Field Validation Study Research Articles

Field Testing of Gamma-Spectroscopy Method for Soil Water Content Estimation in an Agricultural Field.

Gamma-ray spectroscopy (GRS) enables continuous estimation of soil water content (SWC) at the subfield scale with a noninvasive sensor. Hydrological applications, including hyper-resolution land surface models and precision agricultural decision making, could benefit greatly from such SWC information, but a gap exists between established theory and accurate estimation of SWC from GRS in the field. In response, we conducted a robust three-year field validation study at a well-instrumented agricultural site in Nebraska, United States. The study involved 27 gravimetric water content sampling campaigns in maize and soybean and 40K specific activity (Bq kg-1) measurements from a stationary GRS sensor. Our analysis showed that the current method for biomass water content correction is appropriate for our maize and soybean field but that the ratio of soil mass attenuation to water mass attenuation used in the theoretical equation must be adjusted to satisfactorily describe the field data. We propose a calibration equation with two free parameters: the theoretical 40K intensity in dry soil and a, which creates an "effective" mass attenuation ratio. Based on statistical analyses of our data set, we recommend calibrating the GRS sensor for SWC estimation using 10 profiles within the footprint and 5 calibration sampling campaigns to achieve a cross-validation root mean square error below 0.035 g g-1.

Diagnostic performance of two rapid tests for syphilis screening in people living with HIV in Cali, Colombia.

There is insufficient evidence supporting the use of rapid diagnostic tests (RDTs) for syphilis in people living with HIV (PLWH). We evaluated the diagnostic performance of two commercially available RDTs (Bioline and Determine) in PLWH in Cali, Colombia. A cross-sectional field validation study on consecutive adults with confirmed HIV diagnosis attending three outpatient clinics. Both RDTs were performed on capillary blood (CB), obtained by finger prick, and sera, by venipuncture. A combination of treponemal enzyme linked immunosorbent assay (ELISA) and Treponema pallidum haemagglutination assay (TPHA) on serum samples was the reference standard. Rapid plasma reagin (RPR) and clinical criteria were added to define active syphilis. Sensitivity and specificity, predictive values and likelihood ratios (LR) of RDTs were estimated with their corresponding 95% confidence interval (95% CI). Stratified analyses by sample type, patient characteristics, non-treponemal titers, operator and re-training were performed. 244 PLWH were enrolled, of whom 112 (46%) had positive treponemal reference tests and 26/234 (11.1%) had active syphilis. The sensitivities of Bioline on CB and sera were similar (96.4% vs 94.6%, p = 0.6). In contrast, Determine had a lower sensitivity on CB than sera (87.5% vs 99.1%, p<0.001). Sensitivities were lower in PLWH not receiving ART (Bioline 87.1% and Determine 64.5%, p<0.001) and for one of the operators (Bioline 85% and Determine 60%, p<0.001). Specificities of the RDTs were > 95% in most analyses. Predictive values were 90% or higher. For active syphilis, the RDTs showed a similar performance pattern but with decreased specificities. The studied RDTs have an excellent performance in PLWH to screen for syphilis and potentially for active syphilis, yet Determine performs better on sera than CB. Patient characteristics and potential difficulties operators may face in acquiring enough blood volume from finger pricks should be considered for the implementation and the interpretation of RDTs.

Collective Sensing of Workers’ Loss of Body Balance for Slip, Trip, and Fall Hazard Identification: Field Validation Study

Collective Sensing of Workers’ Loss of Body Balance for Slip, Trip, and Fall Hazard Identification: Field Validation Study

Ergonomic evaluation and field validation of the insole padding system

AbstractInsoles are typically worn to increase comfort in performing daily activities. Many studies have investigated the effects of insoles with different properties. This study performed an ergonomic evaluation of three insole types, with a focus on assessing the effectiveness of an insole padding system (IPS). The objectives of this study were (1) to perform an ergonomic evaluation of three insoles and (2) to perform a field validation study to examine the effectiveness of IPS wearing among nurses. The study involved two phases. In the first phase, 15 healthy females participated in an experiment evaluating three insoles (general flat insole, ergo‐insole, and IPS). The outcome measurements were electromyography activity of four muscles, plantar pressure distribution in seven zones, and subjective discomfort rating. In the second phase, 100 nurses were recruited for the Nordic Musculoskeletal Questionnaire survey and 43 nurses participated in the field evaluation study. The results indicated that walking with the IPS was associated with lower plantar pressures in the midfoot and heel regions. Participants who wore ergo‐insole and IPS exhibited lower overall subjective discomfort ratings. Lower‐extremity discomfort was significantly improved after wearing the IPS for 2 weeks. The findings of this study suggest that walking with the IPS can result in less discomfort in the lower extremities than walking with the conventional insoles. IPS wearing is effective in improving lower‐extremity discomfort in persons who require prolonged standing and walking in daily life.

