Is qualitative social research in global health fulfilling its potential?: a systematic evidence mapping of research on point-of-care testing in low- and middle-income contexts

BACKGROUND

Qualitative social research has made valuable contributions to understanding technology-based interventions in global health. However, we have little evidence of who is carrying out this research, where, how, for what purpose, or the overall scope of this body of work. To address these questions, we undertook a systematic evidence mapping of one area of technology-focused research in global health, related to the development, deployment and use of point-of-care tests (POCTs) for low-and middle-income countries (LMICs).

METHODS

We conducted an exhaustive search to identify papers reporting on primary qualitative studies that explore the development, deployment, and use of POCTs in LMICs and screened results to identify studies meeting the inclusion criteria. Data were extracted from included studies and descriptive analyses were conducted.

RESULTS

One hundred thirty-eight studies met our inclusion criteria, with numbers increasing year by year. Funding of studies was primarily credited to high income country (HIC)-based institutions (95%) and 64% of first authors were affiliated with HIC-based institutions. Study sites, in contrast, were concentrated in a small number of LMICs. Relatively few studies examined social phenomena related to POCTs that take place in HICs. Seventy-one percent of papers reported on studies conducted within the context of a trial or intervention. Eighty percent reported on studies considering POCTs for HIV and/or malaria. Studies overwhelmingly reported on POCT use (91%) within primary-level health facilities (60%) or in hospitals (30%) and explored the perspectives of the health workforce (70%).

CONCLUSIONS

A reflexive approach to the role, status, and contribution of qualitative and social science research is crucial to identifying the contributions it can make to the production of global health knowledge and understanding the roles technology can play in achieving global health goals. The body of qualitative social research on POCTs for LMICs is highly concentrated in scope, overwhelmingly focuses on testing in the context of a narrow number of donor-supported initiatives and is driven by HIC resources and expertise. To optimise the full potential of qualitative social research requires the promotion of open and just research ecosystems that broaden the scope of inquiry beyond established public health paradigms and build social science capacity in LMICs.

What are the characteristics of participatory surveillance systems for influenza-like-illness?

Background

Seasonal influenza causes significant morbidity and mortality, with an estimated 9.4 million hospitalisations and 290 000-650 000 respiratory related-deaths globally each year. Influenza can also cause mild illness, which is why not all symptomatic persons might necessarily be tested for influenza. To monitor influenza activity, healthcare facility-based syndromic surveillance for influenza-like illness is often implemented. Participatory surveillance systems for influenza-like illness (ILI) play an important role in influenza surveillance and can complement traditional facility-based surveillance systems to provide real-time estimates of influenza-like illness activity. However, such systems differ in designs between countries and contexts, making it necessary to identify their characteristics to better understand how they fit traditional surveillance systems. Consequently, we aimed to investigate the performance of participatory surveillance systems for ILI worldwide.

Methods

We systematically searched four databases for relevant articles on influenza participatory surveillance systems for ILI. We extracted data from the included, eligible studies and assessed their quality using the Joanna Briggs Critical Appraisal Tools. We then synthesised the findings using narrative synthesis.

Results

We included 39 out of 3797 retrieved articles for analysis. We identified 26 participatory surveillance systems, most of which sought to capture the burden and trends of influenza-like illness and acute respiratory infections among cohorts with risk factors for influenza-like illness. Of all the surveillance system attributes assessed, 52% reported on correlation with other surveillance systems, 27% on representativeness, and 21% on acceptability. Among studies that reported these attributes, all systems were rated highly in terms of simplicity, flexibility, sensitivity, utility, and timeliness. Most systems (87.5%) were also well accepted by users, though participation rates varied widely. However, despite their potential for greater reach and accessibility, most systems (90%) fared poorly in terms of representativeness of the population. Stability was a concern for some systems (60%), as was completeness (50%).

Conclusions

The analysis of participatory surveillance system attributes showed their potential in providing timely and reliable influenza data, especially in combination with traditional hospital- and laboratory led-surveillance systems. Further research is needed to design future systems with greater uptake and utility.

The benefits, challenges, and best practice for patient and public involvement in evidence synthesis: A systematic review and thematic synthesis

INTRODUCTION

Despite the growing evidence on patient and public involvement (PPI) in health research, little emphasis has been placed on understanding its quality and appropriateness to evidence synthesis (ES) and systematic reviews (SR). This study aimed to synthesise qualitative evidence on the benefits, challenges, and best practices for PPI in ES/SR projects from the perspectives of patients/public and researchers.

METHODS

We searched Ovid MEDLINE, Ovid EMBASE, Cochrane Library and CINAHL Plus. We also searched relevant grey literature and conducted hand-searching to identify qualitative studies which report the benefits and challenges of PPI in individual ES/SR projects. Studies were independently screened by two reviewers for inclusion and appraised using the Joanna Briggs Institute's Qualitative Tool. Included studies were synthesised narratively using thematic synthesis.

RESULTS

The literature search retrieved 9923 articles, of which eight studies were included in this review. Five themes on benefits emerged: two from patients'/public's perspective-gaining knowledge, and empowerment; and three from researchers' perspective-enhancing relevance, improving quality, and enhancing dissemination of findings. Six themes on challenges were identified: three from patients'/public's perspective-poor communication, time and low self-esteem; and three from researchers' perspective-balancing inputs and managing relations, time, and resources and training. Concerning recommendations for best practice, four themes emerged: provision of sufficient time and resources, developing a clear recruitment plan, provision of sufficient training and support, and the need to foster positive working relationships.

CONCLUSION

Highlighting the benefits and challenges of PPI in ES/SR projects from different stakeholder perspectives is essential to understand the process and contextual factors and facilitate meaningful PPI in ES/SR projects. Future research should focus on the utilisation of existing frameworks (e.g., Authors and Consumers Together Impacting on eVidencE [ACTIVE] framework) by researchers to help describe and/or report the best approaches and methods for involving patients/public in ES/SRs projects.

