luo2004

SPINE Volume 29, Number 1, pp 79–86
©2003, Lippincott Williams & Wilkins, Inc.
Estimates and Patterns of Direct Health Care
Expenditures Among Individuals With Back Pain in the
United States
Xuemei Luo, PhD,*† Ricardo Pietrobon, MD,† Shawn X Sun, PhD,‡ Gordon G. Liu, PhD,‡ and
Lloyd Hey, MD, MS*†
Study Design. Secondary analysis of the 1998 Medical
Expenditure Panel Survey.
Objective. To estimate total health care expenditures
incurred by individuals with back pain in the United
States, calculate the incremental expenditures attributable to back pain among these individuals, and describe
health care expenditure patterns of individuals with back
pain.
Summary of Background Data. There is a lack of updated information on health care expenditures and expenditure patterns for individuals with back pain in the
United States.
Methods. This study used data from the 1998 Medical
Expenditure Panel Survey, a national survey on health
care utilization and expenditures. Total health care expenditures and per-capita expenditures among individuals
with back pain were calculated. Multivariate regression
models were used to estimate the incremental expenditures attributable to back pain. The expenditure patterns
were examined by stratifying individuals with back pain
by sociodemographic characteristics and medical diagnosis, and calculating per-capita expenditures for each
stratum.
Results. In 1998, total health care expenditures incurred by individuals with back pain in the United States
reached $90.7 billion and total incremental expenditures
attributable to back pain among these persons were approximately $26.3 billion. On average, individuals with
back pain incurred health care expenditures about 60%
higher than individuals without back pain ($3,498 vs.
$2,178). Among back pain individuals, at least 75% of
service expenditures were attributed to those with top
25% expenditure, and per-capita expenditures were generally higher for those who were older, female, white,
medically insured, or suffered from disc disorders.
Conclusions. Health care expenditures for back pain in
the United States in 1998 were substantial. The expenditures demonstrated wide variations among individuals
with different clinical, demographic, and socioeconomic
characteristics. [Key words: health care expenditures,
back pain, expenditure pattern] Spine 2004;29:79 – 86
From the *Center for Clinical Effectiveness and †Division of Orthopedic Surgery, Department of Surgery, Duke University Medical Center,
Durham, North Carolina; and ‡Pharmaceutical Policy & Evaluative
Sciences, School of Pharmacy, University of North Carolina, Chapel
Hill, North Carolina.
Acknowledgment date: February 4, 2003. First revision date: April 24,
2003. Acceptance date: April 30, 2003.
The manuscript submitted does not contain information about medical
device(s)/drug(s).
No funds were received in support of this work. No benefits in any
form have been or will be received from a commercial party related
directly or indirectly to the subject of this manuscript.
Address correspondence to Xuemei Luo, PhD, DUMC 3645, Duke
University Medical Center, Durham, NC 27710; E-mail:
luo00003@mc.duke.edu
Back pain is highly prevalent in the United States. Approximately 80% of Americans experience at least one
episode of back pain during their lifetime1,2 and 15% to
20% tend to report back pain some time in a 1-year
period.1 Because of its high prevalence, back pain is a
leading reason for physician visits, hospitalization, and
utilization of other health care services.3 Despite its importance, no recent studies have investigated health care
expenditures and expenditure patterns for individuals
with back pain in the United States using a nationally
representative database.
Information regarding health care expenditures of a
particular disease is important for health care policy
making since it affects the allocation of limited resources
among different conditions.4 To our knowledge, only a
limited number of studies have been conducted to estimate the health care costs for back pain in the United
States. Grazier et al conducted the most comprehensive
cost analysis in 1984,5 estimating the U.S. back pain
costs using three 1977 national survey data sets and subsequently adjusting all costs to 1984 dollars. These authors found that the direct costs for back pain reached
$12.9 billion annually.5 Frymoyer et al later adjusted the
Grazier et al estimates to 19906 and 1994 dollars.7 Their
adjusted estimates were $24.3 billion in 1990 and $33.6
billion in 1994.
