Use Of Serum Markers Research Articles

Correlation of Interleukin-6, Serum Lactate, and C-Reactive Protein to Inflammation, Complication, and Outcome During the Surgical Course of Patients with Acute Abdomen

In the present scenario, doctors have to rely on radiological methods for diagnosis of acute abdomen in addition to their clinical skill. The use of serum markers for assessing the outcome of such patients is still debatable. Our aim was to evaluate whether the combined use of serum lactate, interleukin (IL)-6, and C-reactive protein (CRP) is able to simultaneously establish both the septic status and the prognosis of acute abdomen. Ninety-nine patients undergoing surgery for acute abdomen were taken up for the study. The patients were divided into 4 groups based on the level of sepsis. Serum lactate, IL-6, and CRP were determined in the serum of all the subjects. It was found that serum lactate determination, using the cutoff value < 3.9 mM, had a high sensitivity (100%) and specificity (83%) in differentiating patients with severe sepsis from those with sepsis. IL-6 came next with a sensitivity of 87% and a specificity of 81%. The AUC for serum lactate (0.922), IL-6 (0.912), and CRP (0.719) in differentiating between patients with severe sepsis and those with sepsis also proves the superiority of serum lactate and IL-6. The combined use of serum lactate and IL-6 would allow us to simultaneously establish the prognosis of patients with acute abdomen (r(2) = 0.368, P = 0.008). The combined use of serum lactate and IL-6 is useful in simultaneously establishing both the severity of sepsis and, hence, the prognosis of acute abdomen.

Serum markers for necroinflammatory activity in patients with chronic viral hepatitis and normal or mildly elevated aminotransferase levels

Reports on the usefulness of serum markers for predicting liver necroinflammation are limited. The aim of this study was to determine the serum markers that predict significant inflammation in patients with chronic hepatitis B (CHB) and C (CHC) and normal or mildly elevated serum aminotransferase levels. Two hundred twenty-seven patients with CHB or CHC with normal or mildly elevated serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels (≤60 IU/L) were enrolled in this study. Significant inflammation was defined as inflammatory grade ≥3 activities using the Batt-Ludwig scoring system. The correlation between liver histology and serum markers of liver inflammation was analysed. Forty-eight (21.1%) and eight patients (3.5%) had grade 3 and 4 inflammation respectively. Univariate analysis revealed that age, platelet coun, and AST, ALT, γ-glutamyl transpeptidase, alkaline phosphatase, hyaluronic acid, haptoglobin, apolipoprotein A1 and procollagen III N-terminal peptide levels were significantly different between the patients with and without significant inflammation. There were no significant differences in the cytokeratin-18 fragment levels between the two groups. On the basis of multivariate analysis, the AST and apolipoprotein A1 levels and stage of fibrosis were highly predictive of significant inflammation. Using AST and apolipoprotein cut-off values ≥44 IU/L and ≤100 ng/ml, respectively, the presence of significant inflammation was predicted with high specificity (96.5%) and with a negative predictive value of 76.3%. The AST and apolipoprotein A1 levels were shown to be independent predictors of significant inflammatory activities in patients with CHB and CHC and normal or mildly elevated aminotransferase levels.

Clinical Features and Diagnostic Evaluation of Biopsy-Proven Ocular Sarcoidosis

To compare the clinical characteristics of uveitic sarcoidosis in African American and non-African American patients with biopsy-proven sarcoidosis and to determine which diagnostic test results were most often suggestive of sarcoidosis in patients who were ultimately diagnosed as having the disease. Retrospective review of consecutive patients with biopsy-proven sarcoidosis evaluated by the uveitis service between 1989 and 2009. A total of 63 patients with uveitic sarcoidosis were identified: 39 (62%) were African American (P <.001) and 43 (68%) were female. African American patients presented at an earlier age (P <.001) and were more likely to have granulomatous anterior segment inflammation (P <.001). The levels of serum markers angiotensin-converting enzyme and lysozyme were elevated in 40% and 42% of patients tested, respectively. The levels of at least 1 marker were elevated in 18 patients (58%). Imaging study results were reported as consistent with sarcoidosis in 25 patients (69%) who underwent chest radiography and in 19 patients (100%) who underwent computed tomography. In this series, African American patients were more likely to be diagnosed as having uveitic sarcoidosis and to present with uveitis if they were younger than 50 years. White patients were more likely to present when they were older than 50 years. A clinical picture that included granulomatous anterior segment inflammation was more common in African American patients. The use of serum markers (angiotensin-converting enzyme and lysozyme) positively identified more patients with biopsy-proven sarcoidosis when used in combination with appropriate chest imaging.

