key: cord-0981402-7bbfy7gk authors: Alboksmaty, Ahmed; Beaney, Thomas; Elkin, Sarah; Clarke, Jonathan M; Darzi, Ara; Aylin, Paul; Neves, Ana-Luísa title: Effectiveness and safety of pulse oximetry in remote patient monitoring of patients with COVID-19: a systematic review date: 2022-03-22 journal: Lancet Digit Health DOI: 10.1016/s2589-7500(21)00276-4 sha: 3c862c56a91d8f4b6e48e518d0fe8b5924ebb661 doc_id: 981402 cord_uid: 7bbfy7gk The COVID-19 pandemic has led health systems to increase the use of tools for monitoring and triaging patients remotely. In this systematic review, we aim to assess the effectiveness and safety of pulse oximetry in remote patient monitoring (RPM) of patients at home with COVID-19. We searched five databases (MEDLINE, Embase, Global Health, medRxiv, and bioRxiv) from database inception to April 15, 2021, and included feasibility studies, clinical trials, and observational studies, including preprints. We found 561 studies, of which 13 were included in our narrative synthesis. These 13 studies were all observational cohorts and involved a total of 2908 participants. A meta-analysis was not feasible owing to the heterogeneity of the outcomes reported in the included studies. Our systematic review substantiates the safety and potential of pulse oximetry for monitoring patients at home with COVID-19, identifying the risk of deterioration and the need for advanced care. The use of pulse oximetry can potentially save hospital resources for patients who might benefit the most from care escalation; however, we could not identify explicit evidence for the effect of RPM with pulse oximetry on health outcomes compared with other monitoring models such as virtual wards, regular monitoring consultations, and online or paper diaries to monitor changes in symptoms and vital signs. Based on our findings, we make 11 recommendations across the three Donabedian model domains and highlight three specific measurements for setting up an RPM system with pulse oximetry. Technological innovation has reshaped the modern world such that health care has become a continuous process rather than service points. 1 Part of this innovation includes the possibility of monitoring patients in their home environment. The unprecedented increase of COVID-19 cases globally has overwhelmed health systems and challenged their capacities, 2,3 leading to extensive risks to patient health and wellbeing. 4 However, the COVID-19 pandemic and the resulting changes in health-care delivery have encouraged the adoption of remote patient monitoring (RPM) models, and represented an opportunity to use RPM as a crucial part of health-care delivery. 5 Digitally enabled health-care models that incorporate RPM could offer a more personalised approach to responding to patients' needs. 6 Evidence shows that peripheral blood oxygen saturation (SpO 2 ) is a critical indicator of deterioration in patients with In this context, pulse oximetry is a convenient tool for monitoring patients' SpO 2 remotely and establishing whether they require hospital care or can be safely managed at home, 8 and different RPM models have included pulse oximeters as part of their monitoring packages for patients with COVID-19. 7, 8 RPM seems to be effective in aiding the triage of patients, enabling the prioritisation of health services for people who need them the most. 9 RPM could help to prevent the unnecessary use of emergency services and to identify in a timely manner patients who are deteriorating, therefore preventing delays in treatment and extended hospital admissions. 10 These RPM models are being used in several countries such as the UK, the USA, and China. 7, [11] [12] [13] These models are similar in concept but differ in method, follow-up systems, clinical supervision level, and monitoring strategies and tools. [11] [12] [13] [14] For example, in the UK, COVID Oximetry @home 15 is a national programme of care for patients with COVID-19 in England. The programme aims to remotely monitor SpO 2 in patients who are at risk of deterioration due to silent hypoxia. This model seeks to improve patient care and ensure more efficient use of National Health Service resources. 7, 9, 14 Ongoing studies are investigating this RPM model using pulse oximetry in larger cohorts. 14 The model could also be adapted for the remote monitoring of patients with cardiovascular or other respiratory diseases for which SpO 2 concentrations could indicate deterioration, alongside other indicators. 