PATIENT AND PUBLIC CONTRIBUTION

This review received great contributions from a recognised PPI partner, the Chair of the Cochrane Consumer Network Executive, to inform the final stage of the review (i.e., interpretation, publication and dissemination of findings). The PPI partner has been included as an author of this review.

Risk of serious COVID-19 outcomes among adults and children with moderate-to-severe asthma: a systematic review and meta-analysis

BACKGROUND

The Joint Committee on Vaccination and Immunisation in the United Kingdom requested an evidence synthesis to investigate the relationship between asthma and coronavirus disease 2019 (COVID-19) outcomes.

OBJECTIVE

We conducted a systematic review and meta-analysis to summarise evidence on the risk of severe COVID-19 outcomes in people with uncontrolled asthma or markers of asthma severity.

METHODS

High-dose inhaled corticosteroids (ICS) or oral corticosteroids (OCS) were used as markers of asthma severity, following international or national asthma guidelines. Risk of bias was assessed using Joanna Briggs Institute tools. Adjusted point estimates were extracted for random-effects meta-analyses and subgroup analyses.

RESULTS

After screening, 12 studies (11 in adults and one in children) met the eligibility criteria. Adults using high-dose ICS or OCS had a pooled adjusted hazard ratio (aHR) of 1.33 (95% CI 1.06-1.67, I²=0%) for hospitalisation and an aHR of 1.22 (95% CI 0.90-1.65, I²=70%) for mortality for COVID-19. We found insufficient evidence for associations between markers on COVID-19 mortality in the subgroup analyses.

CONCLUSIONS

Adults with severe asthma are at increased risk of COVID-19 hospitalisation compared to nonusers. Our analysis highlighted the dearth of studies in children with asthma investigating serious COVID-19 outcomes.

A new diversity index

We introduce here a new index of diversity based on consideration of reasonable propositions that such an index should have in order to represent diversity. The behaviour of the index is compared with that of the Gini-Simpson diversity index, and is found to predict more realistic values of diversity for small communities, in particular when each species is equally represented and for small communities. The index correctly provides a measure of true diversity that is equal to the species richness across all values of species and organism numbers when all species are equally represented, as well as Hill's more stringent 'doubling' criterion when they are not. In addition, a new graphical interpretation is introduced that permits a straightforward visual comparison of pairs of indices across a wide range within a parameter space based on species and organism numbers.

0485 Experience and Attitudes About Prescription Insomnia Medications: Results from an Online Survey of Individuals with Sleeping Difficulties and Insomnia

Introduction

This survey explored several topics related to living with insomnia/sleeping difficulties. Reported here are patient experience, attitudes, and perspectives about and understanding of prescription medications for insomnia.

Methods

The online survey was conducted by The Harris Poll in the U.S. between February 14 and March 8, 2019. Survey respondents (“patients”) were adults age ≥18y who had been diagnosed with insomnia (11% of respondents), or had experienced sleeping difficulties (defined as difficulty falling asleep or staying asleep for ≥3 nights/week for ≥3 months; 89% of respondents). Raw survey data were weighted by relevant factors to be representative of the total U.S. adult population with insomnia/sleeping difficulties.

Results

Among 525 patients (mean age 46y; 55% female) who completed the survey, 83 were currently using prescription medication, 45 used prescription medication previously, and 397 had no prescription medication history. The majority of all patients “somewhat” or “strongly” agreed they were “concerned about the safety risks of sleep medications currently available by prescription” (79%); felt “there have got to be better medications that help people sleep” (74%); and that they “wish there were more medications to choose from” (67%). Within the group of respondents with current/past prescription history (n=128), 63%, 23%, and 14% had tried 1-2, 3-4, or ≥5 different prescription medications, respectively. Among reasons for missing/skipping a dose, ~20% of respondents with current/past prescription history selected for each response that they “do not feel my medication is effective”; “do not like the way my medication makes me feel when I wake up the next morning”; and “prefer not to take my medication every night unless absolutely necessary.”

Conclusion

Results from this online survey provide insights into patient attitudes toward pharmacotherapy and indicate that a significant number of insomnia patients feel dissatisfied with medication treatment options, including concerns regarding safety and side effects.

Support

Eisai Inc.

Abstract P1-13-03: Mature analysis of UK Taxotere as Adjuvant Chemotherapy (TACT) trial (CRUK 01/001); effects of treatment and characterisation of patterns of breast cancer relapse

Introduction: TACT, an investigator-led study in 4162 women with node positive (N+ve) or high risk node negative (N-ve) early breast cancer (EBC), is the largest taxane trial unconfounded by treatment (trt) duration. At principal analysis, with 5 years follow-up (fup), no evidence of improved disease-free survival (DFS) was observed by switching to 4 cycles of docetaxel (D) after 4 cycles of FEC (Ellis, Lancet 2009). Results were provocative in suggesting differential effects according to ER & HER2 status. Longer fup provides opportunity to detect emergence of late trt effects overall & within phenotypic subgroups & explore patterns of recurrence, by tumor characteristics.

Patients & methods: TACT recruited women with histologically confirmed completely resected invasive EBC from 104 centers (UK (103), Belgium (1)) between 02/2001 & 07/2003. Centers chose FEC (600/60/600 mg/m2 q3wk × 8) or E-CMF (E 100mg/m2 q3wk × 4 → CMF 100mg/m2 PO d1-14 or 600mg/m2 IV d1&8/40/600 mg/m2 q4wk × 4) as their control, reflecting standard UK practice. Patients (pts) were randomized to FEC-D (FEC q3wk × 4 → D 100 mg/m2 q3wk × 4) or control. 2523 pts were from FEC centers (FEC = 1265: FEC-D = 1258) & 1639 from E-CMF centers (E-CMF = 824; FEC-D = 815). Endocrine therapy was given for 5 years. Few pts received HER2 directed therapy; 589 pts had unknown HER2 status. Median fup is now 97.5 months; this analysis updates DFS & overall survival in the ITT population. It also explores patterns of relapse by phenotypic & clinical characteristics. Analyses of trt effect are stratified by ER status due to issues of non-proportionality of hazard associated with length of fup.

