There is an implicit acceptance that an evidence-based culture underpins the practice of laboratory medicine, in part because it is perceived as the scientific foundation of medicine. However, several reviews of specific test procedures or technologies have shown that the evidence base is limited and in many cases flawed. One of the key deficiencies in the scientific literature on diagnostic tests often is the absence of an explicit statement of the clinical need, i.e., the clinical or operational question that the use of the test is seeking to answer. Several reviews of the literature on specific procedures have also demonstrated that the experimental methodology used is flawed with, in some cases, significant bias being introduced. Despite these limitations it is recognized that a more evidence-based approach will help in the education and training of health professionals, in the creation of a research agenda, in the production of guidelines, in the support of clinical decision-making, and in resource allocation. Furthermore, as knowledge and technologies continue to be developed, an evidence-based strategy will be critical to harnessing these developments. (+info)
Opportunistic discovery of occult disease by use of test panels in new, symptomatic primary care outpatients: yield and cost of case finding.
(58/1942)
BACKGROUND: Diagnostic test panels have been advocated by the Japan Society of Clinical Pathology for evaluation of presenting complaints of new outpatients in primary care medicine. The tests have additional potential utility for opportunistic finding of asymptomatic diseases, but data are lacking on the number of new conditions identified by the test panels and on the cost per identified case. METHODS: We studied 540 new, symptomatic patients at the Comprehensive Medicine Clinics of National Defense Medical College during 1991-1997. All underwent testing with the "Essential Laboratory Tests" panel (2) [ELT(2) panel]. This panel includes hematologic tests, urinalysis, total protein, C-reactive protein, albumin, cholesterol, triglycerides, glucose, urea nitrogen, creatinine, uric acid, serum protein fractionation, six enzymes, and optional tests, including x-rays, electrocardiogram, and fecal occult blood. RESULTS: The ELT(2) panel uncovered 276 additional diagnoses of asymptomatic disease or abnormal health status. The most frequent occult condition was hyperlipidemia (100 cases) followed by liver dysfunction (53 cases). Clinical efficiency of the panel (occult diseases/patient) varied depending on the category of tentative initial diagnosis, with the highest efficiency in patients with cardiovascular disease. We created smaller panels by combining 11 basic tests [called the ELT(1) baseline panel] with one or more additional tests from the ELT(2) and analyzed their cost-effectiveness. Addition of four tests (total cholesterol, alanine aminotransferase, glucose, and uric acid) improved both clinical efficiency (0.41 occult disease/patient) and economic efficiency [ 2372 yen (approximately $22.50 US)/occult disease] at a cost-effectiveness of 177 yen per incremental case of occult disease. Addition of further tests decreased cost-effectiveness. CONCLUSIONS: Although the ELT(2) panel has supplemental utility for opportunistic screening of some significant, occult diseases and conditions, universal utilization of the full panel is not supported by the cost-effectiveness found in this study. (+info)
The CBC at the turn of the millennium: an overview.
(59/1942)
This review offers a birds-eye view of the state of automated hematology at the turn of the millennium. Despite its shortcomings (mainly flaggings and labor-intensive demands for confirmation), instrument-driven hematology provides much accurate and precise data to clinicians. Advances in technology over the next few decades will undoubtedly improve on the categorization of currently ambiguous mononuclear cells and even introduce channels for the detection and subclassification of poikilocytes. Until then, familiarity with the morphology of blood cell variants will be mandatory for technologists attending to the demands of flagging. (+info)
Flow cytometry: principles and clinical applications in hematology.
(60/1942)
The use of flow cytometry in the clinical laboratory has grown substantially in the past decade. This is attributable in part to the development of smaller, user-friendly, less-expensive instruments and a continuous increase in the number of clinical applications. Flow cytometry measures multiple characteristics of individual particles flowing in single file in a stream of fluid. Light scattering at different angles can distinguish differences in size and internal complexity, whereas light emitted from fluorescently labeled antibodies can identify a wide array of cell surface and cytoplasmic antigens. This approach makes flow cytometry a powerful tool for detailed analysis of complex populations in a short period of time. This report reviews the general principles in flow cytometry and selected applications of flow cytometry in the clinical hematology laboratory. (+info)
Preoperative evaluation.
