Natural history of low back pain. A longitudinal study in nurses

STUDY DESIGN: Longitudinal study. OBJECTIVES: To assess the natural history of low back pain. SUMMARY OF BACKGROUND DATA: Most episodes of low back pain resolve or improve within a few weeks, but chronic or recurrent symptoms are common. Previous studies of natural history have usually relied on people's long-term recall of symptoms, or they have been limited to patients seeking clinical care. METHODS: Nurses (1,165 women) completed a baseline questionnaire and up to eight follow-up questionnaires 3 months apart. Each questionnaire asked whether they had experienced low back pain in the past month. One-month prevalences of pain at specified follow-ups were calculated according to histories of pain reported on earlier questionnaires. RESULTS: The 1-month prevalence of low back pain at individual follow-ups ranged from 16% to 19%. Of 906 women who completed the baseline questionnaire and at least three follow-up questionnaires, 38 (4.2%) reported pain every time they returned a questionnaire, and 190 (21.0%) reported pain on at least three occasions. The presence or absence of low back pain at baseline was highly predictive of future pain throughout follow-up. The longer that back pain was consistently reported, the more likely it was to be present at the next follow-up. Later risk was lowest in women who reported no back pain at baseline or either of the first two follow-ups. Back pain carried a worse prognosis if it was disabling or associated with sciatica. CONCLUSIONS: Our results confirm the importance of back pain duration and the occurrence of associated disability and sciatica as predictors of future symptoms, and allow more reliable quantification of the natural history of back pain in women of working age. In the absence of other information, the differentials in risk associated with a person's history of back pain appear to remain constant for a period of at least 2 years.     

Prospective, multicenter study of spinal cord stimulation for relief of chronic back and extremity pain

STUDY DESIGN: This prospective, multicenter study was designed to investigate the efficacy and outcome of spinal cord stimulation using a variety of clinical and psychosocial outcome measures. Data were collected before implantation and at regular intervals after implantation. This report focuses on 70 patients who had undergone 1 year of follow-up treatment at the time of data analysis. OBJECTIVES: To provide a more generalizable assessment of long-term spinal cord stimulation outcome by comparing a variety of pain and functional/quality-of-life measures before and after management. This report details results after 1 year of stimulation. SUMMARY OF BACKGROUND DATA: The historically diverse methods, patient selection criteria, and outcome measures reported in the spinal cord stimulation literature have made interpretation and comparison of results difficult. Although short-term outcomes are generally consistent, long-term outcomes of spinal cord stimulation, as determined by prospective studies that assess multidimensional aspects of the pain complaint among a relatively homogeneous population, are not well established. METHODS: Two hundred nineteen patients were entered at six centers throughout the United States. All patients underwent a trial of stimulation before implant of the permanent system. Most were psychologically screened. One hundred eighty-two patients were implanted with a permanent stimulating system. At the time of this report, complete 1-year follow-up data were available on 70 patients, 88% of whom reported pain in the back or lower extremities. Patient evaluation of pain and functional levels was completed before implantation and 3, 6, 12, and 24 months after implantation. Complications, medication usage, and work status also were monitored. RESULTS: All pain and quality-of-life measures showed statistically significant improvement during the treatment year. These included the average pain visual analogue scale, the McGill Pain Questionnaire, the Oswestry Disability Questionnaire, the Sickness Impact Profile, and the Back Depression Inventory. Overall success of the therapy was defined as at least 50% pain relief and patient assessment of the procedure as fully or partially beneficial and worthwhile. Using this definition, spinal cord stimulation successfully managed pain in 55% of patients on whom 1-year follow-up is available. Complications requiring surgical intervention were reported by 17% (12 of 70) of patients. Medication usage and work status were not changed significantly. CONCLUSIONS: This prospective, multicenter study confirms that spinal cord stimulation can be an effective therapy for management of chronic low back and extremity pain. Significant improvements in many aspects of the pain condition were measured, and complications were minimal.     

