Research and analysis

Positive Voices 2022: survey report appendices

Updated 12 January 2024

Appendix 1. Survey methodology

Positive Voices 2022 used the same methodology as Positive Voices 2017 with a few exceptions. Recruitment was largely through probabilistic sampling but due to the challenges of recruiting through a pandemic, the strategy was changed for 14 clinics to sequential sampling recruitment.

Most of the questions remained the same for Positive Voices 2022 so the responses could be compared to Positive Voices 2017. However, some sections were extended and a new section on the impact of the coronavirus disease (COVID-19) was added to gain an insight into the impact of the pandemic (see Table 1).

Table 1. Topics in Positive Voices 2022

Topic Details
HIV diagnosis and treatment Year and country of diagnosis, antiretroviral therapy (ART) adherence, side effects, viral load, undetectable = untransmittable (U=U)
Non-HIV medical conditions and treatments Ever diagnosed with health conditions including cardiovascular, joint and bone, mental health, and other long-term medical conditions, and medications taken for mental health
Health and social service use and satisfaction General practice and HIV service use and satisfaction, contact with the National Health Service (NHS), social care and support services in the previous year
Met and unmet needs Need for and receipt of HIV, health, and social and welfare-related services in the previous year
Health and wellbeing Life satisfaction, quality of life (5 dimensions, 5 level, health outcome tool by EuroQoL (EQ-5D-5L)), depression (Patient Health Questionnaire (PHQ-9)), anxiety (General Anxiety Disorder Questionnaire (GAD-7)), social support (Functional Social Support Questionnaire (FSSQ)), and resilience (14-item resilience scale (RS-14) questionnaire)
HIV status sharing, stigma, and discrimination HIV status sharing, stigma, and discrimination
Impact of COVID-19 Impact and history of COVID-19, vaccination, and access to and satisfaction with remote consultations
Sex and relationships Sexual history (main and casual partners), condom use, seropositioning, and sexually transmitted infection (STI) diagnoses
General health and lifestyle Physical activity, body mass index (BMI), alcohol, tobacco, and drug use
Social and demographic information Sexuality, religion, education, employment, housing, financial security

Sampling frame

The HIV and AIDS Reporting System (HARS) is a consultation-based, disaggregated data set which all UK outpatient HIV service providers report to on a quarterly basis. This national surveillance data set is used to monitor the quality of care received by patients and their clinical outcomes.

A two-stage sampling design was used:

1. A total of 178 HIV clinics in England, Wales, and Scotland reporting more than 5 patients were invited to take part.

2. Among participating clinics, a random sample of patients was drawn from the most recent year of HARS attendance data available prior to recruitment (2020), based on the clinic size.

Local clinic staff used the random sample list to identify patients to approach either in person, by phone (call or text message), email, or post. Participants were offered a choice of online and paper versions of the questionnaire to complete. The paper surveys were returned either in clinic or via a freepost envelope, which was included in the survey pack. As an incentive, all participants were offered an unconditional £5 high street voucher which they could redeem online.

Data collection

Data collection involved both the recruitment of HIV clinics and the recruitment of patients, who received HIV care from the participating clinics, as survey participants. Participants were recruited between the beginning of April 2022 and end of March 2023. In total, 101 clinics took part, of which 60% had previously participated in Positive Voices 2017. Recruitment of HIV clinics was initially intended to run for six months, as in Positive Voices 2017, however the survey was extended to 12 months to allow clinics more time to reach their recruitment targets. Local clinic resource pressures, lower numbers of face-to-face clinic appointments among HIV patients after the start of the COVID-19 pandemic, and the Monkeypox outbreak, were all unanticipated challenges encountered during the recruitment period of Positive Voices 2022. 

Two methods were used to recruit patients. All clinics were provided with a selection of patients based on a probabilistic (random) sampling methodology. After 6 months, 14 larger, predominantly London clinics, switched to a sequential, attendance-based sampling methodology, where any participant attending the clinic who met the eligibility criteria could be invited to participate (eligibility criteria included those aged 18 years and over, diagnosed with HIV and accessing HIV outpatient services at one of the participating clinics, and with no language barrier). These 14 clinics were chosen as they had large sample lists but, importantly, they had the highest number of pre-selected patients who had not been approached to participate after the intended 6 months recruitment period due to resource pressures.