16, 17 In this systematic review, we aim to assess the effectiveness and safety of the use of pulse oximetry in the remote monitoring of patients at home with COVID-19. Specific objectives include describing RPM models that use pulse oximetry, assessing the quality of studies that use these models, and evaluating the effectiveness and safety of pulse oximetry in these models or the effect on patients' health outcomes and health-care service use (ie, prevention of complications, decrease in the risk of developing silent hypoxia, referrals to emergency care, and decrease in critical care admissions). As a secondary aim we will identify measures and recommen dations for improving the design of RPM models with pulse oximetry for patients with COVID-19, following the Donabedian model domains (structure, processes, and outcomes). 18 We systematically searched the published literature in three databases accessed via OVID (MEDLINE, Embase, and Global Health), and the medRxiv and bioRxiv databases for preprints. Each database was searched independently; iterative discussions among the research Review team generated the specific subject headings and relevant search terms for each database. A complete list of the medical subject headings and keywords used for all databases is provided in the appendix (p 1). We followed the PRISMA guidelines when conducting this systematic review. 19, 20 The study protocol is registered with PROSPERO, CRD42021254171. All types of study were considered, including feasibility studies, clinical trials, and observational studies. Studies were considered regardless of publication status and included peer-reviewed papers and preprints, to account for the speed of research around COVID-19 and the length of time taken by peer review. No publication date limits were applied in the search, such that resulting studies could date from database inception until April 15, 2021, when our last search was done. However, all studies were published after December, 2019, as this is when COVID-19 was first identified. We applied a set of inclusion and exclusion criteria following the population, intervention, control, and outcome formulation. 21 Studies were included if they targeted adult patients with confirmed or presumptive COVID-19; used a hand-held pulse oximeter as a remote monitoring tool for SpO 2 ; proposed, tested, or evaluated any new or existing RPM system at home, in communitybased settings, or both; and assessed the effectiveness and safety of pulse oximetry in RPM, or the effect on patients' health outcomes (such as prevention of complications, and development of silent hypoxia) and health-care service use (such as hospital referrals, critical care admissions, or referrals to emergency care). Studies were excluded if they exclusively targeted patients who did not have COVID-19; targeted only hospitalised patients; assessed monitoring systems that exclusively used invasive tools to measure SpO 2 , with no use of hand-held pulse oximeters; described an RPM system that did not include SpO 2 monitoring at all; used pulse oximetry with only a proportion of study participants, and results for this subgroup were not reported individually; or assessed the accuracy of a specific pulse oximeter type or brand, without monitoring patient deterioration or health-care service use. We also excluded studies that exclusively targeted individuals aged 18 years or younger. Commentary articles, conference abstracts without an accompanying article, and editorials were excluded as they did not assess an RPM model. However, as some of the studies that were excluded from our analysis included important relevant information, the recommendations we present are based on the literature overall. Studies were screened by two authors (AA and TB). Initial screening was based on the information contained in titles and abstracts, followed by full-text screening. Cohen's κ was used to measure inter-rater agreement in each screening phase. 22 A κ score of greater than 0·6 was considered, on the basis of previous literature, to be a substantial agreement, and was sufficient to proceed to the next step. A third, senior author (PA) was consulted for any disagreements between the initial two authors. Descriptive and technical data and outcomes were extracted from the included studies by one author (AA), and were then discussed with another author (TB). A third author (PA) was consulted for any disagreements between the initial two authors. The extracted data were discussed and agreed upon among the research team. The descriptive data encompassed study authors, country where the study was conducted, state of publication, study period, study design, primary aim, and objectives. The characterisation (technical data and implementation methods) of the intervention included the type of oximeter used, descrip tion of the RPM system, method of recording and reporting the SpO 2 , measurements of SpO 2 (and temperature, where provided), target population (age, gender, presence of comorbidities, and specific characteristics if relevant), and main outcomes on effectiveness and safety. We used the Newcastle-Ottawa Scale (NOS) to assess the quality of and risk of bias in the included studies. This scale uses a star system for assessment, in which nine stars is the maximum score and indicates a study of the highest quality. The NOS tool has been validated with established inter-rater reliability for assessing nonrandomised studies. It evaluates three core aspects: participant selection, the comparability between the study groups, and the ascertainment of outcomes. 