Results: DFS events have been reported for 1329 pts (FEC-D=640, Control=689) giving an unadjusted hazard ratio (HR) & 95%CI (stratified by control regimen & ER status) of 0.93 (0.83, 1.03) overall; p = 0.16 in favor of FEC-D & for ER+ve/HER2-ve of 0.99 (0.84, 1.17), for ER+ve/HER2+ve) 0.97 (0.73, 1.30), for ER-ve/HER2+ve 0.74 (0.53, 1.03), & ER-ve/HER2-ve 0.93 (0.73, 1.17). 1017 patients have died (FEC-D=500, Control=517); unadjusted HR=0.98 (95%CI: 0.86, 1.10); p = 0.69 with intercurrent deaths (prior to distant relapse) reported for 80 pts (FEC-D=40, Control=40).

Annual event rates show different pattern of disease relapse by phenotypic subgroup

Determinants of white-coat hypertension

BACKGROUND

The prevalence of white-coat hypertension (WCH) is considerable in patients referred with elevated office blood pressure. Failure to recognise this phenomenon can lead to the inappropriate use of antihypertensive medications. We undertook this study to determine the profile of patients with WCH.

METHODS

Baseline clinic and daytime ambulatory blood pressures were available from 5716 patients referred over a 22-year period. Individuals were considered to have WCH if they had an elevated clinic blood pressure measurement greater than 140/90 mmHg and normal daytime mean ambulatory blood pressure. Mean age was 53.6 years and 53.2% were female.

RESULTS

The overall prevalence of white-coat hypertension was 15.4%. A higher prevalence was seen amongst older adults, females, and non-smokers.

CONCLUSION

Multivariate logistic regression analysis confirmed these characteristics as independent predictors of WCH.

Emx1-specific expression of foreign genes using "knock-in" approach

Emx1 is a mouse homologue of the Drosophila homeobox gene empty spiracles. Its expression is limited to the neurons in developing and adult cerebral cortex and hippocampus. Because of the highly restricted expression pattern of the Emx1 gene, it would be quite desirable to characterize the promoter of the Emx1 for directing foreign gene expression in the transgenic mouse. We report here that we have achieved the Emx1-specific expression in transgenic mice by inserting the lacZ reporter and cre genes directly into the exon 1 of the Emx1 gene using embryonic stem (ES) cell technology. The distribution of the beta-galactosidase activity in the transgenic mice was consistent with the published results obtained using in situ hybridization and immunohistochemistry. Furthermore, we have demonstrated that Cre protein was present in the cerebral cortex of the transgenic mice and was able to mediate loxP-specific recombination in vitro. The creation of this line of cre transgenic mice, and the demonstration that the insertion site located in the exon 1 of the Emx1 gene could render foreign genes a specific expression pattern restricted to the developing and adult cerebral cortex and hippocampus, should be conducive to further studies of the effect of a gene mutation or overexpression upon the development and plasticity of cerebral cortex and hippocampus.

Diagnosis of white coat hypertension by ambulatory blood pressure monitoring

White coat hypertension (WCH) is common in referred hypertensive patients. Ambulatory blood pressure monitoring (ABPM) is not free from the white coat syndrome. We examined the use of the elevation of the first and last measurements of ABPM for diagnosis of WCH in a hypertensive population that had been referred to a hospital-based hypertension unit. Data were obtained on 1350 patients for clinic and ABPM parameters. WCH, as diagnosed by conventional clinic blood pressure (BP) measurement, was compared with a variety of alternative methods determined from ABPM. In all cases, mean daytime pressure was <135 mm Hg/85 mm Hg with an elevation of clinic BP >/=140 mm Hg systolic or 90 mm Hg diastolic. The definitions tested for this elevation were first hour mean pressure, first reading, maximum reading in first hour, last hour mean pressure, last reading, maximum reading in the last hour and maximum reading in first or last hour. Elevation of the maximum pressure in the first hour or last hour above 140 mm Hg systolic or 90 mm Hg diastolic showed a high level of agreement (kappa=0.91) with classical WCH for diagnosis of the white coat syndrome. Termed ambulatory white coat hypertension, patients with this finding were older than classic white coat patients and had higher daytime (127+/-6/78+/-5 mm Hg versus 121+/-5.5/74+/-6 mm Hg, P<0.005 for systolic and diastolic) and nighttime (114+/-11/67+/-8 mm Hg versus 106+/-9/61+/-6 mm Hg, P<0.005 for systolic and diastolic) pressures. They also had a significantly greater Sokolow-Lyon index (leads V(1)+V(5), 21+/-7 mV versus 18+/-6 mV). Elevation of BP above 140 mm Hg systolic or 90 mm Hg diastolic in the first or last hour of monitoring diagnoses patients with a white coat response in whom there is a higher BP profile than in patients with classic white coat response alone. We suggest, therefore, that this is a better measure of the white coat phenomenon.

Evaluation of the Profilomat II ambulatory blood pressure system according to the protocols of the British Hypertension Society and the Association for the Advancement of Medical Instrumentation

OBJECTIVE

To evaluate the Profilomat II monitor for ambulatory blood pressure measurement according to the protocols of the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI).

DESIGN

The BHS protocol is divided into two parts. Part I, which is the part applicable to this study, comprises the main validation procedure and has five phases: before-use device calibration; static device validation; and report of evaluation.

METHOD

Three Profilomat II recorders passed the before-use device calibration test. They then entered the in-use (field) assessment phase during which the three recorders were each worn by ten subjects for 24-h, after which the calibration was again assessed. Since no difference in calibration testing was observed between the three devices, one was selected randomly and the main validation test was carried out in 85 subjects, who had a wide range of blood pressures, using the sphygmocorder. The results were analysed according to the BHS grading system from A to D. The data was also analysed according to the standard of the Association for the Advancement of Medical Instrumentation (AAMI) which stipulates that the mean difference between the test device and the standard shall be </= 5 mmHg with a standard deviation of </= 8 mmHg.

