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Comparative Analysis of Individuals
With and Without Chiropractic Coverage
Patient Characteristics, Utilization, and Costs
Antonio
P. Legorreta, MD, MPH; R. Douglas Metz, DC;
Craig F. Nelson, DC, MS; Saurabh Ray, PhD;
Helen Oster Chernicoff, MD, MSHS; Nicholas A.
DiNubile, MD
Arch Intern Med. 2004;164:1985-1992.
ABSTRACT
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Background Back pain accounts for more than $100
billion in annual US health care costs and is the second
leading cause of physician visits and hospitalizations.
This study ascertains the effect of systematic access to
chiropractic care on the overall and
neuromusculoskeletal-specific consumption of health care
resources within a large managed-care system.
Methods A 4-year retrospective claims data analysis
comparing more than 700 000 health plan members with
an additional chiropractic coverage benefit and 1 million
members of the same health plan without the chiropractic
benefit.
Results Members with chiropractic insurance
coverage, compared with those without coverage, had lower
annual total health care expenditures ($1463 vs $1671 per
member per year, P<.001). Having chiropractic
coverage was associated with a 1.6% decrease (P =
.001) in total annual health care costs at the health
plan level. Back pain patients with chiropractic
coverage, compared withthose without coverage, had lower
utilization (per 1000 episodes) of plain radiographs
(17.5 vs 22.7, P<.001), low back surgery (3.3
vs 4.8, P<.001), hospitalizations (9.3 vs 15.6,
P<.001), and magnetic resonance imaging (43.2 vs
68.9, P<.001). Patients with chiropractic coverage,
compared with those without coverage, also had lower
average back pain episode–related costs ($289 vs $399,
P<.001).
Conclusions Access to managed chiropractic care may
reduce overall health care expenditures through several
effects, including (1) positive risk selection; (2)
substitution of chiropractic for traditional medical
care, particularly for spine conditions; (3) more
conservative, less invasive treatment profiles; and (4)
lower health service costs associated with managed chiropractic
care. Systematic access to managed chiropractic care not
only may prove to be clinically beneficial but also may
reduce overall health care costs.
INTRODUCTION
In the
United States, back pain is the second leading cause of
physician visits and is second only to childbirth for
hospitalizations.1
It is also the most prevalent chronic medical problem, the
number one cause of long-term disability, and the second
most common cause of restricted activity and use of
prescription and nonprescription drugs.2-3
Ten years ago health expenditures for chronic back pain
were estimated to be $50 billion to $100 billion annually,4
and studies1,
3
suggest expenditures have risen exponentially since that
time. Epidemiologic studies also indicate an upward trend
for back pain in both men and women,5
a trend that is likely to continue as the average age of
the US population continues to increase.
EFFICACY AND SAFETY OF CHIROPRACTIC CARE FOR BACK
PAIN
There is evidence supporting the efficacy of chiropractic
care for back pain. A comprehensive review6
of the literature evaluating the efficacy of chiropractic
treatments for low back pain and other conditions
reported that randomized control trials "show spinal
manipulation to be better, and no trial finds it to be
significantly worse, than conventional treatment."6(p2220)
Despite a number of methodologic limitations in some of
the investigations,6
an overview of the literature, including clinical trials,
case-control studies, and meta-analyses, reflects
favorably on the efficacy of chiropractic care relative
to conventional medical treatment for back pain.1,
3,
5,
7-14
Although serious complications from spinal manipulation
therapy have been reported in a small proportion of
chiropractic patients,15
for most of the population, chiropractic treatment is
associated with a relatively low risk level, on par with
conventional medical treatments.5,
16
On the other hand, comprehensive overview of the
literature reveals that it is essentially unanimous in
reporting that chiropractic care is associated with
significantly higher patient satisfaction compared with
patients who receive conventional treatments.17-20
COST EFFECTIVENESS OF CHIROPRACTIC
CARE
Several studies5
have produced preliminary evidence demonstrating
cost-effectiveness of chiropractic compared with medical
management. A series of studies by Stano and
colleagues21-24
and one study by Dean and Schmids25
report cost benefits of chiropractic care compared with
conventional medical treatment for neuromuscular
conditions in a review of current literature (mostly
workers' compensation studies). For instance, a 1996 cost
comparison study,23
which adjusted for demographic, insurance, and condition
variables, revealed higher total (30% to 217% higher) and
outpatient (27% to 94% higher) mean payments of medical
treatment relative to chiropractic treatment. These later
studies support the applicability of findings to managed
health care settings by including large sample sizes and
examining existing fee-for-service health claims
data.
