FROM:
Medical Care 2001 (Sep); 39 (9): 956–967
Pierre Cote DC, MSc • J. David Cassidy, DC, PhD • Linda Carroll, PhD
Institute for Work and Health,
Toronto, Ontario.
BACKGROUND: Neck and low back pain are leading causes of morbidity and health care utilization. However, little is known about the characteristics that differentiate those who seek from those who do not seek health care for their pain.
OBJECTIVES: The objectives of this study were to: 1) describe health care utilization for neck and back pain; 2) determine the characteristics of individuals seeking health care for neck and back pain; and 3) identify the characteristics of patients who consult medical doctors, chiropractors, or both.
DESIGN: Population-based cross-sectional mailed survey.
SUBJECTS: Subjects were randomly selected adults from the Saskatchewan Health Insurance and Registration File.
MEASURES: Demographic, socio-economic, general health, comorbidity, health-related-quality-of-life, pain severity and health care utilization data were collected. The main outcome was whether subjects with prevalent neck or low back pain visited a health care provider in the previous month.
RESULTS: Twenty-five percent of individuals with neck or low back pain visited a health care provider. Seeking health care was associated with disabling neck or back pain, digestive disorders, worse bodily pain and worse physical-role-functioning. Compared with medical patients, fewer chiropractic patients lived in rural areas or reported arthritis, but they reported better social and physical functioning. More patients consulting both providers reported disabling neck or back pain.
CONCLUSIONS: Individuals seeking care for neck or back pain have worse health status than those who do not seek care. Patients consulting chiropractors alone report fewer comorbidities and are less limited in their activities than those consulting medical doctors.
From the FULL TEXT Article:
Background
Neck and low back pain affect more than 80% of the population during their lifetime. [1-4] In Saskatchewan, 5% to 11% of adults suffer from disabling neck or back pain severe enough to limit their activities of daily living during any 6-month period. [2, 4] Neck and back pain are costly, are common causes of chronic disability, and are responsible for a significant proportion of work absenteeism and lost productivity. [3, 5-7] Further, back pain is one of the most common reasons for visiting primary care physicians. [8]
In the United States, individuals with neck and back pain most commonly seek care from medical doctors and chiropractors. [9-11] Previous studies suggest that back pain patients presenting to medical doctors differ from those who see chiropractors. Specifically, individuals seeking care from medical doctors suffer from more disabling comorbid health conditions and may have more severe pain and disability than chiropractic patients. [5, 11] Moreover, a higher proportion of those seeing chiropractors are male, high-school graduates, single, and employed. [5, 10, 11]
Two recent studies suggest that the decision to seek care for back and neck disorders is related to the severity of the condition and general health. [12, 13] In North Carolina, Carey et al [12] found that seeking health care for acute low back pain was associated with race, duration of pain, pain severity, and sciatica. Using data from the 1989
National Health Interview Survey, Hurwitz and Morgenstern [13] reported that health care utilization for back problems was associated with the presence of comorbidity, health insurance status, history of back trauma, duration of back condition, self-perceived health status, back-related restrictedactivity days in the previous two-weeks, and doctor visits during the previous year.
Improving the understanding of health care utilization for neck and low back pain is important for public health policy, clinical, and research reasons. First, it describes the demands on the primary health care delivery system from these
conditions. Second, it informs clinicians about the characteristics of patients who consult them. Finally, it provides researchers with knowledge about the sampling differences associated with studying clinical versus general populations.
Our study has three objectives. First, we describe the health care utilization for persons with neck and low back pain in Saskatchewan. Second, we identify the factors associated with seeking health care for neck and low back pain. Third, we
determine the characteristics of individuals seeking care from medical doctors, chiropractors, or both types of providers.
