Functional capacity and residual functional capacity and their utility in measuring work capacity

Does self-perceived health correlate with physician-assessed functional limitations in medical work disability assessments?

OBJECTIVE

Our purpose was to obtain information about the correlation between workers' self-perceived health and physician-assessed functional limitations. We also studied whether this correlation differed between workers with subjective health complaints that cannot (SHC) and those that can be explained (non-SHC) by a well-defined medical disease.

METHODS

Baseline data of 2040 participants from a prospective cohort study were used for this study. These participants answered a questionnaire on their self-perceived health and received a medical work disability assessment during which physicians reported functional limitations. Pearson correlation analyses were used to calculate correlations between 4 functional limitation factors and 11 self-perceived health factors. For correlations with coefficients ≥0.30, linear regression analyses were performed to assess possible differences between participants with SHC (n = 363) and those with non-SHC (n = 1677).

RESULTS

We found correlations ≥0.30 between two functional limitation factors and six self-perceived health factors for all participants. SHC participants showed lower correlations than the non-SHC participants between the physical functional limitation and the SF-36 self-perceived physical health factors (-0.49, 95% CI -0.56 to -0.41 vs. -0.60, 95% CI -0.62 to -0.57) and between the mental functional limitation and the SF-36 self-perceived mental health factors (-0.30, 95% CI -0.39 to -0.20 vs. -0.40, 95% CI -0.44 to -0.36).

CONCLUSION

Self-perceived health showed overall low to moderate correlations with physician-assessed functional limitations. Some of these correlations were lower for workers with SHC than for those with non-SHC. This may indicate that physicians rely slightly more on well-defined medical complaints within medical work disability assessments.

Survey of kinesiologists' functional capacity evaluation practice in Canada

BACKGROUND

In Canada, functional capacity evaluations (FCEs) are commonly administered by several health care professions including kinesiologists. Kinesiologists have been recently regulated as health care professionals in Ontario and we know little about their demographics, the frequency of FCE administration, or the types of FCEs used by this group.

OBJECTIVE

The purposes of this study were to identify: 1) the demographic characteristics and FCE education of kinesiology FCE practitioners; 2) the FCE systems most used by these practitioners and 3) the constructs from assessments used to determine functional capacity.

METHODS

A survey was distributed to members of the Canadian Kinesiology Alliance. Descriptive statistics and frequency distributions were calculated from the survey responses (n = 77).

RESULTS

FCE practitioners were represented by kinesiologists (79%) practicing more than 15 years and 1-5 years, who received FCE training from a certification course. ARCON (23%) was the most common FCE system used. Low-level lifting (43%), mid-lift (38%), pulling (38%) and walking (38%) are the most common FCE task components used to assess functional capacity. Although kinesiologists consider multiple factors when making decisions about task component endpoints, biomechanical observations/body mechanics are the primary methods used.

CONCLUSIONS

Kinesiologists are conducting FCEs for the primary purpose of preparing return-to-work or workplace accommodation recommendations. Although functional capacity is determined using multiple factors, there is an emphasis on biomechanics and body mechanics. Focusing FCE training and research on these constructs may provide opportunities to further strengthen the reliability and validity of FCE outcomes.

Quantification of the safe maximal lift in functional capacity evaluations: comparison of muscle recruitment using SEMG and therapist observation

INTRODUCTION

This study aimed to identify any correlation between muscle activity using surface electromyography (SEMG) and therapist determined safe maximal lift (SML) during the bench to shoulder lift of the WorkHab FCE. This would support construct (convergent) validity of SML determination in the WorkHab FCE.

METHOD

An experimental laboratory based study design was used. Twenty healthy volunteers performed the bench to shoulder lift of the WorkHab FCE whilst SEMG of upper trapezius, mid deltoid, thoracic, brachioradialis and bicep muscles were recorded. A summary of the data is presented using descriptive statistics and differences between groups were tested using generalised linear mixed models.

RESULTS

Results showed a significant difference in activity and duration of muscle activation with increasing weight lifted [p = 0.000 and p = 0.024 (brachioradialis)]. There was a significant difference between the up lift (bench to shoulder) and the down lift (shoulder to bench) for all muscles (p = 0.000) except the brachioradialis (p = 0.819). No significant change was found in muscle activity before or after the SML.

