The US Advisory Committee on Immunization Practices has recently recommended a new vaccine against herpes zoster (shingles) for routine use in adults aged > or =60 years. However, estimates of the cost effectiveness of this vaccine vary widely, in part because of gaps in the data on the value of preventing herpes zoster. Our aims were to (i) generate comprehensive information on the value of preventing a range of outcomes of herpes zoster; (ii) compare these values among community members and patients with shingles and post-herpetic neuralgia (PHN); and (iii) identify clinical and demographic characteristics that explain the variation in these values.
Community members drawn from a nationally representative survey research panel (n = 527) completed an Internet-based survey using time trade-off and willingness-to-pay questions to value a series of scenarios that described cases of herpes zoster with varying pain intensities (on a scale of 0 to 10, where 0 represents no pain and 10 represents the worst imaginable pain) and duration (30 days to 1 year). Patients with shingles (n = 382) or PHN (n = 137) [defined as having symptoms for > or =90 days] from two large healthcare systems completed telephone interviews with similar questions to the Internet-based survey and also answered questions about their current experience with herpes zoster. We constructed generalized linear mixed models to evaluate the associations between demographic and clinical characteristics, the length and intensity of the health states and time trade-off and willingness-to-pay values.
In time trade-off questions, community members offered a mean of 89 (95% CI 24, 182) discounted days to avoid the least severe scenario (pain level of 3 for 1 month) and a mean of 162 (95% CI 88, 259) discounted days to avoid the most severe scenario (pain level of 8 for 12 months). Compared with patients with shingles, community members traded more days to avoid low-severity scenarios but similar numbers of days to avoid high-severity scenarios. Compared with patients with PHN, community members traded fewer days to avoid high-severity scenarios. In multivariate analyses, older age was the only characteristic significantly associated with higher time trade-off values. In willingness-to-pay questions, community members offered a mean of $US450 (95% CI 203, 893) to avoid pain of level 3 for 1 month and a mean of $US1384 (95% CI 873, 2050) [year 2005 values] to avoid pain of level 8 for 12 months. Community members traded less money than patients with either shingles or PHN to avoid both low- and high-severity scenarios (p-values <0.05 to <0.001). In multivariate models, male gender, higher income and having experienced shingles or PHN were associated with higher willingness to pay to avoid herpes zoster. When patients were asked to assign a value to avoiding their own case of herpes zoster, those with shingles assigned a mean of 67 days or $US2319, while those with PHN assigned a mean of 206 days or $US18 184. Both the time and monetary value traded were associated with the maximum intensity of the pain the individual had experienced, but neither was associated with the duration of the pain.
We believe that this study provides the most comprehensive information to date on the value individuals place on preventing herpes zoster, and it includes the only such valuation from nationally representative community members as well as patients with herpes zoster. Community members would trade substantial amounts of time or money to avoid herpes zoster, even in the least severe scenarios. The time trade-off results in this study may differ from those in other studies because of important differences in methods of assessing health utilities. Consideration of both community and patient perspectives is crucial to help decision makers fully determine the implications of their policies now that a vaccine against herpes zoster is available.
"These comparative results imply that survey respondents may anticipate adaptation to disease that occurs with pre-existing conditions, or may otherwise believe that newly-occurring conditions are worse than those that have existed over time. On the other hand, Lieu and others found evidence that recent onset conditions were inferred as temporary and thus possibly better (i.e., less negative) than those that are permanent. Some of our data support the hypothesis that long-term conditions are worse to endure rather than better, as indicated by the negative premium placed on prior onset for mild conditions in our subset analysis. "
[Show abstract][Hide abstract] ABSTRACT: Health state descriptions used to describe hypothetical scenarios in community-perspective utility surveys commonly omit detail on the time of onset of a condition, despite our knowledge that among patients who have a condition, experience affects the value assigned to that condition. The debate regarding whose values to use in cost utility analysis is based in part on this observed difference between values depending on the perspective from which they are measured. This research explores the effect on community preferences for hypothetical health states of including the time of onset of a health condition in the health state description, to investigate whether this information induces community respondents to provide values closer to those of patients with experience with a condition. The goal of the research is to bridge the gap between patient and community preferences.