Real-Time Quality Index to Control Data Loss in Real-Life Cardiac Monitoring Applications.

Wearable cardiac sensors pave the way for advanced cardiac monitoring applications based on heart rate variability (HRV). In real-life settings, heart rate (HR) measurements are subject to motion artifacts that may lead to frequent data loss (missing samples in the HR signal), especially for commercial devices based on photoplethysmography (PPG). The current study had two main goals: (i) to provide a white-box quality index that estimates the amount of missing samples in any piece of HR signal; and (ii) to quantify the impact of data loss on feature extraction in a PPG-based HR signal. This was done by comparing real-life recordings from commercial sensors featuring both PPG (Empatica E4) and ECG (Zephyr BioHarness 3). After an outlier rejection process, our quality index was used to isolate portions of ECG-based HR signals that could be used as benchmark, to validate the output of Empatica E4 at the signal level and at the feature level. Our results showed high accuracy in estimating the mean HR (median error: 3.2%), poor accuracy for short-term HRV features (e.g., median error: 64% for high-frequency power), and mild accuracy for longer-term HRV features (e.g., median error: 25% for low-frequency power). These levels of errors could be reduced by using our quality index to identify time windows with few or no data loss (median errors: 0.0%, 27%, and 6.4% respectively, when no sample was missing). This quality index should be useful in future work to extract reliable cardiac features in real-life measurements, or to conduct a field validation study on wearable cardiac sensors.

Developing a modelling approach to quantify quality of care and nurse workload — Field validation study

Background:The effect of policy and managerial decisions on nurse-workload, and subsequent quality-of-care, are difficult to quantify in advance. A tool is needed that can proactively test these changes — Discrete Event Simulation (DES) may help. While computerized simulation models have existed before, there remains a gap to affirm the validity of these models. Objective:Develop an approach to creating a valid computerized simulation model that quantifies the effects of operational decisions on nurse-workload and quality-of-care. Methods:The DES model simulates the process of care delivery for nurses on a task-by-task basis. In an effort to validate this approach, the DES model was adapted to a real-world medical-surgical unit. Model inputs include: historical patient-care data; unit-layout; and programming logic, developed via focus-groups. Nurse-workload outcomes were distance-walked, task-in-queue, direct-care time, and nurse-movement. Quality-of-care outcomes included missed-care; and care-task waiting-time. The model is validated via internal validity checks and a field study that consisted of a ‘step-counter study’, a ‘MISSCARE survey’, ‘nurse job shadowing’, and a ‘time and motion study’. An Intraclass-correlation (ICC) and Spearman ranked correlation analysis were used to compare modelling outcomes to field-study outcomes. Results:The DES model, when adapted to a real-world medical-surgical unit, has been validated. The ICC coefficients show an “excellent” agreement of 0.99, 0.99, 0.85, 0.85, 0.84 between simulation and real-world outcomes, along with a “good” agreement of 0.86 for Spearman ranked correlation. Specific modelling results include a ‘distance walked’ of 7 to 10.6 km with a ‘direct care time’ of 8.3 to 10.4 h with a total of 77 to 84 trips for an average of 12 to 15 ‘tasks in queue’. Quality-of-care was represented by a ‘care task waiting time’ of 0.9 to 1 h that lead to 25 to 31 ‘missed-care’ tasks, where, 27% were ‘non-patient care’; and ‘missed-care delivery time’ was 2 to 2.9 h. Conclusion:This research provides a decision support-system that can help test and inform healthcare system policies that support both care quality and safety. By validating the DES model of a medical-surgical unit, we suggest that the modelling approach will also yield valid result when applied in similar settings. However, the modelling approach needs to be adapted to other healthcare settings and tested before concluding that this approach will consistently yield valid models.

