Spine (Phila Pa 1976). 2005 (Oct 1); 30 (19): 2121–2128 ~ FULL TEXT
Eric L. Hurwitz, DC, PhD, Hal Morgenstern, PhD, and Fei Yu
School of Public Health,
Department of Epidemiology,
University of California-Los Angeles,
Los Angeles, CA 90095-1772, USA.
STUDY DESIGN: Observational study conducted within a randomized clinical trial.
OBJECTIVES: The objective of this study is to estimate the effects of patient satisfaction on subsequent changes in pain and disability among low back pain patients randomized to chiropractic or medical care in a managed-care practice setting.
SUMMARY OF BACKGROUND DATA: Recent studies of low back pain treatments have shown chiropractic patients to be more satisfied with their care than medical patients. However, little is known about the relation between patient satisfaction and clinical outcomes.
METHODS: A total of 681 low back pain patients presenting to three southern California healthcare clinics and screened for serious spinal pathology and contraindications were randomized to medical care with and without physical therapy, and chiropractic care with and without physical modalities, and followed for 18 months. Satisfaction with back care was measured on a 40-point scale and observed at 4 weeks following randomization. The primary outcome variables, observed between 6 weeks and 18 months of follow-up, are average and most severe low back pain intensity in the past week, assessed with 0 to 10 numerical rating scales, low back-related disability, assessed with the 24-item Roland-Morris Disability Questionnaire, and remission from clinically meaningful pain and disability. Perceived change in low back symptoms was a secondary outcome.
RESULTS: Greater satisfaction increased the odds of remission from clinically meaningful pain and disability at 6 weeks (adjusted odds ratio [OR] for 10-point increase in satisfaction = 1.61, 95% confidence interval [CI] = 0.99, 2.68), but not at 6, 12, or 18 months (6 months: adjusted OR = 1.05, 95% CI = 0.73, 1.52; 12 months: adjusted OR = 0.94, 95% CI = 0.67, 1.32; 18 months: adjusted OR = 1.07; 95% CI = 0.76, 1.50). Perception of improvement was greater among highly satisfied than less satisfied patients throughout the 18-month follow-up period. The estimated effects of satisfaction on clinical outcomes were similar for medical and chiropractic patients.
CONCLUSIONS: Patient satisfaction may confer small short-term clinical benefits for low back pain patients. Long-term perceived improvement may reflect, in part, perceived past improvement as measured by satisfaction.
Key words: low back pain, patient satisfaction, randomized trial, chiropractic, managed care.
From the Full-Text Article:
Low back pain is one of the most common reasons for
persons to seek medical care  and the most common reason
for initiating chiropractic care.  Chiropractic is the most
frequently used complementary or alternative therapy in
the United States,  with back problems being the most
frequent complaint.  Indeed, the majority of healthcare
visits for low back pain are to chiropractors.  Although
the rate and duration of back-related disability claims
have decreased in recent years, [6, 7] back pain remains a
leader in healthcare costs, worker absenteeism, and related
Workers’ Compensation claims. 
Observational studies and randomized trials of low
back pain treatments have shown chiropractic patients
to be more satisfied with their care than medical patients. [8–15]
Other studies have shown that patients of
physicians who are more confident in their abilities to
deal with low back pain report greater satisfaction with
the information they received about their condition,16
and patients who report receiving an adequate explanation
of their condition are more likely to be satisfied and
to demand fewer diagnostic tests.  In the UCLA Low-
Back Pain Study, chiropractic and medical patients had
comparable clinical outcomes after 6 months,  yet after
4 weeks of care, chiropractic patients were more satisfied
than medical patients, and pain reduction at 2 weeks was
predictive of patient satisfaction at 4 weeks.  However,
we do not know whether patient satisfaction is predictive
of subsequent clinical improvement.
The purpose of this study is to estimate the effects of
patient satisfaction on subsequent changes in pain and
disability among low back pain patients randomized to
chiropractic or medical care in a managed-care practice
setting and followed for 18 months.
Materials and Methods
Study Design and Source Population.