Methodologic issues in low back pain research in primary care

STUDY DESIGN: Narrative review and discussion of the selected literature. OBJECTIVES: To discuss some important methodologic challenges in low back pain research in primary care. SUMMARY OF BACKGROUND DATA: Many methodologic problems must be confronted when conducting low back pain research. Some of these problems are back pain specific or specific to the primary care setting. METHODS: Methodologic problems related to four research issues will be discussed: study designs, definition of low back pain, determinants of low back pain, and outcome assessment. RESULTS: Two fundamentally different study designs are frequently used in low back pain research, namely observational studies and experimental studies. The definition of low back pain is typically restricted to a highly variables self-reported symptom, the sensation of pain in the back. There clearly is a need for an evidence-based classification system for low back pain. Because a tenable theoretical framework is lacking, it is difficult to know which determinants of low back pain should be quantified. Low back pain studies focus usually on health-related quality-of-life outcome parameters. The identification of the minimum clinically relevant changes for the most important outcome instruments needs further consideration. CONCLUSIONS: In years to come, low back pain researchers are challenged to overcome some of these (and other) problems to enhance the quality of low back pain research in primary care.     

Patterns of ordering diagnostic tests for patients with acute low back pain. The North Carolina Back Pain Project

BACKGROUND: Low back pain is a common reason for visiting a physician. Authors of guidelines and insurance payers are currently scrutinizing use of radiography and computed tomography (CT) or magnetic resonance imaging (MRI). OBJECTIVE: To study the determinants of the use of lumbar spine radiography and either CT or MRI in patients with acute low back pain. DESIGN: Prospective cohort study. SETTING: Community-based practices in North Carolina in six strata: urban primary care physicians, rural primary care physicians, urban chiropractors, rural chiropractors, orthopedic surgeons, and practitioners at a group-model health maintenance organization. PATIENTS: 1580 patients with acute low back pain. MEASUREMENTS: Telephone interviews done after the index office visit and at 2, 4, 8, 12, and 24 weeks or until complete recovery; survey of practitioners; and chart abstraction. RESULTS: During the acute back pain episode, 46% of patients had radiography and 9% had CT or MRI. Patient variables related to use of radiography included pain that began more than 2 weeks before the index visit and no previous episodes of low back pain. Practitioner variables associated with use of radiography were being a chiropractor or orthopedic surgeon and having a solo practice. Use of CT or MRI was associated with white race, neurologic deficit at baseline, sciatica, poor functional status at baseline, and small group-practice size. Practitioners' responses to clinical vignettes were associated with aggregate practitioner behavior: In the vignettes and in real life, practitioners were more likely to order CT for patients with sciatica. However, a practitioner's response to a vignette did not predict that practitioner's use of CT or MRI for similar patients in his or her own practice. CONCLUSION: Radiography is commonly used as a diagnostic test for patients with acute back pain. Clinical factors and provider specialty are major correlates of the use of imaging studies.     

Increase in sick leave rates caused by back pain among pregnant Swedish women after amelioration of social benefits. A paradox

STUDY DESIGN: A retrospective population study. OBJECTIVES: To explore whether the increase in social benefits for pregnant women introduced in Sweden between 1978 and in 1986 was associated with a decrease in the use of sick leave caused by back pain during the same period. SUMMARY OF BACKGROUND DATA: Back pain is a common condition among Swedish pregnant women. It may be regarded as a normal discomfort of pregnancy, because at least 50% of pregnant women experience back pain to some extent during pregnancy. METHODS: Participants were women consecutively delivered in 1978 (n = 1524) and in 1986 (n = 1688). Between these two time points, the number of offered days of parental benefit increased and a new benefit, the pregnancy benefit, was introduced. Data were collected from the antenatal care and delivery records and from pregnant women's social insurance files. RESULTS: From 1978 to 1986 the use of sick leave because of back pain during pregnancy increased. The number of pregnant women granted sick leave employed pregnant women because of back pain increased from 11% in 1978 to 29% in 1986 (P < 0.001). The sick leave rate increased in most occupations and especially among young women. CONCLUSIONS: The Swedish society has provided ample social benefits to allow the pregnant woman to take leave from work, without having to be labeled as "ill," because of normal conditions such as back pain during pregnancy. Instead of an expected decrease in sick leave because of back pain during pregnancy, an increase was observed.     

