Evaluation of serological lateral flow assays for severe acute respiratory syndrome coronavirus-2.

BACKGROUND: COVID-19 has resulted in significant morbidity and mortality worldwide. Lateral flow assays can detect anti-Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) antibodies to monitor transmission. However, standardized evaluation of their accuracy and tools to aid in interpreting results are needed. METHODS: We evaluated 20 IgG and IgM assays selected from available tests in April 2020. We evaluated the assays' performance using 56 pre-pandemic negative and 56 SARS-CoV-2-positive plasma samples, collected 10-40 days after symptom onset, confirmed by a molecular test and analyzed by an ultra-sensitive immunoassay. Finally, we developed a user-friendly web app to extrapolate the positive predictive values based on their accuracy and local prevalence. RESULTS: Combined IgG + IgM sensitivities ranged from 33.9 to 94.6%, while combined specificities ranged from 92.6 to 100%. The highest sensitivities were detected in Lumiquick for IgG (98.2%), BioHit for both IgM (96.4%), and combined IgG + IgM sensitivity (94.6%). Furthermore, 11 LFAs and 8 LFAs showed perfect specificity for IgG and IgM, respectively, with 15 LFAs showing perfect combined IgG + IgM specificity. Lumiquick had the lowest estimated limit-of-detection (LOD) (0.1 µg/mL), followed by a similar LOD of 1.5 µg/mL for CareHealth, Cellex, KHB, and Vivachek. CONCLUSION: We provide a public resource of the accuracy of select lateral flow assays with potential for home testing. The cost-effectiveness, scalable manufacturing process, and suitability for self-testing makes LFAs an attractive option for monitoring disease prevalence and assessing vaccine responsiveness. Our web tool provides an easy-to-use interface to demonstrate the impact of prevalence and test accuracy on the positive predictive values.

Unmet need for referred services as measured by general practice.

INTRODUCTION Unmet needs are a key indicator of the success of a health system. Clinicians and funders in Christchurch, Canterbury, New Zealand were concerned that unmet health need was hidden. AIM The aim of this survey was to estimate the proportion of patients attending general practice who were unable to access clinically indicated referred services. METHODS The survey used a novel method to estimate unserviced health needs. General practitioners (GPs, n = 54) asked their patients (n = 2135) during a consultation about any health needs requiring a referred service. If both agreed that a service was potentially beneficial and not available, this was documented on an e-referral system for review. The outcomes of actual referrals were also reviewed. RESULTS The patient group was broadly representative of the Canterbury population, but over-sampled female and middle-aged people and under-sampled Maori. Data adjusted to regional demographics showed that 3.6% of patients had a GP-confirmed unserviced health need. Elective orthopaedic surgery, general surgery and mental health were areas of greatest need. Unserviced health needs were significantly (P ≤ 0.05) associated with greater deprivation, middle-age, and receiving high health-use subsidies. DISCUSSION To our knowledge, this is the first survey of GP and patient agreement on unserviced referred health needs. Measuring unserviced health needs in this way is directly relevant to service planning because the gaps identified reflect clinically indicated services that patients want and need. The survey method is an improvement on declined referral rates as a measure of need. Key factors in the method were using a patient-initiated GP consultation and an e-referral system to collect data.

Anti-beta 2-glycoprotein I and antiphosphatidylserine antibodies are predictors of arterial thrombosis in patients with antiphospholipid syndrome.

The predictive value (PV) and association of 4 antiphospholipid antibodies with clinical manifestations of the antiphospholipid syndrome (APS) were evaluated in 90 patients with systemic lupus erythematosus (SLE) and 100 with APS. Patients with APS were classified into arterial thrombosis, venous thrombosis, and pregnancy morbidity subgroups. IgG, IgM, and IgA anticardiolipin (aCL), antiphosphatidylserine (aPS), anti-beta 2-glycoprotein I (anti-B2GPI), and antiprothrombin (aPT) antibodies were determined by enzyme-linked immunosorbent assay. Individually, anti-B2GPI and aPS antibodies had the strongest PV for APS (86.4%-94.1%; P < .001) in patients with SLE. The PV for APS reached 100% when 2 or more antibodies were present. Similarly, anti-B2GPI and aPS antibodies had a stronger PV and association for arterial thrombosis (87%-95%; P < .001) compared with venous thrombosis (80%-92%; P = .01). Weak PV and association with pregnancy morbidity were seen with all antibodies. These results suggest an important pathogenic role of anti-B2GPI antibodies in arterial thrombosis. In addition, anti-B2GPI and aPS antibodies seem to provide the best diagnostic value for the laboratory assessment of APS.