Dépistage prénatal de la trisomie 21 par les marqueurs sériques : expérience tunisienne

Maternal marker screening for Down's syndrome is based on an individual risk calculation obtained by weighting the risk due to maternal age by a factor linked to maternal serum markers. The maternal serum markers used in our study are alpha-fetoprotein (AFP) and human chorionic gonadotrophin (hCG), previously known of their efficiency at the second trimester. The AFP and hCG were measured for 241 pregnant women, recruited in the maternity units of the center of Tunisia. The age of pregnancy was known for only 163 women. Using the 1/250 cut off for this double test, only one woman has presented a high risk for Down's syndrome (1/32). The foetal karyotyping was performed and chromosomal abnormality was confirmed. This computerized program allowed us to detect 7.46% of neural tube defects. In addition we found 3.7 % of cases with decrease of hCG demonstrating diminution of foetal viability. It would be desirable to generalize prenatal screening for Down's syndrome to all pregnant women regardless of their age through the use of serum markers in the maternal blood. The dissemination of this double test will limit the use of invasive examinations. Le principe du dépistage de la trisomie 21 fœtale par utilisation des marqueurs sériques au deuxième trimestre repose sur le calcul d’un risque individuel de trisomie 21 obtenu en pondérant le risque lié à l’âge maternel par un facteur lié aux concentrations de marqueurs présents dans le sérum maternel. Les marqueurs qui ont prouvé leur efficacité et qui ont été utilisé dans notre étude sont l’alphafœtoprotéine et l’hormone gonadotrophine chorionique. Deux cent quarante et une femmes enceintes recrutées dans les services de maternité de Sousse et de Monastir ont bénéficié du dosage de ces deux marqueurs sériques. Nous avons pu savoir l’issue de la grossesse chez uniquement 163 femmes. Grâce à ce double test et en fixant le risque seuil décidant ou non d’une amniocentèse à 1/250, nous avons observé un cas positif : une femme présentant un risque accru de trisomie 21 avec une valeur de 1/32 à laquelle a été proposé un caryotype ; celui-ci a confirmé l’existence de cette anomalie chromosomique (vrai positif). Ce même logiciel utilisé pour le dépistage de la trisomie 21 ; nous a permis de détecter chez 7,46 % des femmes un risque de défaut de fermeture de tube neural. 3,7 % des femmes ont présenté un taux faible de l’hormone gonadotrophine chorionique, ce qui est en rapport avec une diminution de la viabilité fœtale. À l’échelle nationale, il serait souhaitable de généraliser le dépistage prénatal de la trisomie 21 à toutes les femmes enceintes quel que soit leur âge grâce à l’utilisation des marqueurs sériques dans le sang maternel. La diffusion de ce double test limitera l’utilisation des examens invasifs.

Pulmonary metastases from primary hepatocellular carcinoma in a 26-year-old patient: a case report

Hepatocellular carcinoma is a primary tumor of the liver, which usually develops in the setting of chronic liver disease, particularly viral hepatitis. The diagnosis of hepatocellular carcinoma can be difficult, and often requires the use of serum markers, one or more imaging modalities, and histological confirmation. The authors describe a case of a 26-year-old woman with hepatocellular carcinoma and multiple pulmonary metastases. She presented with hepatomegaly and sporadic fever, and had negative hepatitis serology, normal alkaline phosphatase, and a rising serum alpha-fetoprotein level. The diagnosis was confirmed by histopathology, after percutaneous liver biopsy. Although the patient was in good health condition and had few symptoms, there was no possibility of treatment due to the extension of the liver tumor and the number of pulmonary metastases.

