Evaluation of directional vacuum-assisted breast biopsy: Report for the National Breast Cancer Centre final report, CHERE Project Report No 21

This project was commissioned by the National Breast Cancer Centre (NBCC). The objectives of the project, as set out in the call for expressions of interest, were to determine: 1. The costs associated with the introduction and use of directional vacuum-assisted breast biopsy(DVA breast biopsy) in Australia; and 2. Whether directional vacuum-assisted breast biopsy used for diagnostic purposes is cost-effectivein Australia when compared to core biopsy. The motivation for commissioning the project was an assessment of directional vacuum-assisted breast biopsy conducted by the Medical Services Advisory Committee (MSAC) which concluded that the procedure is safe and more effective than core biopsy. Although a cost-effectiveness analysis was not conducted as part of the MSAC study, MSAC recommended that the costs associated with the procedure be investigated and that, pending a review of costs, the procedure receive interim Medicare funding at a higher level than was previously available. For the project reported here, data was required to be collected from both public and private sectors on the cost of introducing and using DVA breast biopsy and a cost-effectiveness analysis (CEA) conducted on the introduction and use of DVA breast biopsy with and without a prone table. The research question for the CEA was What is the impact on costs and number of open biopsies performed of using DVA breast biopsy compared to core biopsy for micro-calcification lesions? It is important to note that this question specifies both the outcome the CEA (change in the number of core biopsies performed) and that the investigation was to be confined to micro-calcification lesions only. An expert multidisciplinary working group was assembled to oversee the project. Following collection of data an interim report was produced for the working group. As DVABB is a relatively new technology in Australia the interim report indicated that the current number of sites performing DVABB and the level of experience of users was insufficient to provide meaningful data to achieve the project aims. On the advice of the working group it was agreed to suspend the project at this juncture. The NBCC will consider repeating the survey in the future.Breast cancer, diagnostics, breast biopsy, Australia

Understanding Price Variation Across Stores and Supermarket Chains: Some Implications for CPI Aggregation Methods

The empirical literature on price indices consistently finds that aggregation methods have a considerable impact, particularly when scanner data are used. This paper outlines a novel approach to test for the homogeneity of goods and hence for the appropriateness of aggregation. A hedonic regression framework is used to test for item homogeneity across four supermarket chains and across stores within each of these supermarket chains. We find empirical support for the aggregation of prices across stores which belong to the same supermarket chain. Support was also found for the aggregation of prices across three of the four supermarket chains.Price indexes; aggregation; scanner data; unit values; item homogeneity; hedonics

Can Dissimilarity Indexes Resolve the Issue of When to Chain Price Indexes?

Chaining is used in index number construction to update weights and link new items into an index. However, chained indexes can suffer from, sometimes substantial, drift. The Consumer Price Index Manual (ILO, 2004) recommends the use of dissimilarity indexes to determine when chaining is appropriate. This study provides the first empirical application of dissimilarity indexes in this context. We find that dissimilarity indexes do not appear to be sufficient to resolve the issue of when to chain.Index numbers; price indexes; chain drift; dissimilarity

Using a Constant Elasticity of Substitution Index to Estimate a Cost of Living Index: From Theory to Practice

Indexes often incorporate various biases due to their methods of construction. The Constant Elasticity of Substitution (CES) index can potentially eliminate substitution bias without needing current period expenditure data. The CES index requires an elasticity parameter. We derive a system of equations from which this parameter is estimated. We find that consumers are highly responsive to price changes at the elementary aggregation level. The results support the use of a geometric rather than arithmetic mean index at the elementary aggregate level. However, we find that even the use of a geometric mean index at the elementary aggregate level may not sufficiently account for the observed level of consumer substitution.Price indexes; elasticity of substitution; scanner data

Scanner Data, Time Aggregation and the Construction of Price Indexes

The impact of weekly, monthly and quarterly time aggregation on estimates of price change is examined for nineteen different supermarket item categories over a fifteen month period using scanner data. We find that time aggregation choices (the choice of a weekly, monthly or quarterly unit value concept for prices) have a considerable impact on estimates of price change. When chained indexes are used, the difference in price change estimates can be huge, ranging from 0.28% to 29.73% for a superlative (Fisher) index and an incredible 14.88% to 46,463.71% for a non-superlative (Laspeyres) index. The results suggest that traditional index number theory breaks down when weekly data with severe price bouncing are used, even for superlative indexes. Monthly and (in some cases even) quarterly time aggregation were found to be insufficient to eliminate downward drift in superlative indexes. In order to eliminate chain drift, multilateral index number methods are adapted to provide drift free measures of price change.Price indexes, aggregation, scanner data, chain drift, superlative indexes, unit values, multilateral index number methods, rolling window GEKS, rolli

Trauma exposure, PTSD and psychotic-like symptoms in post-conflict Timor Leste: an epidemiological survey.