Methods
Design
We conducted the Saskatchewan Health and Back Pain Survey, a population-based mailed survey of the epidemiology of neck and low back pain. The design is described in details elsewhere. [4] We report findings from the index cross-sectional survey conducted in September 1995. Saskatchewan is a province of approximately one million
residents with a universal health care system that fully covers medical services and roughly half the costs for chiropractic visits. The eligible population (593,464 residents) included all noninstitutionalized Saskatchewan residents aged 20 to 69 who
held a valid Saskatchewan Health Services card on August 31, 1995. The study excluded inmates of provincial correction facilities, residents under the Office of the Public Trustee, foreign students and workers holding employment or immigration visas, and residents of special care homes.
Study Sample
An age-stratified probability sample was drawn from the Saskatchewan Health Insurance Registration File, which is a complete and current list of all Saskatchewan adults covered under the plan. Participation was voluntary. The University of
Saskatchewan Advisory Committee on Ethics in Human Experimentation approved the survey.
The sample size was calculated based on the prevalence of neck pain measured in a pilot survey of 150 Saskatchewan adults. [4] A total of 2,184 subjects were randomly selected. Of those, 129 were excluded because of mailing errors, immigration, or health reasons. The random sample was representative of the Saskatchewan population in
terms of age, gender, and location of residence. [4] A total of 1,131 subjects (55%) participated. An analysis of the factors associated with nonparticipation indicates that more nonparticipants were
younger, males, or not married. [4] There was no indication that the prevalence of disabling neck pain, low back pain or depressive symptomatology differed between participants and nonparticipants. [2, 4, 14] However, a higher proportion of participants than nonparticipants may have reported nondisabling neck pain that is high in intensity. [7]
Explanatory Variables
The Saskatchewan Health and Back Pain Survey included inventories and questions inquiring about ten categories of variables:
Demographic Characteristics. Age, gender, marital status, location of residence.
Socioeconomic Variables. Educational attainment, household annual income before tax, employment status.
Health-Related-Quality-of-Life. The Medical Outcomes Study SF-36 standard EnglishCanadian version 1.0 was used to measure self-perceived general health status. [15] It comprises eight interrelated health dimensions: physical functioning; role-limitations resulting from physical health problems; bodily pain; general health; vitality (energy/fatigue); social functioning; role-limitations resulting from emotional problems;
mental health (psychological distress/psychological well-being); and reported health transition. The SF-36 is a valid and reliable measure for clinical and general populations. [15-21] The eight dimensions of health are scored from 0 to 100, with higher scores indicating better health status.
Comorbidities. A 15-item self-report instrument was used to measure the presence of comorbidities (eg, headache, cardiovascular disease) and its self-perceived impact on health. [22] The instrument has acceptable test-retest reliability during a 10 to 14 day-period with item-specific weighted kappa coefficients above 0.56. [22] The presence and severity of comorbidities were negatively correlated with the SF-36 physical health and mental health component summary scores
with Pearson’s r ranging from r = –0.36 to r = –0.60. In this study, we did not use the data on neurologic problems, cancer or blood problems because of their low prevalence in the study
sample.
Neck and Low Back Pain. The presence of neck and back pain was measured on a mannequin diagram. Neck pain was defined as pain located between the occiput and the third thoracic
vertebra and low back pain as pain located between the twelfth thoracic vertebra and the gluteal folds. The severity of neck and low back pain was measured with the Chronic Pain Questionnaire. [23]
This questionnaire is a valid and reliable sevenitem self-reported instrument that measures pain and pain-related disability in the previous 6 months. [23–25] It has good psychometric properties in general population samples and in clinical
samples of patients with low back pain, headaches, and temporomandibular joint disorders. [23–26]
The questionnaire provides five ordered
grades of pain severity.
Grade 0 represents no pain;
Grade I represents pain of low intensity and low disability;
Grade II is pain of high intensity and low disability;
Grade III is pain associated with high levels of disability and moderate limitations in activities; and
Grade IV refers to pain with high levels of disability and severe limitations.
Here, “disability” refers to pain-related interference in everyday activities and “limitation” refers to inability to attend work, school, or to perform housework. We assessed the severity of neck and low back pain separately. [2, 4] However, in this report, neck and back pain were combined and the pain grade assigned to each subject represents the highest of the two severity ratings. We combined neck and low back pain for three reasons. First, we
previously reported that the presence and severity of neck and low back pain are strongly associated with each other and commonly occur simultaneously in patients. [27] In our sample, 77% of
subjects sought care for low back pain, 58% for neck pain, and 35% for both conditions (these categories are not mutually exclusive).
