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21/608 Diagnostic accuracy of pulse oximeters


Published: 08 December 2021

Version: 1.0

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The aim of the HTA Programme is to ensure that high quality research information on the clinical effectiveness, cost-effectiveness and broader impact of healthcare treatments and tests are produced in the most efficient way for those who plan, provide or receive care from NHS and social care services. The commissioned workstream invites applications in response to calls for research on specific questions which have been identified and prioritised for their importance to the NHS, patients and social care.

Research question

What is the diagnostic accuracy of different pulse oximeters at oxygen saturation levels (SpO2) relevant to their use by patients at home and how does this vary in people with darker pigmentation and skin tones?

  1. Technology: Pulse oximeters (to be defined and justified by applicants)
    The study design will be expected to have significant focus on fingertip pulse oximeter models used within the NHS COVID Oximetry@home scheme, although other oximetry devices could be included. Additional information on how to access the list of pulse oximeters used in the scheme and how to order these for the purposes of this research is provided below.  
  2. Patient group: Adults
    Applicants must demonstrate that they will recruit a sufficiently large and diverse sample to ensure the research delivers high-quality evidence relating to the impact darker pigmentation and skin tones may have on the effectiveness of the device, to inform the development of care pathways which address any health inequalities in this area. Applicants should define and justify the patient group, which does not have to include those with COVID or suspected COVID infection. In particular, applicants must define the SpO2 range for which the diagnostic accuracy of the technology will be assessed and justify this with reference to its relevance to the NHSE COVID Oximetry@home scheme.

  3. Setting: Any appropriate setting in which measurement of SaO2 levels through arterial blood gas analysis is feasible

  4. Reference standard: Arterial haemoglobin saturation (SaO2) measured through blood gas analysis.

  5. Study design: UK Multi-centre diagnostic accuracy study
    Successful applicants will be expected to contract and start work rapidly and to report meaningful intermediate data early in the contract period (with anticipated contract start date of 1st March 2022). They should ensure that their team is available to start within the required timeframe and consider study designs capable of delivering early reporting to inform NHS practice in the short, as well as the longer, term. They should specify the mitigation measures that will be in place to safeguard against delays.

  6. Primary outcome:  Accuracy of SpO2 measurement, validated through arterial blood gas analysis
    Data should be disaggregated by skin tone to enable robust evaluation of the impact darker pigmentation and skin tones may have on the relevant outcomes and to facilitate the identification of the most effective solutions for the patients concerned.
    If applicable, data should also be disaggregated by relevant diagnoses to establish any impact on accuracy of different conditions and to inform future advice and care pathways, in particular for people with increased risk of hypoxia.  Applicants are also encouraged to report recruitment and findings disaggregated by sex and other demographic factors, where relevant.


Pulse oximeters, which measure the level of oxygen carried by red blood cells around the body and into the vital organs, are a well-established tool within healthcare. They are used in the diagnosis and management of such diverse conditions as asthma, chest pain of suspected cardiac origin, advanced lung disease, obstructive sleep apnoea, or motor neurone disease, as well as the care of patients under anaesthesia, the critically ill, and mothers during labour. Recently they have played a big role in detecting “silent hypoxia” – a dangerous drop in oxygen levels without shortness of breath or any other accompanying symptoms. This condition affects significant numbers of people infected with the SARS-CoV-2 virus which causes COVID-19. It is both directly life-threatening and predictive of more complex healthcare needs.

Patients considered to be at an increased risk of complications from COVID-19 receive pulse oximeters for regular self-monitoring of their blood oxygen levels under the NHS COVID Oximetry@home scheme. Pulse oximeters are also widely available, at a range of prices, to the general public and it has been suggested that they might become as common in households as thermometers, although the Medicines and Healthcare products Regulatory Agency (MHRA) currently discourages their use by members of the public “unless they have been advised to do so by a qualified clinician, have been shown how to take an accurate measurement, and (…) are providing results for clinical review.”