RESULTS

The Profilomat II achieved a BHS grade C rating for systolic blood pressure and grade B for diastolic blood pressure; it satisfied the criteria for accuracy of the AAMI for diastolic but not systolic blood pressure. When the BHS and AAMI criteria were applied to tertiles of pressure (low pressure range < 130/80 mmHg, medium pressure range 130-160/80-100 mmHg, high pressure range > 160/100 mmHg), the Profilomat II was less accurate in the high pressure range, achieving a D/C grading, and failed the AAMI criteria for systolic and diastolic blood pressures. The mean and standard deviation of the first mercury sphygmomanometer measurements were 145+/-34/87+/- 20 mmHg. Subject acceptability was good and the manufacturers manual was satisfactory.

CONCLUSION

On the basis of these results, the Profilomat II cannot be recommended for ambulatory blood pressure measurement in clinical practice where accurate measurements are required.

Evaluation of the Schiller BR-102 ambulatory blood pressure system according to the protocols of the British Hypertension Society and the Association for the Advancement of Medical Instrumentation

OBJECTIVE

To evaluate the Schiller BR-102 monitor for ambulatory blood pressure measurement according to the protocols of the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI).

DESIGN

The BHS protocol is divided into two parts. Part I, which is the part applicable to this study, comprises the main validation procedure and has five phases: before-use device calibration; in-use (field) phase; after-use device calibration; static device validation; and report of evaluation.

METHOD

Three Schiller BR-102 recorders passed the before-use device calibration test, after which they entered the in-use (field) assessment phase during which the three recorders were each worn by 10 subjects for 24 h, after which calibration was again assessed. Because there was no difference in results of calibration testing among the three devices, one was selected randomly and the main validation test was carried out on 85 subjects with a wide range of blood pressures both for the auscultatory mode and for the oscillometric mode using the Sphygmocorder. The results were analysed according to the BHS grading system from A to D. The data were also analysed according to the standard of the Association for the Advancement of Medical Instrumentation (AAMI), which stipulates that the mean difference between the test device and the standard shall be </= 5 mmHg with a standard deviation of </= 8 mmHg.

RESULTS

The Schiller BR-102 achieved a BHS grade B rating for systolic and diastolic blood pressures in the auscultatory mode and satisfied the criteria for accuracy of the AAMI protocol for systolic and diastolic blood pressures. In the oscillometric mode, the Schiller BR-102 achieved grade D for systolic blood pressure and grade B for diastolic blood pressure according to the BHS protocol and satisfied the AAMI criteria for diastolic but not systolic blood pressure. Applying the BHS and AAMI criteria to tertiles of blood pressure (low-pressure range < 130/80 mmHg, medium-pressure range 130-160/80-100 mmHg, high-pressure range > 160/100 mmHg) the Schiller BR-102 was less accurate in the high pressure range for diastolic blood pressure but more accurate for systolic blood pressure, achieving A/C grading, while satisfying the AAMI criteria both for systolic and for diastolic blood pressure in the auscultatory mode. In the oscillometric mode the device performed less accurately in the high-pressure range, achieving grade D/C, while failing to satisfy the AAMI criteria both for systolic and for diastolic blood pressure. The means+/-SD of the first mercury sphygmomanometer measurements were 143+/-32 mmHg for systolic blood pressure and 88+/-21 mmHg for diastolic blood pressure. Acceptability to subjects was good and the manufacturer's manual was satisfactory.

CONCLUSION

On the basis of these results, the Schiller BR-102 can be recommended for ambulatory blood pressure measurement in clinical practice using the auscultatory mode, but the oscillometric mode, which operates only if the device fails in the auscultatory mode, does not provide accurate measurements.

Sensitization to human leukocyte antigen before and after the introduction of erythropoietin

INTRODUCTION

Antibodies directed against human leukocyte antigens (HLAs) impact adversely on renal transplantation. Measures aimed at preventing such antibody formation are thus important. The introduction of recombinant human erythropoietin (rHuEpo) has permitted the reduction of blood transfusion in patients with chronic renal failure. The impact of rHuEpo on the incidence of sensitization in patients awaiting transplantation was therefore studied.

METHODS

A retrospective analysis of the patients awaiting transplantation before (group A) and 4 years after (group B) the introduction of rHuEpo was performed in order to ascertain changing patterns in the use of blood transfusion and causes of sensitization.

RESULTS

The total number of transfusions administered to haemodialysis patients decreased by 34% during the study period. This was accompanied by a significant reduction in the ratio of blood transfusion to haemodialysis treatment episodes (0.095 in group A to 0.06 in group B, P = 0.001). The number of patients sensitized as a consequence of blood transfusion decreased from 63% in group A to 28% in group B (P = 0.0004). The overall incidence of sensitization decreased from 50% in group A to 36.5% in group B (P = 0.008). This decrement was associated with a significant reduction in the mean waiting time for transplantation (42.1 +/- 1.1 vs 15.4 +/- 2.4 months, P < 0.0001). The incidence of sensitization due to previous transplantation increased during the study period from 41% in group A to 77% in group B, (P = 0.0004). There was no change in the number of patients sensitized due to pregnancy.

CONCLUSION

The introduction of rHuEpo has resulted in a significant decrease in the requirements for blood transfusion among patients awaiting transplantation and is associated with a significant reduction in transfusion-related sensitization and mean waiting time for transplantation.

Renal transplantation performed across a positive crossmatch: a single centre experience

The importance of certain positive crossmatches (CM+) in kidney transplantation remains controversial. Fifty consecutive kidney transplants were performed across a CM+ between Jan. 1990-April 1994. In 19 cases there was an isolated B-cell CM+ (Group I), in 24 an historic T-cell IgM CM+ (Group II) and in 7 an historic T-cell IgG CM+ (Group III). Comparing groups I:II:III: early acute rejection affected 32%, 42%, 57% of grafts; mean serum creatinine at 3 months was 166, 150, 229 umol/l (p < 0.05); 1 yr graft survival was 95 per cent, 96 per cent, 71 per cent (p = 0.09). In group III both graft losses were in the setting of an additional current B-cell CM+.