Second, our data suggests that the proportion of subjects seeking care from the various types of care providers is
similar within the low back and neck pain subgroups. For example, 42.6% of those reporting low back pain sought care from a medical doctor whereas 40.3% consulted a chiropractor. Among
those suffering from neck pain, 29% sought care from a medical doctor whereas 33% visited a chiropractor.
Third, we compared the SF-36 subscales across grades of neck and low back pain and found that the mean SF-36 scores for each pain
grade did not vary appreciably by location of pain, suggesting little mis-classification of health-related quality of life. In our analysis, Grades III and IV were combined because of the small number of subjects in these categories.
Depressive Symptomatology. The Center for Epidemiological Studies-Depression Scale (CES-D) was used to measure depressive symptoms. The CES-D is a 20-item self-report scale designed to measure current level of depressive symptoms in epidemiologic research. [28] It is reliable and has been validated in various general population and clinical samples. [28-34] The scores range from 0 to 60. A score equal to, or higher than 16/60 suggests the presence of significant depressive symptomology. [29, 35]
Cigarette Smoking. Nonsmoker, former smoker, or current smoker.
Anthropometric Variables. Height and weight were used to compute the Body Mass Index (BMI) computed as (kg)/(m)2.
Exercise. Average number of days per week participating in a minimum of 30 minutes of exercise during the previous 6 months.
Previous Neck or Back Injury. Self-report of previous lifetime history of injury in motor vehicle collision, or at work.
Outcomes
Health care utilization is defined as a visit to a health care provider for neck or low back pain in the previous 4 weeks. Two questions were used to measure health care utilization: “In the past 4 weeks, have you seen a health care professional for
neck or low back pain?”and “If you have seen any health care professional for neck or low back pain in the past 4 weeks, who did you see?”Self-report of health care utilization has adequate reliability for outpatient medical and chiropractic visits in
Canada. [36]
Two outcomes were defined. The first outcome is a dichotomous variable that describes whether a family practitioner, specialist, chiropractor, physiotherapist, massage therapist, or psychologist was consulted in the previous 4 weeks. The second
outcome has three categories and identifies the type of provider consulted: medical doctor, chiropractor, or medical doctor and chiropractor. Only medical doctors and chiropractors were selected because they were the only two providers reimbursed for their services by the Saskatchewan Health Plan. The medical doctor category includes family practitioners, orthopaedic surgeons, neurologists, neurosurgeons, or rheumatologists.
Analysis
Descriptive statistics were used to report health care utilization. Simple logistic regression was used to measure the associations between subjects’ characteristics and whether health care was sought. The goodness of fit of the models was assessed with the Hosmer-Lemeshow test. [37] We used polytomous logistic regression to measure the associations of subjects’ characteristics with the type of health care provider consulted in the previous 4 weeks (medical doctor, chiropractor, or medical doctor and chiropractor). [37] As proposed by Hosmer and Lemeshow, three tests were used to assess the fit of the polytomous logistic regression models. [37] First, the deviance and Pearson χ2 were computed. However, because of the covariate pattern is high for the final model, the deviance and Pearson χ2 may be unreliable. Therefore, the Hosmer-Lemeshow test statistic was computed for the two binary logistic regression models obtained when one of the outcome categories is excluded from the data. Specifically, the HosmerLemeshow test statistic was computed in the model
that compared chiropractors alone to medical doctors alone, and in the one that compared medical doctors and chiropractors to medical doctors alone. A satisfactory fit for both models suggests a satisfactory overall fit for the polytomous model. [37]
To detect the important associations, a three-hase modelling approach was used. First, the crude odds ratio (OR) and 95% confidence interval (CI) for each variable were computed. Variables that were associated with the outcomes with a
P ≤0.15 on the Wald test were used in the second
phase of the modelling. In the second phase, the independent variables identified in the first phase were grouped into four specific domains: demographic, socio-economic, comorbidity, and general health. The demographic domain included age, gender, marital status, and location of residence. The socioeconomic status domain included income, education, and employment status. The comorbidity domain included various health disorders. Finally, the general health domain incorporated general determinants of health such as self-reported health-related-quality-of-life, smoking status, body mass index, exercise, and previous neck or back injury in a motor vehicle accident or
at work. Variables associated with the outcome (with a P ≤0.10 on the Wald test) were used to obtain the final model. In the third phase, we built the final model by first entering all the important domain-specific variables. Variables that were associated with the outcome (with a P ≤ 0.10 according to Wald test) were retained. The final models were adjusted for age and gender.