It is clear from these previous studies that back pain
has imposed huge burdens on the U.S. health care system. In recent years, the United States has been facing the
challenge of skyrocketing health care expenditures, with
health care expenditures reaching $1.2 trillion and accounting for 13.6% of gross domestic product.8 Since
back pain is one of the most costly diseases,9 it is important to identify the determinants of health care expenditures for this patient population. Such information can
help developing optimal intervention strategies and appropriate health policies.
Describing patterns of health care expenditures is often the first step toward understanding the determinants
of the expenditures. A number of studies have been conducted to describe patterns of health care expenditures
among back pain individuals. These studies found that a
small percentage of high cost back pain patients accounted for most of the expenditures10,11 and that the
expenditures were distributed disproportionately among
workers with different duration of disability.12
An overview of the current literature on the estimates
and patterns of health care expenditures for back pain in
79
80 Spine • Volume 29 • Number 1 • 2004
the United States indicates several limitations. First, the
estimates are relatively outdated. The most comprehensive cost estimates were obtained in 1984 and the primary data sources had to be traced back to 1977.5 Although Frymoyer et al adjusted the above estimates to
1994, their cost estimates were based on various assumptions that may or may not be true in the real world.7
Moreover, because their calculation was based on previous estimates, the approach combined the limitations of
previous studies and those of its own. Second, previous
studies that estimated health care costs for back pain had
a major methodology limitation. The estimates were
based on health care services that back pain was the
primary diagnosis.5 But back pain may cause complications such as depression13 or may increase the severity of
other health problems. The expenditures associated with
these conditions were not included, and such exclusions
may cause underestimation of the costs. Finally, few
studies have examined the patterns of health care expenditures in back pain population at a national level. Previous studies in this area were either conducted in a single
state or the study subjects were limited to a specific patient population such as industry workers.10 –12 It is difficult to generalize the results nationally. Moreover, previous studies mostly focused on expenditure distribution
or the variation of expenditures among people with different levels of disability. How health care expenditures
varied among individuals with different demographic
and socioeconomic characteristics has not been well
established.
One purpose of this study was to use a national survey
database, 1998 Medical Expenditure Panel Survey
(MEPS), to estimate U.S. health care expenditures for
back pain in 1998. Recognizing the methodological limitations associated with previous studies, we took a different and broader approach. We first estimated total
health care expenditures incurred by individuals with
back pain. The strength of this method is that all relevant
expenditures are included. But the approach allows the
estimates to include not only expenditures related to
back pain but also expenditures unrelated to back pain.
To acquire more precise estimates, we subsequently calculated the incremental expenditures attributable to
back pain among these individuals. We hoped that our
estimates would provide policy makers and health care
providers most up-to-date information about the U.S.
health care expenditures for back pain and help the formulation of health care policies for back pain care in the
United States.
Another purpose of this study was to use the 1998
MEPS to describe health care expenditure patterns
among individuals with back pain in the United States.
We focused on describing how the expenditures were
distributed and how the expenditures varied among individuals with different demographic, clinical, and socioeconomic characteristics. We hope that such descriptive
information will guide future studies to identify the determinants of health care expenditures for back pain
population and ultimately help better design intervention strategies and appropriate policies in an attempt to
provide most cost-effective back pain care.