CONCLUSION

Convergent validity of the bench to shoulder lift of the WorkHab FCE was not established as no relationship between the muscle recruitment using SEMG and SML, as determined by therapist observation was identified during this lift.

Measuring clients' perception of functional limitations using the Perceived Functioning & Health questionnaire

BACKGROUND

The Perceived Functioning & Health (PFH) questionnaire was developed to collect, in a standardized manner, which work activities are limited due to health conditions according to the perception of the client. In this study the questionnaire's reliability and validity are investigated.

METHODS

The PFH questionnaire is comprised of 147 questions, distributed over 33 scales, pertaining to the client's psychosocial and physical work limitations. The PFH data of 800 respondents were analyzed: 254 healthy employees, 408 workers on sick leave and 138 recipients of a disability pension. Internal consistency (Cronbach's α) for the scales was established. The test-retest reliability was examined for the data of 52 recipients of a disability pension who filled out the PFH twice within an interval of 1 month. Validation was established by taking the nature of the limitations as a criterion: mental limitations, physical limitations or a mix of both. To this end, the respondents were divided into groups distinguished on the basis of self-classification, as well as classification on the basis of disease codes given by insurance and occupational health physicians: a "healthy" group, subjects with only physical ("physical" group) or mental limitations ("mental" group) or mixed limitations ("mixed" group). The scale scores of these groups were compared and tested using analyses-of-variance and discriminant analyses.

RESULTS

The scales were found to have sufficient to good internal consistency (mean Cronbach's-α = 0.79) and test-retest reliability (mean correlation r = 0.76). Analyses-of-variance demonstrated significant differences between the scores of the mental, physical and healthy groups on most of the expected scales. These results were found both in groups defined by self-classification as well as in groups based on disease codes. Moreover, discriminant analyses revealed that the a priori classification of the respondents into three groups (mental, physical, healthy) for more than 75% of them corresponded with the classification on the basis of scale scores obtained from the questionnaire. Furthermore, limitations due to specific types of complaints (low back pain, fatigue, concentration problems) or diagnosed disorders (musculoskeletal disorders, reactive disorders, endogenous disorders) were clearly reflected in the scores of the related scales of the PFH.

CONCLUSION

The psychometric properties of the PFH with respect to reliability and validity were satisfactory. The PFH would appear to be an appropriate instrument for systematically measuring functional limitations in subjects on sick leave and in those receiving disability pensions, and could be used as a starting point in a disability claim procedure.

Functional capacity evaluation in subjects with early osteoarthritis of hip and/or knee; is two-day testing needed?

INTRODUCTION

The Work Well Functional Capacity Evaluation (WW FCE) is a two-day performance based test consisting of several work-related activities. Three lifting and carrying test items may be performed on both days. The objective of this study was to assess the need for repeated testing of these items in subjects with early osteoarthritis of the hip and/or the knee and to analyze sources of variation between the 2 days of measurement.

METHODS

A standardized WW FCE protocol was applied, including repeated testing of lifting low, lifting overhead and carrying. Differences and associations between the 2 days were calculated using paired samples t-tests, intraclass correlation coefficients (ICC) and limits of agreement (LoA). Possible sources of individual variation between the 2 days were identified by Wilcoxon signed ranks tests. Pearson correlation coefficients were calculated for differences in performances between days and differences in possible sources of variation between days.

RESULTS

Seventy-nine subjects participated in this study, their mean (SD) age was 56.6 (4.8) years, median (min-max) WOMAC (Western Ontario and McMaster Universities) index scores for pain, stiffness and physical function were 5 (0-17), 3 (0-7) and 14 (0-49), respectively. Median (min-max) SF36 physical function was 75 (5-95), and SF36 pain score was 67 (12-76). Mean performance differences ranged from -0.2 to -0.8 kg (P > 0.05). ICC's ranged from 0.75 (lifting overhead) to 0.88 (lifting low). LoA were: lifting low 8.0 kg; lifting overhead 6.5 kg; carrying 9.0 kg. Pearson's correlations were low and non-significant.