Suprachiasmatic nucleus organization

OBJECTIVE: To assess the effect of a combined exercise and motivation program on the compliance and level of disability of patients with chronic and recurrent low back pain. DESIGN: A double-blind prospective randomized controlled trial. SETTING: Physical therapy outpatient department, tertiary care. PATIENTS: Ninety-three low back pain patients were randomly assigned to either a standard exercise program (n = 49) or a combined exercise and motivation program (n = 44). INTERVENTIONS: Patients were prescribed 10 physical therapy sessions and were advised to continue exercising after treatment termination. The motivation program consisted of five compliance-enhancing interventions. Follow-up assessments were performed at 3 1/2 weeks, 4 months, and 12 months. MAIN OUTCOME MEASURES: Disability (low back outcome score), pain intensity, physical impairment (modified Waddell score, fingertip-to-floor distance, abdominal muscle strength), working ability, motivation, and compliance. RESULTS: The patients in the motivation group were significantly more likely to attend their exercise therapy appointments (p = .0005). Four and 12 months after study entry there was a significant difference in favor of the motivation group with regard to the disability score (p = .004) and pain intensity (p < or = .026). At 4 months, there was a significant advantage for the motivation group in the fingertip-to-floor distance (p = .01) and in abdominal muscle strength (p = .018). No significant differences were found in motivation scores, self-reported compliance with long-term exercise, and modified Waddell score. In terms of working ability, there was a trend favoring the combined exercise and motivation program. CONCLUSION: The combined exercise and motivation program increased the rate of attendance at scheduled physical therapy sessions, ie, short-term compliance, and reduced disability and pain levels by the 12-month follow-up. However, there was no difference between the motivation and control groups with regard to long-term exercise compliance.     

Community studies of the health service implications of low back pain

STUDY DESIGN: Retrospective study using primary care physician case notes and a self-report questionnaire on the same randomly selected population sample. OBJECTIVES: To assess the prevalence, management, and outcomes of low back pain in the community, comparing, in the same random sample of registered patients, self-report questionnaire data and primary care physicians' records. SUMMARY OF BACKGROUND DATA: The financial and resource implications of low back pain are extensive. Data on consultations, investigations, and the management of low back pain are fragmentary and there are no comparisons estimating prevalence from case notes and self-report. METHODS: A retrospective study of prevalence, management, referral, and outcome covering the previous 12 months was carried out in three general practices using case notes and a self-report postal questionnaire on a sample of 900 patients over 18 years. RESULTS: Lifetime prevalence of low back pain was 62%. Annual prevalence was 48%, with 16% reporting low back pain at the time of report. Twenty-four percent consulted their primary care physician for low back pain, of whom 17% were referred to a hospital specialist. The annual consultation rate of patients with low back pain was similar to the rate for patients with chronic conditions. The activities of daily living were restricted in less than half, with few taking sick leave. The general health status of those reporting recent low back pain was significantly lower than those not reporting low back pain. Most felt that low back pain was self-limiting and would not consult health professionals for future episodes. There were substantial discrepancies between case notes recorded at consultation with the primary care physician and self-report regarding consultation and investigations. CONCLUSIONS: Prevalence rates were comparable with those reported in other studies. The significant discrepancies between data sources suggest patient recall bias or underrecording in case notes. The low consultation rate, time off, and day-to-day disability indicate that most episodes are self-limiting.     