Wrist-Worn Activity Trackers in Laboratory and Free-Living Settings for Patients With Chronic Pain: Criterion Validity Study.

BackgroundPhysical activity is evidently a crucial part of the rehabilitation process for patients with chronic pain. Modern wrist-worn activity tracking devices seemingly have a great potential to provide objective feedback and assist in the adoption of healthy physical activity behavior by supplying data of energy expenditure expressed as metabolic equivalent of task units (MET). However, no studies of any wrist-worn activity tracking devices’ have examined criterion validity in estimating energy expenditure, heart rate, or step count in patients with chronic pain.ObjectiveThe aim was to determine the criterion validity of wrist-worn activity tracking devices for estimations of energy expenditure, heart rate, and step count in a controlled laboratory setting and free-living settings for patients with chronic pain.MethodsIn this combined laboratory and field validation study, energy expenditure, heart rate, and step count were simultaneously estimated by a wrist-worn activity tracker (Fitbit Versa), indirect calorimetry (Jaeger Oxycon Pro), and a research-grade hip-worn accelerometer (ActiGraph GT3X) during treadmill walking at 3 speeds (3.0 km/h, 4.5 km/h, and 6.0 km/h) in the laboratory setting. Energy expenditure and step count were also estimated by the wrist-worn activity tracker in free-living settings for 72 hours. The criterion validity of each measure was determined using intraclass and Spearman correlation, Bland-Altman plots, and mean absolute percentage error. An analysis of variance was used to determine whether there were any significant systematic differences between estimations.ResultsA total of 42 patients (age: 25-66 years; male: 10/42, 24%; female: 32/42, 76%), living with chronic pain (duration, in years: mean 9, SD 6.72) were included. At baseline, their mean pain intensity was 3.5 (SD 1.1) out of 6 (Multidimensional Pain Inventory, Swedish version). Results showed that the wrist-worn activity tracking device (Fitbit Versa) systematically overestimated energy expenditure when compared to the criterion standard (Jaeger Oxycon Pro) and the relative criterion standard (ActiGraph GT3X). Poor agreement and poor correlation were shown between Fitbit Versa and both Jaeger Oxycon Pro and ActiGraph GT3X for estimated energy expenditure at all treadmill speeds. Estimations of heart rate demonstrated poor to fair agreement during laboratory-based treadmill walks. For step count, the wrist-worn devices showed fair agreement and fair correlation at most treadmill speeds. In free-living settings; however, the agreement for step count between the wrist-worn device and waist-worn accelerometer was good, and the correlation was excellent.ConclusionsThe wrist-worn device systematically overestimated energy expenditure and showed poor agreement and correlation compared to the criterion standard (Jaeger Oxycon Pro) and the relative criterion standard (ActiGraph GT3X), which needs to be considered when used clinically. Step count measured with a wrist-worn device, however, seemed to be a valid estimation, suggesting that future guidelines could include such variables in this group with chronic pain.

Field Validation of a Rapid Recombinase Aided Amplification Assay for SARS-CoV-2 RNA at Customs — Zhejiang Province, China, January 2021

IntroductionThe best approach to preventing the importation of coronavirus disease 2019 (COVID-19) is enhancing the detection capacity at customs. The rapid detection is of utmost importance and therefore highly demanded.MethodsWe conducted a field validation study of a duplex real-time reverse transcription recombinase-aided amplification (RT-RAA) assay in Zhoushan and Hangzhou customs, in Zhejiang Province, China. The reverse transcriptase polymerase chain reaction (RT-PCR) assay kit routinely used at customs was used in parallel, and the duration the two methods took to complete a specific number of samples was compared.ResultsAmong 506 samples collected, RT-RAA results were consistent with the RT-PCR results. The sensitivity and specificity were 100%, the total coincidence rate was 100%, and the Kappa value was 1 (P<0.05) for both methods. The RT-RAA kit took a significantly shorter time in testing the 20–200 samples than the RT-PCR kit. DiscussionThe RT-RAA detection method is more efficient and suitable for use at customs than RT-PCR assay to realize rapid customs clearance of 200 or fewer samples.