We conducted an
observational study within a randomized clinical trial. Ambulatory
low back pain patients were randomized in a balanced
design to four treatment groups: medical care with and without
physical therapy, and chiropractic care with and without physical
modalities. Follow-up questionnaires were mailed to participants
at 6 weeks and 6, 12, and 18 months. At 4 weeks,
patients were telephoned and asked questions about their treatment
visits and satisfaction with care.
The source population was the approximately 100,000
members of a southern California healthcare network, a prepaid
group practice of salaried providers in which the group
accepted capitated payments for the vast majority of its patients.
Members received all their outpatient health care
through one or more of its offices or contract providers. This
study was conducted at three of the group’s ambulatory care
Inclusion and Exclusion Criteria.
Patients were eligible for the
study if they: 1) were health maintenance organization (HMO)
members with the medical group chosen as their healthcare
provider; 2) sought care from a healthcare provider on staff at
one of the three study sites during the intake period from
October 30, 1995 through November 9, 1998; 3) presented
with a complaint of low back pain (defined as pain in the region
of the lumbosacral spine and its surrounding musculature) with
or without leg pain; 4) had not received treatment for low
back pain within the previous 1 month; and 5) were at least
18 years old.
Potential subjects were excluded if they: 1) had low back
pain due to fracture, tumor, infection, spondyloarthropathy, or
other nonmechanical cause; 2) had severe coexisting disease; 3)
were being treated by electrical devices (e.g., pacemaker); 4)
had a blood coagulation disorder or were using corticosteroids
or anticoagulant medications; 5) had progressive, unilateral
lower limb muscle weakness; 6) had current symptoms or signs
of cauda equina syndrome; 7) had plans to move out of the
area; 8) were not easily accessible by telephone; 9) lacked the
ability to read English; or 10) had low back pain involving
third-party liability or Workers’ Compensation.
Patient Screening and Enrollment Protocol.
All patients presenting
with low back pain were interviewed by the field coordinator
to determine eligibility. Patients meeting the inclusion
criteria were given an information sheet describing the study
details and participation requirements and asked if they would
be willing to participate. Patient histories and physical examinations
were conducted by a primary-care provider, and imaging
studies and lab tests were ordered if deemed necessary by
the patient’s physician who was free to decide on which examinations
to perform according to each patient’s specific clinical
presentation. Those patients agreeing to participate and meeting
all eligibility criteria were asked to read and sign an informed
consent form, which was approved by the institutional
review boards from UCLA and the healthcare network.
Randomized assignments in blocks of 12 and stratified by
site were generated by the study statistician who placed each
treatment assignment in a numbered security envelope. When
each patient consented to be in the study, the field coordinator
opened the envelope in sequence and informed the patient of
his or her assignment. After completing the baseline questionnaire,
each subject reported to his or her assigned provider.
Participants received $10 at enrollment and $10 after completion
of the final questionnaire, but they were responsible for
any out-of-pocket costs ($5 to $20 per visit, depending on the
patient’s specific health plan).
The specific therapies received by participants
varied within each treatment group, and our study
protocol did not prescribe the type or amount of care that
should be received by participating patients. Visit frequency
was at the discretion of the medical provider or chiropractor
assigned to the patient.
Participants assigned to medical care only received one or
more of the following at the discretion of the medical provider:
instruction in proper back care and strengthening and flexibility
exercises; prescriptions for pain killers, muscle relaxants,
anti-inflammatory agents, and other medications used to reduce
or eliminate pain or discomfort; and recommendations
regarding bed rest, weight loss, and physical activities. Participants
assigned to medical care with physical therapy also received
instruction in proper back care from the physical therapist,
plus one or more of the following at the discretion of the
physical therapist: heat therapy, cold therapy, ultrasound, electrical
muscle stimulation, soft tissue and joint mobilization,
traction, supervised therapeutic exercise, and strengthening
and flexibility exercises.
Participants assigned to chiropractic care only received spinal
manipulation or another spinal-adjusting technique (e.g.,
mobilization), instruction in strengthening and flexibility exercises,
and instruction in proper back care. Participants assigned
to chiropractic care with physical modalities also received one
or more of the following at the discretion of the chiropractor:
heat or cold therapy, ultrasound, and electrical muscle stimulation.