Back pain and agricultural work among farmers: an analysis of the Colorado Farm Family Health and Hazard Surveillance Survey

BACKGROUND: Back pain is the most prevalent occupational health problem experienced by much of the world's workforce. However, agricultural work-related back pain occurring among US farmers working on small operations or family farms is usually not included in surveillance. With data collected by Colorado Farm Family Health and Hazard Surveillance Survey, this study reports characteristics of and risk factors for back pain among adult farmers living in eight Colorado counties. METHODS: A stratified probability sample of 500 farms was selected in proportion to the number of farms in study areas. During the 4-year period from 1993 through 1996, 458 farms were enrolled in the study and 759 farmers were interviewed using a questionnaire. Information on self-reported back pain and potential risk factors among 742 white farmers was evaluated and reported here. RESULTS: A total of 194 farmers (26.2%) reported to have had at least one episode of back pain lasting for 1 week or more. Males had a slightly higher prevalence of back pain than females (28.6% vs. 22.5%) and the lower back was the predominantly affected part of body among both males and females. In 45.4% of males and 43.9% of females back pain was brought on by repeated activities. Males' activities at work were more likely to cause back pain while females' activities at home were more likely to cause back pain. Three factors were found to be significantly associated with back pain: being depressed (odds ratio (OR) = 3.68, 95% confidence interval (CI) = 2.23-6.09), farming/ranching as main activities (OR = 1.66, CI = 1.17-2.36), and worked in agriculture for 10 to 29 years (OR = 1.62, CI = 1.14-2.30). CONCLUSIONS: Our analyses indicate that back pain is an occupational health problem among farmers on small operations or family farms and that back pain affected males and females differently. The finding of significant positive associations between depression, farming activities, and back pain warrants further attention.     

Back pain in patients with ductal pancreatic cancer. Its impact on resectability and prognosis after resection

BACKGROUND: Back pain is a frequent and often ominous clinical sign in patients with ductal pancreatic cancer. METHODS: From 1971 to 1993 a pancreatic carcinoma could be resected in 192 patients, whereas 261 patients underwent either probatory laparotomy alone or palliative bypass procedures. In a retrospective study including uni- and multi-variate survival analysis we have determined the impact of preoperative back pain on both resectability and long-term prognosis after resection. RESULTS: Among the presenting symptoms of patients with ductal pancreatic cancer back pain was a predictive sign of irresectability. In the presence of preoperative back pain the long-term prognosis after resection of the tumour was also significantly impaired. In a multivariate analysis it could be demonstrated that the prognostic impact of back pain was as strong as the influence of residual tumour, tumour grading, and tumour size. CONCLUSIONS: Back pain often indicates irresectability of ductal pancreatic carcinoma and also impairs the long-term prognosis even after curative resection.     

A randomized trial of a lay person-led self-management group intervention for back pain patients in primary care

STUDY DESIGN: Randomized, controlled trial. OBJECTIVE: To evaluate a four-session self-management group intervention for patients with pain in primary care, led by trained lay persons with back pain. The intervention was designed to reduce patient worries, encourage self-care, and reduce activity limitations. BACKGROUND DATA: Randomized trials of educational interventions suggest that activating interventions may improve back pain outcomes. Expert opinion increasingly regards effective self-management of back pain as important in achieving good outcomes. In this study, an educational intervention designed to activate patients and support effective self-management was evaluated. METHODS: Six to 8 weeks after a primary care visit for back pain, patients were invited to participate in an educational program to improve back pain self-management. Those showing interest by returning a brief questionnaire became eligible for the study. Participants (n = 255) randomly were assigned to either a self-management group intervention or to a usual care control group. The effect of the intervention, relative to usual care, was assessed 3, 6, and 12 months after randomization, controlling for baseline values. The intervention consisted of a four-session group applying problem-solving techniques to back pain self-management, supplemented by educational materials (book and videos) supporting active management of back pain. The groups were led by lay persons trained to implement a fully structured group protocol. The control group received usual care, supplemented by a book on back pain care. RESULTS: Participants randomly assigned to the self-management groups reported significantly less worry about back pain and expressed more confidence in self-care. Roland Disability Questionnaire Scores were significantly lower among participants in the self-management groups relative to the usual care controls at 6 months (P = 0.007), and this difference was sustained at 12 months at borderline significance levels (P = 0.09). Among self-management group participants, 48% showed a 50% or greater reduction in Roland Disability Questionnaire Score at 6 months, compared with 33% among the usual care controls. CONCLUSIONS: Self-management groups led by trained lay persons following a structured protocol were more effective than usual care in reducing worries, producing positive attitudes toward self-care, and reducing activity limitations among patients with back pain in primary care.     