In contrast, a study by Carey et al26
found significantly higher health care costs for patients
with chiropractic or orthopedic care for back pain
(secondary to a greater number of visits) than for
patients who received their back pain care from a primary
care physician at a health maintenance organization.
Patients were interviewed over the telephone for up to 24
weeks to assess use of health care services and outcomes
of care. Patients who received care from doctors of
chiropractic care (DCs) paid more per episode than
patients who received care from primary care physicians
(69% in urban setting and 3% in rural setting). However,
in this study the analyses were limited to outpatient
costs rather than total costs; the costs were estimated
using average statewide charges for a large insurance
carrier; and, although the analyses adjusted for
sciatica, baseline functional status, and duration of
pain,20
the study did not specifically adjust for the variables
comorbidities, severity, and type of diagnosis.
Another study6,
27
that compared cost of care for episodes of back pain
between various kinds of medical practitioners (orthopedists
and chiropractors) found differential costs for care
compared with care provided by a general medical
practitioner. This study, however, based analyses on data
collected up to 25 years ago and thus may not be
applicable to today's health care market. In addition,
these studies were characterized by small sample sizes,
increasing the probability of type II errors (failure to
find a real difference between groups). Given the discrepant
cost-effectiveness findings and significant methodologic
differences that limit study comparisons, the issue of
the benefit of chiropractic care in today's health care
system remains unresolved.
ACCESS TO CHIROPRACTIC CARE
Chiropractors now represent the third largest segment of
health care practitioners in the United States,1
with 50 000 practitioners in 2000 according to the
Bureau of Labor Statistics.28
According to the American Chiropractic Association, an
estimated 21 million to 28 million people now receive
chiropractic services each year, with approximately 192
million annual visits to DCs: between 1990 and 1997,
chiropractic use increased from 10% to 11%.29
With growing public demand,30
the profession is also expected to increase 21% to 35% by
2008.16
A recent study31
of employers in large companies shows that chiropractic
insurance coverage is now being offered to most American
workers who are covered by health insurance and is
increasingly being offered in all health plan types. This
and other studies32
note that although health insurance for chiropractic
services is expanding, insurers often restrict coverage to
manage risk.
Chiropractic coverage is often limited in terms of referral
restrictions, conditions covered, number of visits,
maximum annual dollar benefit, requirement for physician
referral, and amount paid per visit. Some plans do not
provide covered benefits but instead offer a network
program in the form of discounted services. Health plan
designs may impede appropriate access to chiropractic
clinical care and may diminish the strength DCs have in
treating neuromusculoskeletal (NMS) disorders.
The disconnect between evidence regarding the efficacy and
safety of chiropractic care, consumer demand, and the
limited research on cost of chiropractic care in applied
settings has served to hinder integration of chiropractic
coverage in traditional health care services. To help
bridge this divide, improve access to appropriate
chiropractic services, and promote best practices of
chiropractic care, there is a need for community-based research
to ascertain the effect and benefits of chiropractic care
and the associated utilization of health care
resources.
The data analyzed in this study were obtained from a natural
experiment setting. A natural experiment is an experiment
conducted in real-life setting rather than the controlled
environment, where researchers "rely on truly naturally
occurring events in which people have different exposures
that resemble an actual experiment."33(p150)
In this case, the data were collected and analyzed from a
naturalistic setting rather than a laboratory setting.
Although this is not a true experiment, such an approach
is common in health services research because of the high
external validity and generalizibility of the results
obtained from studies that used natural experiment
methods.
