Author: abullen

Direct and indirect mapping of the BATH disease activity and function indices (BASDAI/BASFI) onto the EQ-5D-5L utility index in axial spondyloarthritis

What is the problem?
Clinical studies designed to assess the effectiveness of health technologies would ideally include outcome measures that are directly linked to utility measures of health-related quality of life. Health utilities are preference values that patients attach to their overall health status. This data is required to calculate quality-adjusted life years (QALYs) for use in cost-effectiveness analyses which is an evidence requirement for many decision makers, such as by NICE in the UK. In cases where this does not happen, an alternative solution that is extensively employed is mapping which involves using an additional data set to estimate the (statistical) relationship between outcomes measured in clinical studies and health utility.

What is Axial Spondyloarthritis?
Axial Spondyloarthritis (AxSpA) is a common rheumatic chronic progressive inflammatory disease, leading to joint damage/pain, stiffness, impaired physical function, fatigue and reductions in quality of life. The condition primarily affects the spine and sacroiliac joints. The onset is typically early in adulthood and is more common in men than in women. AxSpA patients incur significant direct NHS costs, which are mainly due to costs associated with prescriptions, and outpatient and day unit use. There are also indirect costs to society as axSpA affects young patients who have to take time off work and in the worst cases may permanently cease paid employment. The introduction of anti-TNF biologic therapies licensed for use in the management of axSpA (e.g., etanercept, adalimumab) has been associated with significantly improved outcomes. However, many of the pivotal trials for new biologics therapies did not include a generic preference-based HRQoL instrument such as the EQ-5D. Consequently, economic models of Health Technology Assessments of axSpA have been based on health utilities estimated from mapping exercises.

Our mapping study
There are no published mapping algorithms that estimate EQ-5D-5L utilities from the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) or the Bath Ankylosing Spondylitis Functional Index (BASFI) scores. We have recently had a journal article published in which we report on new mapping algorithms to obtain EQ-5D indices when only BASDAI/BASFI data are available. This is the first mapping study using a UK data set from the British Society for Rheumatology Biologics Register in AS (BSRBR-AS) which includes observations that come from England, Scotland and Wales.

What we did
Different statistical models to estimate health utility directly, or responses to individual EQ-5D questions (response mapping) indirectly from BASDAI/BASFI scores, were tested for patient self-report questionnaires. A range of metrics were used to compare and assess models performance.

Main findings
Our main study results showed that direct mapping models, and to a slightly lesser degree, response mapping models provided reliable algorithms for predicting EQ-5D-5L utilities from BASDAI/BASFI scores. These algorithms can be used in applied cost-effectiveness analysis in axSpA where EQ-5D-5L is the target outcome of interest.
A user-friendly accessible Excel tool is provided to assist analysis with the implementation of the best performing mapping algorithms (available in the online article Appendix)

The recommended mapping algorithms produced from our recent work allows researchers for the first time to estimate EQ-5D-5L values from BASDAI/BASFI data, enabling cost-utility analyses using datasets where the BASDAI/BASFI but no utility measures were collected.

Article details – this is an Open Access article and is freely available.
Neilson AR, Jones GT, Macfarlane GJ, Pathan EM, McNamee P. Generating EQ-5D-5L health utility scores from BASDAI and BASFI: a mapping study in patients with axial spondyloarthritis using longitudinal UK registry data. Eur J Health Econ. 2022 Feb 3. doi: 10.1007/s10198-022-01429-x. Epub ahead of print. PMID: 35113270.

Info-BC Launch

Author: Alistair Bullen


In January we officially launched the Info-BC survey. The study explores patient and health professional preferences for secondary breast cancer treatments using a health economics tool called a discrete choice experiment (DCE). The launch marks the culmination of over a year of research and hard work including literature reviews, qualitative interviews and analysis of the SMC’s Patient and Clinician Engagement (PACE) statements. Info-BC asks respondents to state their preference between hypothetical treatments which provide different benefits and toxicities to the patient. Patients are asked to imagine that they are considering the treatments for themselves whereas health professions are asked to imagine that they are recommending treatments for our hypothetical patient Irene.

Hypothetical Patient

The decision to include Irene was founded on feedback from health professionals who told us that it would difficult for them to recommend a treatment without knowing a little about the patient. The description we formulated for Irene was designed to reflect a typical secondary breast cancer patient so that responses from health professionals were more relevant to our real-life patient cohort. Official CTCAE descriptions of the grades of toxicities were shown to health professionals and patient language translations were shown to patients. To find out more about the nature of the hypothetical treatments, and the research which helped to design them, please read my previous post here.

Irene our hypothetical patient


Design and Recruitment

There is a finite number of hypothetical treatment decisions which patients are asked to make which were D-efficient and generated by the NGENE choice metrics software. The potential choices were compiled and inputted into our survey which was designed and implemented using the Qualtrics online survey platform. The survey can be accessed using an anonymous link which can be found on our Info-BC landing page. We are recruiting via 4 key channels; 1) our cancer research nurse, Morag McIntyre, at St John’s hospital who has been directly approaching patients who have may complete the survey there and then on a tablet or later at home online 2) via social media channels with help from ECTU, the Usher Institute, Breast Cancer Now, HERU and the CRUK Edinburgh Cancer Centre just to name a few 3) we have been utilising our own personal networks and directly approaching NHS staff who are suitable participants for the survey. 4) a respondent panel organised via Qualtrics. We intend to continue recruiting until April at which point we will conduct a final analysis of the data

Concluding remarks

The Info-BC project is moving into its final stages and we are excited to discover how the survey which we have been working for over a year to design will tell us about patient and health professional preferences for secondary breast cancer treatments. We would like to thank the rest of the patients and NHS staff who participated in our early research, the charities and organisations who have been helping with our recruitment, and all those who have taken time out of their day to complete the questionnaire. We look look forward to updating you on Info-BC in the future.