorized as obese (BMI ≥30 kg/m2)
or nonobese (BMI<30 kg/m2. .
The most recent smoking status was collected. Smoking
status was determined using methodology from
McGinnis et al. that uses EHR Health Factors Smoking
data from clinical reminders. Veterans were categorized
as never, former, or current smokers using a comprehensive
algorithm using key words (e.g., current smoker,
never smoker, tobacco counseling) found in text entries
and results from clinical reminders in CDW. 
McGinnis et al.  found high agreement between EHR
Health Factors smoking data and survey results.
Benzodiazepine receipt was collected during the period+/
– 90 days from the index chiropractic visit and was
defined as at least one filled prescription in that time
The associations between opioid prescription receipt and
demographics/comorbidities were examined among veterans
who were seen at the chiropractic clinic.
Chi-square tests were run for categorical data; t tests and
Wilcoxon rank-sum tests were used for continuous variables.
Multivariate logistic regression analyses were used
to examine the association of pain-related variables on
use of opioids, controlling for potential confounders such
as age, gender, mental health diagnoses, smoking status,
pain intensity, and BMI. We calculated the frequency of
opioid prescription receipt within three 30-day windows
before and three after the index chiropractic visit.
We identified 14,025 OEF/OIF/OND veterans with at
least one VA chiropractic visit. The majority of these veterans
were male (84.1%) and white (68.7%), and the average
age of the sample was 38 years. In terms of health
status, 56.2% reported moderate to severe pain intensity,
54.2% had been disagnosed with PTSD, 47.6% had a diagnosis
associated with depression, 33.8% were current
smokers, 19.8% had a substance use disorder diagnosis,
and the sample generally was overweight (average BMI
= 29.8 kg/m2).
Overall, 4,396 (31.3%) of these veterans received an
opioid prescription within +/– 90 days of the initial chiropractic
visit. The most commonly prescribed opioid
was hydrocodone (42.7%), followed by tramadol
(33.4%) and oxycodone (13.2%). Additional patient
characteristics are organized by opioid receipt+/–90 days
of chiropractic visit in Table 1.
The percentages of veterans receiving opioid prescriptions
tended to be higher in each of the 30-day windows
before the index chiropractic visit than in any of the 30-
day windows after the visit. As seen in Figure 1, this
ranged from a high of 15.9% at –60 to –31 days to a low
of 11.5% at+61 to+90 days.
Several factors were associated with a higher likelihood
of receiving an opioid prescription, including
moderate to severe pain (odds ratio [OR] = 1.87, 95% confidence interval [CI] = 1.72–2.03),
PTSD (OR = 1.55, 95% CI = 1.41–1.69),
depression (OR = 1.40, 95% CI = 1.29–1.553), and
current smoking (OR = 1.39, 95% CI = 1.26–1.52).
Additional factors associated with
a higher likelihood of receiving an opioid are included in
First, our results demonstrate that veterans of recent
wars receiving VA chiropractic services have a high illness
burden. Moderate to severe pain, mental health conditions,
and negative health characteristics were
common. This is consistent with previous work showing
that the overall population of veterans of recent wars has
a high prevalence of musculoskeletal and mental health
disorders , and the overall VA chiropractic patient
population is most commonly seen for management of
musculoskeletal disorders. 
Almost one-third of our sample received an opioid
prescription around the time of receiving VA chiropractic
services. This is consistent with prior reports of opioid
prescription frequency in OEF/OIF/OND patients with
noncancer pain, which have ranged from 23% to 41%. [19, 20]
Several factors were associated with an increased likelihood
of OEF/OIF/OND veterans receiving an opioid
prescription within +/- 90 days of presenting to chiropractic
services. Male gender was associated with a
higher likelihood of an opioid prescription in our sample,
which is consistent with prior research demonstrating
that women veterans with persistent pain are less likely
to initiate chronic opioid therapy.  Data from the civilian
population demonstrate that individuals who are
white [22, 23] and who have higher severity pain complaints  are more likely to be prescribed opioids, consistent
with our sample population. We also found
obesity to be associated with opioid receipt. In a prior
study of OEF/OIF/OND veterans, obesity was associated
with persistent pain.  However, a recent study of all
veterans receiving care at one VA chiropractic clinic
found that 36.5% and 48.9% of patients were overweight
or obese, but neither overweight nor obese was
associated with an objective measure of pain severity or
Both current and former cigarette smoking were associated
with opioid receipt in the sample population, with
a higher likelihood of receiving an opioid for current
smokers than former smokers. Previous work has shown
that opioid receipt was correlated with smoking status
for OEF/OIF/OND veterans.  In the civilian population,
tobacco use is associated with an increased likelihood
of opioid receipt [27–30], and individuals reporting
both cigarette smoking and chronic pain are more likely
to receive opioids. [31–33]
Participants with PTSD had a higher rate of opioid
use, which is consistent with substantial literature supporting
this relationship. [19, 31] Depression, PTSD, and
pain may share biological mechanisms, and these conditions
may be influenced by similar psychosocial factors,
such as lower socioeconomic status, disability, and motivation
to engage with health care. 