CONCLUSIONS

Transplantation performed in either the presence of an isolated B-cell CM+ or in the presence of an historic T-cell IgM CM+ was associated with acceptable outcomes at 1 yr. An historic T-cell IgG CM+ was confirmed as a contraindication to transplantation in most circumstances, especially when coupled with a current B-cell CM+.

A new audiovisual technique for recording blood pressure in research: the Sphygmocorder

OBJECTIVE

To devise a method of blood pressure measurement capable of being substituted for the fallible human observer in validation of blood pressure measuring devices.

DESIGN

A number of components used to measure blood pressure have been combined innovatively with audiovisual recording technology to produce a system, named the Sphygmocorder, which consists of a mercury sphygmomanometer, an occluding cuff, an inflation source, a stethoscope, a microphone capable of detecting Korotkoff sounds, a camcorder and a display screen.

METHODS

To determine the accuracy of the Sphygmocorder against the trained human observer, the Sphygmocorder has been validated in three separate studies in which three devices for self-measurement of blood pressure, the Omron HEM-705CP, the Phillips HP5332 and the Nissei DS-175, were being validated against two trained observers in 85 subjects with a wide range of blood pressure according to the protocol of the British Hypertension Society.

RESULTS

The Sphygmocorder was as accurate as at least one of the observers in each of the validation studies and therefore allows replacement of trained observers by the new device.

CONCLUSION

The Sphygmocorder, which retains the time-honoured technique of blood pressure measurement with a mercury sphygmomanometer and an auscultating observer, and provides, in addition, objective evidence of the measurement recorded, which can be stored and re-examined, can be used as a substitute for human observers in validation studies of blood pressure-measuring devices.

State of the market. A review of ambulatory blood pressure monitoring devices

The introduction of 24-hour ambulatory blood pressure measurement into clinical practice created a large market for ambulatory blood pressure measurement devices. Forty-three such devices from 31 manufacturers or suppliers are now available to satisfy a market demand that is likely to increase. The aim of this article is to identify the devices available and then to examine critically any validation studies assessing accuracy and performance. Of the 43 devices available 18 have been validated according to the protocols of the Association for the Advancement of Medical Instrumentation (AAMI) or the British Hypertension Society (BHS) in 25 reported studies. In 9 of these studies the protocol was not adhered to, and the results, which are therefore questionable, are noted but not considered further. Fourteen devices were evaluated according to the accuracy criteria of both protocols, and of these 9 fulfilled the requirements. From this review of 43 devices on the market it may be concluded that, at the time of writing, there is published evidence for only 9 devices meeting the generally accepted AAMI and BHS criteria for accuracy and performance; these are the A&D TM-2420 models 6 and 7 and TM-2421, CH-Druck, Nissei ABPM DS-240, Profilomat, QuietTrak, and SpaceLabs SL-90202 and SL-90207.

Factors influencing validation of ambulatory blood pressure measuring devices

With the introduction of 24 h ambulatory blood pressure monitoring into clinical practice a vast market for ambulatory blood pressure monitoring devices has been created. To satisfy this market manufacturers are producing an array of ambulatory blood pressure monitoring devices. There is no obligation on manufacturers to have such devices validated independently, even though two national protocols, one from the British Hypertension Society (BHS) and the other from the Association for the Advancement of Medical Instrumentation (AAMI), call for independent validation and state the means of doing so. However, many factors can influence the validation procedure. They include compliance to the protocol being employed; the accuracy of the standard; establishing precisely the model being validated; the influences of blood pressure level, age and exercise on device accuracy; the provisions necessary for special populations, such as pregnant women, the elderly and children; the influence of oscillometric versus Korotkoff sound detection and electrocardiographic gating on comparative measurements; the assessment of performance as distinct from accuracy; and the relevance of general factors, such as the algorithm being employed and computer compatibility. Forty-three ambulatory blood pressure monitoring devices have been marketed for ambulatory blood pressure measurement and of those only 18 have been validated according to either the BHS or the AAMI protocol. The influence of the factors listed above on the validation studies of those devices will be considered and the relevance of validation procedures to the clinical use of ambulatory blood pressure monitoring devices will be discussed.

The ambulatory blood pressure in normotensive and hypertensive subjects: results from an international database

OBJECTIVE

To delineate more precisely an operational threshold for making clinical decisions based on ambulatory blood pressure (ABP) measurement by studying the ABP in subjects who were diagnosed as either normotensive or hypertensive by conventional blood pressure (CBP) measurement.

SUBJECTS

Twenty-four research groups recruited 7069 subjects. Of these, 4577 were normotensive (systolic CBP < or = 140 mmHg and diastolic CBP < or = 90 mmHg) and 1773 were hypertensive (systolic CBP > or = 160 mmHg and/or diastolic CBP > or = 90 mmHg). Of the latter, 1324 had systolic and 1310 had diastolic hypertension.

RESULTS

Ninety-five percent of the normotensive subjects had a 24-h ABP below (systolic and diastolic, respectively) 133 and 82 mmHg. Of the patients with systolic hypertension, 24% had a 24-h systolic ABP of < 133 mmHg. Similarly, 30% of those with diastolic hypertension had a 24-h diastolic ABP of < 82 mmHg. The probability that hypertensive patients had a 24-h ABP below these thresholds was higher in women than in men, increased with age and was 2- to 4-fold greater if the CBP of the patient had been measured at only one visit and if fewer than 3 CBP measurements had been averaged to establish the diagnosis of hypertension. By contrast, for each 10-mmHg increment in systolic CBP, this probability decreased by 54% for the 24-h systolic ABP and by 25% for the 24-h diastolic ABP, and for each 5 mmHg increment in diastolic CBP it increased by 6 and 9%, respectively.

CONCLUSION

The ABP distributions of the normotensive subjects included in the present international database were not materially different from those in previous reports in the literature. One-fifth to more than one-third of the hypertensive patients had an ABP which was below the 95th centile of the ABP in normotensive subjects, but this proportion decreased if the hypertensive patients had shown a higher CBP upon repeated measurement. The prognostic implications of elevated CBP in the presence of normal ABP remain to be determined.