Methods
Data Source. The household survey of the 1998 MEPS was
used as the data source for this study. The MEPS is cosponsored by the Agency for Healthcare Research and Quality and
the National Center for Health Statistics. It is designed to provide nationally representative estimates of health care use, expenditures, source of payment, and insurance coverage for the
civilian noninstitutionalized population of the United States.14
Detailed information about the MEPS can be found at Agency
for Healthcare Research and Quality web site.14
Study Population. The study population was comprised of
survey respondents who were 18 years of age and older. Back
pain was defined as pain experienced in all back areas, regardless of upper or lower part of the back. This included any of the
following three conditions: back disorders, disc disorders, and
back injuries. ICD-9 codes used to identify individuals with
back pain included 720, 721, 722, 723, 724, 805, 806, 839,
846, and 847. A total of 2,120 respondents reported back pain
sometime during 1998. Since the MEPS is a sampling survey,
these individuals are a representative sample of the 25.9 million
adults having back pain in the United States in 1998.
Health Care Expenditures. Health care expenditures were
defined as sum of direct payments for the care provided during
1998. In contrast to the studies of cost of illness, in which the
costs for uncompensated care are included, this study only considered the health care services for which payments were made.
Our estimates of health care expenditures included expenditures associated with the following services: inpatient care, outpatient services, office-based visits, emergency room visits, prescription drugs, home health services, dental care, vision aids,
and medical equipment purchase. Both office-based and outpatient services included visits not only to physicians, but also to
nonphysician providers such as chiropractors, physical therapists, occupational therapists, psychologists, nurse and nurse
practitioners, social workers, and physician’s assistants. Because MEPS is a survey of noninstitutionalized population,
expenditures associated with nursing home care were not included. The health care expenditures were examined from a
societal perspective, including out-of-pocket payments and
payments by all payers, including private insurance, Medicaid,
Medicare, Worker’s Compensation, and other sources.
Data Analysis. The MEPS is a stratified multistage complex
design survey. To account for such complex survey design, all
estimates presented in the text and tables have been weighted to
reflect national estimates and the standard errors were calculated by using PROC SURVEYMEAN AND PROC SURVEYREG (SAS Institute, version 8, Cary, NC).
Total Health Care Expenditures Among Individuals
With Back Pain. Total health care expenditures incurred by
individuals with back pain were estimated by summing overall
health care expenditures across all back pain individuals. We
also divided total expenditures by number of individuals with
back pain to obtain an estimate of per-capita health care
expenditures.
Direct Health Care Expenditures • Luo et al 81
Increment in Health Care Expenditures Attributable to
Back Pain. Average increment in health care expenditures
attributable to back pain was first computed. It was calculated
as the extra expenditures incurred by individuals with back
pain over the expenditures caused by individuals without back
pain. To adjust for the potential difference in sociodemographic characteristics between the two groups of people, a
multivariate regression model was estimated. For the model,
variable total health care expenditures was specified as a function of back pain and sociodemographic factors, including age,
sex, marital status, race, educational level, family income, and
health insurance status. The average increment in total health
care expenditures attributable to back pain was therefore calculated as the difference in adjusted mean expenditure between
individuals with back pain and individuals without back pain.
Total incremental health care expenditures were subsequently
computed by multiplying the average incremental expenditures
with number of individuals with back pain. In addition to the
total incremental expenditures, we also built separate models
estimating incremental expenditures for each health service.
Expenditure data generally do not have normal distribution
and have been transformed into various ways to improve its
distribution. We did not make any transformation of the expenditure variable in this study for the following three reasons.
First, there is no consensus about whether transformation or
untransformation fits expenditure data better. Some studies
recommended against using untransformed data,15,16 whereas
others suggested that models based on untransformed data actually performed better than models based on transformed data.17,18 Second, the sample involved in our study was not small.
When a data set is very large, ordinary least square regression
on untransformed data will provide unbiased estimates of regression parameters.18,19 Third, regression models based on
untransformed data do not require retransformation and can
be easily interpreted.
Expenditure Patterns Among Individuals With Back
Pain. The expenditure patterns were examined by stratifying
individuals with back pain by sociodemographic characteristics and medical diagnosis, followed by the calculation of percapita expenditures for each stratum. Investigated characteristics included age, gender, race, education, family income, and
medical insurance. Family income was determined by the
household income as a percentage of the federal poverty guideline and grouped into five categories: negative or poor, near
poor, low income, middle income, and high income. Medical
insurance was categorized as publicly insured, privately insured, and uninsured. A very important characteristics, Worker’s Compensation insurance, was not investigated in this study
because of a lack of information in the investigated database.