At the study outset, a total of 18,106 patients were randomly sampled from participating clinics in the HARS data set of people who had received HIV care in 2020. The sample represented approximately 20% of the patients who attended each clinic in 2020. Additionally, all people attending the participating clinics who were recorded as being transsexual or gender diverse were invited to participate in the survey, due to this cohort being a small group in which large health inequalities have been observed and to ensure that enough responses were collected to be able to present meaningful data on this cohort.

Overall, 9,184 patients from the 98 clinics that provided information were successfully approached by clinic staff and had either accepted or declined to take part. A further 4,994 had been approached electronically but clinics had received no response. In total, 4,540 participants completed the survey and provided sufficient demographic information to be weighted, which included 4,469 participants from the 98 clinics able to be included in response rate calculations. Thus, the response rate was between 48.7% (4,469 of 9,184) and 31.5% (4,469 out of 9,184 plus 4,994).

The majority (80.1%, 3,636) of patients were recruited from the probabilistic sample.

Paper questionnaires were entered electronically by hand. Queries were highlighted and a record was kept during the data entry stage (for example, illegible handwriting, multiple ticked boxes). Outliers and other uncertainties were reviewed by the study team. This report is based on a single-entered data set of the paper questionnaires.

Data cleaning

Data from paper questionnaires were appended with the online data. Throughout the online questionnaire, routing had been implemented so that participants only answered the questions that should follow based on the answers given. For consistency, the same approach was used for the paper questionnaires, such that responses to questions that should not have been answered based on the routing instructions given were not considered.

Where ‘tick all that apply’ answer options were given, the denominator was calculated to include anyone that had answered a question in that section of the questionnaire, with the assumption that not ticking a box meant it did not apply rather than missing data. All ‘other please specify’ free text fields were reviewed by 2 members of the team. Where participants had described a prelisted condition or prelisted option within the free text, these were recoded accordingly. Comorbidities were classified according to the International Classification of Diseases 11th Revision (ICD-11). All responses could be linked back to the HARS record of the participant via a unique 6-digit passcode they had been allocated.

Weighting

The same weighting methodology was applied to the 2022 survey as in 2017. Two different sets of weights were applied to account for unequal probability of selection:

  • (set 1) clinic weight, Pr(clinic), a constant correcting for the selection of 101 out of 178 eligible HIV clinics
  • (set 2) person weight, Pr(patient), correcting for unequal probability of selection of a patient from eligible patients within each of the participating clinics

Consequently, the sampling weight applied was: weight = 1/Pr(clinic) × 1/Pr(patient)

The following characteristics and categorisations informed the creation of strata used to generate the final weighted data set to allow whole HIV population-based estimates:

  • gender: 0 = men, 1 = women and other genders
  • probable exposure route: 0 = sex between men, 1 = all other exposure routes
  • ethnicity: 0 = white ethnic groups, 1 = black ethnic groups, 2 = other ethnic groups
  • age: 0 = <35, 1 = 35 to 49, 2 = 50 to 65, 3 = >65
  • region of residency: 0 = London, 1 = outside London

A total of 50 strata were created; observed estimates of each of these strata were compared to the proportions of all people accessing care in 2022, using the HARS data set as the reference. The weighting algorithm was applied to align observed proportions in the survey with those in HARS. Due to low numbers, all age categories for heterosexual men based in London of other ethnicity were collapsed, heterosexual men outside London of other ethnicity were grouped into under aged 50 years and aged 50 years and over, heterosexual women outside London of other ethnicity were grouped into under aged 50 years and aged 50 years and over.

Analyses

All analyses were conducted on Microsoft Excel and STATA 17.0. Apart from Chapter 1 Introduction, all percentages are presented as weighted percentages. The analyses were based on a single-entered data set. Future publications will be based on a double-data entered data set and so numbers may differ slightly.

Note on general population comparisons

Where possible, survey estimates for the HIV population have been compared to the general population (from other national surveys) to provide context. These have been referenced throughout. At times population comparisons were presented for England only, due to the small number of participants from Wales and Scotland in Positive Voices 2022.

When comparing Positive Voices with estimates for the general population it should be noted that the demographics of both groups are different and the results presented in this report are not standardised by age, gender or ethnicity.