This study was conducted to identify and describe the
demographics, disease, and utilization patterns of
individuals with access to chiropractic care compared
with individuals without such coverage. Toward this end,
this study compared members of the same health plan, both
with and without an additional chiropractic benefits
rider. This natural experiment offers a particularly rich
opportunity to understand the effects of supplemental
chiropractic coverage on utilization of medical care
because it employs members of the same health plan as a
comparison group. Both groups studied were members of the
same large managed-care system with access to the same
physician network; with the same or similar covered
benefits; with the same rules on referral to specialty
care, high-cost diagnostic tests, and hospital and
surgery approval guidelines; and with the same exclusions
and limitations.
METHODS
STUDY
POPULATION
This 4-year study (April 1, 1997, to March 31, 2001) used
administrative claims data from a large regional
managed-care network in California. These data included
inpatient and outpatient data for more than 1.7 million
continuously enrolled members containing demographic and
enrollment information in addition to diagnosis and procedure
codes as classified under the International Classification
of Diseases, Ninth Revision (ICD-9) and the
Current Procedural Terminology, Fourth Edition.
Administrative claims data from the largest chiropractic
health plan in California, American Specialty Health
Plans, were used to subsequently identify approximately
700 000 of the 1.7 million patients enrolled in the
large managed-care organization who also received
additional chiropractic coverage through an American
Specialty Health Plans benefits rider. These 700 000
members who were enrolled in both plans and had access to
a medical and chiropractic network of practitioners were
compared with the 1 million members who were enrolled in
the managed care network only. For those members enrolled
in both plans, the administrative claims data from the 2
networks were merged into one unique administrative file,
thereby creating 2 main comparative cohorts from the same
large health plan: one with access to chiropractic care
and the other without. The former group had benefits
covering direct access to a DC without the need of a
physician referral. Under this benefit plan the patient
copay for a chiropractic office visit was the same as it
would be in a medical clinic. The benefit allowed for a
maximum of 40 office visits to a DC per year.
STUDY DESIGN
This study applied a retrospective, longitudinal,
quasi-experimental, participant-nonparticipant design.
The carve-out feature of the chiropractic insurance
coverage offered by the managed-care health plan as an
option to its employer groups was used to create
retrospective control cohorts at 3 different levels. At
the first level, managed care members with chiropractic
insurance coverage were compared with the members in the
same health plan without chiropractic coverage. At the
second level, we compared members with and without
chiropractic coverage but only if they had had NMS claims
at any time during the study period. At the third level,
we compared episodes of care for members with NMS
conditions receiving care only from DCs against members
with NMS claims receiving care only from medical doctors
(MDs).
The effect of adding a chiropractic benefit on the health
plan's overall resource consumption was assessed over a
typical horizon for employer-sponsored health insurance.
To achieve this, the observation period and analyses were
annualized to a study period from January 1 to December
31, 2000, when assessing group differences in
demographics, comorbidities, and total plan claim expenditures.
However, to comprehensively compare the effects of treatment
for NMS conditions between DCs and MDs, a longer
observation period was appropriate, because NMS
conditions are typically time limited but recurrent and
can manifest over multiple episodes spanning a longer
period. Therefore, we expanded our analysis period across
4 years from April 1, 1997, to March 31, 2001, to study
the costs and utilization patterns associated with NMS
episode–specific care.
To enable meaningful comparisons of utilization and costs of
medical and chiropractic care for categories of NMS
disorders based on anatomic and clinical similarity, a
classification system grouping individual ICD-9
codes for NMS conditions into more aggregative diagnosis
groups was developed for this study. The classification
also took into account the severity of specific
conditions such as neck and lower back diagnoses. A total
of 654 ICD-9 codes, identified by separate panels
of DCs and MDs as NMS conditions most commonly treated
and eligible for insurance coverage, were sorted into the
following categories: neck, lower back, thoracic spine
and rib disorders, headache, upper extremity, lower
extremity, myalgias or arthralgias, latent effects, and
other. Additionally, severity distinctions were made for
neck and lower back diagnoses by sorting into complicated
and uncomplicated conditions, thus extending the
diagnostic groups to 11. The ICD-9 codes for these
diagnostic groups were comprehensively reviewed for
possible inclusions, exclusions, and crossover by a panel
of DCs and medical NMS experts.
