Zoë Philips

Good Practice Guidelines for Decision-Analytic Modelling in Health Technology Assessment A Review and Consolidation of Quality Assessment

The use of decision-analytic modelling for the purpose of health technology assessment (HTA) has increased dramatically in recent years. Several guidelines for best practice have emerged in the literature; however, there is no agreed standard for what constitutes a ‘good model’ or how models should be formally assessed. The objective of this paper is to identify, review and consolidate existing guidelines on the use of decision-analytic modelling for the purpose of HTA and to develop a consistent framework against which the quality of models may be assessed.The review and resultant framework are summarised under the three key themes of Structure, Data and Consistency. ‘Structural’ aspects relate to the scope and mathematical structure of the model including the strategies under evaluation. Issues covered under the general heading of ‘Data’ include data identification methods and how uncertainty should be addressed. ‘Consistency’ relates to the overall quality of the model.The review of existing guidelines showed that although authors may provide a consistent message regarding some aspects of modelling, such as the need for transparency, they are contradictory in other areas. Particular areas of disagreement are how data should be incorporated into models and how uncertainty should be assessed.For the purpose of evaluation, the resultant framework is applied to a decision-analytic model developed as part of an appraisal for the National Institute for Health and Clinical Excellence (NICE) in the UK. As a further assessment, the review based on the framework is compared with an assessment provided by an independent experienced modeller not using the framework.It is hoped that the framework developed here may form part of the appraisals process for assessment bodies such as NICE and decision models submitted to peer review journals. However, given the speed with which decision-modelling methodology advances, there is a need for its continual update.

Cost-effectiveness of shared pharmaceutical care for older patients: RESPECT trial findings

BACKGROUND Pharmaceutical care serves as a collaborative model for medication review. Its use is advocated for older patients, although its cost-effectiveness is unknown. Although the accompanying article on clinical effectiveness from the RESPECT (Randomised Evaluation of Shared Prescribing for Elderly people in the Community over Time) trial finds no statistically significant impact on prescribing for older patients undergoing pharmaceutical care, economic evaluations are based on an estimation, rather than hypothesis testing. AIM To evaluate the cost-effectiveness of pharmaceutical care for older people compared with usual care, according to National Institute for Health and Clinical Excellence (NICE) reference case standards. METHODS An economic evaluation was undertaken in which NICE reference case standards were applied to data collected in the RESPECT trial. RESULTS On average, pharmaceutical care is estimated to cost an incremental 10 000 UK pounds per additional quality-adjusted life year (QALY). If the NHSs cost-effectiveness threshold is between 20 000 and 30 000 UK pounds per extra QALY, then the results indicate that pharmaceutical care is cost-effective despite a lack of statistical significance to this effect. However, the statistical uncertainty surrounding the estimates implies that the probability that pharmaceutical care is not cost-effective lies between 0.22 and 0.19. Although results are not sensitive to assumptions about costs, they differ between subgroups: in patients aged >75 years pharmaceutical care appears more cost-effective for those who are younger or on fewer repeat medications. CONCLUSION Although pharmaceutical care is estimated to be cost-effective in the UK, the results are uncertain and further research into its long-term benefits may be worthwhile.

Preventive strategies for group B streptococcal and other bacterial infections in early infancy: cost effectiveness and value of information analyses

Objective To determine the cost effectiveness of strategies for preventing neonatal infection with group B streptococci and other bacteria in the UK and the value of further information from research. Design Use of a decision model to compare the cost effectiveness of prenatal testing for group B streptococcal infection (by polymerase chain reaction or culture), prepartum antibiotic treatment (intravenous penicillin or oral erythromycin), and vaccination during pregnancy (not yet available) for serious bacterial infection in early infancy across 12 maternal risk groups. Model parameters were estimated using multi-parameter evidence synthesis to incorporate all relevant data inputs. Data sources 32 systematic reviews were conducted: 14 integrated results from published studies, 24 involved analyses of primary datasets, and five included expert opinion. Main outcomes measures Healthcare costs per quality adjusted life year (QALY) gained. Results Current best practice (to treat only high risk women without prior testing for infection) and universal testing by culture or polymerase chain reaction were not cost effective options. Immediate extension of current best practice to treat all women with preterm and high risk term deliveries without testing (11% treated) would result in substantial net benefits. Currently, addition of culture testing for low risk term women, while treating all preterm and high risk term women, would be the most cost effective option (21% treated). If available in the future, vaccination combined with treating all preterm and high risk term women and no testing for low risk women would probably be marginally more cost effective and would limit antibiotic exposure to 11% of women. The value of information is highest (�67m) if vaccination is included as an option. Conclusions Extension of current best practice to treat all women with preterm and high risk term deliveries is readily achievable and would be beneficial. The choice between adding culture testing for low risk women or vaccination for all should be informed by further research. Trials to evaluate vaccine efficacy should be prioritised.

The Half-Life of Truth: What Are Appropriate Time Horizons for Research Decisions?

Purpose. To evaluate alternative approaches taken to estimate the population that could benefit from research and to demonstrate that explicitly modeling future change leads to more appropriate estimates of the expected value of information (EVI). Methods. Existing approaches to estimating the population typically focus on the time horizon for decisions, employing seemingly arbitrary estimates of the appropriate horizon. These approaches implicitly use the time horizon as a proxy for future changes in technologies, prices, and information. Different approaches to quantifying the time horizon are explored, in the context of a stylized model, to demonstrate the impact of uncertainty in this estimate on EVI. An alternative approach is developed that explicitly models future changes in technologies, prices, and information and that demonstrates the impact on EVI estimates. Results. Explicitly modeling future changes means that the EVI for the decision problem may increase or decrease over time, but the EVI for the group of parameters that can be evaluated by current research tends to decline. The finite and infinite time horizons for the decision problem represent special cases (e.g., price shock or no changes, respectively). This type of analysis can be used to inform policy decisions relating to the timing of research. Conclusions. The value of information depends on future changes in technologies, prices, and evidence. Finite time horizons for decision problems can be seen as a proxy for the complex and uncertain process of future change. A more explicit approach to modeling these changes could provide a more appropriate basis for calculating EVI, but this raises a number of significant methodological and technical challenges.