Influence of harmonic radar tag attachment on nymphal Halyomorpha halys mobility, survivorship, and detectability

AbstractThe brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a polyphagous invasive insect and currently one of the most threatening agricultural pests in the USA and globally. Nymphs are highly mobile, moving among host plants, and causing significant damage. Thus, understanding dispersal biology for all life stages is critical for the development of reliable monitoring and management programs. Here, we evaluated the influence of harmonic radar as a tool to study dispersal ecology of nymphal H. halys; we measured the impact of glues and tag attachment on survivorship and mobility in the laboratory and validated in the field that tagged and released nymphs could be tracked on baited and unbaited host and non‐host plants using harmonic radar. In the laboratory, four glues were evaluated for attaching harmonic radar tags securely to nymphs, and survivorship with attached tags was measured. There were no significant differences in survivorship or vertical and horizontal movement among nymphs with tags affixed with the glue treatments compared with the untagged control. Based on numerically greater survivorship of nymphs with tags affixed with Loctite glass glue, a field validation study of tagged nymphs released in host (apple tree) and non‐host (mowed grass) with or without H. halys pheromonal stimuli present revealed that nymphs could be successfully relocated using harmonic radar after 48 h. Among treatments, 83% of nymphs remained in baited and unbaited apple trees, 50% of nymphs remained in baited mowed grass plots, and in unbaited mowed grass plots, 17% of fifth instars, and 0% of fourth instars were retained. The absence of negative effects on mobility, survivorship, and field tracking validates that harmonic radar can be used to study dispersal ecology of nymphal H. halys.

Parental Perception of Childhood Anaemia and Efficiency of Instrument Assisted Pallor Detection among Mothers in Southeast Nigeria: A Field Validation Study.

Background Control of anemia can be achieved with early detection of pallor by parents at home. However, most parents lack the capacity to recognize pallor; thus most cases of anaemia are detected during hospital visit due to other symptoms. This study aimed to evaluate parental ability to detect pallor when aided with the anaemia screening tool. Methods In the study information on the symptoms of illness and parental knowledge on anaemia. Their ability to detect anaemia aided with the Home-Base anaemia-screen tool (HB-Anae) was compared to the healthcare providers' assessment of pallor. The haemoglobin estimation with the Hb-301 haemoglobinometer was used as the gold standard. Results None of the children in their previous illnesses had paleness as a complaint. Few (20.8%) parents knew what anaemia meant. Only 18.3% knew sites on the body where pallor can be detected. Many (55.1%; 304/552) surveyed children were anaemic (Hb<11g/dl) based on HB 301. Majority (88.8%; 270/304) of the parents aided with the HB-Anae were able to detect pallor on the children who were anaemic compared to 95.1% (289/304) detected by healthcare workers unaided, and the difference was not statistically significant (p=0.25). Conclusion There was poor knowledge on anaemia among parents. The ability of parents to detect anaemia could be improved with the simple HB-Anae screen tool.

Evaluation of the Performance of Haemoglobin Colour Scale and Comparison with HemoCue Haemoglobin Assay in Diagnosing Childhood Anaemia: A Field Validation Study.

Background Anaemia in children has high mortality. We present the results of assessment of the accuracy of Haemoglobin Colour Scale in identifying anaemia compared with HemoCue assay. Methods The presence of anaemia in 524 children from four communities was screened using the Haemoglobin Colour Scale (HCS) and HemoCue assay. Independent healthcare providers that estimated the haemoglobin level using Hb-301 haemoglobinometer were different from those that read the colour scale. The sensitivity, specificity, positive predictive value, and negative predictive value were estimated. Results Of the 524 children surveyed, 44.5% (233/524), 50% (262/524), and 32.2% (168/524) were found to be anaemic using the HemoCue, HCS (p= 0.25), and clinical pallor (p=0.03) respectively. Using the HemoCue as standard, the sensitivity of the HCS and clinical pallor was 89.1% and 72.1%, respectively, and specificity 90.2% and 84.6%, respectively. 74.7 % of the colour scale result was within the 1.0g/dl of the HemoCue reading and 23 % was within 2.0g/dl. Conclusion The HCS can improve the ability to detect anaemia especially where the use of the HemoCue is not feasible as in the resource poor countries. However, every case of anaemia requires further investigation to determine the underlying causes.

