Basic points of clinical research on in vitro diagnostic reagents
Medically correct diagnosis is the basis for effective prevention and treatment, and various diagnostic tests are essential for proper diagnosis. With the development of medical science, the deepening of the understanding of diseases and the application of a large number of new technologies and new equipment, new diagnostic tests will inevitably replace the old diagnostic tests. Because different diagnostic tests have different characteristics and requirements, and have different application values ​​and application scopes, it is necessary to conduct scientific clinical research and evaluation for each diagnostic test.
1. The purpose of clinical research
The purpose of clinical research is to assess the effectiveness of diagnostic reagents by testing clinical samples. The effectiveness of a diagnostic reagent refers to the clinical performance of the reagent test item and the extent to which the reagent detects the target analyte in the patient specimen. Clinical performance is divided into diagnostic accuracy and efficiency, ie the actual application value of the data or the practicality for clinical purposes. Its exact definition is the ability to distinguish between two or more clinical states.
According to the degree of innovation of reagents, it can be divided into two categories: “innovation†and “imitationâ€. "Innovative" and "imitation" products are not identical in terms of clinical research points and methods.
2. Basic points of clinical research
Determination of the gold standard:
The gold standard refers to the most reliable, accurate and best diagnostic method currently recognized, also known as standard diagnostic methods. Clinically common gold standards include histopathological examination (biopsy, autopsy), surgical findings, imaging diagnosis (CT, MRI, color B-ultrasound), bacterial culture, and long-term follow-up. The gold standard is generally a specific diagnosis, which can correctly distinguish between "ill" and "no disease". If there is no specific diagnostic method, it is impossible to correctly distinguish whether the subject is ill or not, which will affect the correct evaluation of the diagnostic test.
Study object selection:
Subjects should include two groups, one with a gold standard for patients with a certain disease, and the other with a gold standard for a person without the disease as a control group. Patients should include typical and atypical symptoms, early, middle and late stages of the disease, mild, moderate, severe, and different age levels, in order to reflect all the characteristics of the disease. The control group should include cases in which the disease is identified and the disease is easily confused with the disease.
3. Issues related to clinical research
Sample size:
The sample size of the clinical study should be determined according to the clinical use of the product and the clinical incidence of the disease and the degree of detection. Under the premise of meeting the minimum sample size requirements of the registration management method, it should also meet the statistical requirements. Specimen samples may be reduced in rare cases, special diseases and special circumstances.
4. Problems and development direction
Due to the high resolution of AFM and its ability to operate under physiological conditions, it has become an indispensable tool in biological research. However, atomic force microscopy has many limitations, but it also has certain limitations. First, the tapered tip becomes dull during use, and the tip is widened, which causes a decrease in resolution. To ensure resolution, the tip must be changed frequently. After observing the sample (especially in liquid form), the tip of the needle will be contaminated by the sample, reused for cleaning, and the tip will cause damage to the biological sample. At present, a solution is to use a carbon nanotube tip, which has been widely used because of its small diameter, large Young's modulus, high mechanical strength, fine structure, and unique chemical properties. In the field of biomolecules, biological structures and other research.
Secondly, when observing a liquid specimen, interference information is generated due to factors such as surface tension and electrostatic repulsion, resulting in a decrease in resolution. In order to solve this problem, some laboratories have proposed to change the pH value of the solution to remove the electrostatic repulsion, but there are obvious limitations. This problem can be solved by electrostatic balancing.
Finally, due to the limitations of the AFM itself, many functions must be combined with other devices. For a complex living system, it is obviously not enough to rely on one type of equipment. AFM must be combined with other equipment or technical means such as near-field microscope, electron microscope, laser confocal microscope, fluorescence microscopy, X-ray diffraction, antibody labeling. Organic integration, such as surface interference, can explore various life systems more effectively.
Clinical research on imported registered products: Although the effectiveness of imported registered products is relatively clear, due to the different target groups and regions, it may affect some of the main technical indicators and effectiveness of the products. For example, the normal reference value of blood lipids in Chinese population is lower than that in European population, so the normal reference value or reference range recommended in the manual may not be suitable for Chinese population. In addition, certain strains or subtypes that are prevalent in different countries or regions may affect the effectiveness of antigen assays, nucleic acid assays, or antibody assay products. Therefore, for imported registered products, while considering the general requirements for clinical research of domestic products, we should pay close attention to the above factors in order to provide more scientific, objective and detailed information for clinical use.
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