Satisfaction as a Predictor of Clinical Outcomes Among
Chiropractic and Medical Patients Enrolled in
the UCLA Low Back Pain StudyThis section is compiled by Frank M. Painter, D.C.
Send all comments or additions to: Frankp@chiro.org
FROM: 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,
Box 951772,
Los Angeles, CA 90095-1772, USA.
ehurwitz@ucla.edu
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:
Introduction
Low back pain is one of the most common reasons for persons to seek medical care [1] and the most common reason for initiating chiropractic care. [2] Chiropractic is the most frequently used complementary or alternative therapy in the United States, [3] with back problems being the most frequent complaint. [4] Indeed, the majority of healthcare visits for low back pain are to chiropractors. [5] 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. [6]
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. [17] In the UCLA Low- Back Pain Study, chiropractic and medical patients had comparable clinical outcomes after 6 months, [18] 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. [15] 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 facilities.
Subject SelectionInclusion 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).Treatment Protocols.
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.Baseline Data. 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. [26] 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. [27] 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). [28] 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.
Patient Satisfaction.
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, [15] 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.
The follow-up 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.
Statistical Methods.
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) [34] was used for data management and analysis. The GENMOD procedure was used for GEE estimation. [35]
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 follow-up week.
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.
Results
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 disorder (1).
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.
Baseline Characteristics
Table 1A
Table 1B 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 [27] but roughly consistent with other back pain populations. [5, 12, 36]
Effects of Patient Satisfaction on Pain and Disability Outcomes
Table 2
Table 3
Table 4
Table 5 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 disability.
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 of follow-up.
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.
Discussion
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, [41] 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. [47] 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.
Conclusion
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.
Key Points
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 follow-up.
Acknowledgments
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 data management.
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