Simultaneous passive sampling of hydrophilic and hydrophobic emerging organic contaminants in water

Passive sampling techniques have been considered robust tools for monitoring freely dissolved concentrations of contaminants in aquatic systems. However, few passive samplers are currently available for the simultaneous sampling of both hydrophilic and hydrophobic chemicals. In this study, we developed a novel passive sampler (a hydrophilic-lipophilic balance sorbent-embedded cellulose acetate membrane (HECAM)) for estimating the time-weighted average (TWA) concentrations of both hydrophilic and hydrophobic organic contaminants in water. In our laboratorial controlled dynamic experiments, the accumulation results of thirty-seven target chemicals (including organophosphorus flame retardants, phenols, estrogens, organophosphorus pesticides, and triazine herbicides) with a wide polarity range (1.44 < log Kow < 9.49) in the HECAM followed first-order kinetics well, and the passive sampling parameters were estimated successfully. The estimated sampling rates for the target chemicals in the HECAM ranged from 0.14 to 6.90 L d−1 in the laboratory experiment, and the log Ksw (equilibrium partition coefficient between the sampler and water) values ranged from 2.75 to 6.00. The HECAM exhibited high sampling rate for moderately hydrophilic and moderately hydrophobic chemicals. The field validation study in an urban river resulted in the detection of four target chemicals (tris(chloroisopropyl)phosphate, tris(1,3-dichloroisopropyl)phosphate, prometryn, and 4-tert-octylphenol) by the HECAM at estimated TWA concentrations of 10.9–179.5 ng L−1, which were in agreement with the measured levels found in traditional grab samples by solid-phase extraction. In summary, both the laboratory tests and field deployment showed practicable results for the HECAM passive sampling, which suggests that it is an efficient approach for simultaneous monitoring of hydrophilic and hydrophobic organic contaminants in water.

Abstract TMP64: In-Field Paramedic Validation of the Ambulance Clinical Triage for Acute Stroke Treatment (ACT-FAST) Algorithm for Endovascular Thrombectomy

Background: Clinical triage for endovascular thrombectomy (EVT) is the most easily deployable solution to reduce unequal geographical access to comprehensive stroke centers, but current tools have limited prehospital validation. We present results of the ongoing paramedic validation study of Ambulance Clinical Triage For Acute Stroke Treatment (ACT-FAST), a published algorithmic severity-based triage tool utilizing only 2 examination steps designed for specificity and practicality. Methods: From July 2017, Ambulance Victoria paramedics assessed ACT-FAST (arm drift followed by speech if right arm weak, or shoulder tap for inattention if left arm weak plus screening eligibility questions) in suspected stroke patients pre-hospital in Melbourne, Australia, and in the Royal Melbourne Hospital Emergency Department. Algorithm results were validated against in-hospital CT imaging. Results: Data were available from n=196 assessments (ED n=76, pre-hospital n=120). Figure 1 shows correlation with CT imaging. Overall, ACT-FAST had 92% sensitivity for ICA/M1 occlusions with NIHSS≥6 (AHA Class 1 indication for EVT). Specificity purely for large vessel occlusion was 83% (positive predictive value 57%). Only a small proportion of distal occlusions (6/46, 13%) or patients with normal imaging (4/67, 6%) were falsely identified. When considering all patients requiring comprehensive stroke center care including neurosurgery (large vessel occlusion, hemorrhage and tumor) generated a positive predictive value for ACT-FAST of 83.3%. Discussion: Current results of the real-world ACT-FAST paramedic field validation study show high accuracy for clinical recognition of patients likely to require EVT or comprehensive stroke center care. The overall benefits of expedited thrombectomy for the majority of patients with large vessel occlusion is likely to outweigh the theoretical harms of delayed thrombolysis for a small minority of patients not requiring EVT.

Implementation of a Sickle Cell Disease Screening Initiative in Uganda with HemoTypeSCTM