BACKGROUND: Studies in developed countries indicate that psychotic-like symptoms are prevalent in the community and are related to trauma exposure and PTSD. No comparable studies have been undertaken in low-income, post-conflict countries. This study aimed to assess the prevalence of psychotic-like symptoms in conflict-affected Timor Leste and to examine whether symptoms were associated with trauma and PTSD. METHODS: The Psychosis Screening Questionnaire and the Harvard Trauma Questionnaire (assessing trauma exposure and PTSD) were administered in an epidemiological survey of 1245 adults (response rate 80.6%) in a rural and an urban setting in Timor Leste. We defined PSQ screen-positive cases as those people reporting at least one psychotic-like symptom (paranoia, hallucinations, strange experiences, thought interference, hypomania). RESULTS: The prevalence of PSQ screen-positive cases was 12 percent and these persons were more disabled. PSQ cases were more likely to reside in the urban area, experienced higher levels of trauma exposure and a greater prevalence of PTSD. PTSD only partially mediated the relationship between trauma exposure and psychotic-like symptoms. CONCLUSIONS: Psychotic-like symptoms may be prevalent in countries exposed to mass conflict. The cultural and contextual meaning of psychotic-like symptoms requires further inquiry in low-income, post-conflict settings such as Timor Leste.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Scanner data and the construction of price indices.

This thesis explores whether scanner data can be used to inform Consumer Price Index (CPI) construction, with particular reference to the issues of substitution bias and choice of aggregation dimensions. The potential costs and benefits of using scanner data are reviewed. Existing estimates of substitution bias are found to show considerable variation.An Australian scanner data set is used to estimate substitution bias for six different aggregation methods and for fixed base and superlative indexes. Direct and chained indexes are also calculated. Estimates of substitution bias are found to be highly sensitive to both the method of aggregation used and whether direct or chained indexes were used. The ILO (2004) recommends the use of dissimilarity indexes to determine the issue of when to chain. This thesis provides the first empirical study of dissimilarity indexes in this context. The results indicate that dissimilarity indexes may not be sufficient to resolve the issue. A Constant Elasticity of Substitution (CES) index provides an approximate estimate of substitution-bias-free price change, without the need for current period expenditure weights. However, an elasticity parameter is needed. Two methods, referred to as the algebraic and econometric methods, were used to estimate the elasticity parameter. The econometric approach involved the estimation of a system of equations proposed by Diewert (2002a). This system has not been estimated previously. The results show a relatively high level of substitution at the elementary aggregate level, which supports the use a Jevons index, rather than Carli or Dutot indexes, at this level. Elasticity parameter estimates were found to vary considerably across time, and statistical testing showed that elasticity parameter estimates were significantly different across estimation methods.Aggregation is an extremely important issue in the compilation of the CPI. However, little information exists about 'appropriate' aggregation methods. Aggregation is typically recommended over 'homogenous' units. An hedonic framework is used to test for item homogeneity across four supermarket chains and across all stores within each chain. This is a novel approach. The results show that treating the same good as homogenous across stores which belong to the same chain may be recommended

Scanner data, time aggregation and the construction of price indexes

We examine the impact of time aggregation on price change estimates for 19 supermarket item categories using scanner data. Time aggregation choices lead to a difference in price change estimates for chained indexes which ranged from 0.28% to 29.73% for a superlative index and an incredible 14.88%-46,463.71% for a non-superlative index. Traditional index number theory appears to break down with weekly data, even for superlative indexes. Monthly and (in some cases) quarterly time aggregation were insufficient to eliminate downward drift in superlative indexes. To eliminate drift, a novel adaptation of a multilateral index number method is proposed.Price indexes Scanner data Chain drift Multilateral index number methods Rolling window GEKS

Changes in antibiotic prescribing following COVID_19 restrictions: Lessons for post_pandemic antibiotic stewardship

AIMS: Public health responses to reduce SARS-CoV-2 transmission have profoundly affected the epidemiology and management of other infections. We examined the impact of COVID-19 restrictions on antibiotic dispensing in Australia. METHODS: We used national claims data to investigate antibiotic dispensing trends from November 2015 to October 2020 and whether changes reflected reductions in primary care consultations. We used interrupted time series analysis to quantify changes in monthly antibiotic dispensing and face-to-face and telehealth GP consultations and examined changes by recipient age, pharmacy State and prescriber specialty. RESULTS: Over the study period, an estimated 19_921_370 people had 125_495_137 antibiotic dispensings, 71% prescribed by GPs. Following COVID-19 restrictions, we observed a sustained 36% (95% CI: 33-40%) reduction in antibiotic dispensings from April 2020. Antibiotics recommended for managing respiratory tract infections showed large reductions (range 51-69%), whereas those recommended for non-respiratory infections were unchanged. Dispensings prescribed by GPs decreased from 63.5 per 1000 population for April-October 2019 to 37.0 per 1000 for April-October 2020. Total GP consultation rates remained stable, but from April 2020, 31% of consultations were telehealth. CONCLUSION: In a setting with a low COVID-19 incidence, restrictions were associated with a substantial reduction in community dispensings of antibiotics primarily used to treat respiratory infections, coincident with reported reductions in respiratory viral infections. Our findings are informative for post-pandemic antimicrobial stewardship and highlight the potential to reduce inappropriate prescribing by GPs and specialists for respiratory viral infections