Remko Soer

Responsiveness and Minimal Clinically Important Change of the Pain Disability Index in Patients With Chronic Back Pain

Study Design. Prospective cohort study. Objective. The objective of this study was to test the responsiveness and minimal clinically important change (MCIC) of the Pain Disability Index (PDI) in patients with chronic back pain (CBP). Summary of Background Data. Treatment of patients with CBP is primarily focused on reduction of disability. For disability measurement, the PDI is a widely used questionnaire. There are, however, no data available on responsiveness and MCIC. Methods. Two hundred forty-two patients with CBP were included in this study. Patients filled in the PDI at baseline and at discharge. The PDI consists of 2 subscales: 1 measuring voluntary activities and 1 measuring obligatory activities. PDI was anchored at 2 self-reported global perceived effect (GPE) scales for complaints and self-care, respectively. Responsiveness was considered sufficient when Area Under the Receiver Operating Characteristics (ROC) Curve (AUC) was higher than 0.70. To test interpretability, change scores and MCIC were calculated. MCIC was tested by determination of optimal cut-off point of the ROC curve and determination of specificity and sensitivity of the optimal cut-off point. Results. AUCs were 0.76 and 0.77 depending on the external criterion. The subscale obligatory activities did not meet the criteria for responsiveness (AUC: 0.63–0.69). MCIC of the PDI was 9.5 points for GPE “complaints” and 8.5 for GPE “self-care.” Conclusion. The total score of the PDI as well as the subscale of voluntary activities is responsive. Partly because of floor effects, the subscale obligatory activities are not sufficiently responsive in patients with CBP. However, the responsiveness of this subscale in other patient groups should be further tested. In patients with CBP, change can be considered clinically important when PDI score has decreased 8.5 to 9.5 points.

Towards Consensus in Operational Definitions in Functional Capacity Evaluation: a Delphi Survey

Introduction The problem of inconsistent terminology in functional capacity evaluation (FCE) has been widely addressed in the international literature. Many different terms seem to be used interchangeably while other terms appear to be interpreted differently. This may seriously hinder FCE research and clinical use. To gain consensus in operational definitions in FCE and conceptual framework to classify terminology used in FCE. Methods A Delphi Survey with FCE experts was conducted which consisted of three rounds of questioning, using semi and full structured questions. The expert group was formed from international experts in FCE. Experts were selected if they met any of the following criteria: at least one international publication as first author and one as co-author in the field of FCE; or an individual who had developed an FCE that was subject of investigation in at least one publication in international literature. Consensus of definitions was considered when 75% or more of all experts agreed with a definition. Results In total, 22 international experts from 6 different countries in Australia, Europe and North America, working in different health related sectors, participated in this study. Conclusion Consensus concerning conceptual framework of FCE was met in 9 out of 20 statements. Consensus on definitions was met in 10 out of 19 definitions. Experts agreed to use the ICF as a conceptual framework in which terminology of FCE should be classified and agreed to use pre-defined terms of the ICF. No consensus was reached about the definition of FCE, for which two potential eligible definitions remained. Consensus was reached in many terms used in FCE. For future research, it was recommended that researchers use these terms, use the ICF as a conceptual framework and clearly state which definition for FCE is used because no definition of FCE was consented.

Extensive Validation of the Pain Disability Index in 3 Groups of Patients With Musculoskeletal Pain

Study Design. A cross-sectional study design was performed. Objective. To validate the pain disability index (PDI) extensively in 3 groups of patients with musculoskeletal pain. Summary of Background Data. The PDI is a widely used and studied instrument for disability related to various pain syndromes, although there is conflicting evidence concerning factor structure, test-retest reliability, and missing items. Additionally, an official translation of the Dutch language version has never been performed. Methods. For reliability, internal consistency, factor structure, test-retest reliability and measurement error were calculated. Validity was tested with hypothesized correlations with pain intensity, kinesiophobia, Rand-36 subscales, Depression, Roland-Morris Disability Questionnaire, Quality of Life, and Work Status. Structural validity was tested with independent backward translation and approval from the original authors. Results. One hundred seventy-eight patients with acute back pain, 425 patients with chronic low back pain and 365 with widespread pain were included. Internal consistency of the PDI was good. One factor was identified with factor analyses. Test-retest reliability was good for the PDI (intraclass correlation coefficient, 0.76). Standard error of measurement was 6.5 points and smallest detectable change was 17.9 points. Little correlations between the PDI were observed with kinesiophobia and depression, fair correlations with pain intensity, work status, and vitality and moderate correlations with the Rand-36 subscales and the Roland-Morris Disability Questionnaire. Conclusion. The PDI-Dutch language version is internally consistent as a 1-factor structure, and test-retest reliable. Missing items seem high in sexual and professional items. Using the PDI as a 2-factor questionnaire has no additional value and is unreliable.