Abstract Sickle Cell Disease (SCD) is a widely prevalent hemoglobinopathy in sub-Saharan Africa that is frequently deadly in early life, killing 70-80% of afflicted children before their fifth birthday. SCD accounts for ~20% of annual childhood deaths in Uganda - one of the first African countries surveyed for SCD prevalence. This health danger is currently addressable: prophylactic intervention programs including hydroxyurea, antibiotics, and immunizations have drastically reduced SCD mortality in developed areas and could be implemented in sub-Saharan Africa in a cost-effective manner. However, the cornerstone of such programs, newborn diagnostic screening, has not been widely implemented in Uganda, or elsewhere in Africa. This dilemma springs from the cost and logistical problems with accepted diagnostic methodologies, which require laboratory equipment, highly-trained operating personnel, uninterrupted electrical supply, and sample transport away from the point-of-care (POC). Clearly, a low-cost, low-complexity, POC diagnostic test for SCD could help diminish this public health crisis. HemoTypeSCTM is an inexpensive competitive lateral-flow immunoassay that uses monoclonal antibodies to detect hemoglobins (Hbs) A, S, and C in a 1.5-μL droplet of whole blood. In this study we conducted a field validation of HemoTypeSC accuracy in children of southeastern Uganda, aimed at providing evidence for the applicability of the test in widespread newborn screening programs in the region. This study was designed as a blinded, prospective diagnostic accuracy trial of HemoTypeSC as an investigational test compared to Hb electrophoresis as a reference method. Jinja Regional Referral Hospital was selected as a low-resource study center due to its relatively high daily patient volume, as well as its suitability as a prototype center for organized newborn SCD screening within Uganda. Exactly 1,000 children five years old and younger were prospectively recruited from the hospital wards and outpatient clinics. HemoTypeSC was compared to Hb electrophoresis for detection of the Hb phenotypes HbAA (normal), HbAS (sickle cell trait), and HbSS (SCD). Initial data analysis indicated that HemoTypeSC correctly identified 998 out of 1,000 phenotypes, for an overall accuracy of 99.8%. This included 720/720 (100%) specimens correctly identified as HbAA, 182/182 (100%) correctly identified as HbAS, and 96/98 (98%) correctly identified as HbSS. The two discordant samples were both identified as HbSS by electrophoresis and HbAS by HemoTypeSC. To resolve these discrepancies, the patients with the discordant HbSS/HbAS results were recalled for repeat testing. During the ensuing phone contact for scheduling, it was discovered that both individuals were in fact previously diagnosed with SCD, and both had been recently transfused. The previous diagnostic result reports for these participants were subsequently viewed and confirmed as HbSS. Because HbA was indeed present in the blood of these two patients at the time of sampling, the HbAS result was determined to be true. A secondary data analysis was therefore conducted, in which these two specimens were included as true positives for HbSS and true negatives for HbAS. It was ultimately determined that HemoTypeSC correctly identified 1,000 out of 1,000 phenotypes across all patients screened, including 96/96 HbSS specimens, for an overall sensitivity, specificity, positive predictive value, and negative predictive value of 100%. These results indicate that HemoTypeSC performs at least as accurately as the gold-standard method of Hb electrophoresis in detecting SCD and sickle cell trait at the POC in a resource-limited setting. This to our knowledge represents the first ever report of a rapid test for SCD displaying 100% sensitivity and specificity in a field validation study. In summary, HemoTypeSC represents a promising tool that can presently enable newborn and general population screening. Widespread combination of HemoTypeSC newborn and population screening programs with appropriate treatment, prophylaxis, and health counseling systems in countries most affected by the disease could save the lives of millions of children over the coming decades. A separate abstract regarding a HemoTypeSC field validation trial in Nigeria has also been submitted as a late-breaking abstract. We would be open to sharing a presentation slot with this group. Disclosures No relevant conflicts of interest to declare.

The Ambulatory Version of the Safety Attitude Questionnaire: Psychometric Validation and Measurement Properties in Nigerian Clinical Setting.

Understanding the safety culture of health care providers can help administrators improve patient safety. However, it is difficult to measure complex constructs such as safety culture without valid and reliable tools. This study determined the measurement properties of the ambulatory version of the safety attitude questionnaire (SAQ-AV) in the Nigerian clinical setting. A multiphase, iterative research involving clinical staff in primary and tertiary level of care in South-south Nigeria. The phases included face and content validity by subject experts, pretesting with clinical staff and a field validation involving 812 clinical staff. The acceptability, reliability (internal consistency), and validity (face, content, and construct) of the SAQ-AV were determined. All quantitative analysis was conducted using the SPSS Version 22 statistical package with statistical significance set at a P value of less than 0.05. A response rate of 53.7% was obtained during the field validation study. The item nonresponse rates were less than 10%, whereas extremes of the response scale were frequently endorsed. The internal consistency of the scale was good (Cronbach's α of 0.91 for entire scale and ranged from 0.62 to 0.76 among the different domains of the tool). Patient safety culture scores from primary and tertiary health care facilities assessed were significantly different. The SAQ-AV is an acceptable, reliable, and valid tool for use in assessing patient safety culture in ambulatory settings in Nigeria. There is a need to determine its dimensionality and factor structure in future research.