At each stage of the modelling, the presence of numerical problem (zero cell count or covariates discriminating the outcome perfectly) was assessed by comparing the estimated standard error to the point estimate. The presence of a large
estimated standard error relative to the point estimate was suggestive of a numerical problem. [37] Continuous variables were first entered in the models as continuous. However, if a continuous
variable was not significantly (P >0.10) associated with the outcome, it was categorized or dichotomized and its association tested. The analysis was conducted using SPSS and SAS PROC
CATMOD. [38, 39]
Results
Prevalence of Neck and Low Back Pain
Table 1-6
|
Our sample includes 907 subjects who reported either neck pain, low back pain, or both conditions in the previous six-month period. Fifty-three percent experienced both neck and low back pain in the previous 6 months. The six-month prevalence
of neck pain, low back pain, and either condition are presented in Table 1. Overall, 63.1% had Grade I pain, 20.9% had Grade II pain, and 16% had Grades III-IV neck or low back pain. The prevalence of chronic neck pain (more than 90 days of
pain in the previous 6 months) was 10%. Fifteen percent had chronic low back pain.
Health Care Utilization
Health care utilization data were available for 95.8% (869/907) of participants and 99.6% (1126/1131) of the entire sample. Among those with complete utilization data, 19.1% (215/1126) of the surveyed population, or 24.7% (215/869) of the sample with back and neck pain visited a health care provider during the 4 weeks before the survey. Overall, 14.1% of subjects visited medical doctors and 12.1% saw chiropractors. Massage therapists
and physiotherapists were consulted by 5.8% and 3.5% of the sample respectively. Table 2 presents the distribution of the various combinations of health care providers (n = 215). Cumulatively, 91% consulted medical doctors or chiropractors or both. Moreover, 31% of those who sought care consulted more than one type of provider.
Factors Associated With Seeking Health Care
A higher proportion of subjects who sought health care than those who did not seek care reported lower education, lower income, and fewer had a full-time job (Table 3). The prevalence of all comorbidities was higher among those who sought health care (Table 4). More care seekers than noncare seekers suffered from more severe neck or low back
pain and more reported a history of neck or back injury in a traffic collision or at work. Finally, those who sought health care had worse health-related quality-of-life scores (Table 4).
Table 5 presents the final logistic regression model describing the association between subjects’ characteristics and seeking health care in the previous 4 weeks. We found important positive associations between digestive disorders, Grade II neck or low back pain, Grade III-IV neck or low back pain, and consulting a provider for neck or low back pain. Furthermore, those who reported less bodily pain and better physical-role-functioning were less likely to have sought care in the previous 4 weeks. These findings suggest that individuals who seek care
for neck or back pain may have more intense pain and more functional limitations than those who do not seek care.
Factors Associated With Selection of Providers
Tables 3 and 4 present descriptive statistics comparing subjects who visited medical doctors, chiropractors, or both. Those who consulted a medical doctor, or a combination of medical doctor
and a chiropractor were slightly older than subjects visiting a chiropractor alone (Table 3). More females and a higher proportion of individuals living in rural areas consulted medical doctors. Individuals who sought care from medical doctors, or a medical doctor and a chiropractor reported
lower educational attainment, lower annual income and fewer had a full-time job than those who consulted a chiropractor alone (Table 3). Subjects who saw medical doctors (alone or with a
chiropractor) reported worse general health as indicated by a higher prevalence of most comorbidities and lower health-related-quality-of life scores (Table 4).