CONCLUSIONS

All three tests show acceptable two-day consistency. WW FCE testing on two consecutive days is not necessary for groups of subjects with early osteoarthritis. Individual sources of variation could not be identified.

Matching FCE activities and work demands: an explorative study

OBJECTIVES

to explore to what extent the standardized Isernhagen Work Systems Functional Capacity Evaluation (IWS FCE) can be matched with observed work demands in workers with chronic low back pain, and, secondly, to explore whether this match can predict sick leave in the year after rehabilitation treatment.

METHODS

An explorative prognostic cohort study with a one-year follow-up (four, eight and twelve months after baseline) was performed (n = 18). Demographics, back complaints and FCE performance were assessed at baseline. In addition, a workplace assessment (WPA) was performed. Eleven FCE activities were matched with work demands. Sick leave associated with low back pain and physical and psychosocial work demands were assessed during follow-up.

RESULTS

Seven activities could be directly matched with WPA data. (Carrying, pushing, pulling, crouching, kneeling, static forward bending, and dynamic bending and rotating.) For some workers, difficulties existed in matching three of the activities (pushing, pulling and crouching). One activity (lifting) could indirectly be matched with WPA data. One activity (walking) could not be matched with WPA data. Two activities (sitting, standing) were excluded from analyses due to practical limitations. No relation was found between FCE performance, work demands, and sick leave during follow-up.

CONCLUSIONS

Seven FCE activities could be directly matched with work demands. However, not all observed work demands could be matched with IWS FCE activities in the eighteen occupations studied. This quantitative and standardized way of assessing work-related disability is not sufficient to predict work ability and sick leave at the present time.

Are functional capacity evaluations affected by the patient's pain?

Functional capacity evaluations (FCE) are comprehensive batteries of performance-based tests used commonly to inform return-to-work decisions for injured workers. As many people undergoing FCE have painful musculoskeletal conditions limiting their work ability, pain becomes a critical factor in the assessment of function. This paper considers the available literature related to the influence of pain on FCE, which clearly indicates FCEs are behavioral assessments influenced by pain intensity and other pain-related constructs. Increasing pain levels are consistently associated with reduced FCE performance levels. As such, for purposes of claims adjudication, FCE should not be considered a purely "objective" indicator of functional impairment independent of subject or evaluator perceptions. FCE may have some value for facilitating return-to-work or re-integrating chronically disabled workers into the workforce, although pain factors must be taken into consideration when making predictions about future work status. Shorter FCEs could potentially be as effective as more lengthy protocols.

Measurement qualities of a self-report and therapist-scored functional capacity instrument based on the Dictionary of Occupational Titles

Studies provide convincing arguments to support the development of functional capacity instruments based on the Dictionary of Occupational Titles (DOT). The purpose of this study is to investigate the item-level measurement qualities of a newly developed DOT-based functional capacity instrument for clients undergoing rehabilitation treatment for back pain. Client and therapist ratings were collected on 124 clients from 27 rehabilitation sites using the newly developed Occupational Rehabilitation Data Base (ORDB) functional capacity instrument. Rasch analysis was used to investigate: (1) unidimensionality, (2) hierarchical item difficulty continuum, (3) rater severity, and 4) person-item match. Overall, the functional capacity scale of the ORDB showed good measurement qualities. All items, except the Handling item fit the Rasch measurement model. Because of high fit statistics and loading on factors independent from the remainder of the items, the "handling" item was removed, from further analyses. Separate client-rated and therapist-rated instruments retained good item-level psychometrics. While client and therapist items showed similar item-difficulty hierarchical structures, clients had a tendency to be more severe in their rating and the correlation between client and therapist ratings was relatively low, 0.32. These findings suggest that Handling items should not be included as a DOT measure for clients with back pain. While the above psychometric study supports using client or therapist ratings as independent instruments, the lack of concordance between these ratings requires further investigation.

The utility of functional capacity evaluation: the opinion of physicians and other experts in the field of return to work and disability claims

OBJECTIVES

This qualitative study explored how Dutch experts perceive the utility of functional capacity evaluation (FCE) for return to work (RTW) and disability claim (DC) assessment purposes.