The percentage of veterans receiving opioid prescriptions
was lower in each of the three 30-day time frames
assessed after the index chiropractic visit than before.
Our work did not attempt to assess causation or otherwise
explain this observation. Veterans may have been
referred to chiropractic care as part of an opioid taper
plan, or those who agreed to chiropractic care may have
been inherently less likely to seek opioid prescriptions.
However, it is also possible that the delivery of chiropractic
care may have been a substitute for opioid use in
our sample, which raises interesting research, policy, and
practice considerations as the VA continues to expand
chiropractic services. This is particularly relevant in light
of other work that has shown a negative correlation between
chiropractic use and opioid use in private sector
A study of administrative claims data from three employer
health plans identified 13,760 patients with episodes
of mechanical low back pain (LBP), almost half
(45%) of whom used narcotic medications, yet patients
who used chiropractic services were less likely to take
narcotic medications within seven days after services
compared with patients who did not use chiropractic
services.  A claims database review of a one-year period
from the University of Pittsburg Medical Center
Health Plan identified 17,148 patients who had services
for LBP. Receiving physical therapy, spinal injections,
magnetic resonance imaging or computed tomography,
and emergency room services was positively associated
with opioid use, whereas receiving chiropractic services
was negatively associated with opioid use (OR=0.5). 
In a population-based study of injured workers in
Washington State over a three-year period, Hispanic ethnicity
and seeing a chiropractor at the time of injury were
the only factors associated with lower odds of long-term
opioid use. Both were substantial negative predictors, yet
patients seeing chiropractors were even less likely
(OR=0.29, 95% CI=0.10–0.84) than Hispanic patients
(OR=0.42, 95% CI=0.19–0.92) to use long-term
opioids.  A time-series analysis of administrative data
from a self-insured workforce at a US manufacturing
company identified 14,787 episodes of spinal pain conditions
(mixed lumbar, thoracic, and/or cervical), in which
patients receiving chiropractic services had the lowest
rate of opioid use, as well as the lowest use of six other
classes of medications, compared with patients receiving
complex medical management, physical therapy, or advice.  Lastly, an analysis of 2011 Medicare Part B data
found that a higher regional per-capita supply of chiropractors
and spending on chiropractic manipulative therapy
were strongly inversely correlated with the
percentage of younger, disabled Medicare beneficiaries
receiving opioid prescriptions. 
Our results add to the existing literature and illustrate
the need for further work to assess the relationship between
chiropractic use and opioid use in VA populations,
particularly the impact of sequencing the initiation of
these therapies. Comparison of chiropractic use over
time can help assess this in light of general changes in
opioid prescription trends. Future work should also aim
to identify the optimal situations (patient factors, disease
factors, treatment timing, and dosage) in which chiropractic
care is more likely to be a replacement for, rather
than an addition to, opioid therapy for chronic
musculoskeletal pain conditions in the VA. Even while
further research is needed, our results, along with the previous
literature, suggest that expanding access to chiropractic
care should be a key policy consideration for the
VA, congruent with national initiatives aimed to increase
the use of evidence-based nonpharmacological treatments
for chronic musculoskeletal pain.
There are several limitations to our findings. Veterans
from recent wars included for analysis had to have at
least one visit to both VA primary care and chiropractic
services. These results may not be generalizable to veterans
of other service eras and veterans who have not
accessed VA care.
This study is a cross-sectional examination,
which inherently limits our ability to make any
claims about causation. In this preliminary work, we did
not assess dose and duration of opioid use, and these
should be included in subsequent studies. The exclusion
of buprenorphine and methadone from the opioid medications
included in our study means that data were not
captured from individuals receiving buprenorphine and
methadone for pain management.
The pain intensity analyzed
was a one-time collection of highest pain score
within+/- 90 days of our index chiropractic visit; therefore,
the precise pain scores on the day of the chiropractic
visit and/or the day of opioid prescription receipt are unknown.
We did not assess the specific diagnoses associated
with the chiropractic visits in our sample; however,
previous work has shown that VA chiropractic patients
are seen overwhelmingly for low back and/or neck musculoskeletal
pain conditions. 
Nearly one-third of OEF/OIF/OND veterans receiving
VA chiropractic services also received an opioid prescription,
yet the frequency of opioid prescriptions was lower
in each of the three 30-day time frames assessed after the
index chiropractic visit than before. Factors associated
with an increased likelihood of receiving an opioid
around the time of a chiropractic visit included moderate
to severe pain, diagnoses of PTSD and/or depression, and
This material is based upon work supported by the Department of Veterans Affairs, Veterans Health Administration, Office of
Research and Development, and Health Services Research and Development IIR 12-118, CIN 13-407, and by the Palmer College Foundation, the NCMIC
Foundation, and with resources from and the use of facilities at the VA Connecticut Healthcare System.
The views expressed in this manuscript are those of the authors and do not necessarily reflect the position or policy of the Department of
Veterans Affairs or the United States Government.
Conflicts of interest:
There are no conflicts to disclose.
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