Sex-Based Differences in Lower Extremity Kinematics During Dynamic Jump Landing Tasks After Neuromuscular Fatigue of the Hip Extensors and Knee Flexors.

Background: Neuromuscular fatigue can increase the activation of antagonist muscles, thereby reducing the moment produced by the agonist. During the deceleration phase of landing, hip extensor and knee flexor muscles contract eccentrically to counteract the external hip flexion moment. Decreased hip flexion is associated with greater knee extensor moments and risk of injury. Purpose: To investigate sex-based differences in kinematics and muscle activity after neuromuscular fatigue of the hip extensors and knee flexors during dynamic single-leg tasks. Study Design: Controlled laboratory study. Methods: In this study, 9 female (age, 22.3 ± 3.4 years) and 7 male participants (age, 21.3 ± 2.6 years) completed the triple hop (THop) for distance and single-leg drop-jump (SJump) tasks before and after a fatigue protocol consisting of eccentric hip extension and knee flexion. Motion capture and electromyography were used to compare lower extremity kinematics and muscular activation between the sexes. Results: During the THop, neuromuscular fatigue resulted in significantly decreased maximum hip flexion angles (P = .01), maximum knee flexion angles (P = .039), and an effect of sex on all hip flexion angles, where both sexes saw decreased hip flexion postfatigue (P = .033). A significant interaction of fatigue and sex on hip flexion angular velocity was observed during the SJump, indicating that men experienced an increase while women experienced a decrease in hip flexion angular velocities due to fatigue (P = .03). Gluteus maximus activation was increased, and erector spinae activation was decreased postfatigue in women during the THop (P = .053 and P = .023, respectively). Conclusion: Results indicate that men and women compensated differently after fatigue of the hip extensors and knee flexors. Clinical Relevance: Women more commonly assumed an erect landing posture associated with increased injury risk after fatigue of the hip extensors and knee flexors.

Incidence and prognosis of mid-back pain in the general population: A systematic review.

BACKGROUND AND OBJECTIVE: Despite being common early in life and affecting individuals' quality of life to the same degree as neck and low back pain, research into epidemiological aspects of mid-back pain (MBP) has been scarce. The purpose of our systematic review was therefore to describe the incidence and prognosis of MBP in the general population. The PRISMA Statement guided the study process. DATABASES: A systematic search was conducted in CINAHL, PEDro, PsycINFO and Scopus. RESULTS: Of 3194 unique records identified, seven were included in our qualitative synthesis. The 3-month and 2-year incidence proportions of MBP in children and adolescents were approximately 4% and 50%, respectively. In adults, the 1-month incidence proportion was less than 1%. The persistence or recurrence of MBP over a 1- to 4-year period was between 13% and 45% in children and adolescents; a change in spinal pain location over time was common. Individuals reporting MBP have an increased risk of future care seeking compared with people without musculoskeletal complaints. No studies assessing adult MBP recovery trajectories or prognostic factors were identified. CONCLUSIONS: Knowledge about the incidence and prognosis of MBP in the general population is limited. The incidence of MBP in children and adolescents seems to be similar to the incidence of neck and low back pain; in adults, it is lower than that of neck and low back pain. Studies investigating recovery trajectories of MBP in adults and prognostic factors for MBP are lacking. WHAT DOES THIS STUDY ADD?: The incidence of mid-back pain (MBP) in young individuals is similar to that of neck and low back pain, and ≤50% report persistent pain; however, the evidence base is limited. Knowledge about adult trajectories and prognostic factors for MBP is lacking.

A population-based, incidence cohort study of mid-back pain after traffic collisions: Factors associated with global recovery.

BACKGROUND: Traffic collisions often result in a wide range of symptoms included in the umbrella term whiplash-associated disorders. Mid-back pain (MBP) is one of these symptoms. The incidence and prognosis of different traffic injuries and their related conditions (e.g. neck pain, low back pain, depression or others) has been investigated previously; however, knowledge about traffic collision-related MBP is lacking. The study objectives were to describe the incidence, course of recovery and prognosis of MBP after traffic collisions, in terms of global self-reported recovery. METHODS: Longitudinal data from a population-based inception cohort of all traffic injuries occurring in Saskatchewan, Canada, during a 2-year period were used. Annual overall and age-sex-specific incidence rates were calculated, the course of recovery was described using the Kaplan-Meier technique, and associations between participant characteristics and time-to-self-reported recovery were explored in 3496 MBP cases using Cox proportional hazards models. RESULTS: The yearly incidence rate was 236 per 100,000 population during the study period, and was highest in women and in young persons. The median time-to-first reported recovery was 101 days (95% CI: 99-104) and about 23% were still not recovered after 1 year. Participant's expectation for recovery, general health, extent of severely affecting comorbidities and having experienced a previous traffic injury were some of the prognostic factors identified. CONCLUSIONS: These findings show that MBP is common after traffic collisions, may result in a long recovery process and that a range of biopsychosocial factors are associated with recovery.