Tumor markers in breast cancer – european group on tumor markers (EGTM) recommendations

Recommendations are presented for the routine clinical use of serum and tissue-based markers in the diagnosis and management of patients with breast cancer. Their low sensitivity and specifi city preclude the use of serum markers such as the MUC-1 mucin glycoproteins (CA 15.3, BR 27.29) and carcinoembryonic antigen in the di- agnosis of early breast cancer. However, serial measure- ment of these markers can result in the early detection of recurrent disease as well as indicate the effi cacy of therapy. Of the tissue-based markers, measurement of estrogen and progesterone receptors is mandatory in the selection of patients for treatment with hormone therapy, while HER-2 is essential in selecting patients with advanced breast cancer for treatment with Her- ceptin (trastuzumab). Urokinase plasminogen activator

Diagnosis and Quantitation of Fibrosis

Hepatic fibrosis is the final common pathway for many different liver insults. Originally considered to be irreversible, hepatic fibrosis is now known to be a dynamic process with a significant potential for resolution. The diagnosis and quantitation of fibrosis have traditionally relied on liver biopsy. However, there are a number of drawbacks including the invasive nature of the procedure, sampling error, and interobserver variability. This article reviews the current role of liver biopsy in the assessment of hepatic fibrosis and discusses the role of the newer noninvasive methods including serum markers and radiologic tests.

Serum markers in community-acquired pneumonia and ventilator-associated pneumonia

This article reviews recent data on the usefulness of serum markers in community-acquired pneumonia and ventilator-associated pneumonia. The focus is on clinical studies, with an emphasis on adult critically ill patients. Serum markers have demonstrated potential value in early prediction and diagnosis of pneumonia, in monitoring the clinical course and in guiding antibiotic therapy. C-reactive protein appears to perform better in diagnosing infection, because several studies have shown that procalcitonin may remain undetectable in some patients, specifically those with pneumonia. Procalcitonin exhibited a better correlation with clinical severity, however. Furthermore, one report demonstrated the efficacy and safety of procalcitonin-guided antibiotic therapy in community-acquired pneumonia. Serum markers should only be used as a complementary tool to support the current clinical approach. Use of serum markers, in particular procalcitonin and C-reactive protein, represents a promising strategy in the clinical decision-making process in patients in whom pneumonia is suspected. Specifically, these markers can be used to guide culture sampling and empirical antibiotic prescription, and to monitor the clinical course, adjust the duration of antibiotic therapy and identify nonresponders, in whom an aggressive diagnostic and therapeutic approach may prevent further clinical deterioration.

ProApolipoprotein A1

Central nervous system (CNS) diagnostics is a promising tool for detection of neurological disorders, including brain metastases. One of the earliest applications of CNS diagnostics was based on serum markers of blood-brain barrier (BBB) dysfunction, which often correlates with acute, chronic, or incipient brain disease. In the case of brain metastases, serum levels of S100beta demonstrated a good negative predictive value comparable to radiologic investigations. However, a confounding factor was the presence of BBB changes due to cerebrovascular disease. Of 103 patients enrolled in a lung cancer study, greater than 50% presented with magnetic resonance imaging (MRI) changes consistent with chronic cerebrovascular disease and reflected by elevated serum S100beta. To unveil serum protein, the authors used proteomic techniques that allow discrimination between patients with brain metastases and lung cancer patients affected by cerebrovascular ischemic changes without infiltrating tumor. ProApolipoprotein A1, transferrin, haptoglobin, and transthyretin were upregulated in patients affected by chronic cerebrovascular disease and brain metastases compared with those affected only by vascular diseases. ProApolipoprotein A1 was significantly increased (p<.05) in patients with CNS disease. In conclusion, these data support the use of serum markers for the early detection of brain metastases. ProApolipoprotein A1 may be used in conjunction with S100beta for serum-based, MRI-independent diagnosis of metastatic brain tumors.