Multivariate polytomous logistic regression analysis suggests that subjects who consulted a chiropractor alone were less likely to live in rural Saskatchewan than those who saw a medical doctor alone (Table 6). Similarly, they were less
likely to report arthritis. Furthermore, chiropracticpatients reported better physical and social functioning, suggesting that their conditions interfered less with their physical and social activities than reported by patients who consulted a medical
doctor alone. Subjects who consulted a medical doctor and a chiropractor during the previous 4 weeks were similar to those who saw a medical doctor alone except that they had more than twice the odds of reporting disabling neck or back
conditions
Discussion
We conducted a detailed analysis of health care utilization for neck and low back pain in a sample of Saskatchewan adults. This study advances the knowledge in this field by providing information from the general population rather than from insurance or clinical subgroups. Further, our analysis is based on survey rather than administrative data. Survey methodology has the advantage of yielding accurate data if response rates are high and conducted with valid and reliable questionnaires.
In Saskatchewan, 24.7% of adults with neck or back pain consulted a health care provider in the previous 4 weeks. These results compare favorably to the National Health Interview Survey in the United States which found that 19.2% of individuals with back problems (including neck pain) sought health care in the previous 2 weeks. [13] However, other studies have reported lower health care utilization rates. For example, Shekelle et al reported from the RAND Health Insurance Experiment that 22% of nonelderly adults had at least one episode of care for back pain during a 3 to 5-year period of enrollment. [40] Furthermore, Croft et al [41] found that 18.4% of Manchester adults with
an incident episode of low back pain consulted
their family practitioner during the following year.
The differences in health care utilization rates may
be attributable to five main reasons. First, the
definition of back and neck pain varies across
studies. Second, the inclusion criteria range from
prevalent and incident cases (acute and chronic
episodes) to incident cases alone. Third, some
analyses are limited to back pain alone whereas
others combine back and neck pain. Fourth, the
reference period used in the various surveys
ranges from weeks to years. Finally, the definition
of health care provider varies from physicians
alone to physicians and complimentary and alternative medicine providers.
Our analysis shows that most subjects consulted medical doctors or chiropractors. This
finding reflects the nature of the Saskatchewan
health care environment, where medical doctors
and chiropractors were the only health professionals reimbursed for their services by all three
government-funded payers: the Saskatchewan
Health Plan, the Workers’ Compensation Board,
and the Saskatchewan Government Insurance
(sole automobile insurer in the province).
An important proportion of those who sought
care (31%) consulted more than one type of
provider. This may be attributable to referral arrangements that exist between medical doctors,
chiropractors, physiotherapists, and massage therapists, but also illustrates the multidisciplinary
philosophy that guides the management of neck
and back pain. [42, 43] However, this finding may
reflect the cross-sectional nature of the survey that
included acute and chronic cases who may have
different patterns of health care seeking.
Clear differences were found between those
who sought care and those who did not. The
univariate analyses suggest that seeking care may
be associated with lower socioeconomic status,
previous injury to the spine and worse health
status. However, the multivariate analysis suggests
that independent associations exist between neck
and low back pain severity, digestive disorders,
bodily pain, and role limitation because of physical
health. Our results suggest that worse health
status drives the health care seeking behaviors of
individuals with neck and low back pain. These
findings agree with the studies by Carey et al [12] and
Hurwitz et al [13] who reported that pain severity
and comorbidities were related to seeking health
care for back pain. However, unlike Hurwitz et
al, [13] we did not find an association between past
trauma to the neck or self-perceived health status
and seeking care.
Medical and chiropractic patients differed according to demographic, socioeconomic, and health status characteristics. Individuals consulting a chiropractor alone were younger, more likely to be male,
living in urban areas, and less likely to be in the
lower socioeconomic categories. Indicators of health
status suggest that those who saw a medical doctor
alone had a higher prevalence of comorbidities and
worse health-related-quality-of-life. These results
agree with an analysis of the National Health Interview Survey (NHIS) in the United States that
showed that individuals who sought care from chiropractors were less likely to suffer from disabling
back or comorbid conditions. [11]
No studies had previously investigated patients
who visited medical doctors and chiropractors
during the same episode. Although the univariate
analyses suggests that they varied with regards to
most characteristics, the multivariate analysis indicates those who saw both types of provider were
similar to those who saw medical doctors alone.