Clinimetric properties of the EuroQol-5D in patients with chronic low back pain

BACKGROUND CONTEXT Clinimetric properties of the EuroQol-5D (EQ-5D) in patients with nonspecific chronic low back pain (CLBP) are largely unknown. PURPOSE To study the criterion validity, responsiveness, and minimal clinically important change (MCIC) of EQ-5D in patients with CLBP. STUDY DESIGN Prospective study design carried out in a multispecialist Spine Center in The Netherlands. PATIENT SAMPLE One hundred fifty-one patients with CLBP. OUTCOME MEASURES Quality of life (QOL) was measured with EQ-5D, consisting of two scales: one scale measuring QOL with five categorical questions and the other measuring health state on a visual analog scale (0-100). Criterion measures were disability, measured with the Pain Disability Index (PDI) and the Roland Morris Disability Questionnaire (RMDQ), and pain intensity, measured with a numeric rating scale (NRS). METHODS Pearson correlation coefficients between the EQ-5D and RMDQ, PDI, and NRS were calculated to test the criterion validity. Correlations were interpreted based on predefined criteria. Responsiveness of the EQ-5D was calculated with area under the receiver operating characteristics (ROC) curve. Minimal clinically important change was calculated with the optimal cutoff point under the ROC curve, and sensitivity and specificity were also calculated. RESULTS Correlations between EQ-5D and criterion measures ranged between 0.39 and 0.59 and were considered moderate to good. Areas under the ROC curve ranged from 0.59 to 0.72 depending on the external criterion and EQ-5D subscale. The MCIC was 0.03 points for the categorical scales of the EQ-5D and 10.5 points for the EQ-5D visual analog scale. CONCLUSIONS The EQ-5D is a valid and responsive QOL scale in patients with CLBP.

Risk and prognostic factors for non-specific musculoskeletal pain: A synthesis of evidence from systematic reviews classified into ICF dimensions

ABSTRACT A wide variety of risk factors for the occurrence and prognostic factors for persistence of non‐specific musculoskeletal pain (MSP) are mentioned in the literature. A systematic review of all these factors is not available. Thus a systematic review was conducted to evaluate MSP risk factors and prognostic factors, classified according to the dimensions of the International Classification of Functioning, Disability and Health. Candidate systematic reviews were identified in electronic medical journal databases, including the articles published between January 2000 and January 2008 that employed longitudinal cohort designs. The GRADE Working Group’s criteria for assessing the overall level of evidence were used to evaluate the reviews. Nine systematic reviews were included, addressing a total of 67 factors. High evidence supported increased mobility of the lumbar spine and poor job satisfaction as risk factors for low back pain. There was also high evidence for intense pain during the onset of shoulder and neck pain and being middle aged as risk factors for shoulder pain. High evidence was also found for several factors that were not prognostic factors. For whiplash‐associated disorders these factors were older age, being female, having angular deformity of the neck, and having an acute psychological response. Similarly, for persistence of low back pain, high evidence was found for having fear‐avoidance beliefs and meagre social support at work. For low back pain, high evidence was found for meagre social support and poor job content at work as not being risk factors.

A comparison of two lifting assessment approaches in patients with chronic low back pain

The Progressive Isoinertial Lifting Evaluation (PILE) and the lifting test of the WorkWell Systems Functional Capacity Evaluation (WWS) are well known as lifting performance tests. The objective of this study was to study whether the PILE and the WWS can be used interchangeably in patients with Chronic Low Back Pain (CLBP) and to explore whether psychosocial variables can explain possible differences. Methods: 53 Patients (32 men and 21 women) with CLBP were tested twice in a counter balanced design. Pearson Correlation Coefficient of r > 0.75 and non-significant differences on two-tailed t tests were considered as good comparability. Results: Pearson Correlation Coefficient was 0.75 (p < 0.01). Lifting performance on the WWS was a mean of 6.0 kg higher compared to the PILE (p < 0.01). The difference between the PILE and the WWS was unrelated to psychological variables. Conclusion: It can be concluded that the PILE and the WWS cannot be used interchangeably. Psychosocial variables cannot explain the differences between both tests.

Decline of Functional Capacity in Healthy Aging Workers

OBJECTIVES (1) To study the natural decline in functional capacity (FC) of healthy aging workers; (2) to compare FC to categories of workload; and (3) to study the differences in decline between men and women. DESIGN Cross-sectional design. SETTING A rehabilitation center at a university medical center. PARTICIPANTS Volunteer sample of healthy workers (N=701) between 20 and 60 years of age, working at least 20 hours per week in the year prior to the study. Subjects were recruited via local press and personal networks. INTERVENTIONS FC was measured with a 14-item Functional Capacity Evaluation. Demographics and health status were measured with a general demographic questionnaire and the RAND-36 questionnaire. MAIN OUTCOME MEASURES Workload was expressed by the workload categories, as described by the Dictionary of Occupational Titles. Descriptive statistics were used to present FC of workers. Change in FC by age was tested with segmented regression analyses with a cutoff point at 45 years of age. RESULTS Significant but small declines of FC under age 45 years were present in repetitive reaching, hand dexterity, and energetic capacity. Up to 45 years of age, hand and finger strength increased on average. Over 45 years of age, lifting, carrying, hand and finger strength, and coordinative tests declined more compared with the group aged less than 45 years. Work capacity of men and women working in sedentary and light work was sufficient in all age categories. There are no differences in decline between men and women. CONCLUSIONS FC of healthy workers declines with age. This study demonstrates substantial variation in the type of FC decline among healthy workers between 20 and 60 years of age. Material handling, hand and finger strength, and hand coordination appear to decline the most in workers over age 45 years. The objective of rehabilitation is to maximize an individuals FC, particularly with respect to environmental demand. Thus, return to work programs must appreciate both FC and workplace demands in an effort to restore/enhance equilibrium between the 2.