Invited commentary

The use of molecular techniques in the staging of malignancy (ie, molecular biologic substaging) may improve the assessment of prognosis and the assignment of therapy for patients with nonsmall cell lung cancer (NSCLC). The current staging system tends to under-stage patients, and clinical staging is even less accurate than pathologic staging. Molecular biologic substaging may be applied to the primary tumor to assess prognosis or chemoresistance, and to lymph nodes, serum, or bone marrow to assess occult systemic metastases. If it were possible to identify which patients with lung cancer will have systemic recurrence develop prior to the development of clinical or radiographic evidence, systemic therapy may be more effective in improving the outcomes of patients after resection. Molecular analysis of the primary tumor has demonstrated the ability to identify patients with increased risk of recurrence after resection for NSCLC, although this technology has not yet been investigated in phase III clinical trials, and clinical efficacy has not yet been proven. Tumor-related proteins may be secreted into the peripheral circulation of patients with cancer and are detectable by protein analysis. The measurement of serum proteins involved in the pathophysiology of invasion and metastases may be effective in providing prognostic stratification and allowing earlier therapeutic intervention. The use of serum markers has not yet reached acceptance in assessing prognosis or assigning therapy after complete resection for NSCLC. In 1997 the American Thoracic Society and The European Respiratory Society jointly published guidelines for assessment of NSCLC, indicating that no serum tumor markers had sensitivity and specificity sufficient to reliably detect occult disease or influence treatment. Most tumor proteins are elevated in a minority of patients prior to resection; using a panel of markers may allow a majority of patients to be eligible for surveillance. Although prognostic information may be attained from initial serum titers of tumor markers, these markers continue to be secreted into the peripheral circulation of patients with continued and recurrent disease. The use of serial serum determinations enables analysis of protein expression within time, and changes in protein levels may be more important than the absolute value of the protein. However, tumor proteins in the serum may be detectable prior to the point at which a recurrent tumor can be identified with conventional radiographic techniques; recently this has been demonstrated. The authors are to be commended for this important study [1Mizuguchi S. Nishiyama N. Iwata T. et al.Clinical value of serum cytokeratin 19 fragment and Sialyl-Lewis X in non-small cell lung cancer.Ann Thorac Surg. 2007; 83: 216-222Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar]. Molecular biologic substaging of patients with early stage NSLCL using proteomic and genomic strategies should be investigated to improve the accuracy of the TNM staging system to assess prognosis, to identify patients who may benefit from adjuvant therapy, and to predict recurrence. Clinical Value of Serum Cytokeratin 19 Fragment and Sialyl-Lewis X in Non-Small Cell Lung CancerThe Annals of Thoracic SurgeryVol. 83Issue 1PreviewThis study aimed to establish the clinical significance of preoperative serum cytokeratin 19 fragment (CYFRA21-1) and sialyl-Lewis x (SLex) as prognostic markers. Full-Text PDF

Combining markers of nephrotoxicity and hepatotoxicity for improved monitoring and detection of chronic alcohol abuse

Most of the commonly used markers of chronic alcohol abuse reflect alcohol hepatotoxicity; however, such abuse is deleterious to the kidneys as well. Combined use of serum markers of liver origin and urinary markers of kidney origin may be of diagnostic advantage. The study was performed in 73 male alcoholics undergoing detoxification and 36 male alcoholics who had maintained abstinence for > or =6 weeks. Factor analysis, discriminant analysis and receiver operating characteristic (ROC) analysis were used to assess the discriminative power of two urinary markers of alcohol nephrotoxicity, namely beta-N-acetylhexosaminidase (Hex, EC 3.2.1.52) and alanine aminopeptidase (EC 3.4.11.2), and of three serum markers of alcohol hepatotoxicity, namely aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2) and gamma-glutamyltransferase (GGT, EC 2.3.2.2), and of their quantitative combinations. The discriminative power of the urinary markers matched that of the serum markers. Hex and GGT appeared to be the best for discriminating the study groups. Their combination given by the equation G&H=0.62 x ln(GGT)+0.72 x ln(Hex) showed excellent discriminative ability (ROC area under the curve 0.92) that was significantly higher than that of any single marker in this report, indicating superior diagnostic accuracy of the compound marker. Kidney-derived urinary markers, particularly Hex, can complement or replace, if necessary, serum markers of chronic alcohol abuse that relate to alcohol hepatotoxicity. The compound marker proposed seems a promising tool for the monitoring and perhaps detection of chronic alcohol abuse and warrants further studies.