To maximize comparability between medical and chiropractic
coding, a subanalysis was performed to examine a small
group of codes that would be equally applicable to
chiropractic and medical practice. This set of codes was
selected for its high frequency of occurrence in both
medical and chiropractic cohorts. To level the playing
field between chiropractic and medical care for these low
back pain–specific analyses, cases that were associated
with any claims for back surgery were excluded from the
subanalysis, because such cases are likely to have
complications for which chiropractic care would not be
appropriate.
DEFINING EPISODES OF CARE
In addition to encounter-specific comparisons, entire
episodes of care were of interest in the study. For each
member with at least 1 NMS claim or a sequence of NMS
claims, an episode of NMS care was determined by the
diagnosis group of the sequence of claims and an
allowable gap between any 2 consecutive claims of less
than 45 days. Claims separated by 45 days or more were
considered separate episodes. The 45-day interval was
derived from a previous study20-22
that used the 9 most common ICD-9 codes for low
back pain to evaluate the percentage of treatment
encounters that were captured using different intervals to
terminate an episode. The study found that for the most
common ICD-9 code (724.2) an interval of 6 weeks
(42 days) captured 86% of all encounters, and the
remaining 8 diagnoses yielded values ranging from 42 to
49 days. A sensitivity analysis of these values demonstrated
that there was little change in the overall study results
if these values were moved upward or downward. Based on
these results and on the clinical consensus of an expert
panel of both DCs and MDs, a value of 45 days was judged
to be appropriate. For neck- and back-related episodes,
which were stratified into complicated and noncomplicated
diagnosis groupings, any switch in diagnosis between
uncomplicated and complicated neck-related conditions
during the 4-year sample period triggered the entire
sequence of claims to be identified within the complicated
neck diagnosis grouping.
OVERALL EXPENDITURES AND UTILIZATION
The primary health care expenditures considered for this
study were total health care claim expenditures,
individual components of total health care claim costs
such as those associated with inpatient and outpatient
services, and costs associated with NMS care at the
episode level. Utilization metrics included the
following: outpatient services, plain radiographs, magnetic
resonance (MR) images, lumbar spine surgical procedures,
and inpatient stays. Health risk characteristics, based
on demographics and comorbidity rates, were used to
compare the risk profiles for different groups. The
health plan expenditures from inpatient, outpatient, and
chiropractic outpatient paid amounts were used in the
calculation of health care costs and reflect the dollar
value of the payers' resource consumption in providing
access to medical and chiropractic care to its members.
Prescription claims and physical therapy claims were not
included during this phase of the ongoing study, and
therefore pharmacy and physical therapy costs were not
included in health care costs.
STATISTICAL ANALYSIS
Descriptive statistics, including mean values, standard
deviations, and column percentages, were computed and
average differences between groups were evaluated. We
used  2 tests to evaluate differences
between categorical variables. This included variables
with proportional values, such as sex, proportion of
patients in the comorbidity and diagnosis groups, and
proportion of complicated episodes. To test the
difference in mean values for continuous variables, such
as age and costs, and to account for the skewed
distribution of variables, we applied nonparametric
analysis of variance instead of conventional parametric
tests such as t tests. We applied the Wilcoxon
test when comparing 2 cohorts and the Kruskal-Wallis test
when comparing 3 cohorts.
A semilogarithmic regression model was also used to estimate
the effect of chiropractic insurance coverage on total
annual health care expenditures. The total health care
costs of plan members with positive utilization during
calendar year 2000 were regressed on their chiropractic
coverage status, after adjusting for their demographic,
NMS, and comorbid characteristics using the following
specification:
The logarithmic transform of the total health care costs was
used as the dependent variable to correct for nonnormality
and heteroscedasticity in the cost distribution. The
comorbidity score, computed as the number of comorbid
conditions that a member was identified with during the
annual period, was used as a risk adjuster in addition to
age, sex, and presence of a NMS condition. The primary
independent variable of interest was the dummy variable,
which was equal to 1 if the member had chiropractic
coverage during the period and equal to 0 if otherwise.
