Challenges in Valuing Temporary Health States for Economic Evaluation: A Review of Empirical Applications of the Chained Time Trade-Off Method.

BACKGROUND: The time trade-off (TTO) technique is commonly used to elicit health state utilities. Nevertheless, when the health states being valued are temporary, the TTO approach may be unsuitable. A variant of TTO- chained TTO-has been suggested to be used when the health states are temporary, but little research has been done on how chained TTO should be conducted. OBJECTIVES: To systematically review the use of chained TTO in valuing temporary health states. METHODS: A systematic literature search was conducted using the following major databases: Ovid MEDLINE(R), Embase, EBM Reviews, and PsycINFO. Abstracts (full articles if necessary) were screened by two independent reviewers, with a third reviewer resolving any disagreements. RESULTS: The resulting number of articles for review was low (n = 9). All the reviewed studies used face-to-face interviews, most had small sample sizes (<100), and all studies valued a small number of health states (<7), with time horizons typically ranging from 4 weeks to 1 year. All studies discussed methodological issues of using chained TTO, and some compared the results with those generated using other preference elicitation methods. CONCLUSIONS: Chained TTO appears to be feasible, consistent, and responsive and allows the valuation of temporary health states that would improve the efficiency and accuracy of decision making in health and health care. Nevertheless, the evidence is limited due to the low number of relevant studies in the literature. Further research is needed to examine the performance and validity of chained TTO compared with conventional TTO in the valuation of temporary health states.

Interventions for hyperhidrosis in secondary care: a systematic review and value-of-information analysis.

BACKGROUND: Hyperhidrosis is uncontrollable excessive sweating that occurs at rest, regardless of temperature. The symptoms of hyperhidrosis can significantly affect quality of life. The management of hyperhidrosis is uncertain and variable. OBJECTIVE: To establish the expected value of undertaking additional research to determine the most effective interventions for the management of refractory primary hyperhidrosis in secondary care. METHODS: A systematic review and economic model, including a value-of-information (VOI) analysis. Treatments to be prescribed by dermatologists and minor surgical treatments for hyperhidrosis of the hands, feet and axillae were reviewed; as endoscopic thoracic sympathectomy (ETS) is incontestably an end-of-line treatment, it was not reviewed further. Fifteen databases (e.g. CENTRAL, PubMed and PsycINFO), conference proceedings and trial registers were searched from inception to July 2016. Systematic review methods were followed. Pairwise meta-analyses were conducted for comparisons between botulinum toxin (BTX) injections and placebo for axillary hyperhidrosis, but otherwise, owing to evidence limitations, data were synthesised narratively. A decision-analytic model assessed the cost-effectiveness and VOI of five treatments (iontophoresis, medication, BTX, curettage, ETS) in 64 different sequences for axillary hyperhidrosis only. RESULTS AND CONCLUSIONS: Fifty studies were included in the effectiveness review: 32 randomised controlled trials (RCTs), 17 non-RCTs and one large prospective case series. Most studies were small, rated as having a high risk of bias and poorly reported. The interventions assessed in the review were iontophoresis, BTX, anticholinergic medications, curettage and newer energy-based technologies that damage the sweat gland (e.g. laser, microwave). There is moderate-quality evidence of a large statistically significant effect of BTX on axillary hyperhidrosis symptoms, compared with placebo. There was weak but consistent evidence for iontophoresis for palmar hyperhidrosis. Evidence for other interventions was of low or very low quality. For axillary hyperhidrosis cost-effectiveness results indicated that iontophoresis, BTX, medication, curettage and ETS was the most cost-effective sequence (probability 0.8), with an incremental cost-effectiveness ratio of £9304 per quality-adjusted life-year. Uncertainty associated with study bias was not reflected in the economic results. Patients and clinicians attending an end-of-project workshop were satisfied with the sequence of treatments for axillary hyperhidrosis identified as being cost-effective. All patient advisors considered that the Hyperhidrosis Quality of Life Index was superior to other tools commonly used in hyperhidrosis research for assessing quality of life. LIMITATIONS: The evidence for the clinical effectiveness and safety of second-line treatments for primary hyperhidrosis is limited. This meant that there was insufficient evidence to draw conclusions for most interventions assessed and the cost-effectiveness analysis was restricted to hyperhidrosis of the axilla. FUTURE WORK: Based on anecdotal evidence and inference from evidence for the axillae, participants agreed that a trial of BTX (with anaesthesia) compared with iontophoresis for palmar hyperhidrosis would be most useful. The VOI analysis indicates that further research into the effectiveness of existing medications might be worthwhile, but it is unclear that such trials are of clinical importance. Research that established a robust estimate of the annual incidence of axillary hyperhidrosis in the UK population would reduce the uncertainty in future VOI analyses. STUDY REGISTRATION: This study is registered as PROSPERO CRD42015027803. FUNDING: The National Institute for Health Research Health Technology Assessment programme.