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.

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.

Test-retest reliability of the Isernhagen Work Systems Functional Capacity Evaluation in patients with chronic low back pain.

The aim of this study was to investigate test-retest reliability of the Isernhagen Work System Functional Capacity Evaluation (IWS FCE) in a sample of patients (n = 30) suffering from Chronic Low Back Pain (CLBP) and selected for rehabilitation treatment. The IWS FCE consists of 28 tests that reflect work-related activities like lifting, carrying, bending, etc. In this study, a slightly modified IWS FCE was used. Patients were included in the study if they were still at work or were less than 1 year out of work because of CLBP. Participants' mean age was 40 years, the duration of low back pain ranged between 5 and 10 years. Fifteen patients (50%) were out of work for a mean of 17 weeks, and they all received financial compensation. Two FCE sessions were held with a 2-week interval in between. Means per session, 95% confidence intervals of the mean difference, one-way random Intra Class Correlations (ICC), limits of agreement, Cohen's kappa and percentage of absolute agreement were calculated where appropriate. An ICC of 0.75 or more, a kappa value of more than 0.60 and a percentage of absolute agreement of 80% were considered as an acceptable reliability. Tests of the IWC FCE were divided into tests with and tests without an acceptable test-retest reliability on the basis of the kappa values, the percentage of absolute agreement and the ICC values. Fifteen tests (79%) showed an acceptable test-retest reliability based on Kappa values and percentage of absolute agreement. Eleven tests (61%) showed an acceptable test-retest reliability based on ICC values.

Immediate and delayed after-effects of long lasting mentally demanding work.

This study investigates the hypothesis that long lasting mental work demands are reflected in after-effects on attention demanding post-test probe tasks. Sixteen subjects were engaged in 2 simulated workdays consisting of mentally demanding tasks. On the difficult day the afternoon consisted of highly demanding information processing tasks; on the easy day the demands during the afternoon were low. The mornings of both days were equally demanding. At the start (pre-test) and the end (post-test) of both days, after 5 min (immediate post-test) as well as after approximately 2 h of recuperation (delayed post-test), a probe task was carried out. A memory-search task (varied mapping) is used as probe task. After-effects were expected in terms of a shift in the ratio between performance and effort on the post-test probe tasks compared with the pre-test probe task. Performance measures were reaction time and errors; effort was indicated by heart rate variability in the 0.07-0. 14 Hz band, referred to as 0.1 Hz component. Dayload manipulation appeared to be effective because of the load-related differences between the urinary excretion rates of adrenaline during both afternoons. Compared with the pre-test, only the number of errors was significantly increased in the post-test, carried out immediately at the end of the difficult afternoon. However, compared with the easy day, in the delayed post-test probe task after the difficult day, subjects tended to shorten reaction times, made significantly more errors, and invested significantly less effort. Moreover, at that time they felt more fatigued and deactivated as indicated by the results of the 'Scale of Experienced Load' (SEB) (fatigue) and 'Groninger Adjective Checklist' (GACL) (mood) questionnaires. The observed shift towards low-effort, more 'risky' task strategies in the post-tests fits well with Hockey's (1993) fatigue after-effects degradation pattern expected after periods of high workload. The repeated measurement of the relation of performance, effort and feelings reveals the dynamics of the pattern of fatigue after-effects over the (recovery) time.

Timing variability in children with early-treated congenital hypothyroidism.

This study reports on central and peripheral determinants of timing variability in self-paced tapping by children with early-treated congenital hypothyroidism (CH). A theoretical model of the timing of repetitive movements developed by Wing and Kristofferson was applied to estimate the central timekeeper (clock) and peripheral implementation (motor delay) variances from the variability in the response intervals. Before it is diagnosed and treated, CH is known to affect proper development of the cerebellum. If this would affect the time-keeper function of the cerebellum, it should be reflected by an increased central clock variability rather than by an increased peripheral motor-delay variability in terms of the Wing and Kristofferson model. Results of 46 children with early-treated CH, differing in severity (21 severe, 25 mild), and 34 normal controls are reported. A refinement of the Wing and Kristofferson model is applied to estimate central clock and peripheral motor delay timing variability more precisely than has been done before. Results show that for children with early-treated CH the estimate of the motor delay variance is four times higher than for the controls, while the estimate of the clock variance does not differ between the groups. It is concluded that motor problems in early-treated CH are associated with peripheral rather than with central timing deficiencies.

Motor and cognitive development in children with congenital hypothyroidism: a long-term evaluation of the effects of neonatal treatment.

Although neonatal thyroid screening programs have been of value in preventing cerebral damage, it is still controversial whether patients with congenital hypothyroidism achieve normal motor and cognitive skills. We studied the motor and cognitive skills of 72 children with early-treated congenital hypothyroidism and 35 control subjects at the ages of 7 1/2 and 9 1/2 years. The relative influence of cause, blood thyroxine concentration at the time of screening, and age at the start of thyroxine replacement therapy on motor and cognitive development was investigated. Despite having received treatment at a mean age of 23 days, children with low neonatal thyroxine concentrations (< 50 nmol/L) at screening, particularly children with thyroid agenesis, had significant motor problems and borderline intelligence scores as late as 9 1/2 years of age. Balance and gross motor functions seemed to decline between 7 1/2 and 9 1/2 years of age, whereas language and memory functions seemed to be maintained. Significant correlations between the start of therapy and both motor scores and performance IQ scores at the age of 7 1/2 years in children with severe hypothyroidism show the importance of early treatment for these patients.

The micro-structure of tapping movements in children.

In order to investigate the development of movement speed in relation to movement organization, children of 5, 6, 7, 8 and 9 years of age and adults carried out a reciprocal tapping task, in which time pressure and distance were manipulated. The duration, velocity, acceleration and accuracy of the movements were compared between age groups. Age differences appeared mainly in the homing time, not in the duration of the distance covering movement phase. Accuracy and velocity of the distance covering movement phase differed with age. Time pressure affected the homing time, but not the duration of the distance covering phase. Distance manipulation affected mainly the velocity and duration of the distance covering movement phase and the homing time. In the discussion it is contended that age differences in homing time may be related to both the accuracy of the distance covering movement phase and the rate of information processing of the subject.

Visually guided hand movements in children with minor neurological dysfunction: response time and movement organization.

Many children with signs of minor neurological dysfunction (MND) are unable to adapt precisely their movements to external goals, in particular when they are under time pressure. Pilot studies in our laboratories suggested that response times in various sorts of tapping tasks were longer in such children than in controls with an optimal neurological status. In the present study an experimental tapping task, presented in 'self-paced mode', is applied to explore further the relationships between response time and spatio-temporal organization of movements in children with MND as compared to optimal controls. Differences were found with respect to inter-response intervals as well as to the organization of the movements; children with MND have longer overall response times than controls, more movement elements per tap and shorter first movement elements. Further, the moment of maximal acceleration comes later in the children with MND than in the controls. Such differences in response time and movement organization may be due to information processing limitations and increased attentional demands for the execution of movements in MND children.