Jackie Brown

Mammography screening : an incremental cost effectiveness analysis of double versus single reading of mammograms

Abstract Objective: To compare mammography reading by one radiologist with independent reading by two radiologists. Design: An observational non-randomised trial at St Margarets Hospital, Epping. Subjects: 33734 consecutive attenders for breast screening in the main trial and a sample of 132 attenders for assessment who provided data on private costs. Interventions: Three reporting policies were compared: single reading, consensus double reading, and non-consensus double reading. Main outcome measures: Numbers of cancers detected, recall rates, screening and assessment costs, and cost effectiveness ratios. Results: A policy of double reading followed by consensus detected an additional nine cancers per 10000 women screened (95% confidence interval 5 to 13) compared with single reading. A non-consensus double reading policy detected an additional 10 cancers per 10000 women screened (95% confidence interval 6 to 14). The difference in numbers of cancers detected between the consensus and non-consensus double reading policies was not significant (95% confidence interval -0.2 to 2.2). The proportion of women recalled for assessment after consensus double reading was significantly lower than after single reading (difference 2.7%; 95% confidence interval 2.4% to 3.0%). The recall rate with the non-consensus policy was significantly higher than with single reading (difference 3.0%; 2.5% to 3.5%). Consensus double reading cost less than single reading (saving pounds sterling4853 per 10000 women screened). Non-consensus double reading cost more than single reading (difference pounds sterling19259 per 10000 women screened). Conclusions: In the screening unit studied a consensus double reading policy was more effective and less costly than a single reading policy. Key messages Key messages Double reading of screening mammograms detects more cancers than does single reading Double reading with consensus reduces recall rates and has a lower total cost than single reading Breast screening units should consider adopting consensus double reporting for the first screening examination in order to improve efficiency Double reading with consensus is also likely to confer benefits at subsequent screening examinations, though the magnitude and cost effectiveness of these benefits are not known

Selecting a decision model for economic evaluation: a case study and review

The increased use of modelling techniques as a methodological tool in the economic evaluation of health care technologies has, in the main, been limited to two approaches – decision trees and Markov chain models. The former are suited to modelling simple scenarios that occur over a short time period, whilst Markov chain models allow longer time periods to be modelled, in continuous time, where the timing of an event is uncertain. In the context of economic evaluation, a less well developed technique is discrete event simulation, which may allow even greater flexibility.Taking the economic evaluation of adjuvant therapies for breast cancer as an illustrative example, the process of building a decision tree, a Markov chain model, and a discrete event simulation model are described. The potential benefits and problems of each approach are discussed.The suitability of the modelling techniques to economic evaluations of health care programmes in general is then discussed. This section aims to illustrate the areas in which the alternative modelling methods may be most appropriately employed.

Performance, treatment pathways, and effects of alternative policy options for screening for developmental dysplasia of the hip in the United Kingdom

Aims: To compare, using a decision model, performance, treatment pathways and effects of different newborn screening strategies for developmental hip dysplasia with no screening. Methods: Detection rate, radiological absence of subluxation at skeletal maturity and avascular necrosis of the femoral head, as favourable and unfavourable treatment outcomes respectively, were compared for the following strategies: clinical screening alone using the Ortolani and Barlow tests; the addition of static and dynamic ultrasound examination of the hips of all infants (universal ultrasound) or restricted to infants with defined risk factors (selective ultrasound); “no screening” (that is, clinical diagnosis only). Results: Universal or selective ultrasound detects more more affected children (76% and 60% respectively) than clinical screening alone (35%), results in a higher proportion of affected children with favourable treatment outcomes (92% and 88% respectively) than clinical screening alone (78%) or no screening (75%), and the highest proportion of these achieved without recourse to surgery (64% and 79% respectively) compared with clinical screening alone (18%). However, ultrasound based strategies are also associated with the highest number of unfavourable treatment outcomes arising in unaffected children treated following a false positive screening result. The detection rate of clinical screening alone becomes similar to that reported for universal ultrasound when based on studies using experienced examiners (80%) rather than junior medical staff (35%). Conclusion: From the largely observational data available, ultrasound based screening strategies appear to be most sensitive and effective but are associated with the greatest risk of potential adverse iatrogenic effects arising in unaffected children.