The antilog of the estimated regression coefficient, after
accounting for its variance, was used to estimate the
effect of chiropractic coverage on the annual total
health care costs of the health plan as follows34:
where Var( ) is
the squared standard error of the estimated regression coefficient
1.
RESULTS
COMPARISON OF MEMBER COHORTS
Year 2000 claims for 707 690 health plan members with
chiropractic coverage and 1 001 995 members
without chiropractic coverage were compared. Demographic
characteristics and comorbid conditions for members with
and without chiropractic insurance coverage are displayed
in the Table.
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| Table. Baseline Demographics*
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Members with chiropractic coverage were younger (mean age,
33 years) than members without chiropractic coverage
(mean age, 36; P<.001). The cohort without
chiropractic coverage contained a slightly higher
percentage of female members (52.1% female) than the
cohort with chiropractic coverage (51.6% female,
P<.001).
Members with chiropractic coverage also were less likely
than members without chiropractic coverage to have
comorbid medical conditions. The proportions of members
who had specific comorbid conditions, including
hypertension, diabetes, cardiac arrhythmias, heart
failure, and nutritional disorders, ranged from 0.6% to
6.5% in the population with chiropractic coverage and 0.9%
to 7.3% in the population without coverage (P =
.001 for each comparison). In particular, heart failure
(0.6% vs 0.9%), cardiac arrhythmias (1.6% vs 2.0%), and
hypertension (6.5% vs 7.3%) were lower in relative
occurrence in the member population with chiropractic
coverage. Annual total health care claim costs of the
member populations with and without chiropractic coverage
for year 2000 are presented in Figure
1. The per-member-per-year (PMPY) cost of members
with chiropractic coverage was $1463, which was $208
lower (P<.001) than the PMPY cost of members without
the coverage ($1671). This translates to a 12% reduction
in annual costs incurred by the managed care organization
on members with chiropractic coverage.
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| Figure 1. Annual total cost
reduction. Members with chiropractic coverage were
associated with $208 lower per-member-per-year
(PMPY) total health care expenditures for the year
2000 (P<.001). ASHP indicates American
Specialty Health Plans.
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COMPARISON OF NMS PATIENT COHORTS
The 141 616 patients with NMS conditions who had
chiropractic coverage were also compared to 189 923
NMS patients without chiropractic coverage. As with
members with and without chiropractic coverage, NMS
patients with chiropractic coverage were younger (mean
age, 41 years) than NMS patients without chiropractic
coverage (mean age, 44 years; P<.001). Similarly to
members with and without chiropractic coverage, NMS
patients with chiropractic coverage were less likely than
NMS patients without chiropractic coverage to have
comorbid medical conditions (P<.001 for each of
the comorbid conditions previously mentioned).
The overall medical expenditures of the patients with NMS
conditions during the year 2000, including the major
components of the expenditures, are presented in Figure
2. The PMPY cost of NMS patients with chiropractic
coverage was $2345, which was $361 lower
(P<.001) than the PMPY cost of NMS patients without
the coverage ($2706). This translates to a 13% reduction
in annual costs incurred by the health plan on NMS
patients with chiropractic coverage.
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| Figure 2. Overall medical
expenditures. Patients with neuromusculoskeletal
conditions who had chiropractic coverage were
associated with $330 lower per-member-per-year
(PMPY) total health care expenditures for the year
2000. The lower cost is derived from both lower
hospital cost by $210 and lower ambulatory cost by
$151. P values were determined using the
Wilcoxon test. Further regression analysis will be
conducted. Hospital costs include outpatient
hospital services, emergency department visits,
and inpatient services. Total costs include
hospital costs and ambulatory costs. ASHP
indicates American Specialty Health Plans.
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Annual per capita hospital cost for NMS patients with
chiropractic coverage ($1224) was $210 lower or 15%
(P<.001) than that for NMS patients without
chiropractic coverage. The annual per capita ambulatory
cost for NMS patients with chiropractic coverage ($1121)
was 12% lower (P = .01) than the corresponding cost
for NMS patients without chiropractic coverage ($1272).
