Joan Crook

The prevalence of pain complaints in a general population

The authors argue that the study of the complaint of pain falls within the purview of epidemiological study. An analytic survey of 500 randomly selected households on the roster of a group family practice clinic was undertaken. The purpose was to determine the self-reported prevalence rates of any pain complaint and to determine the distribution of pain rates according to selected demographic and socioeconomic variables. Sixteen percent of the individuals sampled from a family practice (H.S.O.) had experienced pain within the 2 weeks preceding the survey. The prevalence rate of those with persistent pain was approximately twice that of those with temporary pain. More women than men reported temporary and persistent pain. The age specific morbidity rate for persistent pain increased with age. The back, lower extremities, and head and face were the most frequently identified sites of pain in both subgroups. Persons with persistent pain used health services, both community physicians and hospital care, more frequently than did those with temporary pain. No significant differences between the two groups were reported for physical, social or emotional function although the persistent pain group characterized their general health status more poorly.

Determinants of occupational disability following a low back injury: a critical review of the literature.

The aim of this research was to determine prognostic indicators of work disability in occupational back pain as reported in the literature, by systematically searching the research literature, assessing the methodological quality of the research, and synthesizing the findings into a concise summary. An article was considered eligible for review if research participants had an injury of the back, the article was based on original research, published in English, and involved a cohort with back pain less than 6 months post injury with at least one follow up assessment. Each article was independently reviewed by two “blinded” reviewers using 19 appraisal criteria for methodological quality of prognostic studies. Nineteen studies met the methodological standard to be included. Time since onset, demographic factors, functional disability, psychological distress, pain reports, previous episodes, and work environment were identified as important prognostic factors. Most studies compartmentalized the factors they considered. What is needed is a comprehensive multivariate biopsychosocial job-related model of work disability.

Epidemiology of chronic pain with psychological comorbidity: prevalence, risk, course, and prognosis.

Objective: To review the relation between chronic pain and psychological comorbidities, and the influence on course and prognosis, based on epidemiologic and population studies. Method: We present a narrative overview of studies dealing with the epidemiology of chronic pain associated with mental health and psychiatric factors. Studies were selected that were of good quality, preferably large studies, and those that dealt with prevalences, course and prognosis of chronic pain, risk factors predicting new pain and comorbid disorders, and factors that affect health outcomes. Results: Chronic pain is a prevalent condition, and psychological comorbidity is a frequent complication that significantly changes the prognosis and course of chronic pain. In follow-up studies, chronic pain significantly predicts onset of new depressions, and depression significantly predicts onset of new chronic pain and other medical complaints. Age, sex, severity of pain, psychosocial problems, unemployment, and compensation are mediating factors in course and prognosis. Conclusion: In assessment of chronic pain, the evidence from epidemiologic studies makes it clear that chronic pain can best be understood in the context of psychosocial factors.

Tender points in fibromyalgia

&NA; To establish inter‐rater and test‐retest reliability of use of a pressure algometer, 5 males and 5 females suffering from chronic fibromyalgia (‘fibrositis’), and a normal group of 5 males and 5 females, were examined 2 times by each of 2 independent examiners, using 1 kg/sec rate of application, over 10 paired and typical ‘tender points,’ localized by skin marker. Tenderness thresholds of tender points were coded and analyzed using repeated measures ANOVA, for factors sex, normal/fibromyalgia, and side, rater, and time 1/time 2. There was significantly lower tenderness thresholds of tender points in fibromyalgia compared to normal subjects. Generalizability coefficients were calculated and showed high inter‐rater (0.85), and test‐retest (0.85) reliability. Highly significant differences were found between specific tender points. A further 10 normals and 10 fibromyalgia subjects were then examined for 5 paired tender points and 5 paired non‐tender points. A 2‐way ANOVA was conducted for summed and averaged scores for all tender and non‐tender points, with factors normal/fibromyalgia and tender/non‐tender; again, there was a large difference between normal and fibromyalgia subjects, and between tender and non‐tender points. The interaction was small but significant, but there was a larger difference between fibromyalgia and normal subjects observed on non‐tender points. The low tenderness threshold observed at the tender points of fibromyalgia patients may reflect a more generalized lowering of tenderness thresholds, seen at non‐tender points as well.

An epidemiological follow-up survey of persistent pain sufferers in a group family practice and specialty pain clinic☆

&NA; The course and prognosis of persistent pain are largely unknown. In addition, follow‐up studies of chronic pain sufferers have come from specialized pain clinics and have ignored the question of how representative this special group is to the general population who suffer persistent pain. Because health care planners are assumed to require these data for projection of health care needs, it is important to determine the course of persistent pain in those persistent pain sufferers in the general population as well as those referred to a specialty clinic. An epidemiological study compared 2 groups of self‐reported persistent pain sufferers from a Family Practice Clinic and a Specialty Pain Clinic over a 2 year period. All subjects reporting a persistent problem with pain at the time of the initial survey were contacted 2 years later to determine whether the initial differences between the 2 groups remained constant over time and whether there were any changes within each group over time. Despite the similarities between the study groups on multiple socioeconomic and demographic variables, the Specialty Pain Clinic group remained distinctly different from the Family Practice pain sufferers on many pain behavior and emotional variables. Thirteen percent of the persistent pain sufferers from the Pain Clinic group and 36% of the persistent pain sufferers from the Family Practice group no longer reported pain as a problem at follow‐up. Of those pain sufferers from either group who continued to experience pain at 2 years follow‐up, their pain became more intermittent, psychological distress factors improved, and the use of health services decreased. The implications are that persistent pain does not necessarily continue forever and that persistent pain sufferers in the general population have a better prognosis than those who are referred to a Specialty Pain Clinic. All follow‐up studies need to be interpreted in light of these findings.