A comparison of the British Hypertension Society and Association for the Advancement of Medical Instrumentation protocols for validating blood pressure measuring devices: can the two be reconciled?

BACKGROUND

Experience with the original protocols of the Association for the Advancement of Medical Instrumentation (AAMI) and the British Hypertension Society (BHS) for validating blood pressure has provided valuable insight into the methodological problems associated with device validation and has influenced both the BHS and the AAMI in revising their protocols.

OBJECTIVES

To review the revisions of the original BHS and AAMI protocols; to compare the protocols; and, using the BHS protocol as a framework for validation, to determine how it should be modified to a protocol that will fulfil the criteria of both the AAMI and the BHS.

CONCLUSIONS

The revised protocols have many similarities but there are some important differences. These differences merit consideration so as to facilitate manufacturers seeking to validate devices for acceptance in both Europe and the United States. Of the two protocols, the BHS protocol is the more elaborate in that (1) it takes particular care to ensure that observers are trained to a very high standard, (2) it makes provision for special group validation and (3) it recommends in-use validation of all devices. By modifying the BHS protocol, it is possible to validate blood pressure measuring devices (ambulatory devices require special consideration) to satisfy the criteria of both protocols.

Using Hawksley random zero sphygmomanometer as a gold standard may result in misleading conclusions

We combined a database of paired blood pressure measurements taken using the Hawksley random-zero sphygmonanometer and a standard mercury sphygmomanometer and a database of paired measurements made on a SpaceLabs 90202 ambulatory blood pressure recorder and standard sphygmomanometer to determine how the SpaceLabs 90202 would have fared if it had been assessed against the Hawksley random-zero sphygmomanometer instead of a standard sphygmomanometer. The pooled database contained 255 triplicate readings. Using the standard sphygmomanometer as gold standard, the Spacelabs had a median error of 2 mm/Hg for both systolic and diastolic. Against the Hawksley random-zero sphygmomanometer, median error was -3 mm systolic and -6 mm diastolic. The proportion of errors > 10 mm rose from 11% (systolic) and 9% (diastolic) with the standard sphygmomanometer to 16% and 29% with the Hawksley random-zero sphygmomanometer. Because it underestimates systolic and diastolic pressures, the use of the Hawksley random-zero sphygmomanometer as a gold standard may have resulted in misleading conclusions about performance of some automated BP recorders.

A consistent reference frame for ambulatory blood pressure monitoring is found in different populations

This study investigated the consistency of a reference frame for ambulatory pressure monitoring, which using various approaches was determined in two different populations. The two reference groups were 718 subjects randomly selected from the population and 895 bank employees. The reference values derived in these two groups were subsequently tested in 591 untreated hypertensive patients. The ambulatory pressures equivalent to a conventional pressure of 140 mmHg systolic and 90 mmHg diastolic were calculated by regression analysis in all subjects. In addition, in subjects who were normotensive by conventional sphygmomanometry, the mean +2 and +3 standard deviations and the 90th, 95th and 99th percentiles of the ambulatory measurements were determined. The distributions of the ambulatory measurements were similar in the two reference groups and the aforementioned parameters therefore agreed within 4 mmHg in the two populations. There was considerable overlap in the ambulatory pressures between the two reference groups and the hypertensive patients. Classification of the patients according to the means +3 standard deviations and the regression limits gave the same results because in both reference groups these boundaries approximated to each other within 1 mmHg. For the 24 h pressures in the population sample these boundaries were 140 mmHg systolic and 88 mmHg diastolic. Of the patients with systolic hypertension (> or = 160 mmHg on conventional measurement), 39% had a 24 h systolic pressure of < 140 mmHg and of those with diastolic hypertension (> or = 95 mmHg), 44% had a 24 h diastolic pressure of < 88 mmHg; if the corresponding boundaries derived in the bank employees (143/90 mmHg) were applied, these proportions were 47% and 44%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive therapy and circadian blood pressure profiles: a retrospective analysis utilising cumulative sums

The results of previous studies on the effects of antihypertensive agents on circadian blood pressure patterns are inconclusive, possibly due to the lack of a simple, objective, universally accepted method of quantifying circadian blood pressure profiles. In order to investigate for differences in the effects of antihypertensive drugs on circadian changes we utilised a recently described modified cumulative sums technique to quantify circadian alteration magnitude (CAM). CAM is simply calculated as the difference between crest and trough blood pressures, the mean blood pressures of the 6-h periods of highest and lowest sustained pressures respectively. The records from all 24-h ambulatory blood pressure monitoring performed over a 7 year period on subjects either on no medication (1208), or on treatment with a single first-line antihypertensive agent (578), were examined retrospectively. A sample (n = 40) stratified for trough diastolic blood pressure, age and sex was randomly selected from each of the following 5 groups: subjects on no medication, and subjects being treated with bendrofluazide, atenolol, class 2 calcium-channel blockers or captopril alone. Untreated subjects, those on bendrofluazide and those on a class 2 calcium channel blocker had similar circadian patterns. Subjects on atenolol therapy (25.9 +/- 1.7/18.3 +/- 1.3, systolic CAM +/- SE/diastolic CAM +/- SE) had attenuated circadian changes (p < 0.05) when compared to the untreated group (29.8 +/- 1.8/23.6 +/- 1.1), while those on captopril (34.9 +/- 2.4/25.7 +/- 1.8) exhibited markedly increased systolic and diastolic circadian blood pressure swings, which differed from those of the atenolol treated group (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Short report: ambulatory blood pressure in normotensive compared with hypertensive subjects. The Ad-Hoc Working Group

OBJECTIVE

To delineate more precisely an operational threshold for making clinical decisions based on ambulatory blood pressure (ABP) measurement by studying the ABP in subjects who were diagnosed as either normotensive or hypertensive by conventional blood pressure (CBP) measurement.