The annual per capita cost of providing chiropractic care
was $31, which amounted to only 1% of the total dollar
value of resources consumed ($2376) by NMS patients
between the 2 cohorts.
To adjust for age, sex, presence of an NMS condition, and
comorbidity differences between cohorts, a semilog
regression analysis was also used to estimate the impact
of chiropractic care as a covered benefit on total health
care costs of the health plan for year 2000. The
estimated coefficient for chiropractic coverage indicator
( 1) was –0.0162. The regression results indicate
that the presence of chiropractic insurance coverage was
systematically associated with an approximately 1.6%
lower (P = .001) average total health care cost of
members, after controlling for differences in age, sex,
and the number of comorbidities. The 1.6% reduction in
total health care costs per member is equivalent to
approximately 13% of the $208 PMPY observed cost
difference reported in Figure
1. This translates to an approximately $27 PMPY
potential cost saving that can be attributed to the
presence of chiropractic insurance coverage in the plan,
after accounting for differences in demographic and
comorbidity risks of the members.
BACK PAIN–SPECIFIC TREATMENT
Figure
3 presents data related to the cost of providing care
for back pain, at an episode level, for the 4-year period
(April 1, 1997, to March 31, 2001). The average cost per
back pain episode for patients with chiropractic coverage
was $289, which was $110 or 28% lower (P<.001)
than for back pain patients without chiropractic
coverage. Aggregating episodes for each patient during
the 4-year period, the average cost of back pain
treatment for patients with chiropractic coverage was
$522, which was $45 or 8% lower than the corresponding
back pain treatment cost for patients without
chiropractic coverage.
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| Figure 3. Episode of care
utilization analysis for back pain patients.
Presence of chiropractic coverage was associated
with a $110 reduction in cost per episode and a
$45 reduction in cost per patient for all
expenditures related to neuromusculoskeletal care
during the 4-year period (April 1, 1997, to March
31, 2001) (P<.001). ASHP indicates
American Specialty Health Plans.
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Furthermore, the proportion of complicated back pain
episodes was only marginally higher (10% vs 8%,
P<.001) for patients who received care only
from MDs compared with the patients who received care
only from DCs.
Utilization rates for back pain episodes presented in Figure
4 indicate significantly lower utilization of
resources across all major high-cost areas for NMS
patients with chiropractic insurance coverage compared
with those without. Back pain patients with chiropractic
coverage had fewer inpatient stays than did those without
chiropractic coverage (9.3 vs 15.6 stays per 1000
patients, P<.001). The MR image rate was also lower
for back pain patients with chiropractic coverage
compared with those without chiropractic coverage (43.2
vs 68.9 MR images per 1000 patients, P<.001).
The rate of lower back surgery among patients with
chiropractic coverage was lower as well (3.3 vs 4.8 surgical
procedures per 1000 patients, P<.001). Back pain
patients with chiropractic coverage also received fewer
radiographs (17.5 vs 22.7 per 1000 patients,
P<.001) than did back pain patients without
chiropractic coverage.
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| Figure 4. Breakdown by high-cost
items. Access to chiropractic care was associated
with lower rates of high resource-utilizing
components of neuromusculoskeletal care
(P<.001). ASHP indicates American
Specialty Health Plans; MR, magnetic resonance.
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SUBSTITUTION EFFECTS
Figure
5 presents the distribution of NMS claims reported for
neck and back pain episodes during the 4-year period. This
table compares 2 groups of patients, both who sought care
for NMS complaints from MDs only. However, members of one
of the groups were limited by the absence of access to
chiropractors within the plan due to lack of chiropractic
insurance coverage. The proportion of neck complaints
seen by MDs for patients with chiropractic coverage was
8.3%, 4 percentage points lower (P<.001) than
for the corresponding proportion for patients without
chiropractic coverage. Similarly for back pain, the
proportion of complaints seen by MDs for patients with
chiropractic coverage was 16.4%, 6 percentage points
lower (P<.001) compared with patients without
coverage. Correspondingly, a very high rate (approximately
60%) was also observed for the proportion of neck and back
complaints seen by the network DCs during the same
period. This suggests a substitution of DC care for MD
care for neck and back complaints.
