The effect of information on preferences stated in a choice-based conjoint analysis

Objective: The objective of the study was to investigate the effect of a priori information on preferences for treatment elicited in a discrete choice experiment. - Methods: A convenience sample of 100 subjects was randomly split into two groups. The groups received minimal or extensive information on the treatment of ankle and foot impairment in stroke. Then, they participated in a discrete choice experiment. Possible treatment was described using eight decision criteria with two to four levels each. Part-worth utility coefficients for the criteria levels, criteria importance and overall treatment preference were estimated. It was tested whether the amount of information that was received influenced the outcome of the discrete choice experiment. - Results: \ud In the extensively informed group fewer reversals in the expected order of part-worth utilities were found. Criteria importance for four of the eight criteria and criteria importance ranking between the minimally and extensively informed subject groups were significantly different. The difference in part-worth utility of the levels had a minor effect on the predicted utility of the available treatments. - Conclusion: The lower number of level rank reversals in the extensively informed subjects indicates a better understanding of outcome desirability and thus a better understanding of the decision task. The effect of more extensive information on predicted treatment preference was minimal. - \ud Practice implications: While interpreting the results of a discrete choice experiment, the effect of prior knowledge on the decision problem has to be taken into account. Although information seems to increase the understanding of the decision task, outcomes valuation can also be directed by information and more extensive information increases the cognitive burden which is placed on the subjects. Future research should focus on the exact nature and size of the effects and the results of this study should be clinically validated

Patient preferences for next generation neural protheses to restore bladder function

Study design: A survey administered to 66 individuals with spinal cord injury (SCI) implementing a choice-based conjoint (CBC) analysis. Six attributes with three levels each were defined and used to generate choice sets with treatment scenarios. Patients were asked to choose the scenario that they preferred most. Objectives: To determine the utility weights for treatment characteristics as well as the overall preference for the three types of neural prostheses (NP), that is Brindley, rhizotomy-free Brindley, and pudendal nerve stimulation. Earlier studies have revealed the importance of restoration of bladder function, but no studies have been performed to determine the importance of NP features. Setting: Two academic affiliated medical systems’ SCI outpatient and inpatient rehabilitation programs, Cleveland, OH. Methods: CBC analysis followed by multinomial logit modeling. Individual part-worth utilities were estimated using hierarchical Bayes. Results: Side effects had the greatest significant impact on subject choices, followed by the effectiveness on continence and voiding. NPs with rhizotomy-free sacral root stimulation were preferred (45% first choice) over pudendal afferent nerve stimulation (39% second choice) and sacral root stimulation with rhizotomy (53% third choice). Almost 20% did not want to have an NP at all times. Conclusion: CBC has shown to be a valuable tool to support design choices. The data showed that persons would prefer a bladder NP with minimally invasive electrodes, which would give them complete bladder function, with no side effects and that can be operated by pushing a button and they do not have to recharge themselve

PDB73 – The Expected Value Of Bio-Artificial Pancreas Development In View Of Endocrinologists' And Patients' Preferences

Objectives Islet transplantation is an accepted transplantation method in type I Diabetes Mellitus, yet islet survival is hampered due to an insufficient transplantation site and severe immunological and inflammatory responses. The development of a bio-artificial pancreas (BAP) may contribute to transplanted islet functionality and survival. The objective of this study is to identify the most important transplantation characteristics and to asses patients’ and endocrinologists´ preferences for three potential BAP scenarios in order to guide further development. Methods The current standard of care and characteristics that determine clinical decisions for a particular transplantation method were analysed based on a literature search, semi-structured interviews and focus groups. A decision tree was constructed covering the main attributes effectiveness, patient safety, impact of the treatment for the patient and the required amount of donor material. The analytic hierarchy process was used to obtain the relative weights for each defined attribute in type I DM patients (n=21) and endocrinologists (n=12). Based on these weights, overall preferences for three potential BAP scenarios were calculated and compared to conventional pancreas and islets transplantation. Results The three most important treatment attributes are the effectiveness of the transplant for glucose control, patient safety and the surgical procedure. However, there were considerable differences between patients and endocrinologists in the importance of effectiveness of the transplant (weights were 0.471 and 0.257 respectively) and patient safety (0.331 and 0.423). While considering both endocrinologists’ and patients’ preferences, all three BAP scenarios assessed gained a higher overall preference in comparison to conventional islet transplantation. Conclusions This study indicates the prospects of BAP development. Nevertheless, the study also highlights the discrepancies between endocrinologists’ and type 1 diabetes patients’ preferences. In the future, BAP developers can benefit from this multidisciplinary approach by critically reviewing their BAP design, in view of patient safety and clinical performanc

The influence of voluntary upper body exercise on the performance of stimulated paralysed human quadriceps

In this study the influence of voluntary upper body exercise on the performance of stimulated paralysed human quadriceps was investigated in five subjects with spinal cord lesions in the thoracic spine. The experimental setup consisted of computer-controlled stimulation of the quadriceps using electrodes on the surface of the skin, a dynamometer for isometric or isokinetic loading of the lower leg, and a rowing ergometer for upper body exercise. In all subjects, quadriceps fatigue tests were conducted to study the influence of upper body exercise on knee torque during sustained continuous or intermittent stimulation of quadriceps. The relative asymptotic torque appeared to be significantly higher with the presence of upper body exercise than without. This was consistently found both between trials (starting with or without upper body exercise) as well as within trials, when upper body exercise was started or stopped during the trial. No significant influence of upper body exercise on the time constant of initial torque decline was found

The influence of the reciprocal cable linkage in the advanced reciprocating gait orthosis on paraplegic gait performance

A wide variety of mechanical orthoses is available to provide ambulation to paraplegic patients. Evaluation of energy cost during walking in each of these devices has been acknowledged as an important topic in this field of research. In order to investigate the benefits of a ballistic swing on gait performance in the Advanced Reciprocating Gait Orthosis (ARGO) a study was conducted in which the ARGO was compared with an orthosis with freely swinging legs. This Non Reciprocally linked Orthosis (NRO) was obtained by removing the reciprocal linkage in the subjects' own ARGOs. Subsequently, flexion/extension limits were mounted to permit adjustment of stride length. Six male paraplegic subjects with lesions ranging from T4 to T12 were included in the study. A single case experimental design (B-A-B-A) was conducted in order to improve internal validity. Biomechanical and physiological parameters were assessed and the subjects' preference for either ARGO or NRO was determined.\ud \ud It was found that large inter-individual differences produced insufficient evidence in this study to draw general conclusions about difference in energy expenditure between both orthoses. However, individual analysis of the results showed a reduction of oxygen cost (range: 4%-14%) in the NRO in T9 and T12 lesions, while oxygen cost in subjects with T4 lesions increased markedly (22% and 40%). It is concluded that patients with low level lesions could benefit in terms of oxygen lost from removing the reciprocal cable linkage in the ARGO. However, only one subject preferred the NRO for walking, whereas none of the subject chose the NRO for use in daily living activities. Removal of the reciprocal cable linkage in the ARGO may not be desirable for these patients