SUBJECTS

Twenty-four research groups recruited 7069 subjects. Of these, 4577 were normotensive (CBP < or = 140/90 mmHg), 719 were borderline hypertensive (systolic CBP 141-159 mmHg or diastolic CBP 91-94 mmHg) and 1773 were definitely hypertensive. Of the subjects in the last of these categories, 1324 had systolic hypertension (systolic CBP > or = 160 mmHg) and 1310 had diastolic hypertension (diastolic CBP > or = 95 mmHg). Hypertension had been diagnosed from the mean of two to nine (median two) CBP measurements obtained at one to three (median two) visits.

RESULTS

The 95th centiles of the 24-h ABP distributions in the normotensive subjects were (systolic and diastolic, respectively) 133 and 82 mmHg. Of the subjects with systolic hypertension, 24% had 24-h systolic ABP < 133 mmHg. Similarly, 30% of those with diastolic hypertension had 24-h diastolic ABP < 82 mmHg. The probability that hypertensive subjects had 24-h ABP below these thresholds tended to increase with age and was two- to fourfold greater if the CBP of the subject had been measured at only one visit and if fewer than three CBP measurements had been averaged for establishing the diagnosis of hypertension. By contrast, for each 10-mmHg increment in systolic CBP, this probability decreased by 54% for 24-h systolic ABP and by 26% for 24-h diastolic ABP, and for each 5-mmHg increment in diastolic CBP it decreased by 6 and 9%, respectively.

CONCLUSIONS

The ABP distributions of the normotensive subjects included in the present international database were not materially different from those in previous reports in the literature. One-fifth to more than one-third of hypertensive subjects had an ABP which was below the 95th centile of the ABP of normotensive subjects, but this proportion decreased if the hypertensive subjects had shown a higher CBP upon repeated measurement. The prognostic implications of elevated CBP in the presence of normal ABP remain to be determined.

Evaluation of blood pressure measuring devices

Validation of blood pressure measuring devices is a relatively new field of research. There are two national protocols for validating blood pressure measuring devices: the protocol of the American Association for the Advancement of Medical Instrumentation (AAMI) and the protocol of the British Hypertension Society (BHS), each of which has recently been revised. 19 blood pressure measuring devices have been validated according to one or both of these protocols. These protocols have been beneficial in drawing attention to the potential inaccuracy of blood pressure measuring systems, they permit comparison between devices and they have brought manufacturers of blood pressure measuring devices into closer contact with the profession. There are some inherent weaknesses in both protocols which include the fallibility of the 'gold standard', the lack of provision for validation in special circumstances and in special groups, such as the elderly and pregnant women, and failure to allow for deteriorating accuracy with higher pressure levels. The revised BHS protocol attempts to redress these deficiencies.

Twenty-four-hour ambulatory blood pressure measurement in a primigravid population

OBJECTIVE

To establish the profiles of 24-h non-invasive ambulatory blood pressure measurement (ABPM) during the trimesters of pregnancy and the puerperium in normotensive healthy primigravidae.

DESIGN

A prospective study in which 24-h ABPM was performed on five occasions in each subject: in the first trimester between 9 and 16 weeks' gestation; in the second trimester between 18 and 24 weeks; in the third trimester between 26 and 32 weeks and between 33 and 40 weeks; and finally at 6 weeks post partum.

METHOD

One hundred and six Caucasian primigravid women who were normotensive at their first booking visit were recruited consecutively from the antenatal clinic and had 24-h ABPM performed with the SpaceLabs 90207 ambulatory system.

RESULTS

Of the 106 women recruited, 98 completed 24-h ABPM on four of the five measurement occasions. Four women delivered prematurely before 33 weeks' gestation, thereby missing one ABPM measurement. Changes during pregnancy and the puerperium were assessed against the ABPM performed in the first trimester. There was no difference for daytime or night-time systolic blood pressure between 9 and 33 weeks, but it rose significantly from 33 to 40 weeks. At 6 weeks post partum, systolic blood pressure was not significantly different from the daytime pressure in the first-trimester ABPM but was raised significantly at night. Diastolic blood pressure decreased significantly between 18 and 24 weeks for both daytime and night-time. From 33 to 40 weeks it increased in parallel with systolic blood pressure, and at 6 weeks post partum it was raised significantly compared with first-trimester values for daytime and night-time. The nocturnal fall in blood pressure was preserved throughout pregnancy with a significant difference between daytime and night-time measurements present on all measurement occasions for systolic, diastolic and mean blood pressures and heart rate. There were significant differences between daytime ABPM and clinic blood pressure for both systolic and diastolic blood pressure up to 33 weeks. From 33 weeks until 6 weeks post partum there was no significant difference between daytime ambulatory and clinic blood pressures.

CONCLUSION

This study provides reference values for ABPM in healthy primigravidae with generally uncomplicated pregnancies.

Comparative accuracy of six ambulatory devices according to blood pressure levels

OBJECTIVE

To assess the accuracy of six ambulatory blood pressure measuring systems at low, medium and high blood pressures.

RESULTS

The CH-Druck, Profilomat, SpaceLabs 90207 and Novacor DIASYS 200R, having previously achieved A to C grading for systolic and diastolic blood pressures according to the British Hypertension Society (BHS) protocol and having fulfilled the criteria of the Association for the Advancement of Medical Instrumentation, have been recommended for measurement of ambulatory blood pressure in clinical practice; the Pressurometer IV and Takeda TM-2420, achieved only C and D grades and failed to satisfy the Association for the Advancement of Medical Instrumentation criteria. In this study the data from the original validations are re-analysed for three pressure ranges of systolic and diastolic blood pressures: low range < or = 130/80 mmHg, medium range 130-160/80-100 mmHg and high range > or = 160/100 mmHg. All six devices maintained their overall grading or improved them slightly in the low and medium blood pressure ranges, but in the high blood pressure range the CH-Druck slipped from an overall A/A grading to B/C, the Profilomat from B/A to C/D, the SpaceLabs from B/B to C/C and the Pressurometer IV from C/D to D/D. The Takeda remained unchanged with a D grading, but the results within this grading were worse in the higher blood pressure range, and the Novacor rose from C/C to C/B.