Appendix 2. Calculation of EQ-5D scores

EQ-5D is a standardised instrument for measuring generic health status and quality of life introduced by EuroQol. It has 5 ‘domains’ of physical and mental health. These are:

1. Mobility (walking).

2. Self-care (washing and dressing).

3. Usual activities (for example, work, study, housework, family or leisure activities).

4. Pain and discomfort.

5. Anxiety and depression.

Participants could report having ‘no problems’, ‘slight problems’, ‘moderate problems’, ‘severe problems’, and either ‘extreme problems’ or an ‘inability’ to do the activity . Each answer was given a numeric score from 1 to 5, allowing each participant a health-state whereby 11111 represented no problem in any dimension. These health states were converted to a single number (‘utility score’) by mapping the 5L descriptive system data onto the 3L value set (1 to 2). The utility score is anchored at 0 and 1, where 0 represented a state as bad as being dead and 1 represented the best possible health.

The data was compared to the data from adults aged 16 years and over living in private households in England in 2018 using data from Health Survey for England (HSE) 2018 that had been provided on request from NHS Digital. Utility scores were re-calculated for Positive Voices 2017 using the same value-set, in order to compare data from both rounds of the survey (1 to 2).

Appendix 3. Functional Social Support Questionnaire (FSSQ)

The Duke-UNC Functional Social Support Questionnaire (FSSQ) is an instrument for assessing an individual’s perceived strength of social support network. Positive Voices 2022 included 6 of the 8 FSSQ questions:

1. I have people who care what happens to me.

2. I get love and affection.

3. I get chances to talk to someone I trust about my personal or family problems.

4. I get invitations to do things with other people.

5. I get useful advice about important things in life.

6. I get help when I am sick in bed.

People were asked to consider whether they receive:

1. Much less than they would like.

2. Less than they would like.

3. Some, but would like more.

4. Almost as much as they would like.

5. As much as they would like.

Appendix 4. Resilience (RS-14)

Participants were asked to rate themselves on 14 of the following situations according to a 7-point Likert scale (1 = strongly disagree, 4 = neutral, 7 = strongly agree):

1. I usually manage one way or another.

2. I feel proud that I have accomplished things in my life.

3. I usually take things in my stride.

4. I am friends with myself.

5. I feel that I can handle many things at a time.

6. I am determined.

7. I can get through difficult times because I’ve experienced difficulty before.

8. I have self-discipline.

9. I keep interested in things.

10. I can usually find something to laugh about.

11. My belief in myself gets me through hard times.

12. In an emergency, I’m someone people can generally rely on.

13. My life has meaning.

14. When I’m in a difficult situation, I can usually find my way out of it.

Appendix 5. General Practice Physical Activity Questionnaire

Levels of physical activity were assessed with the General Practice Physical Activity Questionnaire. This tool provides a simple 4-level index (Physical Activity Index (PAI)) to categorise people into one of the following:

1. Active.

2. Moderately active.

3. Moderately inactive.

4. Inactive.

Generally, it is used to guide general practitioners on when to recommend physical activity interventions to mitigate the risk of cardiovascular disease. At times, physical activity may also be recommended to help reduce some mental disorders (anxiety, depression) and improve overall wellbeing.

Appendix 6. Calculation of body mass index (BMI)

BMI is a commonly used health metric to determine whether a person is likely to be carrying excess body weight and consequently assess their risk for developing other associated conditions, such as cardiovascular and metabolic diseases. The National Institute for Health and Care Excellence, (NICE), uses the following classifications:

  • underweight: less than 18.5 kilograms per meter squared (kg/m2)
  • normal weight: 18.5kg/m2 to less than 25kg/m2
  • overweight: 25kg/m2 to less than 30kg/m2
  • obesity: 30kg/m2 and above

Appendix 7. The Alcohol Use Disorders Identification Test (AUDIT-C) scale

Levels of alcohol consumption was assessed using the AUDIT-C scale which consisted of the following 3 questions:

1. How often do you drink?

2. How many units of alcohol do you drink on a typical day when you are drinking?

3. How often have you had 6 or more drinks if you are a woman, or 8 or more drinks if you are a man, on a single occasion in the last 3 months?

Binge drinking was defined as consumption of 8 or more units of alcohol for men, or 6 or more units of alcohol for women, on a single occasion.