Prognostic Variables and Calcitonin in Medullary Thyroid Cancer

Medullary thyroid cancer (MTC) is a nonepithelial, neuroendocrine tumor with a more aggressive clinical behavior than differentiated thyroid cancer. The purpose of the study was to review a single institution's experience with MCT since 1969. Retrospective cohort study. A retrospective review of 30 patients treated for MTC at a tertiary care referral center between 1969 and 2000. There were 17 female and 13 male patients, median age at presentation was 38 years, and median follow-up for survivors was 12.4 years. Seventy percent of patients had sporadic MTC, 6.7% had familial MTC, 16.7% had multiple endocrine neoplasia syndrome type IIA, and 6.7% had multiple endocrine neoplasia syndrome type IIB. The cumulative overall survival rates at 5, 10, and 20 years were 97%, 88%, and 84%, respectively; disease-free survival rates were 97%, 74%, and 29%, respectively. Advanced tumor stage (P = .014) and multiple endocrine neoplasia syndrome type IIB predicted decreased disease-specific survival. Variables affecting disease-free survival were post-thyroidectomy calcitonin level (P = .001), vascular invasion (P = .005), perineural invasion (P = .010), extrathyroidal extension (P < .001), and the presence of nodal metastases (P = .001). Locoregional control rates were 83% at 5 years and 70% at 10 years. Vascular invasion (P = .004), extrathyroidal extension (P = .008), and post-thyroidectomy basal calcitonin level (P = .003) predicted locoregional failure. Many patients in the series experienced prolonged survival despite elevated calcitonin levels. Long-term disease-free survival is uncommon in MTC, but the study data indicate that the majority of patients with MTC live for prolonged periods, despite biochemical evidence of persistent disease. Adverse pathological features such as extrathyroidal extension and vascular and perineural invasion were predictors of disease recurrence. The use of serum markers in the follow-up of patients with MTC must be interpreted within the clinical context.

Serum markers detect the presence of liver fibrosis: A cohort study

Histologic examination of a liver biopsy specimen is regarded as the reference standard for detecting liver fibrosis. Biopsy can be painful and hazardous, and assessment is subjective and prone to sampling error. We developed a panel of sensitive automated immunoassays to detect matrix constituents and mediators of matrix remodeling in serum to evaluate their performance in the detection of liver fibrosis. In an international multicenter cohort study, serum levels of 9 surrogate markers of liver fibrosis were compared with fibrosis stage in liver biopsy specimens obtained from 1021 subjects with chronic liver disease. Discriminant analysis of a test set of samples was used to identify an algorithm combining age, hyaluronic acid, amino-terminal propeptide of type III collagen, and tissue inhibitor of matrix metalloproteinase 1 that was subsequently evaluated using a validation set of biopsy specimens and serum samples. The algorithm detected fibrosis (sensitivity, 90%) and accurately detected the absence of fibrosis (negative predictive value for significant fibrosis, 92%; area under the curve of a receiver operating characteristic plot, .804; standard error, .02; P < .0001; 95% confidence interval, .758-.851). Performance was excellent for alcoholic liver disease and nonalcoholic fatty liver disease. The algorithm performed equally well in comparison with each of the pathologists. In contrast, pathologists' agreement over histologic scores ranged from very good to moderate (kappa = .97-.46). Assessment of liver fibrosis with multiple serum markers used in combination is sensitive, specific, and reproducible, suggesting they may be used in conjunction with liver biopsy to assess a range of chronic liver diseases.

Invited commentary

Invited commentary

Combined serum and nuchal translucency screening in the first trimester achieves 85% to 90% detection rate for Down and Edward syndromes

Question How accurate is combined screening, based on maternal age, using serum and nuchal translucency measurements in first trimester screening for Down and Edward syndromes? Study design Cohort study. Main results Combined screening identified 85.2% (95% CI 73.8 to 93.0%) of babies with Down syndrome with a false positive rate of 9.4% (95% CI 8.8 to 10.1%). In women over 35 years, 89.8% cases were identified and the false positive rate increased to 15.2%. Combined screening identified 90.9% (95% CI 58.7 to 99.8%) of babies with Edward syndrome (trisomy 18) with a false positive rate of 2% (95% CI 1.7 to 2.3). All cases of trisomy 18 were identified among women over 35 years ( n=8). Combined screening was significantly better than use of serum markers alone ( p=0.002) but no more accurate than use of nuchal translucency alone ( p=0.28). Authors’ conclusions Combined screening for Edward and Down syndromes during the first trimester achieved detection rates of 90% and 85%, respectively, with acceptable false positive rates.

Diagnosis and monitoring of hemorrhagic shock during the initial resuscitation of multiple trauma patients: a review

The initial management of the multiple trauma victim requires evaluation for potential hemorrhage and ongoing monitoring to assess the efficacy of resuscitation and avoid complications related to hemorrhagic shock. A variety of strategies exist to assess circulatory status, including hemodynamic monitoring, tissue perfusion measurement, and use of serum markers of metabolism. We review available technologies used to assess fluid status and tissue perfusion in patients with blood loss or hemorrhagic shock, discuss how these methods can be used effectively and efficiently during initial trauma resuscitation to guide therapy and disposition, and suggest directions for future research to improve outcomes by providing more appropriate and timely care and avoiding unnecessary complications.