Valuing temporary and chronic health states associated with breast screening

The aim of this study was to derive quality of life values for the four key breast screening outcomes (true negative, false positive, true positive and false negative), including the quality of life effects of the screening and treatment processes. In doing so, methodological issues in health status measurement were explored, in particular the valuation of temporary health states. The true negative and false positive descriptions were temporary health states, lasting for short term durations (12 months) and the true positive and false negative outcomes were chronic health states lasting for long term durations (rest of life). Descriptions of breast screening outcomes were valued using the time trade-off technique and the visual analogue scale. Paired comparisons between TTO values for states with the same duration found a difference between the true negative and the false positive time trade-off values but no difference for true positive and false negative descriptions. The TTO values for the false positive were low. The study highlights several important methodological issues such as the use of the two stage procedure for valuing temporary health states, the impact of duration on values, the impact of anchor points, and the importance of qualitative analysis of respondents values. Further empirical testing of all these issues is recommended.

Extrapolation of cost-effectiveness information to local settings.

Providers and purchasers of health care are increasingly looking to the results of economic evaluations for guidance when making their decisions. In this paper the authors argue that there are dangers involved in the naive and unthinking use of published cost-effectiveness information outside the setting in which the information was generated. In considering whether the results of a published study are likely to be relevant locally, decision-makers are encouraged to assess whether the values of the key parameters reported in the published study apply locally. The possible sources of variation are described: unit cost differences; differences in the prevalence, incidence or natural history of disease; and differences in the comparators. In situations where the only source of variation is that local unit costs are different, local values can be substituted in the published analysis and local cost-effectiveness results estimated. Where the other sources of variation exist, the decision-maker is required to make an assumption about the nature of the interaction between the sources of variation and the values of the cost-effectiveness parameters. Using an example, the authors argue that local threshold analysis can aid decision-making where the policy change being considered has a high probability either of increasing effectiveness or reducing costs. Without local reanalysis, there is a danger that local policy changes in line with the recommendations of published studies will promote inefficiency. Re-analysis in the local setting is, however, reliant on authors of economic evaluations being explicit about their methods and the comparators used in their analyses.

Improving attendance for breast screening among recent non-attenders: A randomised controlled trial of two interventions in primary care

Objectives To examine the effectiveness and cost-effectiveness of two primary care based interventions aimed at increasing breast screening uptake for women who had recently failed to attend. Setting 13 General practices with low uptake in the second round of breast screening (below 60%) in north west London and the West Midlands, United Kingdom. Participants were women in these practices who were recent non-attenders for breast screening in the third round. Methods Pragmatic factorial randomised controlled trial, with people randomised to a systematic intervention (general practitioner letter), an opportunistic intervention (flag in womens notes prompting discussion by health professionals), neither intervention, or both. Outcome measures were attendance for screening 6 months after randomisation and cost-effectiveness of the interventions. Results 1158 Women were individually randomised as follows: 289 control; 291 letter; 290 flag; 288 both interventions. Attendance was ascertained for 1148 (99%) of the 1158 women. Logistic regression adjusting for the other intervention and practice produced an odds ratio (OR) for attendance of 1.51 (95% confidence interval (95% CI 1.02 to 2.26; p=0.04) for the letter, and 1.39 (95% CI 0.93 to 2.07; p=0.10) for the flag. Health service costs/additional attendance were £35 (letter) and £65 (flag). Conclusions Among recent non-attenders, the letter was effective in increasing breast screening attendance. The flag was of equivocal effectiveness and was considerably less cost-effective than the letter.

Cluster randomised controlled trial comparing the effectiveness and cost-effectiveness of two primary care interventions aimed at improving attendance for breast screening.

Objectives To examine the effectiveness and cost-effectiveness of two interventions based in primary care aimed at increasing uptake of breast screening. Setting 24 General practices with low uptake in the second round of screening (below 60%) in north west London and the West Midlands, UK. Participants were all women registered with these practices and eligible for screening in the third round. Methods Pragmatic factorial cluster randomised controlled trial, with practices randomised to a systematic intervention (general practitioner letter), an opportunistic intervention (flag in womens notes prompting discussion by health professionals), neither intervention, or both. Outcome measures were attendance for screening 6 months after the practices had been screened and cost-effectiveness of the interventions. Results 6133 Women were included: 1721 control; 1818 letter; 1232 flag; 1362 both interventions. Attendance data were obtained for 5732 (93%) women. The two interventions independently increased breast screening uptake in a logistic regression model adjusted for clustering, with the flag (odds ratio (OR) 1.43, 95% confidence interval (95% CI) 1.14 to 1.79; p=0.0019) marginally more effective than the letter (OR 1.31, 95% CI 1.05 to 1.64; p=0.015). Health service costs per additional attendance were £26 (letter) and £41 (flag). Conclusions Although both interventions increased attendance for breast screening, the letter was the more cost-effective. Any decision to implement both interventions rather than just the letter will depend on whether the additional (£41) costs are judged worthwhile in terms of the gains in breast screening uptake.