Can cross country differences in return-to-work after chronic occupational back pain be explained? An exploratory analysis on disability policies in a six country cohort study.

INTRODUCTION: There are substantial differences in the number of disability benefits for occupational low back pain (LBP) among countries. There are also large cross country differences in disability policies. According to the Organization for Economic Cooperation and Development (OECD) there are two principal policy approaches: countries which have an emphasis on a compensation policy approach or countries with an emphasis on an reintegration policy approach. The International Social Security Association initiated this study to explain differences in return-to-work (RTW) among claimants with long term sick leave due to LBP between countries with a special focus on the effect of different disability policies. METHODS: A multinational cohort of 2,825 compensation claimants off work for 3-4 months due to LBP was recruited in Denmark, Germany, Israel, the Netherlands, Sweden, and the United States. Relevant predictors and interventions were measured at 3 months, one and 2 years after the start of sick leave. The main outcome measure was duration until sustainable RTW (i.e. working after 2 years). Multivariate analyses were conducted to explain differences in sustainable RTW between countries and to explore the effect of different disability policies. RESULTS: Medical and work interventions varied considerably between countries. Sustainable RTW ranged from 22% in the German cohort up to 62% in the Dutch cohort after 2 years of follow-up. Work interventions and job characteristics contributed most to these differences. Patient health, medical interventions and patient characteristics were less important. In addition, cross-country differences in eligibility criteria for entitlement to long-term and/or partial disability benefits contributed to the observed differences in sustainable RTW rates: less strict criteria are more effective. The model including various compensation policy variables explained 48% of the variance. CONCLUSIONS: Large cross-country differences in sustainable RTW after chronic LBP are mainly explained by cross-country differences in applied work interventions. Differences in eligibility criteria for long term disability benefits contributed also to the differences in RTW. This study supports OECD policy recommendations: Individual packages of work interventions and flexible (partial) disability benefits adapted to the individual needs and capacities are important for preventing work disability due to LBP.

Deterioration in the health-related quality of life of persons with multiple sclerosis: the possible warning signs.

Baseline data from a population-based study examining the health-related quality of life (HRQL) of MS patients about to begin disease modifying therapy was used to determine the factors associated with the HRQL of Saskatchewan adults with relapsing-remitting MS. Participants completed a self-report questionnaire regarding demographic and socioeconomic status, fatigue, comorbid medical conditions, disability level (EDSS), number of attacks in past 6 months, illness intrusiveness (Illness Intrusiveness Ratings Scale), depression (Beck Depression Inventory), and HRQL (SF-36 Health Status Survey). Multiple linear regression models were used to identify the factors associated with the physical and mental health summary scores of the SF-36. We found poorer physical HRQL in those who are female; older; not working; have musculoskeletal or respiratory problems; greater fatigue, higher disability scores, and more MS attacks. High illness intrusiveness; digestive system problems; genitourinary problems; and headaches were associated with poorer mental HRQL. Interestingly, we found an interaction between sex and age in mental HRQL, with worse mental health in older men but better mental health in older women. These findings may assist health care providers in identifying patients who may be at risk for decline in their HRQL, permitting appropriate and timely interventions.

A re-examination of the whiplash associated disorders (WAD) as a systemic illness.