23 One author (AA) assessed each study and discussed the outcome with a second author (TB) to reach a joint agreement. Disagreements were escalated to a third author (PA) to reach a final decision. The quality assessment of each included study was summarised and reported. We conducted a narrative synthesis in which the safety and effectiveness of RPM models were described as reported in the included studies, including SpO 2 measurement and reporting methods and follow-up strategies. Owing to the heterogeneity of objectives and outcomes in the included studies, a meta-analysis was not feasible. We identified common features of RPM models that were applied across the included studies that used pulse oximetry, and identified measures for improvement for similar care models on the basis of the strengths, limitations, and recommendations stated in the included studies. Future researchers and policy makers could consider these as recommendations for setting up a See Online for appendix www.thelancet.com/digital-health Vol 4 April 2022 e281 Review successful RPM model. These recommendations are presented in terms of Donabedian model domains. 18 We have provided a brief description under each domain to clarify the concepts that we described within each one (figure 1). Our search identified 561 records, including 495 peerreviewed, published results and 66 preprints (figure 2). We removed 156 duplicates and excluded 370 records after screening titles and abstracts, after which we reviewed the full text of 35 records. Of these 35 records, 13 were conference abstracts with little available information and were excluded. 11, 12, [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] The RPM models in eight studies did not include pulse oximetry as a monitoring tool for all participants but only for specific subgroups, and these studies were excluded. [35] [36] [37] [38] [39] [40] [41] [42] One study was excluded owing to reporting irrelevant outcomes, focusing on therapeutic options with less emphasis on the RPM model. 43 We calculated the Cohen's κ score to estimate the interrater agreement in each screening phase. Good agreement was achieved in both phase 1 (0·71; screening titles and abstracts) and phase 2 (0·72; full-text screening). 13 studies with a combined total of 2908 participants were included in our systematic review (table 1). 14,44-55 All participants had either confirmed or presumptive COVID-19, except for 12 healthy individuals who acted as a control group in one study by Motta and colleagues. 45 Another study by Gordon and colleagues 44 involved a control group of patients with COVID-19 who were not given pulse oximeters for remote monitoring. All the studies followed a cohort, open-label design, and 11 studies had no control group. Most of the studies were conducted during the first wave of the pandemic in each respective country. Patients with different characteristics were involved in the studies, including older patients with multimorbidity, 14 young people, 48 and obstetric patients (pregnant and post partum). 51 Some studies targeted only patients with mild and intermediate risks of deterioration, while recommending that the same model be tested among patients with more complex health needs to compare outcomes. 48, 53 Ko and colleagues 49 also used an RPM model to monitor the SpO 2 of male migrant workers in Singapore in a specific, resource-limited setting, and the model was reported to be effective and safe. One study 44 scored seven stars on the NOS tool, indicating good quality. Seven studies 14,45-50 scored five or six stars, indicating fair quality, whereas five studies 51-55 scored four or fewer stars. The absence of a control group in most of the studies negatively influenced the quality by scoring zero out of two stars in the comparability aspect of the NOS tool. 23 We present the quality score for each study in table 1. Patients were monitored for an unweighted average of 12·7 days, as reported in 11 of the 13 studies. [44] [45] [46] [47] [48] [49] [50] [52] [53] [54] [55] RPM models used pulse oximeters in addition to other monitoring tools, such as thermometers, a peak flow measuring tool, 45 a blood pressure cuff, 51 and symptom monitoring charts. All studies offered a 24/7 (ie, 24 h every day) emergency telephone line for their patients. The studies used different SpO 2 thresholds at which advanced care might be needed. An SpO 2 of 92% or less was the threshold at which to escalate care in four studies. 