A survey of community-perspective preferences for hypothetical health states was conducted among a convenience sample of healthy adults recruited from a hospital consortium's research volunteer pool. Standard gambles for three hypothetical health states of varying severity were compared across three frames describing time of onset: six months prior onset, current onset, and no onset specified in the description. Results were compared within health state across times of onset, controlling for respondent characteristics known to affect utility scores. Sub-analyses were conducted to confirm results on values meeting inclusion criteria indicating a minimum level of understanding and compliance with the valuation task.
Standard gamble scores from 368 completed surveys were not significantly different across times of onset described in the health state descriptions regardless of health condition severity and controlling for respondent characteristics. Similar results were found in the subset of 292 responses that excluded illogical and invariant responses.
The inclusion of information on the time of onset of a health condition in community-perspective utility survey health state descriptions may not be salient to or may not induce expression of preferences related to disease onset among respondents. Further research is required to understand community preferences regarding condition onset, and how such information might be integrated into health state descriptions to optimize the validity of utility data. Improved understanding of how the design and presentation of health state descriptions affect responses will be useful to eliciting valid preferences for incorporation into decision making.
Health and Quality of Life Outcomes 01/2011; 9:6. DOI:10.1186/1477-7525-9-6 · 2.12 Impact Factor
"At least one study has shown that, compared with people who have not experienced HZ, those who have had HZ or PHN place higher value on preventing this disease. In this study, both groups questioned (community members and patients with HZ or PHN) said that they would be willing to pay substantial amounts of money to prevent HZ . "
[Show abstract][Hide abstract] ABSTRACT: The potentially serious nature of herpes zoster (HZ) and the long-term complication post-herpetic neuralgia (PHN) are often underestimated. One in four people will contract herpes zoster in their lifetime, with this risk rising markedly after the age of 50 years, and affecting one in two in elderly individuals. Pain is the predominant symptom in all phases of HZ disease, being reported by up to 90% of patients. In the acute phase, pain is usually moderate or severe, with patients ranking HZ pain as more intense than post-surgical or labour pains. Up to 20% of patients with HZ develop PHN, which is moderate-to-severe chronic pain persisting for months or years after the acute phase. We review the available data on the effect of HZ and PHN on patients' quality-of-life.
Findings show that HZ, and particularly PHN, have a major impact on patients' lives across all four health domains--physical, psychological, functional and social. There is a clear correlation between increasing severity of pain and greater interference with daily activities. Non-pain complications such as HZ ophthalmicus can increase the risk of permanent physical impairment. Some elderly individuals may experience a permanent loss of independence after an acute episode of HZ. Current challenges in the management of HZ and PHN are highlighted, including the difficulty in administering antiviral agents before pain becomes established and the limited efficacy of pain treatments in many patients. We discuss the clinical rationale for the HZ vaccine and evidence demonstrating that the vaccine reduces the burden of the disease. The Shingles Prevention Study, conducted among >38,000 people aged >or=60 years old, showed that the HZ vaccine significantly reduces the burden of illness and the incidence of both HZ and PHN. In the entire study population, zoster vaccination reduced the severity of interference of HZ and PHN with activities of daily living by two-thirds, as measured by two questionnaires specific to HZ.
A vaccination scheme may positively impact the incidence and course of HZ disease, thereby improving patients' quality-of-life.
BMC Medicine 06/2010; 8(1):37. DOI:10.1186/1741-7015-8-37 · 7.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Packet classification is a technique that classifies the flows into different classes. Nowadays the packet classification plays an important role for many new Internet services. Rectangle search is a well-known packet classification scheme which is based on multiple hash accesses for different filter length. It shows good scalability with respect to the number of filters; however, the lookup performance is not fast enough. For example, through experiments, each packet classification takes about 40 hash accesses in a 100,000-filter database and each hash access may take more than one memory access. Obviously, this is not capable to provide gigabits throughput. We propose an efficient scheme to improve the rectangle search. The scheme consists of two parts. In the first part, the "tuple reduction algorithm" based on filter duplication is proposed. In spite of the increased number of filters, the pre-computation information is dramatically reduced. The performance has increased two times while only about one quarter storage is required. Secondly, we propose a novel "lookahead caching" which can further improve the lookup performance. The basic idea is to find out the "un-matched" case for each incoming packet, thus it is different from the traditional caching mechanism. The experimental results indicate that the proposed scheme can fulfill OC-192 throughput.
Networks, 2002. ICON 2002. 10th IEEE International Conference on; 02/2002
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