Appendix 8. List of drug(s) participants used in the previous 3 months, alongside their street names

The following is a list of drugs that survey participants reported using in the previous 3 months:

  • Cannabis also known as marijuana (grass, hash, skunk, superskunk, weed, spliff)
  • Ecstasy (E, MDMA, molly, mandy)
  • Crystal Meth (Tina, ice, glass)
  • GHB or GBL (G, Liquid X, Fantasy)
  • Amphetamine (speed, billy whizz, uppers, billy)
  • Amyl Nitrates (poppers, liquid gold, rush)
  • Cocaine (coke, charlie, sniff)
  • Ketamine (K, Special K)
  • Mephedrone (M, Drone, MCAT, meow meow)
  • Acid or LSD (tabs, trips)
  • Crack (rock, stones, white)
  • Heroin (smack, skag, H, brown, gear, horse)
  • Viagra also known as Kamagra or Cialis
  • Anabolic steroids (testosterone, HGH)

Appendix 9. Employment status

The employment status of the participants was defined as follows:

  • employed: those who actively contributed to the economy, whether full-time, part-time, or self-employed
  • unemployed: those who were able to work but were not currently employed
  • retired: those who had retired and were not currently employed
  • sick or disabled: those who were long-term or temporarily sick or disabled and were not currently employed
  • other: those currently not working but were not considered unemployed as they were unable to seek employment, for example asylum seekers, stay at home parents or carers and full-time students

