Norway is one of several European countries that lacks a national value set and hence scoring algorithm for the EQ-5D, as well as norm data from the general population to inform interpretation of the five-level version of the EQ-5D (EQ-5D-5L) scores. The original aims of the project addressed these issues, but the COVID-19 pandemic meant that data for the national value set, which involves face to face interviews with the general population, could not be collected within the project time frame. Norm data was collected through a postal survey and a follow-up of survey respondents, assessed the effects of the COVID-19 pandemic on the health and quality of life of the general population for Norway.
Norwegian EQ-5D-5L value set
Modelling of a national value set for the EQ-5D-5L was to be based on values elicited from a representative sample of 1000 Norwegian adults from the general population in terms of region, age, sex, and level of education. Multi-stage random sampling and quota-sampling were used to give representativeness. The most recent EQ-5D valuation protocol was followed, including computer assisted face-to-face interviews. Data collection was stopped in March 2020 at approximately the halfway stage following 542 interviews undertaken at 45 locations in Akershus East, Kristiansand and Bergen. The pandemic ruled out completion before the project finish date.
The value set data followed a successful sampling strategy and the published methodology will inform the remainder of data collection, including face-to-face interviews with additional hygiene measures or remote methods that meet scientific criteria currently under development. Within the current project, available data are being used to address important methodological issues including the role of parenting responsibilities in value elicitation.
Norwegian EQ-5D-5L norm data
Norm data was collected from the general population aged 18 years and over randomly selected from the National Registry of the Norwegian Tax Administration (Folkeregisteret). Based on similar published surveys, 12,807 people were selected to give approximately 3,000 respondents to a postal questionnaire. The questionnaire also included the Patient-Reported Outcomes Measurement Information System (PROMIS) PROMIS-29 adult profile and sociodemographic questions. Completed questionnaires were returned by 3,200 respondents a few weeks before the COVID-19 safety measures were first implemented in Norway. The norm data are now published, and Norwegian users, including several national quality registers, can use the data for comparisons with patient populations to aid interpretation of EQ-5D-5L scores.
PROMIS is the most important development within the field of patient-reported outcomes since short-form measures, such as the EQ-5D and SF-36, became available 30 years ago. International evidence suggests that the PROMIS-29 will supplant existing short-form profiles such as the SF-36. The newly published first evaluation of the measurement properties of the PROMIS-29 in the Norwegian general population, will promote PROMIS and the uptake of this advanced system of measurement in Norway.
Follow-up survey under the COVID-19 pandemic
The survey took take place in October 2020 and 2466 (77.1%) respondents from baseline returned a questionnaire. The comparison with data collected before the pandemic will give unique national data assessing the effect of the pandemic on the health of the general population. In addition to the EQ-5D and PROMIS-29, the follow-up questionnaire included instruments and questions that are relevant to the COVID-19 pandemic: concerns relating to the pandemic, experiences with information from government agencies and the psychological impact of the pandemic. The results will provide important information on the impact of pandemic on the Norwegian general population, together with reference scores or norm data under the pandemic for the Norwegian Intensive Care and Pandemic Register and research involving COVID-19 patients.
The EQ-5D-5L norm data is now available to help users in the interpretation of scores for specific health problems and outcomes, which will enhance application in clinical and health services research, clinical practice and health care quality indicators work. The Central Norway Regional Health Authority responsible for the electronic data collection and reporting of results for the EQ-5D within the National Quality Registers, has been informed and is considering the feasibility of reporting the norm data alongside EQ-5D-5L scores for patients. The Norwegian Institute of Public Health in its role of PROMIS National Center (PNC), is responsible for supporting PROMIS users in Norway, including the distribution of PROMIS measures such as the PROMIS-29. Norwegian translations of PROMIS profiles and short forms are being used in clinical, health services research and quality measurement.
The Norwegian EQ-5D-5L value set and normative data will be derived following surveys of representative samples of the Norwegian general population. The EuroQol EQ-5D-5L protocol will be followed in the derivation of the value set including the application EuroQol-Valuation Technology (EQ-VT). The project leader will support a PhD student responsible for the day to day running of the project.
1 Survey planning and organisation
A structured review of the methodology underpinning existing national value sets and the EuroQol EQ-5D protocol will inform the survey methodology for deriving the value set. The project leader and PhD student will receive training in EQ-VT including quality control procedures. Up to six interviewers with a Masters level education and/or relevant experience of interviewing will be recruited and trained by the lead applicant and PhD student. Interviewers will train with colleagues with quality control procedures being applied before the pilot surveys.
The survey sampling and recruitment procedures will be designed to ensure representativeness of the Norwegian general population. The procedures will be based on the findings of the structured review and discussions with EuroQol Foundation, experts in sampling/survey methodology and research partners.
2 Pilot survey
Piloting will replicate the conditions of the main surveys. The results will determine the appropriateness of recruitment through response rates and the data will be used to assess interview quality by means of the quality control criteria built into EQ-VT. Recruitment strategies and interview training will be modified where necessary.
3 Main surveys
The EQ-5D-5L protocol recommends 10,000 responses for the derivation of hypothetical health state value sets. Each respondent values 10 health states, giving a sample size of 1000 individuals. To enhance participation, interviewees will be offered a gift card or similar incentive. The normative data will be collected from 3,000 members of the general population by means of a postal survey with two reminders and a gift card or similar incentive.
4 Statistical analysis
Completed survey questionnaires will be scanned and analysed using statistical software including R, STATA or equivalent. Following the testing of alternative regression models, the value set will be derived. Normative data will include scores will broken down by sociodemographic characteristics such as age, gender and education level.
In addition to several peer review scientific articles the study methodology and results will be presented at appropriate forums including national and international health economics conferences. Presentations will be given to users of the research including research centres that widely use the EQ-5D in clinical, health services and health economics research. The Norwegian scoring algorithm and normative data will be made freely available to users.
The Norwegian EQ-5D scoring algorithm based on the most recent five-level version and values of representative Norwegians, will improve the validity of cost-per-QALY calculations in Norway. The results will make a substantial contribution to health economics and policy makers acting on the results of economic evaluation.