Possible postmortem serum markers for differentiation between fresh-, saltwater drowning and acute cardiac death: a preliminary investigation

The aim of the present study was to investigate the differences in postmortem blood biochemistry between fresh-, saltwater drowning and acute myocardial infarction/ischemia (AMI) ( n=11, n=15 and n=23, respectively; postmortem interval <48 h). Left and right cardiac blood samples were examined for the serum markers: sodium (Na), chloride (Cl), magnesium (Mg), blood urea nitrogen (BUN), creatinine (Cr), pulmonary surfactant-associated protein A (SP-A) and cardiac troponin T (cTn-T). The most efficient markers were the left–right cardiac BUN ratio for determination of drowning (hemodilution) and the left heart blood Mg level for differentiation between fresh- and saltwater aspiration. A characteristic feature of saltwater drowning was a low left–right BUN ratio and a marked elevation in the serum Cl, Mg and Ca levels of the left heart blood. Serum cTn-T level was usually low in drownings, showing a difference from most cases of AMI. Freshwater drowning showed a significant elevation of serum SP-A, although there was considerable overlapping with saltwater drowning and AMI. These findings suggested the usefulness of serum markers in the investigation of death from drownings.

Is It Safe to Send This Patient Home? ED Markers of ACS Move Upstream

The best method for identifying patients at risk for serious complications from among the 6 to 7 million individuals who present to emergency departments each year with chest pain or possible acute coronary syndromes (ACS) has been the subject of much debate and research. Use of serum markers is widespread, and the specificity they provide has proven to be of great value in triaging patients with ACS to the appropriate level of care and in identifying acute myocardial infarction earlier, particularly when the electrocardiogram is not diagnostic. The troponins are 30%-40% more sensitive in identifying patients with myocardial necrosis than is creatine kinase-MB fraction, which in turn was a significant improvement over older serologic tests, such as unfractionated …

New technologies for biomarker analysis of prostate cancer progression: Laser capture microdissection and tissue proteomics

The widespread use of serum markers during cancer screenings has led to the belief that there may be tumor markers yet to be discovered that offer better specificity and sensitivity than prostate-specific antigen (PSA). Proteomics, the analysis and characterization of global protein modifications, will add to our understanding of gene function and aid in biomarker and/or therapeutic target discovery. In the past, most proteomic studies were either performed using tumor cell lines or homogenized bulk tissue. Unfortunately, these approaches may not accurately reflect molecular events that take place in the actual ductal epithelium that change as a consequence of the malignant process. This report describes alternative proteomic-based approaches aimed at the identification of protein markers in the actual premalignant and frankly malignant epithelium.

Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting With Suspected Acute Myocardial Infarction or Unstable Angina

This clinical policy focuses on critical issues in the evaluation and management of patients with acute myocardial infarction or unstable angina. A MEDLINE search for articles published between January 1993 and December 1998 was performed using combinations of the key words chest pain, acute myocardial infarction, unstable angina, thrombolytics, primary angioplasty, 12-lead ECG, ST-segment monitoring, cardiac serum markers, and chest pain centers. Subcommittee members and expert peer reviewers also supplied articles with direct bearing on the policy. This policy focuses on 5 areas of current interest and/or controversy: (1) ECG eligibility criteria for fibrinolytic therapy, (2) role of primary angioplasty in patients with acute myocardial infarction, (3) use of serum markers to diagnose acute myocardial infarction, (4) serial 12-lead ECGs during the initial evaluation, and (5) chest pain evaluation units. Recommendations for patient management are provided for each of these 5 topics based on strength of evidence (Standards, Guidelines, Options). Standards represent patient management principles that reflect a high degree of clinical certainty; Guidelines represent patient management principles that reflect moderate clinical certainty; and Options represent other patient management strategies based on preliminary, inconclusive, or conflicting evidence, or based on panel consensus. This guideline is intended for physicians working in hospital-based emergency departments or chest pain evaluation units. [American College of Emergency Physicians. Clinical policy: critical issues in the evaluation and management of adult patients presenting with suspected acute myocardial infarction or unstable angina. Ann Emerg Med. May 2000;35:521-544.]