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| Figure 5. Medical care substitution.
Presence of chiropractic coverage was associated
with a shift in the case distribution away from
medical doctors (MDs) to doctors of chiropractic
care (DCs) for neck and back problems, indicating
a substitution of chiropractic for physician care.
All proportional differences are statistically
significant at the P<.001 level.
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COMMENT
The high
prevalence and recurrent incidence of back pain, as well
as the heavy economic and disability burden that it imposes
on society as documented in the literature, point to a
major area of public health concern. Simultaneously,
there is growing evidence for the low risks associated
with chiropractic spinal manipulation in most cases and
favorable evidence for its effectiveness in treating low
back pain. In addition, patients treated for back pain by
DCs tend to be more satisfied than patients treated by
MDs. However, despite this evidence for safety, effectiveness,
and growing public demand, health insurance coverage for
chiropractic care continues to remain restricted,
relative to other health services, particularly in the
managed care sector.
This restriction of access to health insurance for
chiropractic care is not due to a lack of DCs, however.
Rather, chiropractic care is becoming increasingly
prevalent in the American health care system. The
increasing acceptance of chiropractic care as a source of
comprehensive complementary care for NMS problems is
reflected in that the chiropractic field is the fastest growing
among all doctoral-level health professions.17
To date, there has been little research linking chiropractic
and medical utilization data at a patient level. Thus, a
powerful opportunity to compare the effects of
chiropractic and medical management of costly NMS
conditions, such as back pain, in a real-world managed
care setting has been underused. This study integrated
and analyzed comprehensive administrative data from a
large managed medical care organization and the chiropractic
care plan that provided an additional chiropractic benefit
to more than 40% of its members. By comparing members
within the same medical managed care plan both with and
without direct access to chiropractic care, this study
provides additional information on the effect of
chiropractic insurance benefits on the resource
utilization within a managed care network.
For the managed care plan studied, the presence of a
supplementary chiropractic insurance option was
associated with favorable member selection by the plan.
This is evident in that members with covered chiropractic
benefits were significantly younger and had less
comorbidity burden. This favorable selection could have
been an artifact of 2 factors that reflect employer and
employee preferences. The larger companies in particular,
in the interest of maintaining a large productive
workforce, may have been likely to offer additional
benefits, such as supplementary insurance, to attract
younger and healthier individuals. At the same time,
potential employees, particularly those who maintain a
healthier lifestyle may have been more likely to seek
employment in companies that offer benefits covering
complementary care (eg, chiropractic or acupuncture) that
can be perceived as less aggressive treatment
modalities.
This study found that members with chiropractic coverage had
a 12% lower annual medical care cost, not adjusting for
member risk characteristics. After controlling for the
cost-saving effects associated with favorable demographic
and medical risk factors, the regression analysis found a
statistically significant 1.6% reduction in total medical
care costs that can be isolated to the presence of
chiropractic coverage. Most of this 1.6% reduction in the
plan's total medical costs is likely derived from the 13%
reduction in the total medical costs observed for the
subset of members with NMS conditions who also had chiropractic
coverage. In our study population of 0.7 million members
who had chiropractic coverage in the medical plan, we
estimated an annual reduction of approximately $16
million as a result of lower utilization of high-cost
items. This is a conservative estimate of the cost
savings for the plan that can be associated with members
in the medical plan using their supplementary benefits to
seek chiropractic treatment of their NMS problems. The
estimated cost saving appears to more than offset the
amount spent to cover the associated costs of the
chiropractic benefit.
The analyses related to NMS episodes elucidate sources of
these cost savings relating to chiropractic treatment of
common NMS complaints, such as neck and back pain.
Focusing on low back pain diagnoses that were selected
specifically for comparability between medical and
chiropractic practice, our analysis found that patients
with chiropractic coverage had significantly lower rates
of use of resource-intensive technologies, such as x-ray
examinations, MR image, and surgery, and lower use of more
expensive patient care settings, such as inpatient care.