Biopsychosocial Multivariate Predictive Model of Occupational Low Back Disability

Study Design. To establish outcome, 253 workers with subacute and chronic low back conditions were assessed with a comprehensive multimethod biopsychosocial protocol at baseline, 3 days after the initial examination, and 3 months later. Objective. To validate empirically a biopsychosocial model for prediction of occupational low back disability. Summary of Background Data. Costs of low back occupational disability continue to spiral despite stabilization of low back injury rates. An empirically based model to predict occupational disability in workers with low back injuries is required. Methods. Workers with subacute low back injuries (4–6 weeks after injury, n = 192) and those with chronic back pain (6–12 months after injury, n = 61) were the study participants. The biopsychosocial protocol included five groups of variables: 1) sociodemographic, 2) medical, 3) psychosocial, 4) pain behavior, and 5) workplace-related factors. Predictive validity was investigated through a 3-month follow-up assessment, at which time the return to work outcome was determined. Stepwise logistic regression models were developed to predict work status. Results. The final integrated model consisted of variables from a wide biopsychosocial spectrum: vitality, health transition, feeling that job is threatened due to injury, expectations of recovery, guarding behavior, perception of severity of disability, time to complete walk, and right leg typical sciatica. Conclusions. The “winning” variables identified in the integrated model are dominated by cognitions, which are accompanied by disability behaviors. A cognitive–behavioral model with an adaptation-oriented rather than a pathology-oriented focus is favored for early intervention with high-risk workers since cognitions are amenable to change.

Predicting return to work after low back injury using the Psychosocial Risk for Occupational Disability Instrument: a validation study.

Introduction: This paper reports on the predictive validity of a Psychosocial Risk for Occupational Disability Scale in the workers’ compensation environment using a paper and pencil version of a previously validated multimethod instrument on a new, subacute sample of workers with low back pain. Methods: A cohort longitudinal study design with a randomly selected cohort off work for 4–6 weeks was applied. The questionnaire was completed by 111 eligible workers at 4–6 weeks following injury. Return to work status data at three months was obtained from 100 workers. Sixty-four workers had returned to work (RTW) and 36 had not (NRTW). Results: Stepwise backward elimination resulted in a model with these predictors: Expectations of Recovery, SF-36 Vitality, SF-36 Mental Health, and Waddell Symptoms. The correct classification of RTW/NRTW was 79%, with sensitivity (NRTW) of 61% and specificity (RTW) of 89%. The area under the ROC curve was 84%. Conclusions. New evidence for predictive validity for the Psychosocial Risk-for-Disability Instrument was provided. Implications: The instrument can be useful and practical for prediction of return to work outcomes in the subacute stage after low back injury in the workers’ compensation context.

Models of Diagnosis and Rehabilitation in Musculoskeletal Pain-Related Occupational Disability

Musculoskeletal, pain-related occupational injuries are among the most common and disabling impairments in the working population and pose a formidable health care problem for industry. Annually, 2% of the national work force incurs industrialrelated back injuries, with approximately 1.4% of these resulting in a period of work absence (1). Despite the good prognosis for most episodes, musculoskeletal injuries consume considerable resources in medical care, absence from work, productivity losses and compensation benefits. Spitzer (1) found that about three-quarters of workinjured employees return to work in two to three weeks. Only about 7% had not returned by six months; however, these few accounted for about 75% of costs to the compensation system in lost hours, indemnities, and utilization of health services.

Reliability of the lumbar flexion, lumbar extension, and passive straight leg raise test in normal populations embedded within a complete physical examination

Study Design. The study measured the reliability of the passive straight leg raise (SLR) test and lumbar range of motion (LROM) tests measured as continuous variables embedded within a comprehensive physical examination. Objectives. To determine the reliability of the SLR and LROM test scores when they are measured with a Cybex electronic inclinometer (Lumex, Inc., New York, NY) within a physical examination. Summary of Background Data. Good published empirical reliability exists for the Cybex and for SLR and LROM tests when the measurements are taken in isolation from other physical examination procedures. Reliability of the Cybex for continuous SLR and LROM measurement within a physical examination has not been assessed, however. Methods. Forty-five participants were seen by one of two physician/physiotherapist teams. Participants were examined by both team members. The first examiner conducted the first tests and retested 1 week later (intrarater reliability). The second examined the participants the day after their first appointment (inter-rater reliability). Results. Only two scores showed substantial reliability (defined as r ≥ 0.60). These scores were left (r = 0.81) and right (r = 0.79) SLR intrarater reliability. All other scores fell below the specified cutoff. Conclusions. SLR and LROM scores used clinically are collected during comprehensive physical examinations. Most scores gathered under these conditions were not reliable. These findings have implications for the use of clinically derived SLR and LROM scores.

An Exploration of Seniors' Ability to Report Pain

The purpose of this study was to evaluate the ability of a group of elderly residents to use self-report methods to measure their pain in an accurate fashion. Using a comparative descriptive design, completion rates of three pain assessment tools and the self-report skills of a sample of 130 long-term care residents with varying levels of cognitive impairment were evaluated. The majority of residents with mild to moderate cognitive impairment were able to complete at least one of the verbal pain assessment tools, with the Present Pain Intensity and Numerical Rating Scales being the preferred choices for use in clinical settings. However, the Faces Pain Scale appeared to be more challenging for residents to complete, suggesting that it requires further testing before it can be recommended for clinical use.