METHODS

Twenty-one RTW case managers and 29 DC experts were interviewed by telephone using a semi-structured interview schedule.

RESULTS

The RTW case managers valued the utility of FCE on a scale of 0-10. Their mean valuation was 6.5 (SD 1.5). The average valuation for DC experts was 4.8 (SD 2.2). Arguments in favor of FCE were (1) its ability to confirm own opinions and (2) the objectivity of its measurement method. Arguments against FCE were (1) the redundancy of the information it provides and (2) the lack of objectivity. Indications for FCE were musculoskeletal disorders, a positive patient self-perception of ability to work, and the presence of an actual job. Contraindications for FCE were medically unexplained disorders, a negative patient self-perception of ability to work, and the existence of disputes and legal procedures.

CONCLUSIONS

The responding RTW case managers perceived FCE to be more useful than the responding DC experts. The question of whether the arguments presented for and against the utility of FCE are valid is one that should be addressed in a future study.

A simple self-rating assessment method of residual work capability for occupational permanent disabilities

BACKGROUND

To explore the validity, reliability, and determinants of a simple self-rating assessment method of residual work capability (RWC) after occupational permanent disabilities.

METHODS

Five hundred and thirty-nine compensated permanent disability workers answered three consecutive visual analogue questionnaires wherein they self-rated their residual work capability in terms of speed (RWCS), quality (RWCQ) and a combination of speed and quality (RWCC). At two major hospitals in Taiwan, 169 of these subjects were evaluated with physical capacity assessment (PCA), cognition and sensation assessment (CSA), the work ability index (WAI), and the 12-item Chinese health questionnaire (CHQ-12).

RESULTS

High test-retest reliability (Pearson's correlation coefficient 0.77) and satisfactory concurrent validity were shown for RWCS and RWCC. All PCA, CSA and WAI showed significant correlation with RWCs, while CHQ-12 displayed borderline correlation. Employment status after injury and status of the victim's salary as the main source of income for his/her family before injury, were the major determinants of RWCs, in addition to the scales of PCA, CSA and WAI.

CONCLUSIONS

The RWCC resulting from the self-rating method may be used as a simple assessment of a victim's residual work capability after occupational permanent disabilities.

Validity of the dictionary of occupational titles residual functional capacity battery

BACKGROUND DATA

The Dictionary of Occupational Titles (DOT) is a U.S. government publication that defines each job in the United States according to 20 job factors. Fishbain et al. (Spine 1994;19:872-80) developed a DOT residual functional capacity (RFC) battery whose predictive validity for employment/unemployment had not been tested previously.

OBJECTIVES

The purposes of this study were as follows: (a) to determine whether results of a DOT-RFC battery performed at completion of pain facility treatment predicted employment status at 30 months' follow-up and (b) to determine whether the DOT-RFC battery predicted employment capacity as determined by the DOT employment levels of the chronic pain patients' (CPPs) jobs.

STUDY DESIGN

This is a prospective low back pain CPP pain facility treatment study using employment status and the DOT occupational levels as outcome measures.

METHODS

One hundred eighty-five consecutive CPPs who fitted the selection criteria completed a DOT-RFC battery at the completion of pain facility treatment and were contacted at 1, 3, 6, 12, 18, 24, and 30 months for determination of their employment status and DOT employment level. Eight DOT job factors plus pain and worker compensation status were found to be significantly different between employed and unemployed CPPs and between those employed in different DOT employment levels. For the 10 variables, stepwise discriminant analysis was used to select final predictor variables. Sensitivity and specificity were calculated along with pain level cutpoints that separated the groups.

RESULTS

The eight DOT job factors found to be statistically significant between groups were the following: stooping, climbing, balancing, crouching, feeling shapes, handling left and right, lifting, carrying, and pain and worker compensation status. In the discriminant analysis, these variables could discriminate between the employed and unemployed categories, with a sensitivity and specificity of approximately 75%. The pain level cutpoint between employed and unemployed was 5.4 on a 10-point scale.