OBJECTIVE: To describe the systemic nature of the illness reported after motor vehicle collisions using data from a large, population based cohort of individuals making an injury insurance claim. METHODS: All subjects who submitted a claim or were treated for whiplash injury following a motor vehicle collision in Saskatchewan, Canada during an 18 month period were examined. Demographics of claimants, collision related data, pre-collision health data, symptom prevalence, and scores on the short form 36 item general health survey (SF-36) were obtained on average within one month post-collision. RESULTS: Of 9006 potentially eligible claimants, 7462 (83%) met criteria for whiplash injury and provided information regarding demographics and injury related symptoms; 45% of these consented to complete the SF-36 at baseline. For most subjects, neck pain was only one of many diffuse and intense symptoms, including, often, low back pain. The range of symptoms, including fatigue, dizziness, paraesthesiae, headache, spinal pain, nausea, and jaw pain, could be interpreted as a systemic disorder. SF-36 scores showed low physical and mental functioning one month post-collision. CONCLUSIONS: What is commonly referred to as whiplash associated disorders (WAD) is best appreciated as a syndrome extending well beyond what can be labelled as a neck injury. More research is needed for a better understanding of the underlying mechanisms involved so that treatment can be directed at the broad spectrum of the illness rather than focusing on finding a focal neck injury.

A systematic review of the prognosis of acute whiplash and a new conceptual framework to synthesize the literature.

STUDY DESIGN: Systematic review of prognostic studies of acute whiplash. OBJECTIVES: To update the systematic review on the prognosis of acute whiplash published by the Quebec Task Force on Whiplash-Associated Disorders and to propose a new conceptual framework to conduct systematic reviews on prognosis. SUMMARY OF BACKGROUND DATA: In 1995, the Quebec Task Force published a systematic review of the literature on whiplash and concluded that its prognosis is favorable. However, few prognostic factors were identified. Recent studies have added to this knowledge, and there is a need to update the review conducted by the Quebec Task Force. METHODS: A bibliographic search of four electronic databases was performed to identify prognostic studies of acute whiplash published after 1995. The literature was appraised with standard review criteria. The consistency of evidence across studies was assessed. A conceptual framework was designed to classify the literature according to methodologic quality, target population, and phases of investigation. RESULTS: Thirteen cohort studies were included in the review. The framework used in this study demonstrates that most of the recent prognostic studies are descriptive in nature. The prognosis of acute whiplash varies according to the population sampled and the insurance/compensation system under which individuals are allowed to claim benefits. Besides age, gender, baseline neck pain intensity, baseline headache intensity, and baseline radicular signs and symptoms, there is little consistency in the literature about the prognostic factors for the recovery of whiplash. CONCLUSIONS: Scant knowledge about the prognosis of whiplash has been gained since the release of the Quebec Task Force report. However, it is becoming obvious that the insurance and compensation systems have a large impact on recovery from acute whiplash injuries. The conceptual framework used in this study demonstrates that large cohort studies investigating a wide range of prognostic factors are necessary to improve the understanding of this problem.

The treatment of neck and low back pain: who seeks care? who goes where?

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.

The association between exposure to a rear-end collision and future health complaints.

Different symptoms, together with neck pain, have been attributed to persons with persistent complaints after a previous motor vehicle crash (MVC) and are sometimes referred to as the "late whiplash syndrome." A cohort study was conducted to determine whether exposure to a rear-end collision, with or without whiplash injury, is associated with future health complaints. The results regarding future neck or shoulder pain have previously been described, and the objective of the present report was to focus on outcomes other than neck pain. Included in the study were persons 18 to 65 years of age and covered by traffic insurance at one of the largest insurance companies in Sweden. Claim reports were collected from the period November 1987 to April 1988. Drivers exposed to a rear-end collision were divided into two subgroups: those with reported whiplash injury (n = 232) and those without reported whiplash injury (n = 204). For comparison, 3688 subjects who were unexposed to MVCs were selected, with consideration taken to the age and gender distribution in the exposed subgroups. The prevalence of different health complaints among the study subjects was estimated according to a mailed questionnaire at follow-up in 1994, 7 years after the rear-end collision. When exposed subjects with whiplash injury were compared to unexposed subjects, increased relative risks in the range of 1.6-3.7 were seen for headache, thoracic and low back pain, as well as for fatigue, sleep disturbances and ill health. No corresponding increased risks were found among the exposed subjects without reported whiplash injury. We conclude that rear-end collisions resulting in reported whiplash injuries seem to have a substantial impact on health complaints, even a long time after the collision. There is a need to identify factors that predict a non-favorable outcome in order to improve clinical management.

The association between neck pain intensity, physical functioning, depressive symptomatology and time-to-claim-closure after whiplash.