Data Collection and Variables.
Sources of data include the
baseline history and physical examination; questionnaires at
baseline and at 6 weeks and 6, 12, and 18 months; and a
telephone interview at 4 weeks.
Disability from low back pain was assessed
with the 24-item Roland-Morris Low Back Disability Questionnaire. [19, 20] Patients respond by answering “yes” or “no” to
indicate whether or not each statement is a true description of
their current disability due to low back pain. Scores may range
from 0 (indicating no disability) to 24 (indicating severe disability).
This instrument has been shown to be reliable and
valid, [19–21] and to be more responsive to change over time than
many other measures of functional status. [22–25]
Numerical rating scales were used to assess intensity of pain
(most severe pain and average level of pain in the past week),
where 0no pain and 10unbearable pain. These scales have
been shown to have excellent reliability and validity for measuring
back pain.  A 6-point ordinal scale assessed frequency
of low back pain in the past week (none, rarely, sometimes,
often, a lot, all the time). Expectation of treatment success was
also assessed with a 0- to 10-point numerical rating scale,
where 0 indicates “not confident” and 10 indicates “confident”
that treatment will be successful.
The Medical Outcomes Study 36-Item Short-Form Health
Survey (SF-36) was used to measure psychological, physical,
and general health status.  Five of 8 subscales of this previously
validated instrument were used: 1) limitations in physical
activities because of physical or emotional problems; 2) limitations
in usual role activities because of physical health problems;
3) limitations in usual role activities because of emotional
health problems; 4) general health perceptions; and 5) general
mental health (psychological distress and well-being).  All five
measures are scored on scales of 0 to 100.
Socio-demographic variables included age, sex, race/
ethnicity, education, household income, marital status, and
current employment status.
At 4 weeks postrandomization, participants
were asked about their satisfaction with care by a phone
interviewer masked to group assignment. Data on patient satisfaction
were obtained with an adaptation of a previously
validated 10-item (40 point) patient satisfaction instrument. [29, 30] This instrument has three subscales (information,
caring, and effectiveness) and a coefficient alpha of 0.87 for the
total scale in the study population,  indicating high internal
consistency reliability. The 4-week interview also included 10
self-care advice items that may have been offered by the provider,
average length of treatment visits, and a question about
whether or not the provider gave an explanation about the
patient’s low back pain treatment plan.
Follow-up Data and Outcome Variables.
questionnaires addressed low back pain severity, improvement,
frequency, and related disability. Functional status was measured
by repeat Roland-Morris Low-Back Disability Questionnaires
at every follow-up assessment. Pain status was measured
by repeat numerical rating scales and scales of global pain improvement
(a lot worse to a lot better) at every follow-up assessment.
The 6-point ordinal scale for pain frequency was also
repeated at each follow-up assessment.
Four primary outcome variables were used to estimate the
effect of patient satisfaction: 1) average level of low back pain
in the past week, assessed with a 0 to 10 numerical rating scale;
2) most severe low back pain in the past week (0–10 scale); 3)
low back-related disability, assessed with the 24-item Roland-
Morris Disability Questionnaire; and 4) remission from clinically
meaningful pain and disability, defined as pain scores of
less than 2, a Roland-Morris score of less than 3, and infrequent
pain (never, rarely, or sometimes) in the past week. Perceived
changes in low back symptoms (a lot better vs. not a lot
better and a little or a lot better vs. the same or worse) were
considered as secondary outcome measures.
To estimate effects of patient satisfaction,
we used multiple logistic and linear regression modeling
with generalized estimating equations (GEE) to estimate associations
adjusted for the effects of potential confounders. For
logistic modeling, the low back scales were dichotomized at
values reflecting clinically meaningful pain severity (2 + vs. <2), frequency (no or infrequent pain), disability (3 + vs. <3),
and remission (defined above). The analyses used GEE with
robust standard error estimates to take into account withinsubject
correlations of the outcomes during the 18-month follow-
up period. [31–33] SAS 8.1 (Cary, NC)  was used for data
management and analysis. The GENMOD procedure was used
for GEE estimation. 