Giant congenital nevocellular nevus overlying an encephalocele

OBJECTIVE: To compare patients with knee osteoarthritis (OA) who have and do not have back pain, and evaluate the prevalence, characteristics, and consequences of back pain among knee OA patients. METHODS: During a 3-year period, consecutive patients attending an outpatient rheumatology clinic were evaluated for the presence of back pain, and 368 were found to have OA of the knee. Clinical status was evaluated by the Clinical Health Assessment Questionnaire, radiographs, and joint examinations. RESULTS: Back pain was present in 54.6% of patients with OA of the knee. Almost every clinical status measure was worse among those reporting back pain, including Health Assessment Questionnaire (HAQ) disability, pain, global severity, fatigue, and psychological status. Back pain was more common in women and the obese, but was not associated with age, marital status, formal education, smoking history, or knee radiographic scores. In multivariate analyses the strongest correlates of back pain in knee OA patients were anxiety, night pain, HAQ disability, and global severity. CONCLUSION: Back pain is prevalent among OA clinic patients, more common than in rheumatoid arthritis or population studies, is linked to body mass index, and is associated with clinically significant increases in pain and other measures of clinical distress.     

The need for accurate target and dose specifications in conventional and conformal radiation therapy--an introduction

Back pain in children has long been considered a serious condition with an organic cause. The staff of the Shriner's Hospital had been informally noting that diagnoses among children with back pain had been changing. We conducted a retrospective study of 648 patients with spinal disorders treated at the Shriner's Hospital for Crippled Children, Spokane Unit, between January 1991 and June 1993. The patients were divided into two groups: those with pain and those without pain. It was found that back pain with no organic cause was the primary diagnosis in 57% of the group having pain. Only one child had a diagnosis of malignancy, and there were no cases of active infection. In the group with pain, three interesting associations were found concerning psychosocial problems, disability, and litigation. It was found that the diagnoses in children with back pain treated at this referral center during the study period parallel those in the adult population with back pain.     

Back pain in relation to pregnancy: a 6-year follow-up

STUDY DESIGN: A prospective randomized controlled 6-year follow-up study of women with back pain during pregnancy. OBJECTIVES: To describe the long-term development of back pain in relation to pregnancy and to identify the effects of a physiotherapy and patient education program attended during pregnancy. SUMMARY OF BACKGROUND DATA: Pain incidence and intensity during pregnancy can be reduced by physiotherapy. No study has described the development of pain experienced for a period of years after delivery or the long-term effect of physiotherapy. METHODS: Pregnant women, registered consecutively, were randomly assigned to one control group and to two intervention groups and were observed throughout pregnancy, with follow-up after 3 months and 6 years. RESULTS: The first phase of the study was completed by 362 women. After 3 months, 351 and after 6 years, 303 women had been observed. Back pain among 18% of all women before pregnancy and among 71% during pregnancy declined to 16% after 6 years. Pain intensity was highest in Week 36 (visual analog score, 5.4) and declined markedly 6 years later (visual analog score, 2.5). Slow regression of pain after partus correlated with having a back pain history before pregnancy, (r = 0.30; P < 0.05), with high pain intensity during pregnancy (r = 0.45; P < 0.01), and with much residual pain 3 months after pregnancy (r = 0.41; P < 0.01). These correlations were not found in the intervention groups. Furthermore, frequency of back pain attacks at 6 years correlated with frequency of attacks during pregnancy (r = 0.41; P < 0.01) and with a vocational factor (r = -0.25; P < 0.01). Physiotherapy and patient education had no effects on back pain development among women without pain during pregnancy. CONCLUSIONS: Back pain during pregnancy regressed spontaneously soon after delivery and improved in few women later than 6 months post partum. Expected correlations between back pain in relation to pregnancy and back pain 6 years later were not present in the intervention groups who had attended a physiotherapy and education program during pregnancy. The program had no prophylactic effects on women without back or pelvic pain during pregnancy.     