Individuals in each category of medical insurance may or may
not have Worker’s Compensation benefits.
Results
Health Care Expenditures Among Individuals With
Back Pain
A total of 25.9 million adults reported back pain sometime in 1998. For this back pain population, more than
50% were female (55%) and about 61% were married.
The average age was 48 years. The majority were white
(88.3%). The most prevalent back diagnosis was ICD
724, which included spinal stenosis, lumbago, sciatica,
Table 1. Characteristics Among Individuals With Back
Pain (N ⴝ 25.9 million)
Age (yr)
Gender (%)
Female
Male
Education (%)
⬍12 grade
ⱖ12 grade
Marital status (%)
Married
Widowed or separated or divorced
Single
Race (%)
White
Black
Other
Diagnosis* (%)
Ankylosing spondylitis and other inflammatory
spondylopathies (ICD 720)
Spondylosis and allied disorders (ICD 721)
Intervertebral disc disorders (ICD 722)
Other disorders of cervical region (ICD 723)
Other and unspecified disorders of back (ICD 724)
Fracture of vertebra without mention of spinal cord
injury (ICD 805)
Fracture of vertebra with spinal cord injury (ICD 806)
Other, multiple, and ill-defined dislocations (ICD 839)
Sprains and strains of sacroiliac region (ICD 846)
Sprains and strains of other and unspecified parts
of back (ICD 847)
47.9
55.0
45.0
19.2
80.8
60.9
23.8
15.3
88.3
8.1
3.6
0.3
5.1
14.2
9.6
59.5
2.2
0.03
2.1
2.2
16.2
* The sum of the percentage for each diagnosis is larger than 100%. This is
because some people have more than one diagnosis.
and other unspecified back disorders (59.5%). Other diagnoses that had prevalence larger than or close to 10%
were ICD 847 (back sprains and strains; 16.2%), ICD
722 (disc disorders; 14.2%), and ICD 723 (other disorders of cervical region; 9.6%) (Table 1).
Total health care expenditures incurred by individuals
with back pain in the United States in 1998 were approximately $91 billion. The expenditures for inpatient care
($27.9 billion) accounted for the largest proportion of
the total expenditures (31%), followed by the expenditures for office-based visits ($23.6 billion, 26.0%). Other
health care services responsible for more than 10% of the
total expenditures included prescription drugs ($14.1
billion, 15.6%) and outpatient service ($11.9 billion,
13.1%). Emergency room visits ($2.7 billion) and home
health services ($2.7 billion) contributed the least to the
total expenditures, each accounting for 3% of the total
expenditures.
Table 2 summarizes per-capita expenditures in 1998
for individuals with back pain and individuals without
back pain. The per-capita total expenditures for individuals with back pain were $3,498, compared with $2,177
for individuals without back pain. Back pain individuals
therefore incurred total health care expenditures about
1.6-fold higher, on average, than individuals without
back pain. Investigation of each health service demonstrated that individuals with back pain had higher percapita expenditures across all services than individuals
without back pain (Table 2).
82 Spine • Volume 29 • Number 1 • 2004
Table 2. Comparison of Health Care Expenditures Between Individuals With Back Pain and Individuals Without Back
Pain (N ⴝ 198.7 million)
Per Capita Expenditures ($)
Service Type
Individuals With Back Pain
(N ⫽ 25.9 million)
Individuals Without Back Pain
(N ⫽ 172.7 million)
Ratio of Back Pain to
Non-Back Pain Individuals
Office-based
Outpatient
Emergency room visits
Inpatient
Home health
Prescription drugs
910.0
460.4
102.7
1,075.7
105.5
541.5
425.9
248.8
61.5
774.4
92.2
340.1
2.1
1.9
1.7
1.4
1.1
1.6
Total
3,498.1
2,177.9
1.6
Incremental Expenditures Attributable to Back Pain
The increment in health care expenditures attributable to
back pain was calculated. Back pain caused a per-capita
increment of $1,014.6 in overall service expenditures.