Field efficacy of brief exposure of adults of six storage pests to nitrogen-controlled atmospheres

The efficacy of a brief exposure (1, 7, and 10 days) to a nitrogen-controlled atmosphere (N-CA) for major storage&lt;br /&gt;pests in a field validation study in the Czech Republic is reported. The main goal was to estimate how quickly the&lt;br /&gt;mobile adult stages of six species of storage beetles (Oryzaephilus surinamensis, Cryptolestes ferrugineus, Tribolium&lt;br /&gt;confusum, Tribolium castaneum, Sitophilus granarius, and Sitophilus oryzae) are killed after introduction of the&lt;br /&gt;infested commodity to prevent their further spread to the surrounding storage bins. The trials were conducted in a&lt;br /&gt;metal bin containing 25 t of seeds using the system of continual top-down nitrogen filling to replace the oxygen. The&lt;br /&gt;composition of N-CA in the silo was measured continually. The target N-CA concentration (i.e., ≤ 1% O&lt;sub&gt;2&lt;/sub&gt; and 99% N&lt;sub&gt;2&lt;/sub&gt;)&lt;br /&gt;was reached at the bottom of the silo after 12 h of the purging phase of nitrogen silo filling. A one-day exposure to&lt;br /&gt;N-CA corresponds to top-down filling, which initially gives higher concentrations of N2 in the upper than in the lower&lt;br /&gt;part of the silo: low efficacy was reached at the silo bottom (0–33.3%), while higher efficacy (16.7–100%) was reached&lt;br /&gt;at the top of the silo bin. The mortality variation at both locations was species dependent: the most sensitive was O.&lt;br /&gt;surinamensis, and the least sensitive were S. granarius and S. oryzae. Seven days of N-CA exposure led to 100% mortality&lt;br /&gt;of all tested species except for S. granarius (96.7% mortality at the bottom), while 10 days of N-CA exposure led&lt;br /&gt;to 100% mortality of all adults located at both the bottom and the top of the silo. This experiment showed that one&lt;br /&gt;day of exposure to N-CA caused significant mortality to reduce the spread of insects from the top of the silo but not&lt;br /&gt;from the silo bottom, and 10 days of exposure completely prevent the adult mobile pest stages of all tested species&lt;br /&gt;from spreading from the treated silo and causing cross-infestation in the storage facility.

Field validation study of a time and temperature indexed autoregressive with exogenous (ARX) model for building thermal load prediction

Building load prediction algorithms are becoming an essential component of building energy technologies as intelligent building technologies are rapidly evolving and require accurate load predictions to make real-time operational decisions. This paper presents a field validation study of an autoregressive with exogenous (ARX) model, indexed with respect to time and temperature, and used for hourly building thermal load prediction with an aim for integration with real time predictive control strategies. Indexing of the ARX model implies that different sets of coefficients are used in the predictive equation depending on different time intervals and temperature ranges. Although many regressive prediction models have been proposed, no field validation has been reported in the literature, which is an essential step before implementation in actual practice. The validation study was carried out using field data from three buildings located in the main campus of Mississippi State University. The proposed model was able to predict hourly thermal load accurately and within the uncertainty bounds of the measured thermal load most of the time. Results also demonstrated that proper indexing of the model allowed it to capture different cooling and heating load profiles and abrupt changes in the load pattern.