Time-to-claim-closure is a common outcome in cohort studies of whiplash injuries. However, its relationship to health recovery is unknown. We investigated the association between neck pain, physical functioning, depressive symptomatology and time-to-claim-closure in a Saskatchewan cohort of 5398 whiplash claimants in 1994-1995. Participants were surveyed five times over 1 year. In 1995, the insurance system changed from tort to no-fault, eliminating compensation for pain and suffering. Under tort, a 10-point increase in pain reduced the claim-closure rate by 13-24% while a 10-point increase in physical functioning increased it by 17%. Depressive symptomatology reduced the claim-closure rate by 37%. Under no-fault, a 10-point increase in pain reduced the claim-closure rate by 18% while a 10-point increase in physical functioning increased it by 10-35%. The presence of depressive symptomatology reduced the claim-closure rate by 36%. The results suggests lower pain, better function and the absence of depressive symptoms are strongly associated with faster time-to-claim-closure and recovery after whiplash, independent of the insurance system.

The association between exposure to a rear-end collision and future neck or shoulder pain: a cohort study.

Neck pain is the most frequently reported feature in connection with whiplash injury, but it is also a common complaint in the general population. Therefore it is crucial to include an unexposed comparison group when evaluating the association between neck pain and a previous motor vehicle crash (MVC). To determine whether exposure to a rear-end collision, without or with whiplash injury, is associated with future neck or shoulder pain, a cohort study was conducted. The study population consisted of persons covered by traffic insurance at one of the largest insurance companies in Sweden. Claim reports were collected from the period November 1987 to April 1988. Drivers exposed to a rear-end collision were divided into two subgroups, without reported whiplash injury (n = 204) and with reported whiplash injury (n = 232). Two comparison groups, unexposed to MVCs, consisting of 1599 and 2089 persons, were selected with consideration taken to the age and gender distribution in the exposed subgroups. A questionnaire concerning neck or shoulder pain and other subjective health complaints was mailed to all the study subjects at follow-up in 1994, 7 years after the rear-end collision. The relative risk of neck or shoulder pain at follow-up was 1.3 (95% CI 0.8-2.0) in the exposed subjects without whiplash injury compared with the unexposed. The corresponding relative risk in subjects with whiplash injury was 2.7 (95% CI 2.1-3. 5). We conclude that there is no increased risk of future neck or shoulder pain in drivers who did not report whiplash injury in connection with a rear-end collision 7 years earlier. In drivers with reported whiplash injury, the risk of neck or shoulder pain 7 years after the collision was increased nearly three-fold compared with that in unexposed subjects.

Coping with neck and low back pain in the general population.

This study had 2 objectives: (a) to assess the psychometric properties of the Pain Management Inventory (PMI; G. K. Brown & P. M. Nicassio, 1987) with individuals in the general population with neck or low back pain, and (b) to assess the relationship between pain severity and coping. Data were taken from a mailed survey of a random sample of adults residing in Saskatchewan, Canada. Results validated the 2-factor structure of the PMI and provided evidence for the internal consistency of the coping subscales. Regression analyses revealed that passive coping was associated with being married, greater pain severity, depression, and poor health. Active coping was associated with female gender, higher education, less depression, good health, and frequent exercise. This study provides psychometric data to support the use of the PMI and information about factors associated with use of active and passive coping strategies in pain sufferers.

The factors associated with neck pain and its related disability in the Saskatchewan population.

STUDY DESIGN: Population-based, cross-sectional mailed survey. OBJECTIVE: To identify factors associated with neck pain and its related disability in Saskatchewan adults. SUMMARY OF BACKGROUND INFORMATION: Little is known about the etiology of neck pain and its related disability. Previous cross-sectional population-based studies have suggested that neck pain may be associated with age, female gender, lower socioeconomic status, physically demanding work, and other comorbidities. METHODS: The Saskatchewan Health and Back Pain Survey was mailed to 2184 randomly selected Saskatchewan adults 20 to 69 years of age. Fifty-five percent of the study population participated. The survey collected demographic, socioeconomic, and health-related information. Neck pain and its related disability was classified into four categories using the Chronic Pain Questionnaire: no neck pain (Grade 0), low intensity/low disability neck pain (Grade I), high intensity/low disability neck pain (Grade II), and high disability neck pain (Grades III-IV). Polytomous logistic regression was used to identify associations between demographic, socioeconomic, and health-related variables and various grades of neck pain severity. RESULTS: Of the 1131 respondents, 54% had experienced neck pain at some point in the 6 months before the survey, and almost 5% were highly disabled by neck pain. The prevalence of Grade I neck pain was lower in individuals with low education attainment, but higher for those reporting headaches, low back pain, better general health, and a history of neck injury resulting from a motor vehicle collision, some of whom may have received compensation for their injury. Grade II neck pain was strongly associated with headache, low back pain, and a history of neck injury during a motor vehicle collision and weakly associated with digestive disorders and current cigarette smoking. Grades III-IV neck pain was strongly associated with low back pain, headaches, cardiovascular disorders, digestive disorders, and a history of neck injury during a motor vehicle collision. CONCLUSION: This study suggests that important associations exist between comorbidities, a past history of neck injury resulting from a motor vehicle collision, and graded neck pain. Importantly, individuals who are significantly disabled by neck pain also have comorbidities that have a moderate or severe impact on their health, suggesting that chronic disorders tend to cluster in some individuals.