Appendix 10. Clinic collaborators

  • 10 Hammersmith Broadway Clinic, London (Ann Sullivan, Rachel Jones, Mohammed Hassan, Serge Miodragovic)
  • 56 Dean Street, London (Ann Sullivan, Victoria Tittle, Mohammed Hassan, Serge Miodragovic)
  • Abbey View Clinic, iCaSH Suffolk, Bury St Edmunds (Sarah Edwards)
  • Alexis Clinic, Alexis Clinic, London (Melanie Rosenvinge, Allison Mascagni, Rosa Harrington, Claudia Adade)
  • Axess Clinic, Bath Street Health and Wellbeing Centre, Warrington (Emily Clarke, Sandra Mason)
  • Axess Clinic, Eagle Bridge Health and Well Being Centre, Crewe (Emily Clarke, Elaine Priest)
  • Axess Clinic, Halton General Hospital (Emily Clarke, Sandra Mason)
  • Axess Clinic, Macclesfield Hospital (Emily Clarke, Elaine Priest)
  • Axess Clinic, Royal Liverpool University Hospital (Emily Clarke, Melissa Martin)
  • Barking Community Hospital Sexual Health Clinic, London (Athavan Umaipalan, Julie Field)
  • BBV Clinic, Milton Keynes University Hospital (Clare Woodward, Felicity Williams)
  • Beckenham Beacon Sexual Health, Kings College Hospital, London (Liz Hamlyn, Lucy Campbell)
  • Birmingham Heartlands HIV Service (Steve Taylor, Gerry Gilleran, Satwant Kaur)
  • Branston Clinic, Burton-on-Trent (Cathy Ormiston, Laura Wilson-Powell, Kate Saunders)
  • Breydon Clinic, iCaSH Norfolk, Great Yarmouth (Meena Gupta, Julia Ball)
  • Bristol HIV Service, Southmead Hospital (Mark Gompels, Louise Jennings, Malgorzata Slowinska)
  • Brookside Clinic, Aylesbury (Angela Bailey, Sandra Rushwaya)
  • Brotherton Wing Clinic, Leeds General Infirmary (Sarah Schoeman, Tadas Mazeika)
  • Buryfields Sexual Health Clinic, Surrey Sexual Health Service, Guildford (Shalini Andrews, Laura Noonan)
  • Caldecot Centre, Kings College Hospital, London (Liz Hamlyn, Lucy Campbell)
  • Cardiff Royal Infirmary (Darren Cousins, Catherine Oliver)
  • Chalmers Sexual Health Centre, Edinburgh (Daniel Clutterbuck, Connor Dalby, Amy Shepherd)
  • Chesterfield ISHS (Anura Piyadigamage, John Martin)
  • Chichester Sexual Health, St Richard’s Hospital (Judith Zhou, Barbara Hayman, Emma Rutland)
  • Churchill Hospital, Oxfordshire Sexual Health Service (Paola Cicconi, Charlie Wells)
  • Clinic 1a, Addenbrooke’s Hospital, Cambridge (Fiona Wilson)
  • Clinic 6, The Oaktree Centre, Huntingdon (Claudia Krause, Su Jenkins)
  • Clover Street Clinic, Chatham (Anitha Vidhyadharan, Samantha Harwood)
  • Cobridge Community Health Centre, Stoke-on-Trent (Lisa Goodall, Alison Bridgwood, Laura Wilson-Powell)
  • Coelho Clinic, Chelmsford (Suzanne Francis, Kirsty Mynard, Mandy Austin)
  • Crawley Sexual Health, Crawley Hospital (Judith Zhou, Farai Mukazi, Chloe Hoskins)
  • Croydon Sexual Health Centre, Croydon University Hospital, London (Ian Cormack)
  • Devon Sexual Health, Barnstaple (Jonathan Shaw, Amanda Smith)
  • Devon Sexual Health, Torbay (Nadia Khatib, Julie Walsh)
  • Dewsbury Health Centre (Sarah Schoeman, Tadas Mazeika)
  • East Kent HIV Service, Folkestone Health Centre (Anitha Vidhyadharan, Brenda Hollier)
  • East Sussex Sexual Health, Eastbourne (Martin Jones, Penny Boxall)
  • Florence Nightingale Community Hospital, Derby (Ade Apoola, Catherine Gatford)
  • Fountains Sexual Health Clinic, Chester (John Evans-Jones, Jennifer Harrison)
  • Grahame Hayton Unit, Royal London Hospital, London (Nashaba Matin, Moses Shongwe)
  • Greenway Centre, Newham General Hospital, London (Nashaba Matin, Moses Shongwe)
  • Harrogate Sexual Health Centre (Ian Fairley)
  • Hastings Clinic, Station Plaza, East Sussex Sexual Health (Martin Jones, Zoe Cuthbertson, Penny Boxall)
  • Hathersage Centre, Manchester Centre for Sexual Health (Chitra Babu, Denise Donahue)
  • Ian Charleson Day Centre, Royal Free Hospital, London (Fiona Burns, Katie Spears, Thomas Fernandez)
  • iCaSH Peterborough (Graham McKinnon, Rachael Bridgman)
  • Kobler Clinic, Chelsea and Westminster Hospital, London (Ann Sullivan, James Hardie, Mohammed Hassan, Serge Miodragovic)
  • Lawson Unit HIV Clinic, University Hospitals Sussex NHS Foundation Trust, Brighton (Amanda Clarke, Lisa Barbour, Carole Cable)
  • Luton Sexual Health (Mohanarathi Kawsar, Memory Kakowa)
  • Mortimer Market Clinic, London (Richard Gilson, Gosala Gopalakrishnan, Abigail Severn)
  • Newington Road Clinic, Ramsgate (Anitha Vidhyadharan, Kate Castro-Sanchez)
  • North Manchester General Hospital (Andrew Ustainowski, Fahd Niaz)