Patient-maintained analgesia with target-controlled alfentanil infusion after cardiac surgery: a comparison with morphine PCA

Intuitively it seems obvious that unrelieved, severe acute pain after surgery may have a number of undesirable effects [1]. Many experienced clinicians maintain that the immediate postoperative course as well as long-term outcome may be influenced by the quality of pain relief after surgery or trauma [1, 2]. However, there are conflicting data from published clinical studies concerning the beneficial effects of postoperative pain management on short-term and long-term outcome of surgery [3].     

Should extended disability be an exclusion criterion for tertiary rehabilitation? Socioeconomic outcomes of early versus late functional restoration in compensation spinal disorders

STUDY DESIGN: A prospective cohort design with two groups of patients representing short-term or long-term disability (n = 497) who were selected from a larger cohort (n = 938) of consecutively treated spinal disorder patients with chronic compensation injuries. OBJECTIVES: To prospectively evaluate the impact of length of spinal disability on socioeconomic outcomes of medically directed rehabilitation. SUMMARY OF BACKGROUND DATA: Despite an increasing tendency of managed care organizations to limit rehabilitation services for disabled workers with chronic spinal disorders, there has been a surprising lack of prospective research evaluating the impact of length of disability on objective socioeconomic treatment outcomes. Although only approximately 10% of all patients with spinal disorders are disabled beyond 4 months, they account for nearly 80% of all workers' compensation expenditures. Little is known about whether relatively early intervention improves outcomes after chronicity has been established or whether any predictors distinguish between these groups. METHODS: Two comparison groups of functional restoration tertiary treatment graduates were identified from the same community referral pool. The "long-term disabled" group involved a minimum of 18 months of disability (n = 252). This group was compared with a "short-term disabled" group (n = 245), no more than 8 months since injury, but chronic based on a minimum of 4 months after injury. The long-term disabled group showed significantly higher rates of pretreatment surgery than the short-term disabled group (P < 0.001). All patients were evaluated prospectively with specific physical, psychological, and occupational measurements. They also underwent a structured interview 1 year after treatment evaluating work status, health care use, and recurrent injury. RESULTS: The short-term disabled group showed statistically higher return to work (P < 0.001) and work retention (P < 0.05) relative to the long-term disabled group. However, health care use and recurrent lost time injury claims were low in both groups and did not differ significantly. No predictors of outcome were found among the prospectively collected physical performance or psychosocial variables. CONCLUSIONS: This study suggests that early tertiary nonoperative care, once patients with chronic spinal disorders are identified as having potentially high-cost chronic pain and disability, is efficacious in achieving goals of better work return and work retention. Such early rehabilitation may also prevent significant indemnity expense, as well as some late surgical interventions sought by progressively more desperate patients. However, individuals with long-term disability achieve respectable work return and retention rates, while faring no worse on other socioeconomic outcomes that represent major "cost drivers" to the workers' compensation system. Early intervention is not a panacea or a necessary condition for the successful rehabilitation of workers with disabling chronic spinal disorders.     