44, 46, 54, 55 Participants were trained and instructed to selfmeasure their SpO 2 in all models. Participants in five studies received reminders by telephone call or Review through text message; however, the frequency of reminders varied. 44, 46, 49, 53, 54 For instance, reminders were set at once per day in three models, 44, 53, 54 twice per day in one model, 49 and were based on a predefined schedule in other models. 46, 51, 52 The rationale behind the frequency of reminders was not evident in most cases. Krenitsky and colleagues 51 linked the frequency of teleconsultations, for both follow-up and reminders, with the severity of symptoms; consultations were scheduled every 24 h if symptoms were severe and every 48-72 h if symptoms were mild. In five studies, a mobile app or an online portal was developed for patients to self-report their SpO 2 readings. 44, 45, [47] [48] [49] Blair and colleagues 46 and Kodama and colleagues 50 assessed and compared outcomes for at-rest and postexertional SpO 2 (table 2) . Our systematic review could not identify clear evidence for the effects of RPM with pulse oximetry on the health outcomes of patients. However, monitoring SpO 2 at home was a safety net to enable identification of an early sign of deterioration: a decrease in SpO 2 . 48, 53, 54 For instance, in one study, 54 an incidental reading of low SpO 2 without worsening of any other symptoms was the only reason that 50% of patients who were ultimately hospitalised returned to the emergency department. Monitoring SpO 2 helped to triage patients with COVID-19 remotely and guided care escalation. Nunan and colleagues 53 considered patients to be stable if their at-rest SpO 2 was greater than 94% and their decrease in SpO 2 after a rapid walking test (postexertional) was 5% or less; otherwise, patients were advised to call emergency services. Shah and colleagues 54 found that patients with an at-rest SpO 2 of less than 92% were more likely to need hospitalisation (risk ratio 7; 95% CI 3·4-14·5; p<0·0001) than were patients with higher SpO 2 . Remote monitoring reduced unnecessary contact of health-care professionals with patients with COVID-19, which could control the risk of infection transmission and enable resources to be redirected to those who need them the most. 47 To assess the effectiveness of the use of pulse oximetry in identifying deterioration in patients monitored at home with COVID-19 *** For quality assessment, we used the Newcastle-Ottawa Scale for assessing the risk of bias and the quality of the included studies; more stars means a lower risk of bias and higher quality. RPM=remote patient monitoring. NS=not specified. We identified recommendations that could help to set up successful RPM systems using pulse oximetry. These recommen dations are presented in the Discussion and are in alignment with the included studies and other relevant literature. Our systematic review has shown that the use of pulse oximetry as a monitoring tool for patients at home with COVID-19 helped to triage patients on the basis of their SpO 2 concentrations, detect the risk of deterioration, and promote patient safety. The data were insufficient to assess the effect on other proxies of effectiveness (eg, health outcomes) and dimensions of care quality compared with other care models. Pulse oximeters were used alone or as part of remote monitoring packages. The models varied in terms of the frequency of measurement, reporting methods, and monitoring periods (12·7 days on average). The use of pulse oximetry for monitoring appeared safe and seemed Review applicable to different patient groups in terms of demographics, disease severity, and existence of comorbidities. Cost-effectiveness was reported and confirmed in only one study. 53 There was no consensus on the SpO 2 threshold at which to escalate care, or a common pathway by which to do so. At-rest SpO 2 of 92% or less was considered critical in many models. 44, 46, 54, 55 Relying on video consultations, telephone calls, or face-to-face visits to follow up with patients was decided on a case-by-case basis in each study. The effect on the use of health-care resources was not conclusive, because most of the studies did not include control groups to compare. We identified recommendations for setting up an RPM system on the basis of our systematic review of the included studies and other relevant literature. The recommendations are distributed across the three domains of the Donabedian model (panel). RPM models were designed considering various factors, such as target population characteristics, available resources, and the surrounding environment. 40, 42, 48, 50, 56 We identified three measures that were highlighted across the models we reviewed. These measures can help to standardise some model criteria when pulse oximetry is used to monitor patients with COVID-19. Firstly, both at-rest and postexertional SpO 2 should be monitored in patients with COVID-19. Although most models monitored only at-rest SpO 2 , evidence has shown that patients with COVID-19 usually have an abrupt, not a gradual, decrease in SpO 2 , which could be detected early by assessing postexertional SpO 2 . 