Carolyn Czoski-Murray

Estimation of a Preference-Based Index from a Condition-Specific Measure: The King's Health Questionnaire

Background. Generic preference-based measures of health may not adequately cover the impact of some conditions. There is therefore increasing interest in developing condition-specific preference-based measures. Objectives. The purpose of this study was to estimate a preference-based measure from a condition-specific measure of health for urinary incontinence, the 21-item Kings Health Questionnaire, for use in economic evaluation. Methods. The Kings Health Questionnaire (KHQ) was revised into a 5-dimensional health state classification amenable to valuation using items selected using psychometric evidence. Forty-nine states were valued using standard gamble by a representative sample of patients with urinary incontinence attending UK hospital outpatient clinics. Each respondent was asked to value 9 health states. Models have been estimated for predicting health state valuations for all 1024 states defined by the KHQ classification. The modeling had to cope with the clustering of data by respondent and its skewed distribution. Results. In total, 110 usable interviews were obtained from 169 patients approached to participate in the study. These responders generated 959 health state valuations. Mean health state values ranged from 0.77 to 0.98. Models were estimated using mean health state values and random effects models of individual-level health state values. These models generated robust estimates of the `main effects,` and in general, the results support the ordinality of the KHQ health state classification. There were problems modeling interaction effects, and a number of alternatives were explored. Conclusion. The recommended model for estimating a preference-based measure from the condition-specific KHQ is presented.

Model-based cost-effectiveness analysis of interventions aimed at preventing medication error at hospital admission (medicines reconciliation).

RATIONALE Medication errors can lead to preventable adverse drug events (pADEs) that have significant cost and health implications. Errors often occur at care interfaces, and various interventions have been devised to reduce medication errors at the point of admission to hospital. The aim of this study is to assess the incremental costs and effects [measured as quality adjusted life years (QALYs)] of a range of such interventions for which evidence of effectiveness exists. METHODS A previously published medication errors model was adapted to describe the pathway of errors occurring at admission through to the occurrence of pADEs. The baseline model was populated using literature-based values, and then calibrated to observed outputs. Evidence of effects was derived from a systematic review of interventions aimed at preventing medication error at hospital admission. RESULTS All five interventions, for which evidence of effectiveness was identified, are estimated to be extremely cost-effective when compared with the baseline scenario. Pharmacist-led reconciliation intervention has the highest expected net benefits, and a probability of being cost-effective of over 60% by a QALY value of pound10 000. CONCLUSIONS The medication errors model provides reasonably strong evidence that some form of intervention to improve medicines reconciliation is a cost-effective use of NHS resources. The variation in the reported effectiveness of the few identified studies of medication error interventions illustrates the need for extreme attention to detail in the development of interventions, but also in their evaluation and may justify the primary evaluation of more than one specification of included interventions.

Effectiveness of appropriately trained nurses in preoperative assessment: randomised controlled equivalence/non-inferiority trial

Abstract Objective: To determine whether preoperative assessments carried out by appropriately trained nurses are inferior in quality to those carried out by preregistration house officers. Design: Randomised controlled equivalence/non-inferiority trial. Setting: Four NHS hospitals in three trusts. Three of the four were teaching hospitals. Participants: All patients attending for assessment before general anaesthesia for general, vascular, urological, or breast surgery between April 1998 and March 1999. Intervention: Assessment by one of three appropriately trained nurses or by one of several preregistration house officers. Main outcome measures: History taken, physical examination, and investigations ordered. Measures evaluated by a specialist registrar in anaesthetics and placed in four categories: correct, overassessment, underassessment not affecting management, and underassessment possibly affecting management (primary outcome). Results: 1907 patients were randomised, and 1874 completed the study; 926 were assessed by house officers and 948 by nurses. Overall 121/948 (13%) assessments carried out by nurses were judged to have possibly affected management compared with 138/926 (15%) of those performed by house officers. Nurses were judged to be non-inferior to house officers in assessment, although there was variation among them in terms of the quality of history taking. The house officers ordered considerably more unnecessary tests than the nurses (218/926 (24%) v 129/948 (14%). Conclusions: There is no reason to inhibit the development of nurse led preoperative assessment provided that the nurses involved receive adequate training. However, house officers will continue to require experience in preoperative assessment.