Separate logistic and linear models were fit to estimate associations
of patient satisfaction with each outcome measure.
Data from the 6-week and 6, 12, and 18-month follow-up
assessments were used simultaneously in all analyses. Satisfaction
was modeled in two ways: as a continuous measure and as
a dichotomous measure with the cutpoint at the 75th percentile.
In addition to the patient satisfaction measure, all models
included the following covariates: age, sex, baseline duration of
low back pain episode, assigned treatment group, baseline
value of the outcome variable, baseline SF-36 mental health
index score, baseline confidence in assigned treatment, average
visit duration, explanation of treatment, self-care advice, and
Models with clinical remission and perceived improvement
as the outcomes also included as covariates most severe low
back pain and low back disability at baseline and indicator
variables representing baseline frequency of low back pain.
Number of treatment visits in the first 4 weeks and change in
clinical outcome from baseline to 2 weeks (before measurement
of satisfaction) were included in subsets of models; however,
the inclusion of these variables did not influence the satisfaction
estimates and were thus excluded from the final models. Product
terms representing interactions of patient satisfaction with
assigned treatment group and follow-up week were also included
in preliminary models; but since the estimated treatment-
group interactions were negligible (i.e., the estimated effects
of satisfaction were similar for chiropractic and medical
patients), they were excluded from the final models, and results
are presented by follow-up week only.
Screening, Enrollment, and Follow-up
We screened a total of 2,355 patients. A total of 886
(37.6%) patients were excluded for the following reasons,
in descending order of frequency (in parentheses):
low back pain treatment in the past 1 month (270), pain
not primarily in the lumbosacral area (144), fee-forservice
or no health insurance (119), Medi-Cal or Medicare
coverage only (80), third-party liability or Workers’
Compensation case (55), inability to read English (46),
under 18 years old (43), plans to move out of the area
(18), and not easily accessible by telephone (40). In addition,
patients were excluded for the following medical
reasons: low back pain due to fracture, tumor, or infection
(40), severe coexisting disease (37), use of anticoagulant
medications (13), ankylosing spondylitis or other
rheumatic disease (7), treatment with electrical device
(5), progressive or severe unilateral lower limb muscle
weakness (2), abdominal aortic aneurysm (1), symptoms
or signs of cauda equina syndrome (1), and blood coagulation
Of the 1,469 eligible patients, 788 (53.6%) did not
participate. Reasons for refusal, in descending order of
frequency (in parentheses) were: not interested (345),
inconvenient (137), prefers medical care (116), prefers
chiropractic care (105), does not want to be limited to
one treatment mode (45), and cannot afford multiple
copayments (31). Nine otherwise eligible and willing potential
subjects were judged incapable of giving adequate
informed consent. Of 1469 eligible patients, 681 were
enrolled in the study.
The 4-week patient satisfaction interview was completed
by 678 participants (99.6%). Six-week and
6-month follow-up questionnaires with complete outcome
data were returned by 675 (99.1%) and 652 subjects
(95.7%), respectively. A total of 610 of the 681
patients enrolled (89.6%) were followed for 18 months.
Table 1 shows the baseline distributions of sociodemographic,
low back pain, and health status variables.
Participants were on average 51 years old and slightly
more likely to be female. Sixty percent were white, 30%
Hispanic, about 30% had a college degree, the majority
were married or living as married, and two thirds were
employed. About one fourth of the participants had had
low back pain for less than 3 weeks at baseline, while
almost half had been in pain for more than a year. The
median low back disability score of 11 reflects moderate
disability, whereas the median pain intensity scores of 5
and 7 for average and most severe pain are indicative of
appreciable levels of pain perception. The SF-36 mental
health mean score of 71 and the general health perceptions
mean of 68 are slightly below the population means
of 75 and 72, whereas the physical functioning and role
limitations scores are well below U.S. general population
norms  but roughly consistent with other back pain
populations. [5, 12, 36]
Effects of Patient Satisfaction on Pain and Disability Outcomes
Table 2 shows estimated adjusted effects (odds ratios) of
satisfaction on clinically meaningful improvements in
pain and disability at 6 weeks and 6, 12, and 18 months.