Multiplying this estimate by the number of individuals
with back pain (25.9 million), the total incremental expenditures attributable to back pain reached 26.3 billion. When investigated by each service, office-based visits had the highest per-capita incremental expenditures
($428.4), followed by outpatient services ($181.3), inpatient care ($173.4), prescription drugs ($148.7), and
emergency room visits ($40.5). The per-capita incremental expenditures for home health services was negative
(⫺$7.4), suggesting that individuals with back pain incurred lower home health expenditures than individuals
without back pain. Multiplying the per-capita incremental expenditures with the number of individuals with
back pain, the sum of incremental expenditures for office-based visits exceeded $10 billion ($11.1 billion). The
sum of incremental expenditures for the other services
was neither small: $4.7 billion for outpatient services,
$4.5 billion for inpatient care, $3.9 billion for prescription drugs, and $1.1 billion for emergency room visits.
Patterns of Health Care Expenditures Among
Individuals With Back Pain
The health care expenditures were not equally distributed among individuals with different levels of expenditures. Table 3 shows the percentage of service expenditures attributable to the high expenditure cases. For each
health service, the 10% most expensive individuals accounted for ⬎50% of the service expenditures. The 25%
most expensive individuals accounted for ⬎75% of the
service expenditures. The 50% most expensive individuals accounted for 90% to 100% of the service expenditures (Table 3). Such pattern was particularly clear for
inpatient care, outpatient services, and emergency room
visits. Close to 100% of the expenditures for inpatient
care, 87% for outpatient services, and 90% for emergency room visits were accounted for by the 10% most
expensive individuals (Table 3).
Per-capita expenditures varied among individuals
with different back pain diagnoses (Table 4). Only diag-
noses with prevalence ⬎5% were investigated. Individuals with disc disorders and individuals with spondylosis
and allied disorders had per-capita total expenditures
exceeding $5,000, with disc disorder individuals incurring the highest per-capita expenditures ($6,010.7). As a
comparison, the per-capita total expenditures for individuals with spinal stenosis, lumbago, sciatica and other
unspecified back disorders (ICD 724) and individuals
with other disorders of cervical region (ICD 723) were
much lower, with each reaching close to or less than
$3,500. Individuals with back sprains and strains had
even lower per-capita total expenditures (Table 4). Analysis of each health service indicated that the per-capita
expenditures for office-based visits and emergency room
visits were not dramatically different among individuals
with different diagnoses. Per-capita expenditures for
home health services were also similar except that individuals with back sprains and strains had much lower
per-capita expenditures than the other groups (Table 4).
The per-capita expenditures for inpatient care were very
different among different diagnosis groups. Individuals
with disc disorders had the per-capita inpatient care expenditures reaching $2,816, compared with only $634
for individuals with back sprains and strains. Per-capita
expenditures for outpatient services and prescription
drugs were also different among different diagnosis
groups but not so dramatic as that for inpatient care
(Table 4).
Table 3. Percentage of Service Expenditures Attributable
to the Top Expenditure Individuals
Service Type
Office-based
Outpatient
Emergency visit
Inpatient
Prescription drugs
Top 10% by
Expenditures/
% of Total
Expenditures*
Top 25% by
Expenditures/
% of Total
Expenditures
Top 50% by
Expenditures/
% of Total
Expenditures
51.8
86.6
90.2
98.7
52.5
76.0
99.96
100
100
80.5
93.0
100
100
100
96.6
* This percentage was calculated as following: sum of expenditures for individuals whose service expenditures were on top 10%/total expenditures for
the service.