Developing a questionnaire to measure the psychosocial impact of an abnormal cervical smear result and its subsequent management: the TOMBOLA (Trial Of Management of Borderline and Other Low-grade Abnormal smears) trial

This paper describes the process of developing and testing a new questionnaire, Process Outcome Specific Measure (POSM), including an assessment of its content validity and reliability. The questionnaire was developed within the context of Trial Of Management of Borderline and Other Low-grade Abnormal smears (TOMBOLA) to assess the psychosocial impact of a low-grade abnormal cervical smear result and the subsequent management. A literature search, focus groups and thorough pre-testing involving experts and patients resulted in a short (15-item), easily completed and understood questionnaire. Questions address issues including cancer, health, fertility and sexual concerns. Repeatability was assessed in 110 TOMBOLA recruits using weighted κ; all but one of the questions showed levels of reliability near to, or above, 0.5. Cronbach’s standardised α was 0.73, indicating acceptable internal consistency. Each POSM item was correlated with the anxiety and depression sub-scales of the Hospital Anxiety Depression Scale (HADS). All except one of the questions correlated more highly with the total POSM score than with the HADS sub-scales thus indicating discriminant validity. The POSM will enable comparison of the alternative management policies for low-grade cervical smears in terms of the benefits (or otherwise) perceived by the women managed by these policies.

Priority setting for research in health care: An application of value of information analysis to glycoprotein IIb/IIIa antagonists in non-ST elevation acute coronary syndrome

The purpose of this study is to explain the rationale for the value of information approach to priority setting for research and to describe the methods intuitively for those familiar with basic decision analytical modeling. A policy-relevant case study is used to show the feasibility of the method and to illustrate the type of output that is generated and how these might be used to frame research recommendations. The case study relates to the use of glycoprotein Ilb/Illa antagonists for the treatment of patients with non-ST elevation acute coronary syndrome. This is an area that recently has been appraised by the National Institute for Health and Clinical Excellence.

United Kingdom cervical cancer screening and the costs of time and travel

OBJECTIVES The aim of this study was to estimate the time and travel costs generated by women when attending for Papanicolaou (Pap) smear tests or colposcopy appointments in the United Kingdom, both absolutely and relative to the health service cost of the national cervical cancer screening programs. METHODS Data were obtained from questionnaires completed by two samples of women participating in a three-center trial of management of low-grade abnormalities detected by screening (n = 1,106 for Pap smears and n = 1,203 for colposcopy appointments). Women were 20 to 59 years of age and resident in Grampian or Tayside, Scotland, or Nottingham, England. Questionnaire data were supplemented with sociodemographic information previously collected at the time of recruitment to the trial. RESULTS The mean total time and travel costs per attendance at a smear test and at a colposcopy appointment were estimated to be 9.2 pounds and 27.4 pounds, respectively, averaged across the three trial areas (valued at 2002 prices). Statistically significant intercenter disparities in time and travel costs were identified, particularly with respect to colposcopy appointments. For these, time and travel costs in Nottingham were substantially less than those in Grampian and Tayside (22.9 pounds, 30.2 pounds, and 32.1 pounds, respectively). Time and travel costs amount to 26 and 33 percent, approximately, over and above the direct health service costs of the English and Scottish screening programs, respectively. CONCLUSIONS The time and travel costs associated with participation in the UK cervical cancer screening programs are substantial and are not spatially uniform across the country.

Introducing HPV Triage into the English Cervical Cancer Screening Program: Consequences for Participation

ABSTRACT Objective: To predict the likely impact of adding human papillomavirus (HPV) triage for minor abnormalities on participation in the English cervical cancer screening program. Method: Contingent valuations of the existing Pap program and a possible HPV-augmented screening program, obtained from questionnaires completed by 1141 women in east-central England. Results: The value of participating in Pap screening was negatively associated with age, positively associated with educational level, and positively associated with the level of household income. Higher levels of worry about cervical cancer were associated with higher valuations of screening. Adding HPV-based triage to the Pap program lowered the value of screening participation for only two women, whereas for the sample as a whole, it increased the average valuation by about 47 per cent. Supposedly-negative characteristics of HPV testing, when described, were expected to trigger psychosocial concerns in respondents and thereby give rise to significant decreases in valuations of participating in a Pap-plus-HPV program. For most women, however, such information changed their valuations of participation in screening little, if at all. Conclusions: Accepting the proposition that higher contingent valuations indicate stronger behavioural preferences, our results offer insubstantial grounds for believing that the inclusion of HPV triage would detrimentally affect participation in Pap screening for cervical cancer.

Management of low‐grade cervical abnormalities detected at screening: which method do women prefer?

Objective:  To establish whether women with low‐grade abnormalities detected during screening for cervical cancer prefer to be managed by cytological surveillance or by immediate colposcopy.

Communicating mild and borderline abnormal cervical smear results: how and what are women told?

The way in which women are informed about borderline or mild smear results can have a significant psychological impact. By means of a questionnaire survey of general practices in Nottingham, England, this study audited the means by which abnormal smear results were normally communicated to subjects and analysed the content of these communications. Transmitting abnormal smear results, either by letter or by telephone call, was typically the responsibility of the practice nurse, and communications varied widely in informational content. We conclude that the method and content of communications imparting mild or borderline smear results differs between general practices, even within a small geographical area.