Satisfaction was predictive of clinically significant
changes in pain and disability at 6 weeks. For example,
the estimated OR, corresponding to the adjusted effect of
a 10-point increase in satisfaction on a 2 points or more
improvement in average low back pain, was 1.54 (95%
CI = 1.09, 2.16). At 6, 12, and 18 months, however,
higher satisfaction continued to be associated only with
Table 3 shows estimated adjusted effects of
satisfaction on pain and disability treated as continuous
variables. The estimated mean differences in pain and
disability, while favoring more satisfied patients, are of
marginal clinical significance throughout the 18 months
Table 4 shows estimated adjusted effects (odds ratios)
of satisfaction on remission from clinically important
pain and disability at 6 weeks and 6, 12, and 18 months.
Greater satisfaction increases the odds of remission from
clinically meaningful pain and disability at 6 weeks (adjusted
OR for 10-point increase in satisfaction = 1.61,
95% CI = 0.99, 2.68), but not at 6, 12, or 18 months.
Effects of Patient Satisfaction on Perceived Improvement
Table 5 shows estimated adjusted effects (odds ratios) of
satisfaction on perceived improvement at 6 weeks and 6,
12, and 18 months. Greater satisfaction was positively
associated with the perception of any improvement at
6 weeks, but this association did not persist at subsequent
follow-up assessments. Nevertheless, highly satisfied
patients were more likely than less satisfied patients
to perceive their improvement as a lot better throughout
the 18-month follow-up period.
Among low back pain patients randomized to chiropractic
or medical care in a managed-care practice setting,
satisfaction with care may confer small clinical benefits
at 6 weeks. There is little evidence for associations of
satisfaction with clinically meaningful improvements in
low back pain at 6, 12, and 18 months, although there is
some evidence for associations of satisfaction with clinically
meaningful improvements in low back disability at
these follow-up points. In addition, highly satisfied patients
at 4 weeks were more likely than less satisfied
patients to perceive greater pain improvement throughout
the 18-month follow up. Rather than an effect of
satisfaction with care, this latter finding may reflect, at
least in part, satisfaction with past improvement, which
patients continue perceiving throughout follow-up.
Recent findings from the UCLA Low-Back Pain Study
show that 1) reductions in low back pain at 2 weeks were
associated with higher satisfaction levels at 4 weeks, and
2) chiropractic patients were more satisfied with their
care than medical patients (unadjusted difference in
means = 5.5; 95% CI = 4.5, 6.5). Much of this latter
difference in satisfaction was explained by the greater
amount of information given by chiropractors to their
patients.15 The difference in satisfaction between medical
and chiropractic patients attenuated to nearly zero
for patients who received 4 or more items of self-care
advice and an explanation of their treatment (adjusted
difference = 0.1; 95% CI = 2.6, 2.9). These findings
suggest that increasing communication between physician
and patient, especially as it relates to providing information
about low back pain treatment and advice on
self-care, may improve satisfaction, as other studies in
primary care have shown, [17, 37, 38] which may lead to better
clinical outcomes in the short-term and to perhaps
greater perceived improvement in the longer term for
both medical and chiropractic patients. Thus, we now
have evidence, albeit limited, suggesting that not only
does clinical improvement from low back pain affect patient
satisfaction with care, but also that satisfaction may
affect clinical outcome.
Studies of ambulatory patients with nonmechanical
pain have also shown higher levels of patient satisfaction
to be associated with interpersonal characteristics, including
enhanced communication, between patients and
providers. For example, cancer pain patients were more
satisfied if their providers told them that pain relief was
an important goal and if they were given instructions for
managing their pain at home. [39, 40] Improvements in pain
and sustained pain relief have also been shown to be
associated with greater patient satisfaction. [39, 40] Similar
findings have been reported in other populations of pain
patients,  although changes in pain and disability did
not predict satisfaction in two studies of medical patients
with low back pain. [42, 43]
The relation between patient satisfaction and appropriateness
of care has not been addressed in low back
pain patient populations, although it has been studied in
patients with depression and other psychiatric disorders. [44–46] A well-designed longitudinal study of depressed
patients in managed care did not find higher
technical quality of care (as measured by appropriateness
of dose and duration of antidepressant medication and
counseling) predictive of patient satisfaction (as measured
by interpersonal quality of care), but it did find
higher patient satisfaction predictive of higher quality
depression care 6 months later.  If applicable to low
back pain, patient satisfaction may improve the quality
of subsequent care and pain outcomes. This hypothesis
should be the focus of future studies.