Direct Health Care Expenditures • Luo et al 83
Table 4. Per-Capita Expenditures ($) Among Back Pain Individuals With Different Diagnosis
Diagnosis
N (millions)
Office-Based
Outpatient
Emergency
Visit
Inpatient
Home Health
Prescription
Drug
Total
1.3
1043.7
545.3
122.5
2033.4
167.9
877.6
5042.2
3.7
1157.5
725.1
111.8
2816.4
131.5
785.5
6010.7
2.5
1088.6
410.7
136.3
821.2
140.4
380.4
3336.5
15.4
931.0
513.6
87.8
973.5
124.6
530.8
3513.6
4.2
841.1
252.5
121.0
634.0
12.2
417.5
2494.4
ICD721: spondylosis and
allied disorders
ICD722: intervertebral
disc disorders
ICD723: other disorders
of cervical region
ICD724: other and
unspecified disorders
of back
ICD847: sprains and
strains of other and
unspecified parts of
back
The per-capita expenditures varied among individuals
with different demographic and socioeconomic characteristics. As shown in Table 5, the per-capita total expenditures or per-capita expenditures for each service were
different among different age groups. Except emergency
room visits, as age increased, the per-capita expenditures
also increased (Table 5). Like age, except emergency
room visits, the per-capita expenditures for each service
or the per-capita total expenditures were different between different gender groups, with females incurring
higher expenditures, on average, than males (Table 5).
Such difference also existed among different race groups,
with whites generally having higher per-capita expenditures than blacks or other races (Table 5). However, for
individuals having different levels of education, the difference in per-capita expenditures was not consistent
across all services. For office-based visits and home
health services, individuals with an education at the 12th
grade level or above had higher per-capita expenditures
when compared with their counterparts. But for other
services, the results were the opposite (Table 5). The
investigation of per-capita service expenditures or percapita total expenditures among individuals with different levels of family income did not demonstrate any clear
trend (Table 5). Finally, except for emergency room visits, individuals with either private or public insurance
incurred higher per-capita total expenditures and higher
per-capita expenditures for each service than uninsured.
Among the insured, individuals with public insurance
had higher per-capita total expenditures and higher percapita expenditures for all services, except emergency
room visits, than privately insured (Table 5).
Discussion
Our analysis indicates that the total health care expenditures incurred by individuals with back pain in the
Table 5. Per-Capita Expenditures ($) Among Individuals With Different Characteristics
Characteristic
Age (yr)
18–44
45–64
ⱖ65
Gender
Male
Female
Race
White
Black
Other
Education
⬎12 grade
ⱕ12 grade
Family income
Negative or poor
Near poor
Low income
Middle income
High income
Insurance
Any private
Public only
Uninsured
N (millions)
Office-Based
Outpatient
Emergency
Visit
Inpatient
Home Health
Prescription
Drug
All Services
12.4
8.7
4.8
718.6
925.4
1378.7
369.9
462.6
691.5
107.3
72.7
145.7
582.3
1046.3
2407.8
19.0
41.6
446.4
285.4
647.2
1012.9
2334.7
3538.8
6443.8
11.7
14.3
657.9
1116
376.3
529.1
102.5
102.9
887.7
1229.2
28.1
168.7
398.7
658.2
2708.9
4142.9
22.9
2.1
0.96
941.3
655.8
723.5
479.1
377.3
198.3
98.3
144.4
117.1
1148.3
589.5
414.0
108.5
77.5
94.7
555.6
477.9
345.7
3647.9
2519.2
2083.4
12.9
13.0
965.4
854.0
460.3
464.3
86.8
118.4
547.8
1607.3
114.5
97.0
475.5
605.0
3027.5
3976.3
2.6
1.0
3.2
8.6
10.6
741.7
1046.7
1061.9
856.4
936.1
293.1
633.4
401.3
545.1
433.3
129.7
64.4
82.4
116.5
94.7
1142.8
839.4
1283.9
1226.3
896.9
221.8
227.9
422.8
31.7
31.3
639.8
639.3
654.3
572.2
450.0
3438.8
3700.1
4104.9
3606.1
3224.7
19.3
4.0
2.6
953.0
1088.9
307.5
476.4
636.7
65.1
102.7
97.8
110.7
880.4
2534.1
262.0
26.5
551.9
0.4
485.6
950.7
321.7
3256.3
6124.6
1208.5
84 Spine • Volume 29 • Number 1 • 2004
United States in 1998 reached approximately $91 billion
and the incremental expenditures attributable to back
pain totaled $26 billion. Because our estimates did not
include the expenditures for nursing care, they are likely