Efficiency of alternative policy options for screening for developmental dysplasia of the hip in the United Kingdom

Aims: To assess, using a decision model, the efficiency of ultrasound based and clinical screening strategies for developmental dysplasia of the hip. Methods: The additional cost per additional favourable outcome was compared for the following strategies: clinical screening alone using the Ortolani and Barlow tests; addition of static and dynamic ultrasound examination of the hips of all infants (universal ultrasound) or restricted to infants with defined risk factors (selective ultrasound); “no screening” (that is, clinical diagnosis only). Results: Ultrasound based screening strategies are predicted to be more effective but more costly than clinical screening or no screening. Estimated total costs per 100 000 live births are approximately £4 million for universal ultrasound, £3 million for selective ultrasound, £1 million for clinical screening alone, and £0.4 million for no screening. The relative efficiency of selective ultrasound and clinical screening is poorly differentiated, and depends on how infants are selected for ultrasound as well as the expertise of clinical screening examiners. If training costs less than £20 per child screened, clinical screening alone would be more efficient than selective ultrasound. Relative to no screening, each of the 16 additional favourable outcomes achieved as a result of selective ultrasound costs approximately £0.2 million, while each of the five favourable outcomes achieved through universal ultrasound screening, over and above selective ultrasound, costs approximately £0.3 million. Conclusions: Policy choice depends on values attached to the different outcomes, willingness to pay to achieve these and total budget.

Tamoxifen plus chemotherapy versus tamoxifen alone as adjuvant therapies for node-positive postmenopausal women with early breast cancer a stochastic economic evaluation

AbstractBackground: There remains uncertainty around the appropriate choice of adjuvant therapies to offer postmenopausal women with node-positive early breast cancer. Objective and study design: To present the results derived from a discrete event simulation (DES)model that compared tamoxifen plus chemotherapy versus tamoxifen alone in node-positive postmenopausal women diagnosed with early breast cancer. Methods: The data populating the model were mainly derived from the existing literature, which was analysed to specify probability distributions describing the uncertainty around the true value of each input parameter. The specified probability distributions facilitated the stochastic analysis of the decision model, whereby distributions of the model’s outputs [aggregate costs and quality-adjusted life years (QALYs)] were estimated. Results: The baseline results show that the addition of chemotherapy to tamoxifen in this patient group is relatively cost effective (under £4000 per additional QALY), but the distribution of the incremental cost-effectiveness ratio shows a wide range, including 10% of observations in which tamoxifen dominates tamoxifen plus chemotherapy. Conclusions: The results demonstrate the intuitive nature of stochastic evaluations of healthcare technologies, which may ease decision-makers’ interpretation of cost-effectiveness results.

Two view mammography at incident screens: cost effectiveness analysis of policy options

Abstract Objective: To determine the cost effectiveness of two view mammography at incident screens. Design: Incremental cost effectiveness analyses recognising differences in current reading policy, based on effectiveness data from an observational study. Setting: Breast screening programmes in England and Wales. Main outcome measures: Health service costs, cancers detected, incremental cost effectiveness ratios per cancer detected, whole time equivalent staff. Results: For programmes currently using one view with some form of double reading, the incremental cost effectiveness ratio of two view mammography at incident screens ranged between £6589 and £6716, depending on the reading policy. For programmes currently using one view with single reading, two policy options were found to be more efficient than two view single reading: one view with double reading (arbitration; incremental cost effectiveness ratio of £210) and two view double reading (arbitration). If programmes using one view with single reading changed to double reading (arbitration) and then subsequently to two views double reading (arbitration), additional cancers could be detected with an incremental cost effectiveness ratio of £7983 The implementation cost of two view mammography at incident screens in programmes in England and Wales would be £2.9 million and would require 13.4 whole time equivalent radiologists. Conclusions: The cost effectiveness of two view mammography at incident screens depends on the film reading policy. A policy of two view mammography at incident screens in England and Wales would be efficient only if programmes using single reading moved to double reading. Given limited resources, priority should be given to introducing double reading in the subset of programmes currently using single reading as this requires fewer additional radiologists and is more cost effective. Key messages The NHS breast screening programme is currently considering whether to introduce two view mammography at incident (subsequent) screens in England and Wales. As individual screening programmes operate different reading policies it is important to recognise that both two views and double reading may independently increase the cancer detection rate and thus affect cost effectiveness. A policy of two view mammography at incident screens is efficient only if programmes that use single reading also move to double reading. Implementation of two view mammography at incident screens in programmes in England and Wales would cost £2.9 million and require 13.4 whole time equivalent radiologists. Given the current shortage of radiologists, priority should be given to introducing double reading in the subset of programmes currently using single reading as this requires fewer additional radiologists and is more cost effective.