Questions have been raised about the accuracy of pulse oximeters in detecting oxygen saturation levels in people with darker pigmentation and skin tones. A rapid review by the NHS Race and Health Observatory (RHO) reported that ‘There is a growing body of evidence (…) that pulse oximetry is less accurate in darker skinned patients. Given the increased mortality amongst ethnic minority patients during the Covid-19 pandemic, it is possible that the differential accuracy of pulse oximetry is a contributing factor to this health inequality.’ Despite the growing body of evidence, there remain uncertainties around the accuracy of pulse oximeters, which may vary depending on the level of blood saturation, the specific model of oximeter, as well as factors specific to each patient, including pigmentation and skin tone.

Given these concerns, NHS England & NHS Improvement have asked NIHR to support further research. Consequently, the NIHR HTA Programme is interested in commissioning high-quality research into the diagnostic accuracy of pulse oximeters, with particular focus on people with darker pigmentation and skin tones, to establish the accuracy of self-administered pulse oximetry. This research will contribute to the Department for Health and Social Care (DHSC) review into the impact of potential bias in the design and use of medical devices.

While this call is primarily focused on supporting the delivery of the NHS COVID Oximetry@home scheme, applications for funding of research into other aspects of pulse oximetry (including different patient groups, settings, and outcomes) are encouraged through the HTA researcher-led pathway,  the researcher-led pathway of the EME Programme for research into mechanisms by which the accuracy of pulse oximetry is affected by factors such as skin pigmentation and darker skin tones, as well as other NIHR funding programmes, as appropriate based on the proposed research question. Moreover, further research may be commissioned in the future to inform the design of service interventions within different clinical pathways to ensure they are effective for all communities.

Webinar for potential applicants

The NIHR will be holding a webinar to discuss this call on 17th December at 10:30 am - 11:30 am. This will provide an opportunity for potential applicants to learn more about what is expected and ask any questions they may have for NIHR or NHS England & NHS Improvement. To find out more please join the webinar.

Pulse oximeters to be used for this research

To obtain a list of fingertip pulse oximeters used within the NHS COVID Oximetry@home scheme for the purpose of putting together an application to this call, please e-mail

Several of the models in use will be available to successful applicants to use in this research.  They can be ordered by using the COVID Oximetry @home: Pulse Oximeter Request Form (NIHR) , for delivery within 3 – 5 working days. Any queries about the ordering or delivery of pulse oximeters should be directed to

Applicants are encouraged to consider other types or models of pulse oximeters, in addition to those already in use. These will have to be obtained from other sources. 

Additional commissioning brief background information

A background document is available that provides further information to support applicants for this call. It is intended to summarise what prompted the call and the existing evidence base, including relevant work from the HTA and wider NIHR research portfolio. It was researched and written on the basis of information from a search of relevant sources and databases, and in consultation with a number of experts in the field. If you would like a copy please email

Making an application

Applications to this call will be assesed using a single-stage process. If you wish to submit a Stage 2 application for this call, the online application form can be found on the Funding opportunities page.  To select this call, use the filters on the right of the screen or search using the call name and/or number.

Your application must be submitted on-line no later than 1pm on the 27 January 2022. Applications will be considered by the HTA Funding Committee at its meeting in February 2022. Guidance notes and supporting information for HTA Programme applications are available. Applications received electronically after 1300 hours on the due date will not be considered.

For commissioned topics, the Programme strongly discourages the practice of the same co-applicant joining more than one competing team. There may be unusual circumstances where the same person could be included on more than on application eg a lead from a named charity or a unique national expert in a condition.

For such exceptions (i) each application needs to state the case as to why the same person is included (ii) the shared co-applicant should not divulge application details between teams and (iii) both teams should acknowledge in their application that they are aware that one of their co-applicants is part of a competing application and that study details have not been shared.