45, 54 The safety of conducting exertional desaturation tests on patients with COVID-19 needs further assessment. 57 So far, evidence has shown the safety of self-conducting exertional tests only in patients with an at-rest SpO 2 of at least 96%; otherwise, medical supervision in a prepared health-care facility is needed. 57 Secondly, an SpO 2 of 92% or less should be considered as a minimum, preset threshold to indicate care escalation in patients with COVID-19. 44,46,54,55 Some models considered a higher threshold (SpO 2 ≤94%), adding an extra layer of safety. 52, 55 For postexertional SpO 2 , a decrease of 5% or more should be considered critical and indicate care escalation. 36, 53 Some evidence put the threshold as a decrease of 3% or more if patients were vulnerable with multimorbidity. 57 These figures might differ in some clinical conditions, such as patients with chronic obstructive pulmonary disease. 53 Finally, the method by which SpO 2 is self-assessed should be standardised. For example, at-rest SpO 2 should be assessed after 5-10 min of rest (further recommendations to ensure accuracy of this method are below). 11 Postexertional SpO 2 should be measured after conducting the 1-min sit-to-stand test, which has been validated in the literature with reasonable sensi tivity (88%), specificity (81%), and negative predictive value (89%). 58 Other tests could be considered, such as a 6-min walk test or a 40-step walk; 46, 53, 58 however, further research is needed to validate these tests. 57 To our knowledge, this is the first systematic review of evidence on the use of pulse oximetry as an affordable and widely available tool for monitoring patients with COVID-19 in non-hospital settings. In 2021, a systematic review was conducted by Vindrola-Padros and colleagues 42 on the adoption of general home-monitoring systems for patients with COVID-19. Their review highlighted the importance of properly training patients and supporting their involvement as a determinant of success for any home-monitoring system. Based on the findings of our systematic review, we agree with these points. 36, [40] [41] [42] The use of pulse oximetry in RPM could help to alleviate the pressure on health systems during the COVID-19 pandemic; however, the risk of digital health inequalities should not be overlooked. 59 Social and cultural aspectssuch as technology literacy and accessibility, and financial hardship-could undermine the effect of RPM and restrain its uptake and use. 9 Further qualitative research is needed to explore the potential exclusion of disadvantaged populations who might not be able to benefit from digital health services, to provide tailored care according to the patients' needs and available resources, and to provide support to ensure health equity. The studies included in our systematic review did not highlight the inclusion of racially and ethnically diverse populations, and the number of participants was quite low in some studies. Therefore, it is recommended that trials of RPM with pulse oximetry are conducted among diverse populations. Different models proposed different staff-to-patient ratios to support and ensure the safety of the monitored patients. A ratio of one nurse to 50 patients was reported by Kodama and colleagues, 50 whereas Hutchings and colleagues 48 reported a ratio of 1:25 per shift (and in the overall programme). Another model in the literature had one physician per 29 at-risk patients, defined as being older than 75 years, having a body-mass index of greater than 30 kg/m², and having a history of chronic lung disease. 40 Few studies have discussed an explicit rationale or criteria for the appropriate staff-to-patient ratio needed for RPM. 56 It is mainly considered to be adjustable depending on the characteristics of the patients, the severity of illness, the monitoring technology and tools, and staff proficiency. 40,42,48,50,56, The studies in the literature overall highlighted the availability, affordability, and accessibility of the monitoring tools as determinants to ensure the effectiveness of any RPM model. 25, 41, 60 Some studies tested smartphone oximeters as a potential widely available option, and found clinically insignificant differences in readings compared with traditional pulse oximeters; however, further research is needed to test the validity and reliability of different types and brands. 61 Researchers have developed software and mobile apps to link SpO 2 Review measurements with patient data as a superior reporting and recording method to paper-based systems. [62] [63] [64] Such a method would also boost staff capacity-a trained healthcare professional would be able to monitor more patients by enabling digital care models than by use of traditional methods. 