Communication problems for patients hospitalized with chest pain

In many settings, primary care physicians have begun to delegate inpatient care to hospitalists, but the impact of this change on patients' hospital experience is unknown. To determine the effect on physician-patient communication of having the regular outpatient physician (continuity physician) continue involvement in hospital care, we surveyed 1,059 consecutive patients hospitalized with chest pain. Patients whose continuity physicians remained involved in their hospital care were less likely to report communication problems regarding tests (20% vs 31%, p =.03), activity after discharge (42% vs 51%, p =.02), and health habits (31% vs 38%, p =. 07). In a setting without a designated hospitalist system, communication problems were less frequent among patients whose continuity physicians were involved in their hospital care. New models of inpatient care delivery can maintain patient satisfaction but to do so must focus attention on improving physician-patient communication.     

Outcome of nonspecific right iliac fossa pain syndromes

One-third of all cases of abdominal pain and a quarter of cases of right iliac fossa pain urgently admitted to hospital leave hospital with no precise diagnosis. Based on a series of 400 patients hospitalised for right iliac fossa pain, comprising 107 cases with no identified aetiology, this prospective study was designed to assess the medium-term outcome of these patients, with or without surgical exploration. 67 cases were reviewed at five years. No major diagnosis was missed. Over this 5-year period, 30 patients (45%) experienced another episode of abdominal pain. Among the third of patients (21 cases, 31%) reviewed for another episode of right iliac fossa pain, 7 were readmitted to hospital, with 5 operations, for histologically confirmed acute appendicitis in 3 cases (5% of the series). The patient and his attending physician must be informed of the nonspecific diagnosis established during the first hospitalisation. There is no significant evidence to suggest a psychological component in the recurrent nature of the pain. Cancer must be formally excluded in patients over the age of 50. When surgical exploration is performed, nowadays by laparoscopy, appendicectomy is recommended. This procedure does not decrease the risk of recurrent pain, but confirms the real absence of histopathological abnormality and decreases the number of subsequent hospitalisations.     

Protective effects of grape seed proanthocyanidins and selected antioxidants against TPA-induced hepatic and brain lipid peroxidation and DNA fragmentation, and peritoneal macrophage activation in mice

OBJECTIVES: The purpose of this paper is to describe the demographic and clinical characteristics of chiropractic patients and to document chiropractic visit rates in 6 sites in the United States and Canada. METHODS: Random samples of chiropractors from 5 US sites and 1 Canadian site were selected. A record abstraction system was developed to obtain demographic and clinical data from office charts. RESULTS: Of the 185 eligible chiropractors sampled, 131 (71%) participated. Sixty-eight percent of the selected charts showed that care was sought for low back pain, while 32% recorded care for other reasons. Spinal manipulative therapy was recorded in 83% of all charts. There was a greater than 2-fold difference in the median number of visits related to low back pain per episode of care across sites. The chiropractic visit rates in the US sites and Ontario are estimated to be 101.2 and 140.9 visits per 100 person-years, respectively. CONCLUSIONS: The chiropractic use rate in these sites is twice that of estimates made 15 years ago. The great majority of patients receive care for musculoskeletal conditions of the back and neck. The number of visits per episode varies appreciably by site.     

Essential promoter elements are located within the 5'' untranslated region of human insulin-like growth factor-I exon I

The connection between work-related exposures and the onset of back injury or pain is complex and not clearly understood. This paper raises design issues related to the planning and conduct of cohort studies of industrial low back pain (or injury)(LBP), with care given to definition and measurement of exposure and outcome events. These issues include sample size, outcome definition, study biases, and practical considerations when seeking and maintaining company collaboration with a research effort. Without resolving these issues, the authors conclude: (1) cohort studies of worksite-based LBP are needed to elucidate the causal associations between work tasks and LBP onset, (2) both acute and cumulative exposures should be assessed as risk factors for low back injury or pain, and (3) attention should be paid to the planning of such studies and minimization of potential biases that can limit the validity of the results. These design issues will benefit researchers and companies engaged in the planning and conduct of cohort studies of industrial LBP.