(61/1942)
A history and physical examination, focusing on risk factors for cardiac, pulmonary and infectious complications, and a determination of a patient's functional capacity, are essential to any preoperative evaluation. In addition, the type of surgery influences the overall perioperative risk and the need for further cardiac evaluation. Routine laboratory studies are rarely helpful except to monitor known disease states. Patients with good functional capacity do not require preoperative cardiac stress testing in most surgical cases. Unstable angina, myocardial infarction within six weeks and aortic or peripheral vascular surgery place a patient into a high-risk category for perioperative cardiac complications. Patients with respiratory disease may benefit from perioperative use of bronchodilators or steroids. Patients at increased risk of pulmonary complications should receive instruction in deep-breathing exercises or incentive spirometry. Assessment of nutritional status should be performed. An albumin level of less than 3.2 mg per dL (32 g per L) suggests an increased risk of complications. Patients deemed at risk because of compromised nutritional status may benefit from pre- and postoperative nutritional supplementation. (+info)
Use of biochemical profile in children's hospital: results of two controlled trials.
(62/1942)
Two controlled trials of the use of a biochemical profile were conducted in a childern's hospital to see whether the profile led to diagnoses which would not otherwise [have been made and to see what effect it had on the number of extra requests for pathololgical investigations and the length of stay in hospital]. Altogether 2816 children were examined and 13 new diagnoses made. There was a significant increases in the total number of pathorequests but the profile did not alter the length of stay in hospital. We conclude that the profile mad only a small contribtuion to the overall care of the pateints. (+info)
Laboratory assessment of fitness to fly in patients with lung disease: a practical approach.
(63/1942)
To identify patients with respiratory disease, who may be at risk of developing respiratory distress during commercial air travel, a hypoxia inhalation test (HIT) can be performed. This paper reports our experience of using such a test combined with an interpretation algorithm in a routine respiratory function laboratory. Twenty-eight patients were studied. Baseline oxygen saturation (Sa,O2) was measured using a pulse oximeter. If Sa,O2 was < 90% no HIT was performed and the patient was assessed as unfit for air travel. If baseline Sa,O2 was > or = 90% an HIT was performed by the patient breathing through a 35% Venturi mask supplied with 100% nitrogen which reduced inspiratory oxygen fraction to 15.1+/-0.2%. Results were interpreted using a locally derived algorithm, and validation was attempted using a questionnaire to investigate subsequent symptoms during travel. All patients tolerated the assessment well. Twenty-two patients were assessed as "fit to fly" with a further two patients "fit to fly with supplemental O2". Four patients were considered unfit to fly. Hypoxic response could not be predicted from either forced expiratory volume in one second, or pretest saturation. Validation of such protocols is difficult, but the hypoxia inhalation test may be a useful tool for predicting hypoxia during air travel in patients with chronic respiratory disease. (+info)
Reminders of drug effects on laboratory test results.
(64/1942)
Drug effects on laboratory test results are difficult to take into account without an online decision support system. In this study, drug effects on hormone test results were coded using a drug-laboratory effect (DLE) code. The criteria that trigger the reminders were defined. To issue reminders, it was necessary to write a computer program linking the DLE knowledge base with databases containing individual patient medication and laboratory test results. During the first 10 months, 11% of the results from hormone samples were accompanied by one or more DLE reminders. The most common drugs to trigger reminders were glucocorticoids, furosemide, and metoclopramide. Physicians facing the reminders completed a questionnaire on the usefulness of the reminders. All respondents considered them useful. In addition, DLE reminders had caused 74% of respondents to refrain from additional, usually performed examinations. In conclusion, drug effects on laboratory tests should always be considered when interpreting laboratory results. An online reminder system is useful in displaying potential drug effects alongside test results. (+info)