to be lower than the real value. Even with the underestimation, the health care expenditures for back pain in the
United States are staggering. The $90 billion spent on
behalf of the individuals with back pain accounted for
about 1% of the gross domestic product in 1998,20
whereas the $26 billion incremental expenditures attributable to back pain represented about 2.5% of national
health care expenditures for that year.21 Consistent with
previous estimates, these findings demonstrate that the
economic impacts of back pain in the United States are
enormous.
Estimates of the Health Care Expenditures for
Back Pain
The health care expenditures for back pain have been
estimated in 1977 using national survey data.5 As compared with this earlier publication, the biggest strength
of our study is the use of the 1998 MEPS, a very current
national data on health care expenditures. After 1977,
significant changes have occurred in the U.S. health care
system. The most dramatic change is probably the rapid
penetration of managed care.22 In the meantime, more
aggressive prevention methods have been developed and
new technologies and drugs have emerged. There have
also been changes in health care policy, such as the introduction of federal guidelines.23 All these changes can
impact the health care costs of back pain but were unable
to be accounted for in the earlier studies. Using the current data allows us to provide more accurate estimates
than the earlier studies.
Different method and different data sources make it
difficult to directly compare our estimates with those
from earlier studies. But we still made the comparison
since it allowed us to examine the trend of health care
expenditures for back pain in the United States. Because
the study by Frymoyer et al7 was based on the estimates
from Grazier et al,5 we include in our comparison only
the Grazier et al estimates. Also, because total health care
expenditures include expenditures related to back pain
and unrelated to back pain, the comparison was made by
only using estimates of the incremental expenditures attributable to back pain. The comparison showed two
interesting trends. First, in the Grazier et al5 estimates,
the costs for hospital inpatient care (hospital service plus
physician inpatient care) accounted for the largest proportion (about 40%) of the total back pain costs.5 However, in our incremental estimates, inpatient care accounted for only about 17% of the total incremental
expenditures. Unlike the study by Grazier et al,5 the expenditures for nursing home care were not included in
our total estimates. Based on their study, such expenditures accounted for about 20% of total expenditures for
back pain. If we included the expenditures based on the
estimates by Grazier et al,5 the percentage of the total
incremental expenditures attributable to inpatient care
should be even lower. The decline of inpatient expenditures observed in our study may be partly caused by the
penetration of the managed care as studies demonstrated
that individuals with managed care plans tended to have
lower hospital admission rates and shorter hospital
length of stay than individuals with a traditional indemnity plan.24 The decline in inpatient care services is expected to result in a higher use of physician offices and
outpatient services as well as higher expenditures for
these services. Indeed, in our estimates, office-based visits
and outpatient services contributed to about 50% of the
total incremental expenditures even after we considered
the potential nursing home expenditures. This is in contrast to 16% in the Grazier et al5 estimates. The second
interesting trend was observed for drug expenditures. In
the estimates by Grazier et al, drug expenditures accounted for ⬍1% of total health care costs for back
pain.5 But in our estimates, drug expenditures accounted
for ⬎10% of the total incremental expenditures. Investigation of all service expenditures shows that the increase of drug expenditures is the most rapid. This is in
agreement with general consensus that drug expenditures increased at a very rapid speed in recent years.25
How to control drug expenditures for back pain may
deserve special attention in the future.
