Trends and outlook for clinical diagnostics testing

Summary

Clinical diagnostic tests have traditionally involved antibody-based recognition of proteins or disease markers, but these immunoassays are prone to both false negative and false positive results, and cannot detect numerous disease markers in one test. In recent years there has been growing interest in using more accurate, efficient and reliable technologies such as mass spectrometry. Despite the important scientific advantages of such technologies, many clinical diagnostics scientists have continued to use traditional immunoassays, due to perceived barriers such as the need for investment and expertise in mass spectrometry (MS) technologies. This report describes the results of a recent independent survey of clinical diagnostics scientists worldwide. The survey explored respondents’ current diagnostic assays, instrument and reagent usage; conference attendance; purchasing behaviours and future technology needs. Key findings from the survey showed that the majority of respondents still use immunoassay-based diagnostics and around one third use liquid chromatography with tandem mass spectrometry (LC-MS/MS). There was broad awareness of MS techniques, with a greater proportion intending to purchase MS platforms rather than immunoanalyzers over the next 12 months. However, the majority of respondents said they did not fully understand the concepts or have expert knowledge of MS technologies, despite using these technologies in their labs. Therefore there is an urgent need for improved understanding of MS in clinical labs, so that more scientists can adopt these technologies for more accurate and confident diagnostics.

Introduction

Clinical diagnostics tests are carried out in hospital laboratories, Physician Office Labs and CLIA Labs (or equivalent European labs) worldwide, through analysis of human blood and other tissue samples. These in vitro diagnostic (IVD) tests are typically carried out to detect wide-ranging diseases and conditions such as cystic fibrosis, metabolic disorders and vitamin D deficiency, and to monitor levels of drugs in patients, including therapeutic drugs and immunosuppressants, as well as drugs of abuse. For many years, clinical scientists have used immunoassays such as ELISAs (enzyme-linked immunosorbent assays) for diagnostics. More recently, however, there has been growing concern about the accuracy of immunoassays for diagnostics. In particular, immunoassays are susceptible to interference that can lead to both false negative and false positive results, which can have serious impacts on patient care as well as increasing costs and labor burdens for health authorities^1-3. Immunoassays can also show variation in results, between labs using the same assays as well as between different assays⁴. Furthermore, immunoassays are not always able to detect certain metabolites or can even over-estimate their levels, which can complicate diagnosis of conditions such as vitamin D deficiency that depend on accurate detection of both the vitamin D₂ and D₃ 25-OH metabolites⁵. These concerns have driven the development of alternative testing methods based on mass spectrometry techniques, which offer higher accuracy and robustness than immunoassays. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) is particularly powerful for high-resolution separation, identification and quantitation of proteins and peptides, even at very low levels of expression. LC-MS/MS methods are also very versatile and can be developed rapidly for the analyte of interest; moreover numerous proteins can be detected and quantified in a single run, saving considerably on precious samples, as well as time, labor and reagent costs. These benefits for diagnostics are clear, but clinical laboratories have been slow to adopt LC-MS/MS. Part of the reluctance to switch technologies may be attributed to a traditional perception that only mass spectrometry experts could run the instruments and analyse results. Accordingly, instrument providers have made a number of developments to improve the simplicity, ease-of-use and robustness of LC-MS/MS systems in recent years. These include the introduction of in vitro diagnostic (IVD) MS analyzers and reagents kits that have been CE marked to the European in vitro diagnostics Directive (98/79/EC), and registration of the MS analyzers as general medical devices in other selected countries around the world. These products are developed specifically to be safe and effective for routine clinical diagnostics laboratories, and designed to bring down costs by delivering accurate, rapid and reliable results.

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