Effect of eliminating compensation for pain and suffering on the outcome of insurance claims for whiplash injury.

BACKGROUND AND METHODS: The incidence and prognosis of whiplash injury from motor vehicle collisions may be related to eligibility for compensation for pain and suffering. On January 1, 1995, the tort-compensation system for traffic injuries, which included payments for pain and suffering, in Saskatchewan, Canada, was changed to a no-fault system, which did not include such payments. To determine whether this change was associated with a decrease in claims and improved recovery after whiplash injury, we studied a population-based cohort of persons who filed insurance claims for traffic injuries between July 1, 1994, and December 31, 1995. RESULTS: Of 9006 potentially eligible claimants, 7462 (83 percent) met our criteria for whiplash injury. The six-month cumulative incidence of claims was 417 per 100,000 persons in the last six months of the tort system, as compared with 302 and 296 per 100,000, respectively, in the first and second six-month periods of the no-fault system. The incidence of claims was higher for women than for men in each period; the incidence decreased by 43 percent for men and by 15 percent for women between the tort period and the two no-fault periods combined. The median time from the date of injury to the closure of a claim decreased from 433 days (95 percent confidence interval, 409 to 457) to 194 days (95 percent confidence interval, 182 to 206) and 203 days (95 percent confidence interval, 193 to 213), respectively. The intensity of neck pain, the level of physical functioning, and the presence or absence of depressive symptoms were strongly associated with the time to claim closure in both systems. CONCLUSIONS: The elimination of compensation for pain and suffering is associated with a decreased incidence and improved prognosis of whiplash injury.

Is a lifetime history of neck injury in a traffic collision associated with prevalent neck pain, headache and depressive symptomatology?

The objective of this study is to determine whether independent associations exist between a history of neck injury related to a motor vehicle collision and: (1) graded neck pain in the past 6 months; (2) headaches in the past 6 months and; (3) depressive symptomatology during the past week. We used data from the Saskatchewan Health and Back Pain Survey, a population-based cross-sectional survey mailed to a stratified random sample of 2184 Saskatchewan adults aged 20-69 years. Fifty-five percent of the eligible population participated. The exposure was collected by asking subjects whether they had ever injured their neck in a motor vehicle collision. The outcomes: 6-month prevalence of graded neck pain, 6-month prevalence headache and depressive symptomatology during the past week were measured with valid and reliable questionnaires. Sixteen percent of the study sample reported a lifetime history of neck injury in a traffic collision. The association between neck injury and the outcomes was determined from polytomous and binary multivariate logistic regression with adjustment for age, gender and other covariates. A history of neck injury was positively associated with low intensity/low disability neck pain (OR = 2.81; 95% CI 1.81-4.37), positively associated with high intensity/low disability neck pain (OR = 4.46; 95% CI 2.49-4.99) and with disabling neck pain (OR = 3.30; 95% CI 1.48-7.39). Similarly, we found a positive association between a history of neck injury in a motor vehicle collision and headaches that moderately/severely impact on one's health (OR = 2.09; 95% CI 1.27-3.44). No association was found between neck injury and depressive symptomatology (OR = 0.84; 95% CI 0.50-1.40). Our cross-sectional analysis suggests that neck pain and severe headaches are more prevalent in individuals with a history of neck injury from a car collision. However, the results should not be used to infer a causal relationship between whiplash and chronic neck pain and headaches.