Although the study has several strengths, including its
relatively large sample and low attrition, extended follow-
up with both short- and long-term assessments, and
use of previously validated measures of satisfaction and
low back pain and disability, our results must be considered
in light of limitations potentially affecting the
study’s internal validity and generalizability. Effect estimates
of satisfaction on clinical outcomes may be confounded
by prognostic factors not included in the models.
Many prognostic factors were considered in the
multivariable models; however, confounding may have
occurred because of other predictors of improvement
that are associated with satisfaction, such as unmeasured
interpersonal or technical components of care.47 Although
not feasible in the current setting, repeated assessments
of patient satisfaction during back care and
after discharge would have been preferable to a single
measure, especially if satisfaction changes over the
course of treatment. Resulting misclassification could
have biased estimated associations of satisfaction with
clinical outcomes and perceived improvement.
Differences in patients and providers between the
study setting and other environments may limit generalizability
of the findings. More than 50% of eligible patients
refused to participate; thus, the study population
may not be representative of low back pain patients in
the community or in other settings. Furthermore, the
healthcare providers in our healthcare organization may
have styles of practice or be subject to utilization or other
policies differing from providers in other managed-care
and private settings, possibly influencing the estimated
satisfaction effects if such variations in physician-patient
relationships modify satisfaction effects. However, the
provision of chiropractic and medical care is consistent
with recent utilization studies, [48–50] and we are not aware
of any differences in practice style or specific managedcare
policies that may have influenced effects.
There appears to be a small short-term benefit of satisfaction
with care on clinical outcomes among low back
pain patients enrolled in a clinical trial of medical and
chiropractic care in managed care. The effect of satisfaction
beyond 6 weeks appears to be greater for functional
status than for pain. These findings, coupled
with others from the UCLA Low-Back Pain Study,
suggest that clinical improvement may be predictive of
patient satisfaction, and satisfaction may be predictive of
clinical improvement, at least in the short-term, although
subsequent investigations should attempt to confirm
such findings. The finding that higher satisfaction is associated
with greater perceived improvement but little or
no association with clinical improvement at longer-term
follow-up should also be explored in future studies. It
may be that patient satisfaction does not affect long-term
perceived improvement but that satisfaction measured
early in the course of care reflects past improvement,
which persists over time.
An observational study conducted within a clinical
trial was conducted to estimate the effects of
patient satisfaction on subsequent changes in pain
and disability among low back pain patients randomized
to chiropractic or medical care in a managed-
care practice setting.
A total of 681 patients presenting to a managedcare
facility were randomized to chiropractic or
medical care; 610 (89.6%) were followed up
through 18 months.
Satisfaction with care appears to confer small
clinical benefits at 6 weeks, whereas there is little
evidence for associations of satisfaction with clinically
meaningful improvements in low back pain at
6, 12, and 18 months. There is some evidence for
associations of satisfaction with clinically meaningful
improvements in low back disability at these
follow-up points, however.
Highly satisfied patients at 4 weeks were more
likely than less satisfied patients to perceive greater
pain improvement throughout the 18-month
The authors thank the former executive officers of
Friendly Hills HealthCare Network, Dr. Albert Barnett
and Gloria Mayer, for their initial interest and support;
Dr. Gary Pirnat and his staff of chiropractors for their
active involvement and cooperation; the medical and
physical therapy providers for their patient care services;
the clinic management teams and front-office personnel
from La Habra, Brea, and Buena Park, CA, for their help
with patient enrollment; Karen Hemmerling and Stan
Ewald for coordinating patient recruitment and followup;
Emerlinda Gonzalez and Silvia Sanz for assistance
with enrollment and tracking; and He-Jing Wang for
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