Basis for an FCE Methodology for Patients With Work-Related Upper Limb Disorders

A reported reduction in work-related functional capacity in Work-related Upper Limb Disorders (WRULD) patients is among the most common problems in WRULD. The extent to which this reduction in functional capacity can be objectified remains unknown. A validated instrument to test functional capacity in this patient group is unavailable. The objective of this study was to design a Functional Capacity Evaluation (FCE) for WRULD patients working with Visual Display Units (VDU) and provide evidence for content validity. A review to epidemiological literature was conducted to identify physical risk factors for VDU-related WRULD. The results indicate that physical risk factors were related to repetition, duration, working in awkward and static positions and forceful movements of the upper extremity and neck. An FCE was designed based on the risk factors identified. Eight tests were selected to cover all risk factors: the overhead lift, overhead work, repetitive reaching, handgrip strength, finger strength, wrist extension strength, fingertip dexterity, and a hand and forearm dexterity test. Content validity of this FCE was established by providing the rationale, specific objectives and operational definitions of the FCE. Further research is needed to establish reliability and other aspects of validity of the WRULD FCE.

Reference values for isometric muscle force among workers for the Netherlands: a comparison of reference values

BackgroundMuscle force is important for daily life and sports and can be measured with a handheld dynamometer. Reference values are employed to quantify a subject’s muscle force. It is not unambiguous whether reference values can be generalized to other populations. Objectives in this study were; first to confirm the reliability of the utilization of hand-held dynamometers for isometric strength measurement; second to determine reference values for a population of Dutch workers; third to compare these values with those of a USA population.Methods462 Healthy working subjects (259 male, 203 female) were included in this study. Their age ranged from 20 to 60 years with a mean (sd) of 41 (11) years. Muscle force values from elbow flexion and extension, knee flexion and extension, and shoulder abduction were measured with the break method using a MicroFet 2 hand-held dynamometer. Reliability was analyzed by calculating ICC’s and limits of agreement. Muscle force expressed in Newton, means, and confidence intervals were determined for males and females in age groups ranging from twenty to sixty years old. Regression equations and explained variances were calculated from weight, height, age, and gender. The mean values and 95% CI were compared to the results from other studies.ResultsReliability was good; the ICC ranged between 0.83 to 0.94. The explained variance ranged from 0.25 to 0.51. Comparison of data for the Dutch population mean muscle force values with those from the USA revealed important differences between muscle force reference values for the American and Dutch populations.ConclusionsMuscle force measurements demonstrate a sound reliability. Reference values and regressions equations are made available for the Dutch population. Comparison with other studies indicates that reference values differ between countries.

Construct validity of functional capacity tests in healthy workers

BackgroundFunctional Capacity (FC) is a multidimensional construct within the activity domain of the International Classification of Functioning, Disability and Health framework (ICF). Functional capacity evaluations (FCEs) are assessments of work-related FC. The extent to which these work-related FC tests are associated to bio-, psycho-, or social factors is unknown. The aims of this study were to test relationships between FC tests and other ICF factors in a sample of healthy workers, and to determine the amount of statistical variance in FC tests that can be explained by these factors.MethodsA cross sectional study. The sample was comprised of 403 healthy workers who completed material handling FC tests (lifting low, overhead lifting, and carrying) and static work FC tests (overhead working and standing forward bend). The explainable variables were; six muscle strength tests; aerobic capacity test; and questionnaires regarding personal factors (age, gender, body height, body weight, and education), psychological factors (mental health, vitality, and general health perceptions), and social factors (perception of work, physical workloads, sport-, leisure time-, and work-index). A priori construct validity hypotheses were formulated and analyzed by means of correlation coefficients and regression analyses.ResultsModerate correlations were detected between material handling FC tests and muscle strength, gender, body weight, and body height. As for static work FC tests; overhead working correlated fair with aerobic capacity and handgrip strength, and low with the sport-index and perception of work. For standing forward bend FC test, all hypotheses were rejected. The regression model revealed that 61% to 62% of material handling FC tests were explained by physical factors. Five to 15% of static work FC tests were explained by physical and social factors.ConclusionsThe current study revealed that, in a sample of healthy workers, material handling FC tests were related to physical factors but not to the psychosocial factors measured in this study. The construct of static work FC tests remained largely unexplained.