Determinants of health related quality of life and health state utility in patients with age related macular degeneration: the association of contrast sensitivity and visual acuity

BackgroundThere has been increasing interest in the use of measures of health related quality of life (HRQoL) and health state utility values in Age Related Macular Degeneration (ARMD). Visual acuity has been found to be an important determinant of such measures in previous studies. More recently, another measure of visual impairment, contrast sensitivity has received considerable attention. We designed a study to examine whether the contribution of contrast sensitivity in explaining HRQoL and health utilities over and above that of visual acuity.Methods209 patients with unilateral or bilateral ARMD were recruited into a cross-sectional study of patients from a large teaching hospital. Patients underwent visual tests (near and distant visual acuity, contrast sensitivity) and completed a vision function questionnaire, the VF-14, HUI3, and time trade-off.ResultsUsing multivariate regression analysis, the study revealed that contrast sensitivity remained a statistically significant predictor of all outcome measures even when visual acuity was included. This result was supported by the correlation coefficients between measures.ConclusionsThe measurement of contrast sensitivity appears to be better related to a person’s HRQoL and health utility. Future studies should consider incorporating contrast sensitivity in addition to visual acuity. Studies, in particular economic evaluations, may underestimate the effect of treatment unless contrast sensitivity is considered.

Cost-effectiveness of screening high-risk HIV-positive men who have sex with men (MSM) and HIV-positive women for anal cancer.

BACKGROUND Anal cancer is uncommon and predominantly a disease of the elderly. The human papillomavirus (HPV) has been implicated as a causal agent, and HPV infection is usually transmitted sexually. Individuals who are human immunodeficiency virus (HIV)-positive are particularly vulnerable to HPV infections, and increasing numbers from this population present with anal cancer. OBJECTIVE To estimate the cost-effectiveness of screening for anal cancer in the high-risk HIV-positive population [in particular, men who have sex with men (MSM), who have been identified as being at greater risk of the disease] by developing a model that incorporates the national screening guidelines criteria. DATA SOURCES A comprehensive literature search was undertaken in January 2006 (updated in November 2006). The following electronic bibliographic databases were searched: Applied Social Sciences Index and Abstracts (ASSIA), BIOSIS previews (Biological Abstracts), British Nursing Index (BNI), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, NHS Database of Abstracts of Reviews of Effects (DARE), NHS Health Technology Assessment (HTA) Database, PsycINFO, Science Citation Index (SCI), and Social Sciences Citation Index (SSCI). STUDY SELECTION Published literature identified by the search strategy was assessed by four reviewers. Papers that met the inclusion criteria contained the following: data on population incidence, effectiveness of screening, health outcomes or screening and/or treatment costs; defined suitable screening technologies; prospectively evaluated tests to detect anal cancer. Foreign-language papers were excluded. Searches identified 2102 potential papers; 1403 were rejected at title and a further 493 at abstract. From 206 papers retrieved, 81 met the inclusion criteria. A further treatment paper was added, giving a total of 82 papers included. DATA EXTRACTION Data from included studies were extracted into data extraction forms by the clinical effectiveness reviewer. To analyse the cost-effectiveness of screening, two decision-analytical models were developed and populated. RESULTS The reference case cost-effectiveness model for MSM found that screening for anal cancer is very unlikely to be cost-effective. The negative aspects of screening included utility decrements associated with false-positive results and with treatment for high-grade anal intraepithelial neoplasia (HG-AIN). Sensitivity analyses showed that removing these utility decrements improved the cost-effectiveness of screening. However, combined with higher regression rates from low-grade anal intraepithelial neoplasia (LG-AIN), the lowest expected incremental cost-effectiveness ratio remained at over 44,000 pounds per quality-adjusted life-year (QALY) gained. Probabilistic sensitivity analysis showed that no screening retained over 50% probability of cost-effectiveness to a QALY value of 50,000 pounds. The screening model for HIV-positive women showed an even lower likelihood of cost-effectiveness, with the most favourable sensitivity analyses reporting an incremental cost per QALY of 88,000 pounds. LIMITATIONS Limited knowledge is available about the epidemiology and natural history of anal cancer, along with a paucity of good-quality evidence concerning the effectiveness of screening. CONCLUSIONS Many of the criteria for assessing the need for a screening programme were not met and the cost-effectiveness analyses showed little likelihood that screening any of the identified high-risk groups would generate health improvements at a reasonable cost. Further studies could assess whether the screening model has underestimated the impact of anal cancer, the results of which may justify an evaluative study of the effects of treatment for HG-AIN.