50, 65 The assessment of cost-effectiveness was scarce in the literature. An analysis by Crawford and colleagues 66 showed that the use of pulse oximetry to monitor moderate-to-severely ill patients at home with COVID-19 resulted in a better cost-utility outcome and increased number of quality-adjusted life-years than the standard care. There is a need for a comprehensive cost analysis of RPM models that use pulse oximetry, including the cost of oximeters, staffing, and monitoring operations, and the time consumed by professionals to maintain the system. Few studies have assessed the effect of monitoring patients with pulse oximeters on health outcomes and the use of health-care services. 37, 67 A prospective trial estimated an almost 50% reduction in unnecessary emergency and hospital readmissions among participants. 44 In a study by Panel: Recommendations for setting up and evaluating outcomes in an at-home remote patient monitoring (RPM) system for COVID-19 patients using pulse oximetry Structure Infrastructure preparedness and technology development needed for monitoring • Build an online portal, mobile app, or a monitoring platform to monitor peripheral blood oxygen saturation (SpO 2 ) readings and link them with patient health records readings. [1] [2] [3] 6, 9 The readings were self-recorded automatically via a smart system, or self-reported by patients via follow-up calls. Providing sufficient human resources for monitoring patients (staffto-patient ratio) • To be adjusted on the basis of severity of illness and the expected risk of deterioration among monitored patients. For instance, in the study by Kodama and colleagues, 50 there was one nurse per 50 patients per shift (and for the programme in general), and in the study by Hutchings and colleagues, 48 there were 25 patients per nurse per shift. Safe delivery of pulse oximetry to the participating patients • To plan for safe delivery of pulse oximetry to patients within a convenient period of time from enrolment. 5, 7, 9 Patient education on self-using pulse oximetry • To train patients before starting the programme on how to self-measure their SpO 2 by pulse oximetry. This training can be via educational videos, 8, 9 online calls, 4 or written guidance. 5 All patients should be trained well in SpO 2 measurement to ensure the accuracy and effectiveness of the system, and to ensure patient safety. 7,10 Continuation of monitoring for a sufficient period of time to detect deterioration • Monitoring periods varied between different models, ranging from 5 days 11 up to 30 days. 3 The average period of actual monitoring among all the included studies in our review was 12·7 days, and this is suggested as the minimum when developing a monitoring programme. Percentage of patients who needed escalated care after reporting a critical SpO 2 concentration • An SpO 2 threshold should be predetermined to identify and escalate care for patients who might be at risk. It was set as an at-rest SpO 2 of 92% or less in most models, 5, 6, 8, 12 although some models set an alarm for attention when SpO 2 reaches 94% or for additional safety. 5 For postexertional SpO 2 , this threshold was set as a decrease of SpO 2 of more than 3% after exertion, 12 and a decrease of more than 5% in other models. 11, 16 Number of online consultations needed per patient during the monitoring period • In non-emergency situations, online consultations should be considered as a first option for clinical assessment. These consultations can be escalated to a face-to-face visit or a hospital referral on a case-by-case basis. 12, 17, 18 Percentage of patients who needed hospital referrals • Consider the effect of RPM systems on the health outcomes of participating patients. Future researchers and policy makers should include the percentage of patients who needed hopsital referrals as one of the outcome measures to assess the effectiveness of an RPM programme. Median days to hospitalisation among the patients • The median days to hospitalisation must be reported to assess the effect on patients' quality of life and their use of health-care services. In the study by Shah and colleagues, 54 this value was reported as 6 days (IQR 4-8). Shah and colleagues, 54 33% of participants stated that they would be more likely to visit hospitals, at least for reassurance, if they were not monitored remotely. Various approaches for the measurement of SpO 2 were noted among the different models. Some studies relied only on at-rest SpO 2 , 14, 44, 47, 48 whereas other studies considered the change in postexertional SpO 2 as an indicator of deterioration. 