Patterns of Health Care Expenditures Among
Individuals With Back Pain
The enormous health care expenditures incurred by individuals with back pain indicate a need to effectively
control such expenditures. Examining the expenditure
patterns is our first step to achieve this goal. In this study,
we found that a small percentage of high expenditure
individuals accounted for a large proportion of the total
health care expenditures. Previous studies using data
from industry workers or enrollees of insurance programs found similar results.10,11 Also, consistent with
previous studies,10 we found that back pain individuals
with disc disorders incurred much higher per-capita expenditures than individuals with other back pain diagnoses, especially those with back strains or sprains. A
closer examination of the expenditures for each health
service among individuals with disc disorder indicated
that the inpatient expenditures accounted for nearly
50% of the total expenditures and their per-capita inpatient expenditures were much higher than that of individuals with other diagnoses. How to prevent the health
care expenditures for disc disorder patients, especially
the inpatient expenditures, deserves special attention in
the future.
The health care expenditures also varied among back
pain individuals with different demographic and socioeconomic characteristics. In this patient population, the
elderly incurred higher expenditures, on average, than
younger individuals, which is consistent with the results
observed in the general population.26 It is interesting to
find that females incurred higher expenditures, on aver-
Direct Health Care Expenditures • Luo et al 85
age, than males. The reason for the difference is not clear
and needs further investigation. The findings that whites
had higher per-capita expenditures than blacks or other
races and that per-capita expenditures were much higher
for medically insured versus the uninsured suggest that
there may be barriers of access to care among back pain
individuals who were blacks or medically uninsured. Finally, we found that publicly insured incurred much
higher expenditures, on average, than privately insured,
especially for expenditures in inpatient care, home health
service, or prescription drugs. Because both these groups
were insured, it would be interesting to investigate
whether the difference in the expenditures is caused by
the difference of insurance programs.
graphic, socioeconomic, and clinical factors impact the
health care expenditures of these individuals.
Key Points
● Health care expenditures for back pain in the
United States in 1998 were substantial.
● Health care expenditures demonstrated wide
variations among back pain individuals with different clinical, demographic, and socioeconomic
characteristics.
References
Limitations
This study is constrained by several limitations. First, our
expenditure estimates may be understated. As discussed
above, we did not include expenditures associated with
nursing home care, which accounted for about 20% of
total health care expenditures for back pain in the previous studies.5 Moreover, we used ICD-9 codes to determine back pain, and the ICD 9 codes in the MEPS were
limited to major categories (3-digit codes) with no subclassification. Individuals with infectious or malignant
back pain may have been classified under the main ICD
categories such as infectious diseases or neoplasm. As a
consequence, the expenditures for these cases may have
been missed from the estimation. Second, because of the
lack of information about disability in the MEPS, we did
not examine how health care expenditures differed between individuals who were not disabled and individuals
who were disabled by back pain, especially those with
chronicle disability. This is an important issue since previous studies found that 5% of people with back pain
disability accounted for 75% of direct and indirect costs
for back pain2 and the costs rose at an accelerating rate
as the duration of disability increased.11 Finally, also
because of the lack of information, we did not analyze
how the expenditures were different between individuals
receiving and not receiving Worker’s Compensation benefits. It is important to examine Worker’s Compensation
since it had a negative impact on the length of disability
and the recovery from back pain3 and was a major contributor to back pain costs.11
Conclusion
This study provides an important descriptive analysis of
health care expenditures and expenditure pattern for
back pain population in the United States. The health
care expenditures for this patient population are enormous and also vary widely across individuals with different clinical, socioeconomic, and demographic characteristics. Significant savings to the health care system
could be realized if the back pain population could receive more cost-effective treatments. Future research
should be warranted to better understand how demo-
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