Every Monday our authors provide a round-up of some of the most recently published peer reviewed articles from the field. We don’t cover everything, or even what’s most important – just a few papers that have interested the author. Visit our Resources page for links to more journals or follow the HealthEconBot. If you’d like to write one of our weekly journal round-ups, get in touch.
Analytic considerations in applying a general economic evaluation reference case to gene therapy. Value in Health Published 17th May 2019
For fledgling health economists starting in the world of economic evaluation, the NICE reference case is somewhat of a holy text. If in doubt, check the reference case. The concept of a reference case for economic evaluation has been around since the first US Panel on Cost-Effectiveness in Health and Medicine in 1996 and NICE has routinely used its own reference case for well over a decade. The primary purpose of the reference case is to improve the quality and comparability of economic evaluations by standardising methodological practices. There have been arguments made that the same methods are not appropriate for all medical technologies, particularly those in rare diseases or where no treatment currently exists. The focus of this paper is on gene therapy: a novel method that inserts genetic material into cells (as opposed to a drug/surgery) to treat or prevent disease. In this area there has been significant debate as to the appropriateness of the reference case and whether a new reference case is required in this transformative but expensive area. The purpose of the article was to examine the characteristics of gene therapy and make recommendations on changes to the reference case accordingly.
The paper does an excellent job of unpicking the key components of economic evaluation in relation to gene therapy to examine where weaknesses in current reference cases may lie. Rather than recommend that a new reference case be created, they identify specific areas that should be paid special attention when evaluating gene therapy. Additionally, they produce a three part checklist to help analysts to consider what aspects of their economic evaluation they should consider further. For those about to embark on an economic evaluation of a gene therapy intervention, this paper represents an excellent starting point to guide your methodological choices.
Heterogeneous effects of obesity on mental health: evidence from Mexico. Health Economics [PubMed] [RePEc] Published April 2019
The first line of the ‘summary’ section of this paper caught my eye: “Obesity can spread more easily if it is not perceived negatively”. This stirred up contradictory thoughts. From a public health standpoint we should be doing our utmost to prevent increasing levels of obesity and their related co-morbidities, whilst simultaneously we should be promoting body positivity and well-being for mental health. Is there a tension here? Might promoting body positivity and well-being enable the spread of obesity? This paper doesn’t really answer that question, instead it sought to investigate whether overweight and obesity had differing effects on mental health within different populations groups.
The study is set in Mexico which has the highest rate of obesity in the world with 70% of the population being overweight or obese. Previous research suggests that obesity spreads more easily if not perceived negatively. This paper hypothesises that this effect will be more acute among the poor and middle classes where obesity is more prevalent. The study aimed to reveal the extent of the impact of obesity on well-being whilst controlling for common determinants of well-being by examining the impact of measures of fatness on subjective well-being, allowing for heterogeneous effects across differing groups. The paper focused only on women, who tend to be more affected by excess weight than men (in Mexico at least).
To assess subjective well-being (SWB) the General Health Questionnaire (GHQ) was used whilst weight status was measured using waist to height ratio and additionally an obesity dummy. Data was sourced from the Mexican Family and Life Survey and the baseline sample included over 13,000 women. Various econometric models were employed ranging from OLS to instrumental variable estimations, details of which can be found within the paper.
The results supported the hypothesis. They found that there was a negative effect of fatness on well-being for the rich, whilst there was a positive effect for the poor. This has interesting policy implications: policy attempt to reduce obesity may not work if excess weight is not perceived to be an issue. The findings in this study imply that different policy measures are likely necessary for intervening in the wealthy and the poor in Mexico. The paper offers several explanations as to why this relationship may exist, ranging from the poor having lower returns from healthy time (nod to the Grossman model), to differing labour market penalties from fatness due to different job types for the rich and the poor.
Obviously there are limits to the generalisability of these findings, however it does raise interesting questions about how we should seek to prevent obesity within different elements of society, and the unintended consequences that shifts in attitudes may have.
ICECAP-O, the current state of play: a systematic review of studies reporting the psychometric properties and use of the instrument over the decade since its publication. Quality of Life Research [PubMed] Published June 2019
Those who follow the methodological side of outcome measurement will be familiar with the capability approach, operationalised by the ICECAP suite of measures amongst others. These measures focus on what people are able to do, rather than what they do. It is now 12-13 years since the first ICECAP measure was developed: the ICECAP-O designed for use in older adults. Given the ICECAP measures are now included within the NICE reference case for the economic evaluation of social care, it is a pertinent time to look back over the past decade to assess whether the ICECAP measures are being used and, if so, to what degree and how. This systematic review focusses on the oldest of the ICECAP measures, the ICECAP-O, and examines whether it has been used, and for what purpose as well as summarising the results from psychometric papers.
An appropriate search strategy was deployed within the usual health economic databases, and the PRISMA checklist was used to guide the review. In total 663 papers were identified, of which 51 papers made it through the screening process.
The first 8 years of the ICECAP-O’s life is characterised by an increasing amount of psychometric studies, however in 2014 a reversal occurred. Simultaneously, the number of studies using the ICECAP-O within economic evaluations has slowly increased, surmounting the number examining the psychometric properties, and has increased year-on-year in the three years up to 2018. Overall, the psychometric literature found the ICECAP-O to have good construct validity and generally good content validity with the occasional exception in groups of people with specific medical needs. Although the capability approach has gained prominence, the studies within the review suggest it is still very much seen as a secondary instrument to the EQ-5D and QALY framework, with results typically being brief with little to no discussion or interpretation of the ICECAP-O results.
One of the key limitations to the ICECAP framework to date relates to how economists and decision makers should use the results from the ICECAP instruments. Should capabilities be combined with time (e.g. years in full capability), or should some minimum (sufficient) capability threshold be used? The paper concludes that in the short term, presenting results in terms of ‘years of full capability’ is the best bet, however future research should focus on identifying sufficient capability and establishing monetary thresholds for a year with sufficient capability. Given this, whilst the ICECAP-O has seen increased use over the years, there is still significant work to be done to facilitate decision making and for it to routinely be used as a primary outcome for economic evaluation.
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