Cost-utility analysis of screening high-risk groups for anal cancer

OBJECTIVES Cost-utility analysis of screening for anal cancer in high-risk groups from a UK perspective. METHODS Criteria for the assessment of screening programmes were combined in a Markov model representing the natural history of anal cancer and HIV infection in the UK population of men who have sex with men (MSM). Alternative screening programmes were overlaid on the natural history model to evaluate their impact. The model was populated using data derived from a systematic review of the literature, and calibrated probabilistically to represent joint uncertainty in the input parameters. RESULTS Reference case results showed screening is unlikely to be cost-effective. Sensitivity analyses identified two important parameters: regression from low-grade anal intra-epithelial neoplasia (AIN) and utility effects. Increased AIN regression rates resulted in a minimum incremental cost per QALY gained of 39,405 pounds, whereas a best case scenario reduced the ratio to 20,996 pounds. CONCLUSIONS There are major areas of uncertainty. New analyses of existing primary data, undertaken specifically to inform regression rates may usefully update key parameters at little additional cost. If these analyses increase the likelihood that screening is cost-effective, further studies of the utility effects of treatment for high-grade AIN, and potential screening attendance rates may be justified.

Valuing condition specific health states using simulation contact lenses

OBJECTIVE This article reports on a study that used contact lenses to simulate the effects of a visual impairment caused by age-related macular degeneration (ARMD). The primary objective was to examine the feasibility of using this method of simulation. A secondary objective was to compare the results from this experiment with those obtained from ARMD patients (n = 209) using generic preference-based measures (Health Utilities Index 3 (HUI3) and EUROQOL 5 Dimensions (EQ-5D) and patient time trade-off (TTO). METHODS Utility values were elicited from healthy participants (n = 108) for three ARMD states simulated using contact lenses. RESULTS A significant relationship was found between visual acuity and TTO values elicited from our sample population (n = 108). It was stronger than that found for HUI3, EQ-5D, and own TTO values from patients (n = 209). Our sample values informed by the experience of simulation were found to be significantly different from values from patient TTO and generic preference-based measures obtained from patients for the same level of visual impairment. Sociodemographic characteristics did not significantly affect results, although baseline TTO utility values were positively associated with TTO values for simulated states. Nevertheless, the patient population was significantly older than the sample population. CONCLUSIONS ARMD has a major impact on our sample values TTO health state values. Differences across four visual health severity groups appear larger than those found for a generic preference-based measure and patient TTO values. For conditions that are difficult to describe and imagine, simulation methods may offer an additional tool when combined with usual methods of description for obtaining better informed general population preferences.