CONCLUSIONS

We cannot as yet predict DOT-RFC employment levels. However, if a CPP can pass the above eight DOT job factors and has a pain level less than the 5.4 cutpoint, that CPP will have a 75% chance of being employed at 30 months after treatment at the pain facility. Therefore, some DOT-RFC battery job factors demonstrate a predictive validity in the "real work world."

Is work status of low back pain patients best described by an automated device or by a questionnaire?

STUDY DESIGN

A prospective cohort study of patients with subacute occupational back pain.

OBJECTIVES

To study the relation between a marketed opto-electric device measuring trunk kinematics, a widely used specific functional capacity questionnaire, and work status in back pain patients, and to assess the responsiveness to change in work status of the opto-electric device and the questionnaire.

SUMMARY OF BACKGROUND DATA

Several instruments have been developed to evaluate the functional capacities of patients with back pain, but the relation between these instruments and work status has rarely been studied.

METHODS

The relation between the opto-electric device, the questionnaire, and work status in patients with back pain was evaluated. The study population was a prospective cohort of patients with subacute back pain who were absent from regular work for more than 4 weeks. All data were compiled blindly on the same day, at study entry (4 weeks after work accident), and at 12, 24, and 52 weeks after the work accident. The validity of the questionnaire and opto-electric device scores was assessed with partial correlation analyses, standardized response mean, logistic regression analyses, and receiver operating characteristics curves.

RESULTS

The correlation between the questionnaire and opto-electric device scores was low. The questionnaire scores were significantly related to work status, but the opto-electric device scores were not. The questionnaire was responsive to change in work status, whereas the opto-electric device was not.

CONCLUSIONS

The opto-electric device scores were not related to either functional capacity scores (questionnaire) or work status in patients with low back pain, and the opto-electric device was not responsive to change in work status. Conversely, the questionnaire was related to work status and was responsive to change in work status.

"Movement" in work status after pain facility treatment

STUDY DESIGN

This was a randomized prospective follow-up study of pain facility treatment of chronic pain patients with low back pain, with return to work and work capacity as the outcome measures.

OBJECTIVES

To determine if after pain facility treatment chronic pain patients "move" in and out of work and in their work capacity; to determine the patterns of "movement;" and to determine the post-pain facility treatment follow-up sampling time points that would maximize the number of chronic pain patients correctly classified according to their final work and work capacity status.

SUMMARY OF BACKGROUND DATA

Past research and empiric observation have indicated that chronic pain patients may "move" after pain facility treatment in and out of work and in their job work capacity. Such "movement" can affect the results of outcome studies.

METHODS

Two hundred thirty-six consecutive chronic pain patients who fit study selection criteria were followed up at 1, 3, 6, 12, 18, 24, and 30 months after pain facility treatment for determination of work and work capacity status and separated according to the pattern of movement. Stepwise discriminant analysis was used to answer the study objectives. "Movement" in and out of work for these chronic pain patients also was compared with the US general population.

RESULTS

Chronic pain patients demonstrated eight work and four work capacity movement patterns. The 24- and 1-month time points predicted final work status correctly for 97.0% and 77.0% of the chronic pain patients, respectively, whereas the most significant predictor for correct work capacity status was the 24-month point. The annual percentage change in employment status for these chronic pain patients was more than in the US general population.

CONCLUSIONS

Because chronic pain patients "move" in and out of employment and for work capacity status after pain facility treatment, future outcome studies using these measures will have to consider carefully the impact of "movement" on their results.

Overlooked physical diagnoses in chronic pain patients involved in litigation, Part 2. The addition of MRI, nerve blocks, 3-D CT, and qualitative flow meter

This study followed 120 chronic pain patients referred to a multidisciplinary pain center. The referral diagnosis for many patients, such as "chronic pain," "psychogenic pain," or "lumbar strain," was frequently found to be incomplete or inaccurate (40%) following a multidisciplinary evaluation that used appropriate diagnostic studies, including magnetic resonance imaging, computed tomography, nerve blocks, and qualitative flowmeter. Significant abnormalities were discovered in 76% of the diagnostic tests. An organic origin for pain was found in 98% of these patients. The patients were discharged with objective verification of diagnoses including facet disease, nerve entrapment, temporomandibular joint disease, thoracic outlet syndrome, and herniated discs.