Should you have any queries please contact us on

Frequently asked questions

NIHR HTA Programme: Diagnostic Accuracy of Pulse Oximeters

Please note that these FAQs will be reviewed and may be updated from time to time.


Q1: Is this only a diagnostic type accuracy study or can we include a combined diagnostic type accuracy study& implementation study design?
Potential applicants should be aware that at this stage, the commissioned call is focused on a diagnostic type accuracy study ONLY. Additional studies may be commissioned at a later date that relate to implementation/ care pathways in home oximetry.


Q1: Can we approach manufacturers of oximeters so we can report a range of oximeters accuracy?
There is no barrier to linking with manufacturers. However it is important the study is conducted soon and IP/ access/ contracts may take some time with individual commercial entities. Several of the models in use are available to successful applicants to use in this research.  They can be ordered using the form COVID Oximetry @home: Pulse Oximeter Request Form (NIHR) (, for delivery within 3 – 5 working days. Any queries about the ordering or delivery of pulse oximeters should be directed to .

Q2: How many oximeter types does the COVID Oximetry @home programme use and should we ONLY use them?
To date, the programme has used eight oximeters. Applicants are advised that the study design should heavily focus on including these. Additional oximeter models can be included, as long as there is relevance to the wider NHS and there are no supply/IP issues.

Patient group

Q1: Is this study focussed on patients with COVID?
No. This study will be a step in helping manage those affected with COVID but the required study design does not have to focus on those with COVID. It could be delivered without including patients with COVID but must include participants recruiting across a range of skin tones and oxygen saturation levels.

Study design

Q1: What sample size is expected?
There is no pre specified expected sample size. Applicants should be advised that a range of skin tones are important to be studied and applicants will need to consider how best to power the study to ensure sufficient diversity in skin tones is included.

Q2: What ranges of oxygen saturations are expected to be tested?
The study design should focus on reporting accuracy in the relevant oximetry range. Researchers may therefore need to recruit participants with a range of saturations. It is ideal to include participant groups or scenarios where normal saturations and lower than normal saturations are encountered.  Applicants must select and justify their population choice but examples could include adult participants with congenital heart disease, COPD or other conditions linked with lower than normal saturation or patients in the intensive care unit or operating theatre who have arterial lines in place.

Q3: Can one participant provide data for more than one accuracy assessment?
Applicants are asked to justify this in their design, balancing participant burden vs attaining target sample size. However, applicants are advised that studies may lack generalisability if they rely too heavily on a small number of participants in each of the groups studied.

Q4: Can we confirm the gold standard expected in the study design? Can we use capillary gases?
Applicants are advised that expert opinion has suggested for this brief that the preferred gold standard is arterial blood gases. Applicants will need to justify why any alternative gold standard is proposed.

Q5: How long should this study take to complete?
Applicants are advised that the study is preferred to complete as soon as possible. A study design that incorporates interim analyses is welcomed.

Q6: What level of Patient and Public Involvement (PPI) is expected?
We accept that the commissioning timescales for this call are much shorter than usual and that developing a comprehensive PPI plan may be challenging by the application deadline. Therefore, we expect applicants to have undertaken extensive PPI consultation at outset and outline future plans, specifically on equality, diversity and inclusion, and how they will link with specific community or diversity groups. While these plans may be outlines rather than fully formed plans at the time of submission, a comprehensive PPI plan will be expected at the time of contracting or included as an early project milestone.

What other particular elements of this call are noteworthy?

The results of the data are required as soon as possible to support decision making in clinical practice.

  • Prolonged study set up, delays in contracting or recruiting are strongly discouraged; multicentre design is encouraged to promote rapid recruitment.
  • Several oximeter models to be tested will be supplied to the research team by NHSE&I.
  • Applicants would be advised to provide evidence/ planning showing local support for efficient set up including approvals and inclusion of sites where recruiting participants with diversity of skin tones would reflect local community participation.