Informing disinvestment through cost-effectiveness modelling

The mandatory nature of recommendations made by the National Institute for Health and Clinical Excellence (NICE) in the UK has highlighted inherent difficulties in the process of disinvestment in existing technologies to fund NICE-approved technologies. A lack of evidence on candidate technologies means that the process of disinvestment is subject to greater uncertainty than the investment process, and inefficiencies may occur as a result of the inverse evidence law.This article describes a potential disinvestment scenario and the options for the decision maker, including the conduct of value of information analyses. To illustrate the scenario, an economic evaluation of a disinvestment candidate (screening for amblyopia and strabismus) is presented. Only very limited data were available. The reference case analysis found that screening is not cost effective at currently accepted values of a QALY. However, a small utility decrement due to unilateral vision loss reduced the incremental cost per QALY gained, with screening expected to be extremely cost effective.The discussion highlights the specific options to be considered by decision makers in light of the model-based evaluation. It is shown that the evaluation provides useful information to guide the disinvestment decision, providing a range of focused options with respect to the decision and the decision-making process.A combination of explicit model-based evaluation, and pragmatic and generalizable approaches to interpreting uncertainty in the decision-making process is proposed, which should enable informed decisions around the disinvestment of technologies with weak evidence bases.

A Hybrid Cohort Individual Sampling Natural History Model of Age-Related Macular Degeneration: Assessing the Cost-Effectiveness of Screening Using Probabilistic Calibration

Background. Age-related macular degeneration (AMD) is a leading cause of visual impairment and blindness. It is likely that treatment of AMD at earlier stages is more effective than later treatment; thus, screening for AMD should be considered. The aim of this study was to develop a natural history model of AMD to estimate the cost-effectiveness of screening. Methods. A hybrid cohort/individual sampling decision analytic model was developed. Primary data sets, expert elicitation, and data from the literature were used to populate the model. To incorporate joint parameter uncertainty, and to populate unobservable parameters, an innovative form of probabilistic calibration was applied to a range of output parameters. Results. In the reference case, annual screening from age 60 y is the most cost-effective option, although this is subject to high levels of uncertainty. Alternative, age-specific utility values show that screening is predicted to be less cost-effective, assuming interventions that reduce progression to wet AMD moderately improve the cost-effectiveness of screening, whereas the addition of anti—vascular endothelial growth factor therapy for juxtafoveal or subfoveal wet AMD lesions improves the cost-effectiveness of screening significantly. Conclusions. The extent of the uncertainty around the mean results, and the additional resources and possible reorganization of services required to implement screening, indicate that it may be preferable to reduce the level of uncertainty before implementing screening for AMD. Initial actions may be best targeted at assessing how routine data may be used to describe clinical presentation, a screening pilot study, and a secondary costing study.

Diagnosis, medication, and surgical management for patients with trigeminal neuralgia: a qualitative study

BackgroundTrigeminal neuralgia (TN) is a serious health problem, causing brief, recurrent episodes of stabbing or burning facial pain, which patients describe as feeling like an electric shock. The consequences of living with the condition are severe. There is currently no cure for TN and management of the condition can be complex, often delayed by misdiagnosis. Patients’ qualitative experiential accounts of TN have not been reported in the literature. Capturing subjective experiences can be used to inform the impact of the condition on quality of life and may contribute to a better understanding of current clinical practice with the aim of improving patient care.MethodsParticipants with TN (n = 16; 11 female), including those who have and have not undergone surgical intervention(s), took part in one of four focus groups. We conducted a thematic analysis within an essentialist framework using transcripts.ResultsThe impact of TN and treatment on the lives of participants emerged as four predominant themes: (1) diagnosis and support with TN, (2) living in fear of TN pain, (3) isolation and social withdrawal, and (4) medication burden and looking for a cure. Each theme is discussed and illustrated with extracts from the transcripts.ConclusionsKey issues to address in the management of patients with TN include continued delays in diagnosis, persistent side effects from medication, and a lack of psychological support. Developing strategies to enhance the management of patients with TN, informed by a biopsychosocial approach and multidisciplinary team working, is essential to enhancing the provision of current care.