The Saskatchewan Health and Back Pain Survey: the prevalence and factors associated with depressive symptomatology in Saskatchewan adults.

OBJECTIVES: To determine the one-week period prevalence of depressive symptomatology among Saskatchewan adults and to identify sociodemographic and health factors associated with depressive symptomatology. METHODS: The Saskatchewan Health and Back Pain Survey was mailed to an age-stratified random sample of adults. Of the 2,184 eligible subjects, 55% (n = 1131) responded to the survey. We report age-standardized prevalence estimates stratified by age, gender and spinal pain severity. Logistic regression was used to measure the presence and strength of association between various factors and depressive symptomatology. RESULTS: 22.2% (95% CI 19.6-24.9) of adults experienced depressive symptomatology during the previous week, with higher rates in younger adults, in females, and in those with disabling spinal pain. Depressive symptomatology was associated with age, income, smoking, health status, gastro-intestinal problems, headaches and spinal pain. CONCLUSIONS: Depressive symptomatology is common in the Saskatchewan adult population, and is related to age, pain severity and general health.

Impairment and work disability due to whiplash injury following traffic collisions. An analysis of insurance material from the Swedish Road Traffic Injury Commission.

A study was set up to determine the trends in medical impairment and work disability ratings for persons affected by whiplash associated disorders (WAD) and other injuries secondary to road traffic collisions, and into the influence of age, gender, professional status, and final medical impairment rating on final work disability. A cross-sectional study was carried out of insurance files of 2,523 subjects in 1989 and 3,223 subjects in 1994 judged to have a permanent medical impairment of 10% or more and work disability due to road traffic injury. Files were obtained from the Swedish Road Traffic Injury Commission. The main outcome measures were the crude frequency and age-specific, standardized percentage of traffic injuries with a medical impairment of 10% or more for the years 1989 and 1994. Final work disability status was analysed with respect to age, gender, type of injury, degree of medical impairment, and professional status. The proportion of medical impairment due to WAD was found to have increased from 16% in 1989 to 28% in 1994, but the proportion of work disability was found to have remained the same. Age over 40 years, low professional status, and having a medical impairment judgement of 15% or more were independently associated with reduced or full work disability.

The Saskatchewan health and back pain survey. The prevalence of low back pain and related disability in Saskatchewan adults.

STUDY DESIGN: Population-based, cross-sectional, mailed survey. OBJECTIVES: To determine the lifetime, 6-month period, and point prevalence of low back pain and its related disability among Saskatchewan adults and to investigate the presence and strength of selective response bias. SUMMARY OF BACKGROUND DATA: There have been many reports of the prevalence of low back pain in different populations, and the estimates vary widely depending on case definition. However, most studies fail to differentiate between trivial and disabling back pain, which raises the issue of the usefulness of these estimates. No studies have yet documented the prevalence of graded low back pain severity and its related disability in a North American, general, population-based survey. METHODS: The Saskatchewan Health and Back Pain Survey was mailed to a probability sample of 2184 Saskatchewan adults between 20 and 69 years of age. Fifty-five percent of the eligible population responded to the survey. Respondents were compared with nonrespondents, and the presence of selective response bias by back pain status was investigated by wave analysis. The point and lifetime prevalence of low back pain was determined by simple questions, and the 6-month period prevalence of low back pain was determined by the Chronic Pain Questionnaire. All estimates were age standardized to the Saskatchewan population. RESULTS: The authors estimate that at the time of the survey 28.4% (95% confidence interval, 25.6-31.1) of the Saskatchewan adult population were experiencing low back pain, and 84.1% (95% confidence interval, 81.9-86.3) had experienced it during their lifetime. Overall, 48.9% (95% confidence interval, 45.9-52.0) of the population had experienced low intensity/low-disability low back pain in the previous 6 months, 12.3% (95% confidence interval, 10.3-14.4) had experienced high-intensity/low-disability low back pain, and an additional 10.7% (95% confidence interval, 8.8-12.5) had experienced high-disability low back pain in the previous 6 months. There was little variation in the estimates over age groups, but women experienced more high-disability back pain than men. There was no evidence of selective response bias by low back pain status in the survey. CONCLUSION: Low-intensity/low-disability low back pain is a common problem in the general population. Approximately 11% of the adult population studied had been disabled by low back pain in the previous 6 months.