ReEBOV Antigen Rapid Test kit for point-of-care and laboratory-based testing for Ebola virus disease: a field validation study

At present, diagnosis of Ebola virus disease requires transport of venepuncture blood to field biocontainment laboratories for testing by real-time RT-PCR, resulting in delays that complicate patient care and infection control efforts. Therefore, an urgent need exists for a point-of-care rapid diagnostic test for this disease. In this Article, we report the results of a field validation of the Corgenix ReEBOV Antigen Rapid Test kit. We performed the rapid diagnostic test on fingerstick blood samples from 106 individuals with suspected Ebola virus disease presenting at two clinical centres in Sierra Leone. Adults and children who were able to provide verbal consent or assent were included; we excluded patients with haemodynamic instability and those who were unable to cooperate with fingerstick or venous blood draw. Two independent readers scored each rapid diagnostic test, with any disagreements resolved by a third. We compared point-of-care rapid diagnostic test results with clinical real-time RT-PCR results (RealStar Filovirus Screen RT-PCR kit 1·0; altona Diagnostics GmbH, Hamburg, Germany) for venepuncture plasma samples tested in a Public Health England field reference laboratory (Port Loko, Sierra Leone). Separately, we performed the rapid diagnostic test (on whole blood) and real-time RT-PCR (on plasma) on 284 specimens in the reference laboratory, which were submitted to the laboratory for testing from many clinical sites in Sierra Leone, including our two clinical centres. In point-of-care testing, all 28 patients who tested positive for Ebola virus disease by RT-PCR were also positive by fingerstick rapid diagnostic test (sensitivity 100% [95% CI 87·7-100]), and 71 of 77 patients who tested negative by RT-PCR were also negative by the rapid diagnostic test (specificity 92·2% [95% CI 83·8-97·1]). In laboratory testing, all 45 specimens that tested positive by RT-PCR were also positive by the rapid diagnostic test (sensitivity 100% [95% CI 92·1-100]), and 214 of 232 specimens that tested negative by RT-PCR were also negative by the rapid diagnostic test (specificity 92·2% [88·0-95·3]). The two independent readers agreed about 95·2% of point-of-care and 98·6% of reference laboratory rapid diagnostic test results. Cycle threshold values ranged from 15·9 to 26·3 (mean 22·6 [SD 2·6]) for the PCR-positive point-of-care cohort and from 17·5 to 26·3 (mean 21·5 [2·7]) for the reference laboratory cohort. Six of 16 banked plasma samples from rapid diagnostic test-positive and altona-negative patients were positive by an alternative real-time RT-PCR assay (the Trombley assay); three (17%) of 18 samples from individuals who were negative by both the rapid diagnostic test and altona test were also positive by Trombley. The ReEBOV rapid diagnostic test had 100% sensitivity and 92% specificity in both point-of-care and reference laboratory testing in this population (maximum cycle threshold 26·3). With two independent readers, the test detected all patients who were positive for Ebola virus by altona real-time RT-PCR; however, this benchmark itself had imperfect sensitivity. Abundance Foundation.

Rapid diagnostics for Ebola in emergency settings

Rapid diagnostics for Ebola in emergency settings

Validity and usability of low-cost accelerometers for internet-based self-monitoring of physical activity in patients with chronic obstructive pulmonary disease.

BackgroundThe importance of regular physical activity for patients with chronic obstructive pulmonary disease (COPD) is well-established. However, many patients do not meet the recommended daily amount. Accelerometers might provide patients with the information needed to increase physical activity in daily life.ObjectiveOur objective was to assess the validity and usability of low-cost Internet-connected accelerometers. Furthermore we explored patients’ preferences with regards to the presentation of and feedback on monitored physical activity.MethodsTo assess concurrent validity we conducted a field validation study with patients who wore two low-cost accelerometers, Fitbit and Physical Activity Monitor (PAM), at the same time along with a sophisticated multisensor accelerometer (SenseWear Armband) for 48 hours. Data on energy expenditure assessed from registrations from the two low-cost accelerometers were compared to the well validated SenseWear Armband which served as a reference criterion. Usability was examined in a cross-over study with patients who, in succession, wore the Fitbit and the PAM for 7 consecutive days and filled out a 16 item questionnaire with regards to the use of the corresponding deviceResultsThe agreement between energy expenditure (METs) from the SenseWear Armband with METs estimated by the Fitbit and PAM was good (r=.77) and moderate (r=.41), respectively. The regression model that was developed for the Fitbit explained 92% whereas the PAM-model could explain 89% of total variance in METs measured by the SenseWear. With regards to the usability, both the Fitbit and PAM were well rated on all items. There were no significant differences between the two devices.ConclusionsThe low-cost Fitbit and PAM are valid and usable devices to measure physical activity in patients with COPD. These devices may be useful in long-term interventions aiming at increasing physical activity levels in these patients.