This is reflected in the significantly lower cost, at
both the episode level and the patient level, of
providing care for back pain. The difference in
episode-specific and patient-level resource utilization did
not seem to be due solely to a difference in severity of
cases seen by DCs and physicians, since the estimated 2%
difference in severity between chiropractic and medical
patients of back pain did not constitute a clinically
meaningful difference. In addition, the substitution of
chiropractic for physician care evident from the shift in
the case distribution between physicians and DCs when
chiropractic coverage was present also contributed to the
conservation of health care resources.
Although the results from the study may carry policy
implications in the managed care industry, the
limitations of this study are worth noting, especially
since they also open up avenues for future research. This
study only analyzes effects of chiropractic coverage in a
large but specific managed care population. Future
research covering geographically diverse populations
across several plans is needed to ascertain and validate
the effect of a chiropractic benefit on utilization
patterns and cost effects, after controlling for
differences arising from factors, including location,
plan-specific benefit design, industry type, and other
undetected biases, such as patient burden of disease.
Comorbidity score and demographic characteristics such as
age were controlled for in the regression model. However,
the significantly more favorable profile of the plan
members who selected chiropractic coverage poses some
concern regarding the generalizability of the results to
a sicker, older population. Especially as the average age
of the American population continues to increase in the
next decade, the safety and appropriateness of chiropractic
care for elderly patients will need to be more thoroughly
evaluated. Further research is also necessary to quantify
utilization and costs associated with DC vs MD care for
other NMS conditions, and to ascertain clinical outcomes
for specific NMS conditions.
The substitution of chiropractic utilization for medical
care is central to the issue of providing cost-effective
care for NMS conditions in a managed care environment,
since the provision of chiropractic benefits as
supplementary insurance raises the possibility of induced
demand for medically unnecessary care. This study found
evidence that a substantial portion of the chiropractic
care sought by the members with insurance coverage was
more often substituted for medical care rather than add-on
care. Further research is needed to quantify this
substitution effect. The effects of substitution of
chiropractic care utilization for medical care could be
further pursued by analyzing data on patients with
episodes of NMS care comanaged by DCs and MDs, which was
beyond the scope of this study. Although most back pain
patients have nonspecific syndromes, a few back pain cases
are caused by severe underlying conditions. Accurate
diagnosis and appropriate referral are essential for this
subset of low back pain cases and demand an integrative
approach. This point is especially important in light of
the substitution between DCs and internists found by this
study. Finally, questions continue to remain regarding
the effectiveness of chiropractic care relative to the
cost of care and quality of the health care received.
Future research using patient surveys (quality-of-life and
patient satisfaction measures) in conjunction with
medical record review are warranted to further evaluate
the cost-effectiveness of chiropractic care in managed
care settings.
This study provides additional information regarding the
economic benefits and utilization patterns associated
with systematic access to chiropractic care. Furthermore,
it offers an integrated baseline (combining chiropractic
and medical utilization claims data for a common cohort
of members) for future research evaluating the effect of
alternative clinical management approaches to medical
conditions (ie, back pain specifically) with high direct
and indirect consumption of medical resources and a high
derivative societal cost given the absenteeism and burden
of disease associated with them.
AUTHOR INFORMATION
Correspondence: Antonio P. Legorreta, MD,
MPH, Health Benchmarks Inc, 21650 Oxnard St, Suite 2150,
Woodland Hills, CA 91367-4975 (alegorreta{at}healthbenchmarks.com
).
Accepted for publication November 7, 2003.
From the Department of Health Services, UCLA School of Public
Health, Los Angeles, Calif (Dr Legorreta); American Specialty Health
Plans, San Diego, Calif (Drs Metz and Nelson); Health Benchmarks
Inc, Woodland Hills, Calif (Drs Ray and Chernicoff); and Department
of Orthopedic Surgery, Hospital of the University of Pennsylvania,
Philadelphia (Dr DiNubile). Dr Metz is a corporate officer of
American Specialty Health Plans.
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