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The Lowdown on High Doses: Opioid Medications for Chronic Low Back Pain
Joshua Splinter, Tamara Armstrong PsyD, Sandra Burge PhD
University of Texas Health Science Center at San Antonio
Christus Santa Rosa Family Medicine Residency Program, San Antonio TX
INTRODUCTION
Low back pain will affect 90% of all people in the United States in
their lifetimes and is the leading cause of missed work and disability.
It is responsible for $20 billion in direct healthcare costs each year1.
The more severe cases will be prescribed opioid medications in an
effort to relieve the patient’s pain. These medications pose their own
risks, including physical dependence, sedation, and host of other
negative side effects, common with long term opioid use2. Previous
studies have found that opioid users often report a lower general
health, as well as an increased propensity for issues that lower the
users’ quality of life. These issues include increased sleep disturbance,
headaches, and depression/anxiety when compared to their nonuser
counterparts3. This study aims to analyze some of the effects these
powerful drugs have on the patient’s daily life. In this analysis we
compare nonusers of opioid medications with moderate and high users
to determine group differences in physical function, role function,
BMI, receipt of disability payments, and employment status.
RESULTS
RESULTS
Table 1. Group Differences in Pain Severity and BMI
Variable
Average Pain Level
Body Mass Index
p-value No Opioid Use Opioid <50mg
0.001
5.16
7.05
0.046
32.62
32.78
Opioid >50mg
POPULATION
6.42
6.04
38.6
33.3
METHODS
Subjects. In 2009, student research assistants sought one-year
followup data from 213 patients enrolled in 2008. These patients had
low back pain for 3 months or longer; investigators excluded pregnant
women and patients with cancer. Students completed medical records
of 204 patients (96% followup), and surveys of 137 patients (64%
followup).
Measurement and Procedure. From participants’ medical records,
students gathered information about causes of low back pain,
treatments for pain, comorbidities, and Body Mass Index(BMI). A 5page patient survey addressed demographic characteristics, pain
duration, frequency and severity, physical functioning and general
health, anxiety, depression, substance abuse, and risk for opioid
misuse.
To assess role function, subjects responded to four yes/no questions
and generated a function score ranging from 0 to 4 points. To evaluate
physical function, patients responded to ten items addressing
limitations in physical activities for a score ranging from 10 to 30
points. In both functional status scales, a higher score indicates higher
function.
Analysis. In this analysis, the key outcome variables were physical
and role function, BMI, disability status, and employ-ment status. The
predictor variable included level of opioid use, defined as no use,
moderate use (≤50 mg morphine-equivalent per day), and high use (>
50 mg per day). High users represented the top quartile of opioid
dosing in our sample.
This analysis is based on information from the 137 subjects who
responded to the follow-up survey in 2009. 73.7% were female, 34.3%
were Hispanic, and 49.6% were non-Hispanic White. The average age
was 56.2, ranging from 19 to 90. Participants were divided into three
groups: nonusers of opioid meds (N=68), moderate users (N=55), and
high users (N=14).
Pain Severity- Daily Average Pain was higher in both opioid-using
groups compared to the nonusers. The high-use group reported lower
pain than the moderate-use group. (Table 1)
Body Mass Index (BMI) – BMI increased less than 1% between
nonusers and moderate opioid users. However, BMI was
approximately 15% higher in the high-use group compared to the
other two groups. (Table 1) All groups had an average BMI
considered obese (BMI>30).
Employment - Employment status declined and disability recipients
increased as opioid use increased. (Figure 1)
Function - A significant inverse trend was observed when
comparing opioid use to physical and role function. Higher users
reported the lowest (worst) function. (Figure 2)
CONCLUSIONS
Opioid users have more pain, worse functioning, and a higher
likelihood of being unemployed and on disability. One might expect
that those with the highest opioid use would be the most incapacitated
by their original ailment or by the increased drug use.
When focusing on BMI, the non-use and moderate-use groups
differed only slightly. However, the high-use group was considerably
heavier. This can be attributed to larger patients’ need for higher doses,
or perhaps the BMI is a result of a more sedentary lifestyle in response
to the high dosage. Recent studies have shown opioid agonists play a
role in overriding satiety responses and increasing obesity in animal
models4.
Group differences in pain severity were unexpected. Reported pain
was higher in the moderate-use group compared to the high-use group.
Perhaps the moderate-use group felt more pain simply due to not being
medicated as much .If this is the case, the result highlights the crux of
the clinician’s balancing act - to find the proper dosage to ameliorate
the patients’ pain, but also to prevent negative effects of elevated opioid
use.
ACKNOWLEDGEMENTS
This study was conducted in the Residency Research Network of Texas (RRNeT) with support from
the Texas Academy of Family Physicians, the South Texas Area Health Education Center, and the
Dean’s Office, School of Medicine, UTHSCSA.
REFERENCES
1. Rives, P., Douglass, A. (2004).. Journal of the American Board of Family Practice, Nov-Dec;17
2. Benyamin, R., et al. (2008).. Pain Physician 2008: Opioid Special;11
3. XDillie,K., Fleming, M., Mundt,M. & French,M.(2008). The Journal of the American Board of Family
Medicine, Mar-Apr;21(2)
4. Zheng,H., Patterson, L., & Berthoud, H. (2007).. The Journal of Neuroscience, Oct. 10;27(41)