12, 36, 46, 53, 58, 68 For at-rest SpO 2 , studies recommended resting for 10 min before initiating the measurement, 46 observing the reading for 30-60 s to get the most accurate result, avoiding moving the finger to which the oximeter is attached, measuring the SpO 2 through the index or middle finger and avoiding toes or ear lobes, removing nail polish before starting the measurement, and warming cold extremities. 11 For postexertional SpO 2 , various tests were used: the measurements were recorded after a 1-min sit-to-stand test, 12,58 a 6-min walk, 58 a 40-step walk, 53 a 30-m walk, 53 or exercise for 30-60 s. 46 Further research might help to identify the best approach to get the most accurate, standardised, and reliable measurements of at-rest and postexertional SpO 2 . We applied a rigorous set of inclusion and exclusion criteria for screening the search results. Since November, 2020, our team has been conducting a living horizon scanning of literature on the use of pulse oximetry for monitoring patients at home with COVID-19, as part of the COVID Oximetry @home programme. 14, 15 The horizon scanning is updated weekly, keeping the team updated with any evolving evidence. The screening, data extraction, and quality assessment were each conducted by two authors, who had a good agreement at all stages as assessed by Cohen's κ score. 22 We also present recommendations for implementing an effective RPM model with pulse oximetry based on the models applied in the included studies and in other relevant literature. We included peer-reviewed publications and preprints in our search to ensure that all available evidence was considered. The WHO Working Group on Ethics and COVID-19 69 proposed an ethical obligation for researchers to share their relevant research findings as soon as they become available, without waiting for peer review, to support the public health emergency response with evolving evidence. We acknowledged this and applied extra care in reviewing the search results to ensure the validity and accuracy of publications that had not yet undergone peer review. The final studies in our review included only two preprints, one of which 70 was subsequently peer-reviewed and was published on Sept 14, 2021. The included studies did not explicitly describe the effect of RPM with pulse oximetry on health outcomes compared with other models of care, due to relatively short monitoring periods and the absence of control groups in most of the studies. The accessibility, acceptability, and safety of using RPM models with pulsed oximetry in different populations with varied sociocultural characteristics need further research to better understand the potential risk of health inequities. Quantitative metrics cannot solely verify the success of the RPM model, but further qualitative research is needed regarding how users feel about remotemonitoring technologies, to ensure equity and effectiveness. A meta-analysis was not feasible owing to the heterogeneity of the outcomes of the included studies. Most of the studies had no control groups; as such, the data were insufficient to assess the impact of RPM with pulse oximetry and its effectiveness compared with other monitoring models. Preferences for systems through which SpO 2 readings are reported were inconsistent between the studies. A similar inconsistency was observed when identifying an SpO 2 threshold at which to escalate care. Further research is needed to standardise these measures to ensure best practice. The COVID-19 pandemic has placed RPM as a leading interest in public health research. Given the knowledge to date about COVID-19, pulse oximetry is potentially an effective tool for monitoring deterioration and keeping patients safe at home. The model was deemed safe for application and use in some different contexts among different populations. Research into the cost-effectiveness of RPM with pulse oximetry is scarce at present, and available data about its effect on the use of health-care services are inconclusive. Further research is needed to inform the future implementation of pulse oximetry in monitoring patients with COVID-19. This research should involve more diverse populations, test the system in resource-limited settings, and assess the effect on health outcomes compared with other systems. All authors contributed to the conceptualisation of the study and the protocol development. AA and TB initially screened the data and assessed quality, and PA provided senior advice. AA, TB, JMC, PA, and A-LN participated in data curation and analysis. SE, PA, AD, and A-LN advised on data validation and result presentation. AA drafted the initial full manuscript. TB, SE, JMC, AD, PA, and A-LN reviewed and provided feedback on the manuscript. All authors approved the final version of the manuscript. We declare no competing interests. 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We acknowledge support from the Imperial NIHR Biomedical Research Centre.