The relationship of medical, demographic and psychosocial factors to direct and indirect health utility instruments in rheumatoid arthritis.

OBJECTIVES: Cost-effectiveness analysis (CEA) is essential for the comparison of treatments for rheumatoid arthritis (RA). CEA centres on accurate measurement of health utility (HU) preferences. Direct measures of HU in RA patients demonstrate weaker correlations with health status (functional disability and pain) than indirect measures. We examined whether demographic and psychosocial factors relate to HU in RA patients. METHODS: HU was measured for 142 RA patients (76% women; mean age 58.75 yr) directly through standard gamble (SG) and time trade-off (TTO), and indirectly on the EuroQol (EQ-5D). Current pain (100 mm visual analogue scale) and recent functional disability (Health Assessment Questionnaire; HAQ) were assessed. A subsample of 48 provided demographic and psychosocial information (education, employment, marital/family status, knowledge about RA, medication beliefs, desirable responding, social support, optimism, and the Hospital Anxiety and Depression Scale; HADS). RESULTS: Direct HU had higher means (SG = 0.88, TTO = 0.86) than indirect HU (EQ-5D = 0.52). HAQ functional disability correlated with SG (r = - 0.28), TTO (r = - 0.31) and EQ-5D (r = - 0.67). Current pain correlated with TTO (r = - 0.19) and EQ-5D (r = - 0.36). HADS depression correlated with TTO (r = - 0.35) and EQ-5D (r = - 0.64); HADS anxiety also correlated with EQ-5D (r = - 0.46). CONCLUSIONS: Demographic and psychosocial factors cannot completely explain either the significant differences between direct and indirect HUs in RA patients or the moderate correlations of direct HUs with health status. Characteristics of the SG and TTO may make them inappropriate for HU assessment and CEA among RA patients.

Use of a corporate needs assessment to define the information requirements of an arthritis resource centre in Birmingham: comparison of patients' and professionals' views.

OBJECTIVES: Education and information are important components of the management of chronic disease, though provision of these in the routine clinic setting may be suboptimal. We carried out a corporate needs assessment, both to evaluate stakeholders' perceived usefulness of potential facilities that could be offered by a community-based arthritis resource centre in Birmingham and to compare the views of patients with rheumatological conditions and health professionals. METHODS: Rheumatology patients (n = 201 responders/309 contacted) and health professionals (n = 232/430) were asked to complete a questionnaire to assess both current rheumatology service provision and perceived needs for further information that could be offered within the proposed resource centre. Views of patients and professionals were compared using odds ratios. Logistic regression analysis determined patient characteristics associated with perceived usefulness of various information types. RESULTS: The overall response rate was 58%. Most patients were currently receiving medication but only 38% received written information on arthritis. Over 80% of responders felt that more information would be useful, particularly information in written leaflets. Compared with professionals, patients gave higher value to certain types of medical, non-medical, support and skills information, particularly individual information from trained volunteers, and specific information on benefits, diet and alternative therapy, and symptom management. Non-Caucasian patients gave higher value to the provision of material in different languages and the availability of multilingual volunteer staff. CONCLUSION: Rheumatology patients and professionals identified a relative lack of information for patients. There was wide interest in the provision of more information, with value placed on the provision of material in different languages, at an educational resource centre. This work has been used to develop the facilities currently offered at the Birmingham Arthritis Resource Centre. Further research is needed to investigate the effectiveness of the provision of good quality information to patients with arthritis.

The influence of previous experience on predictive motor control.

Anticipating the consequences of our motor commands is a fundamental component of sensorimotor control. For example, when one hand pulls on an object held in the other, the restraining hand generates an anticipatory increase in grip force thereby preventing the object from slipping. To investigate how such anticipation is learned subjects held an object, whose properties were under computer control, between their hands. This allowed instant changes in the behaviour of the manipulated object on a trial by trial basis. The extent of grip force modulation seen in one hand, when the other pulled on the object was found to depend in a systematic way on the object's properties experienced over at least the previous three trials.

Learning and decay of prediction in object manipulation.

Anticipating the consequences of our own actions is a fundamental component of normal sensorimotor control and is seen, for example, during the manipulation of objects. When one hand pulls on an object held in the other hand, there is an anticipatory increase in grip force in the restraining hand that prevents the object from slipping. This anticipation is thought to rely on a forward internal model of the manipulated object and motor system, enabling the prediction of the consequences of our motor commands. Here we investigate the development of such a predictive response. Each hand held an object that was attached to its own torque motor. On each trial the subject was required to pull on the object held in the left hand and to maintain the position of the object held in the right hand. The torque motors were computer controlled so that the objects could be either "linked" so that the forces on the objects were equal and opposite, acting as though they were a single object, or "unlinked," so that they acted as two independent objects. A predictive response in the restraining hand is only necessary when the objects are linked and is unnecessary in the unlinked condition where there is no risk of the object slipping. To examine the learning and decay of predictive responses, we measured the grip force responses during unlinked trials that followed a linked trial. After a single linked trial, anticipatory grip force was quick to develop, but decayed slowly over the following unlinked trials. Varying the time between trials showed that the rate of decay depended on the number of trials since the last linked trial rather than time. Increasing the frequency of linked trials showed an increased level of subsequent grip force modulation, but did not alter the decay rate. When the torque motors simulated a linked object that did not have normal physical properties, prediction was reduced. These results show that the use of predictive responses has a different time course for learning and decay, and the response depends on experience and the physical properties of the objects.

Predictive motor learning of temporal delays.

Anticipatory responses can minimize the disturbances that result from the action of one part of the body on another. Such a predictive response is evident in the anticipatory increase in grip force seen when one hand pulls on an object held in the other hand, thereby preventing the object from slipping. It is postulated that such a response depends on predicting the consequences of the descending motor command, as signaled by efference copy, using an internal model of both one's own body and the object. Here we investigate how the internal model learns the temporal consequences of the motor command. We employed two robots to simulate a virtual object held in one hand and acted on by the other. Delays were introduced between the action of one hand on the object and the effects of this action on the other hand. An initial reactive grip force response to the delayed load decayed with the development of appropriate anticipatory grip force modulation. However, no predictive modulation was seen when the object's movement was not generated by the subject, even when the motion was cued by a tone. These results suggest that, when an internal model learns new temporal relationships between actions and their consequences, this learning involves generating a novel response rather than adapting the original predictive response.