  • Northampton General Hospital (Sophie Herbert, Helen Reboul)
  • Nottingham Sexual Health Service, Nottingham City Hospital (Ashini Fox, Sarah Chadwick)
  • Oak Street Clinic, iCaSH Norfolk, Norwich (Nelson David, Megan Khan)
  • Open Clinic, Bishton Court, Telford (Andrea Ng, Julia Rogers, Katie Saunders)
  • Open Clinic, Sexual Health Services - Shropshire, Shrewsbury (Andrea Ng, Julia Rogers, Katie Saunders)
  • Open Clinic, Stafford (Cathy Ormiston, Amandeep Gill, Laura Wilson-Powell, Katie Saunders)
  • Portsmouth Sexual Health Service (Alison Blume, Natalie Parker)
  • Queen Elizabeth Hospital, Birmingham (Jonathan Ross, Sindiso Masuka)
  • Rosehill Clinic, St Helier Hospital, London (Olubanke Davies, Analyn Alipustain, Maheshraj Radhakrishnan)
  • Rotherham General Hospital (Nadi Gupta, Nicola Williams)
  • Salisbury District Hospital (Helen Iveson)
  • Scarborough Sexual Health Centre, The Mulberry Unit (Ian Fairley)
  • Sexual Health at Wycombe (Angela Bailey, Sandra Rushwaya)
  • Sexual Health Calderdale, Broad Street Plaza, Halifax (Emma Street, Andrew Sealy)
  • Sexual Health Clinic, Monkgate Health Centre, York (Ian Fairley, Tom Yucebiyik)
  • Sexual Health Dorset, Bournemouth (Elbushra Herieka, Kevin Turner)
  • Sexual Health Service, Isle of Wight (Alison Blume, Felicity Young)
  • Sexual Health Sheffield, Royal Hallamshire Hospital, Sheffield (Karen Rogstad, Jessica Mcneill, Gareth Stephens)
  • SHiP, Derriford Hospital, Plymouth (Zoe Warwick, Angela Robinson, Elaine Freeman)
  • Sir Ludwig Guttman Centre, Stratford, London (Nashaba Matin, Moses Shongwe)
  • Southend Hospital (Laura Hilton, Donna Stookes)
  • Spectrum Community Health, Wakefield (Sarah Schoeman,Tadas Mazeika)
  • St Helens Hospital Sexual Health (genitourinary medicine (GUM)) Service (Elizabeth Okecha)
  • St Lukes Hospital, Bradford (Nicola Fearnley, Jackie Todd, Sue Kimachia)
  • Stevenage Clinic (Ann Sullivan, Sarah Edwards, Mohammed Hassan)
  • Summers Unit, Kettering Hospital (Sophie Herbert, Helen Reboul)
  • Swindon Sexual Health Department, The Great Western Hospital (Jessica Daniel, Mary-Jane Harding)
  • The Centre, Sidwell Street, Exeter (Jonathan Shaw, Abbey Eboigbe, Ashley Hanson)
  • The Courtyard Clinic St George’s Hospital, London (Liz Hamlyn, Katie Toler)
  • The Florey Sexual Health Services, Royal Berkshire Hospital, Reading (Fabian Chen, Emma Wainwright, Felix Kpodo)
  • The Garden Clinic, Upton Hospital, Slough (Nisha Pal, Clare Megson)
  • The Gate Clinic, Canterbury (Anitha Vidhyadharan, Matt Waller)
  • The James Cook University Hospital, Middlesborough (David Chadwick, Jessica Roberts)
  • The Jonathan Mann Clinic, Homerton Hospital, London (Iain Reeves, Tracey Fong)
  • The Orwell Clinic, iCaSH Suffolk, Ipswich (Raouf Moussa, Melissa Milsom)
  • The Portland Clinic, Huddersfield Royal Infirmary (Emma Street, Mike Ward)
  • The Riverside Clinic, Riverside Health Centre, Bath (Lucy Twigger, Charlotte Swift)
  • The Royal South Hants Hospital, Southampton (Raj Patel, Jane Whitehead)
  • The Starling Clinic, Musgrove Park Hospital, Taunton (Sathish Thomas William, Jane Holder)
  • The Trafalgar Clinic, Queen Elizabeth Hospital, Greenwich, London (Stephen Kegg, Rosa Harrington, Allison Mascagni, Claudia Adade)
  • The Wolverton Centre for Sexual Health, Kingston Hospital, London (Lewis Haddow, Jessica Osorio)
  • Twickenham House, West Middlesex Hospital, London (Ann Sullivan, Marie-Louise Svensson)
  • Vancouver House, iCaSH Norfolk, King’s Lynn (Sandra Underwood, Helen Pollitt)
  • Vicarage Lane Clinic, Ashford (Anitha Vidhyadharan, Brenda Hollier)
  • Watford Clinic (Ann Sullivan, Samantha Hill)
  • Weymouth Community Hospital, Sexual Health Dorset, Weymouth (Sara Scofield, Jenny Murira)
  • Wharfside Clinic, St Mary’s Hospital, London (Nicola Mackie, Sophia Taylor, Romina Tajik)
  • Withington Community Hospital, Manchester (Orla McQuillan, Denise Donahue)
  • Worthing Sexual Health (Judith Zhou, Rebecca Murdock, Elaine Banks)

References

1. Van Hout B, Janssen MF, Feng YS, Kohlmann T, Busschbach J and others. ‘Interim scoring for the EQ-5D-5L: mapping the EQ-5D-5L to EQ-5D-3L value sets’. Value Health. 2012; volume 15 issue 5: pages 708 to 715 (viewed 23 November 2023)

2. National Institute for Health and Care Excellence (NICE). ‘Position statement on use of the EQ-5D-5L value set for England (updated October 2019)’. (viewed 23 November 2023)