However, they were more likely to report disabling
and limiting neck and back problems suggesting
that more severe cases are not managed in
isolation.
Our finding that individuals consulting chiropractors predominantly reside in urban centers
raises important issues about the access and availability of chiropractic care in rural regions. In
Saskatchewan, 59% of chiropractors practice in the
two main urban centers of Regina and Saskatoon
which together account for slightly more than 40%
of the province’s population. [44] Because location of
residence was strongly associated with the type of
provider consulted, but not with the decision to
seek care, it is possible that the lower utilization of
chiropractors in rural areas is mainly related to
their availability rather than to other individual
characteristics that influence the selection of
health care providers. Another possible explanation is that the overall costs of chiropractic care
may be higher for rural residents because they
would have to travel to a city or miss work to
access chiropractic care. This would result in an
increased cost differential between medical and
chiropractic care in rural areas and act as a deterrent for some.
The results from our survey should be interpreted in light of its limitations. First, the response rate for the survey was 55% and it is
possible that the nonrespondents differed from
respondents. Previous analyses of this sample
found that the nonrespondents were younger,
males, not married, and had a lower prevalence
of Grade II neck pain. [4] However, no selfselection bias was found with regards to disabling neck pain, back pain or significant depressive symptomatology. [2, 4, 14] Although these
figures provide confidence that these conditions
may not have influenced participation, we do
not know whether care seeking behaviors or
health care provider preferences differ among
respondents and nonrespondents. Second, short
reference periods were used to minimize misclassification and recall bias. Nevertheless, it is
possible that subjects reported health care visits
that occurred more than 4 weeks before the
survey. This would have inflated the health care
utilization rates. Comorbidities were measured
with a self-administered questionnaire. It is
possible that individuals who consulted a medical doctor reported more comorbidities because
they were more likely to be diagnosed with
other conditions. However, this is unlikely because medical patients reported worse healthrelated-quality-of-life scores, suggesting that
they had had poorer health. Finally, our sample
includes a mix of prevalent and incident cases.
Therefore, the odds ratios cannot be interpreted
as measures of risk to classify subjects into
seekers or nonseekers, or to categorize them by
provider type.
This study has important implications for future
research. First, it highlights the differences between population and clinical samples. For example, studying the clinical course of back pain in a
clinical sample may offer a bleaker picture than
studying the natural history in a population sample simply because those who seek health care
have worse health status. In addition, studying a
clinical sample from physicians’ offices will yield
different patient characteristics than clinical samples from chiropractors’offices. Second, the results
show the importance of performing extensive
case-mix adjustment when conducting cohort
studies or pragmatic trials of the effectiveness of
medical and chiropractic care. Finally, to better
understand the factors associated with seeking
health care, it highlights the need to conduct
population-based cohort studies.
Conclusion
The health care seeking behaviors of individuals
suffering from neck and low back pain are related
to the severity of their pain, to the level of functional limitations, and to their overall health status. The type of health care provider consulted for
an episode of neck or back pain is also associated
with health status, but is strongly dependent on
issues of access and availability of care with chiropractic care being mainly available in urban
centers. Patients consulting chiropractors alone
suffer with fewer comorbidities and are less limited in their activities than those consulting medical doctors.
Acknowledgment
We acknowledge the financial support of Saskatchewan Health and the Chiropractors’ Association of
Saskatchewan. This paper was also made possible
through the financial support of the Workplace Safety
and Insurance Board of Ontario and Health Canada
through a National Health Research and Development
Program PhD Training Award to Pierre Côté.
This paper was presented at “The Fourth International
Forum for Primary Care Research on Low Back Pain” in
Eilat, Israel, March 16 to 18, 2000.
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