Although much has been written on the role of randomized controlled trials and mechanistic reasoning in the evaluation of therapeutic treatments, philosophers of medicine have not yet turned their attention to the question of how diagnostic tests and procedures should be evaluated. I aim to begin to fill this gap by examining each of the following questions: What is the best way to determine the accuracy of a diagnostic test? What is the best way to determine the clinical effectiveness of a diagnostic test? Can an accurate diagnostic test be considered medically valuable even if it is not clinically effective? I argue that while diagnostic accuracy is a minimum requirement for both clinical effectiveness and medical value, accuracy and effectiveness are not sufficient for determining the value of a diagnostic test, because diagnostic value extends beyond patient outcomes.
We demonstrate a Google Glass-based rapid diagnostic test (RDT) reader platform capable of qualitative and quantitative measurements of various lateral flow immunochromatographic assays and similar biomedical diagnostics tests. Using a custom-written Glass application and without any external hardware attachments, one or more RDTs labeled with Quick Response (QR) code identifiers are simultaneously imaged using the built-in camera of the Google Glass that is based on a hands-free and voice-controlled interface and digitally transmitted to a server for digital processing. The acquired JPEG images are automatically processed to locate all the RDTs and, for each RDT, to produce a quantitative diagnostic result, which is returned to the Google Glass (i.e., the user) and also stored on a central server along with the RDT image, QR code, and other related information (e.g., demographic data). The same server also provides a dynamic spatiotemporal map and real-time statistics for uploaded RDT results accessible through Internet browsers. We tested this Google Glass-based diagnostic platform using qualitative (i.e., yes/no) human immunodeficiency virus (HIV) and quantitative prostate-specific antigen (PSA) tests. For the quantitative RDTs, we measured activated tests at various concentrations ranging from 0 to 200 ng/mL for free and total PSA. This wearable RDT reader platform running on Google Glass combines a hands-free sensing and image capture interface with powerful servers running our custom image processing codes, and it can be quite useful for real-time spatiotemporal tracking of various diseases and personal medical conditions, providing a valuable tool for epidemiology and mobile health.
Maintaining quality, competitiveness and innovation in global health technology is a constant challenge for manufacturers, while affordability, access and equity are challenges for governments and international agencies. In this paper we discuss these issues with reference to rapid diagnostic tests for malaria. Strategies to control and eliminate malaria depend on early and accurate diagnosis. Rapid diagnostic tests for malaria require little training and equipment and can be performed by non-specialists in remote settings. Use of these tests has expanded significantly over the last few years, following recommendations to test all suspected malaria cases before treatment and the implementation of an evaluation programme to assess the performance of the malaria rapid diagnostic tests. Despite these gains, challenges exist that, if not addressed, could jeopardize the progress made to date. We discuss recent developments in rapid diagnostic tests for malaria, highlight some of the challenges and provide suggestions to address them.
Although new diagnostics may advance the time of diagnoses in selected patients, they will increase the frequency of false alarms, overdiagnosis, and overtreatment in others. Bjorn Hofmann and H. Gilbert Welch explain how to minimise harm
As technology advances, diagnostic tests continue to improve, and each year we are presented with new alternatives to standard procedures. Given the plethora of diagnostic alternatives, diagnostic tests must be evaluated to determine their place in the diagnostic armamentarium. The first step involves determining the accuracy of the test, including the sensitivity and specificity, positive and negative predictive values, likelihood ratios for positive and negative tests, and receiver operating characteristic (ROC) curves. The role of the test in a diagnostic pathway has then to be determined, following which the effect on patient outcome should be examined.
Abstract Borrelia burgdorferi was discovered to be the cause of Lyme disease in 1983, leading to seroassays. The 1994 serodiagnostic testing guidelines predated a full understanding of key B. burgdorferi antigens and have a number of shortcomings. These serologic tests cannot distinguish active infection, past infection, or reinfection. Reliable direct-detection methods for active B. burgdorferi infection have been lacking in the past but are needed and appear achievable. New approaches have effectively been applied to other emerging infections and show promise in direct detection of B. burgdorferi infections. Serologic tests for Lyme disease have significant drawbacks. A single antibody test cannot indicate active infection, and there is a long lag from onset of infection to positivity. Direct assays, effective with other infections, can overcome these drawbacks and are being tested.
The Stanford Canary Center researchers have a prototype built with over-the-counter test strips that measure 10 urinary factors such as acidity and glucose concentrations, which can indicate risk of kidney stones and diabetes, respectively. The Japanese toilet manufacturer Toto has a Flowsky model with built-in sensors in the toilet bowl that allow the measurement of urine volume and flow rate, and other models measure body mass index, blood glucose, and blood pressure. [...]it would be practical for the physician to control which test is performed and at what frequency, because there are risks associated with consumer testing.