CONCLUSIONS

This analysis suggests that the CH-Druck is the most accurate ambulatory system across the pressure range, although it does not perform as well in the high blood pressure range as in the medium and low blood pressure ranges. The SpaceLabs 90207 is accurate in the low and medium blood pressure ranges and reasonably accurate in the high blood pressure range. If blood pressures only in the low and medium ranges are to be measured, a wider selection of ambulatory systems becomes available because, in addition to the CH-Druck and SpaceLabs 90207, the Profiloat and Novacor DIASYS 200R are accurate.

Defining normal ambulatory blood pressure

Providing normal reference values and the means to interpret such values in practice is an urgent issue requiring consensus. Five basic approaches to defining normalcy for 24 h blood pressures (BP) are considered: 1) the relationship of ambulatory blood pressure (ABP) to morbidity and mortality, 2) the relationship of ABP to end-organ involvement, 3) ABP levels in normal populations, 4) the relationship of ABP to clinic BP, and 5) the relationship of 24 h indices to risk. Although there now is considerable evidence demonstrating that ambulatory measurement correlates more strongly with end-organ damage, the first two approaches are scientifically the best. It will be some time before levels of normalcy can be derived. There is a large volume of data on population samples permitting derivation of normalcy for clinical practice. Rounded upper limits of normal can be calculated as 140/90 mm Hg for 24 h ambulatory pressure, 150/90 mm Hg for daytime pressure, and 130/80 mm Hg for nighttime pressure. There are, however, considerable differences for age and gender which need to be taken into consideration.

Measurement error in the Hawksley random zero sphygmomanometer: what damage has been done and what can we learn?

The Hawksley random zero sphygmomanometer is used in all aspects of blood pressure research, from clinical trials to evaluation of new blood pressure recorders. It is designed to reduce observer bias in blood pressure measurement. The problem is that it also underestimates blood pressure. Furthermore, this was first reported more than two decades ago. In this paper Rónán Conroy and colleagues explore the consequences of using an inaccurate instrument for important research and why prestigious organisations like the World Health Organisation continue to use it.

The quest for better validation: a critical comparison of the AAMI and BHS validation protocols for ambulatory blood pressure measurement systems

Two validation procedures are currently available for the evaluation of ambulatory blood pressure measurement systems--the standard of the Association for the Advancement of Medical Instrumentation (AAMI) and the protocol of the British Hypertension Society (BHS). Both are in the process of revision. Four systems for measuring 24-hour ambulatory blood pressure--SpaceLabs 90207, Novacor DIASYS 200, Del Mar Avionics Pressurometer IV, and Takeda TM-2420--were evaluated according to the BHS protocol, which incorporates many of the features of the AAMI standard, under similar conditions by the same personnel and in the same subjects, so as to examine the relative merits of the two evaluation procedures. Three recorders of each model were subjected to a before-use inter-device variability test, followed by an in-use phase and an after-use inter-device variability test. The main validation test was carried out in 86 subjects with a wide range of pressures, the results being analyzed according to the BHS grading system and the AAMI validation criteria. The SpaceLabs 90207 and the DIASYS 200 achieved B and C grades, respectively, according to the BHS protocol and also satisfied the AAMI criteria for accuracy. The Pressurometer IV achieved a Grade C rating for systolic pressure and a Grade D rating for diastolic pressure and the Takeda TM-2420 achieved Grade D ratings for both systolic pressure and diastolic pressure. Both these devices failed to fulfil the AAMI criteria for accuracy and both failed to function in the main validation test and had to be replaced.(ABSTRACT TRUNCATED AT 250 WORDS)

The increase in blood pressure with age and body mass index is overestimated by conventional sphygmomanometry

This cross-sectional study investigated whether the technique of blood pressure measurement used (conventional sphygmomanometry vs. ambulatory monitoring) affects the relation between blood pressure and both age and body mass index. Two independent data sets were analyzed. The first comprised 328 subjects (48% men) drawn from the population of a small Belgian town, and the second comprised 776 Irish bank employees (51% men). Age ranged from 17 years to 81 years, and body mass index (weight (kg)/height (m)2) ranged from 16.6 to 40.2. Twenty-four-hour ambulatory blood pressure was lower than blood pressure measured by a nurse in both the Belgian population sample (118/71 mmHg vs. 122/73 mmHg) and the Irish employees (118/72 mmHg vs. 119/76 mmHg). When blood pressure was measured by an observer, the well-established relations between systolic and diastolic blood pressure and both age and body mass index were evident. When the analyses were repeated using 24-hour measurements, the increment (cross-sectionally assessed) in blood pressure with age was weaker, especially in young and middle-aged subjects (20-60 years), while the increase in blood pressure with body mass index was also reduced. The within-subject differences between the conventional and ambulatory blood pressure measurements increased with older age and greater body mass index. Several other relations with blood pressure as the response variable may require revision in light of the present findings.

Cumulative sums in quantifying circadian blood pressure patterns

The plotting of cumulative sums (cusums), a technique of proven value in the detection of trends in data collected at intervals of time, may be modified to analyze circadian blood pressure patterns quantitatively. Mean 24-hour ambulatory blood pressure is taken as the reference value and is subtracted from each pressure value. The products of the remainders and the corresponding time intervals are summed in sequence and are plotted against time to form a modified cusum plot. The slope of the plot over any given time period equals the difference between mean blood pressure during that period and mean 24-hour blood pressure. Crest and trough blood pressures (the mean blood pressures of the 6-hour periods of highest and lowest pressures) may be identified as the 6-hour periods where plot slopes are most steeply ascending and descending, respectively. The magnitude of the circadian blood pressure change, defined as the difference between crest and trough blood pressure, is calculated from the difference between crest and trough plot slopes. The height of the cusum plot, which reflects pressure alteration extent and duration, may also be used as a measure of circadian pattern. The modified cusums technique and cusum-derived statistics are illustrated using ambulatory blood pressure profiles of hypothetical and actual hypertensive subjects. Independence from fixed time periods improves precision and reproducibility. Cusum-derived statistics are simply calculated from raw ambulatory data and should prove useful in the quantitative analysis of circadian blood pressure profiles.