Comparison of Digital Rectal Examination and Serum Prostate Specific Antigen in the Early Detection of Prostate Cancer: Results of a Multicenter Clinical Trial of 6,630 Men.

To compare the efficacy of digital rectal examination and serum prostate specific antigen (PSA) in the early detection of prostate cancer, we conducted a prospective clinical trial at 6 university centers of 6,630 male volunteers 50 years old or older who underwent PSA determination (Hybritech Tandom-E or Tandem-R assays) and digital rectal examination. Quadrant biopsies were performed if the PSA level was greater than 4 µg./l. or digital rectal examination was suspicious, even if transrectal ultrasonography revealed no areas suspicious for cancer. The results showed that 15% of the men had a PSA level of greater than 4 µg./l., 15% had a suspicious digital rectal examination and 26% had suspicious findings on either or both tests. Of 1,167 biopsies performed cancer was detected in 264. PSA detected significantly more tumors (82%, 216 of 264 cancers) than digital rectal examination (55%, 146 of 264, p = 0.001). The cancer detection rate was 3.2% for digital rectal examination, 4.6% for PSA and 5.8% for the 2 methods combined. Positive predictive value was 32% for PSA and 21% for digital rectal examination. Of 160 patients who underwent radical prostatectomy and pathological staging 114 (71%) had organ confined cancer: PSA detected 85 (75%) and digital rectal examination detected 64 (56%, p = 0.003). Use of the 2 methods in combination increased detection of organ confined disease by 78% (50 of 64 cases) over digital rectal examination alone. If the performance of a biopsy would have required suspicious transrectal ultrasonography findings, nearly 40% of the tumors would have been missed. We conclude that the use of PSA in conjunction with digital rectal examination enhances early prostate cancer detection. Prostatic biopsy should be considered if either the PSA level is greater than 4 µg./l. or digital rectal examination is suspicious for cancer, even in the absence of abnormal transrectal ultrasonography findings.

Immune monitoring with iTAg MHC Tetramers for prediction of recurrent or persistent cytomegalovirus infection or disease in allogeneic hematopoietic stem cell transplant recipients: a prospective multicenter study.

Cytomegalovirus (CMV) infection is an important cause of morbidity and mortality in hematopoietic stem cell transplant recipients despite the introduction of posttransplantation viral monitoring and preemptive antiviral therapy. We evaluated the use of HLA class I tetramers in monitoring CMV-specific T-cell recovery to predict patients at risk for CMV-related complications. This prospective multicenter clinical trial obtained nearly 1400 tetramer/allele results in more than 800 biweekly blood samples from 83 patients monitored for 1 year after transplantation. Major HLA types were included (A*0101, A*0201, B*0702, B*0801, B*3501). iTAg MHC Tetramers (Beckman Coulter) were used to enumerate CMV-specific CD8(+) T cells by flow cytometry using a single-platform absolute counting method. Assay variability was 8% or less and results were available within 3 hours. Delayed recovery of CMV-specific T cells (< 7 cells/µL in all blood samples during the first 65 days after transplantation) was found to be a significant risk factor for CMV-related complications; these patients were more likely to develop recurrent or persistent CMV infection (relative risk 2.6, CI 1.2-5.8, P = .01) than patients showing rapid recovery, which was associated with protection from CMV-related complications (P = .004). CMV tetramer-based immune monitoring, in conjunction with virologic monitoring, can be an important new tool to assess risk of CMV-related complications and to guide preemptive therapeutic choices.

Improved differential diagnosis of anemia of chronic disease and iron deficiency anemia: a prospective multicenter evaluation of soluble transferrin receptor and the sTfR/log ferritin index.

Anemia of chronic disease (ACD) and iron deficiency anemia (IDA) are the most prevalent forms of anemia and often occur concurrently. Standard tests of iron status used in differential diagnosis are affected by inflammation, hindering clinical interpretation. In contrast, soluble transferrin receptor (sTfR) indicates iron deficiency and is unaffected by inflammation. Objectives of this prospective multicenter clinical trial were to evaluate and compare the diagnostic accuracy of sTfR and the sTfR/log ferritin index (sTfR Index) for differential diagnosis using the automated Access(®) sTfR assay (Beckman Coulter) and sTfR Index. We consecutively enrolled 145 anemic patients with common disorders associated with IDA and ACD. Subjects with IDA or ACD + IDA had significantly higher sTfR and sTfR Index values than subjects with ACD (P < 0.0001). ROC curves produced the following cutoffs for sTfR: 21 nmol/L (or 1.55 mg/L), and the sTfR Index: 14 (using nmol/L) (or 1.03 using mg/L). The sTfR Index was superior to sTfR (AUC 0.87 vs. 0.74, P < 0.0001). Use of all three parameters in combination more than doubled the detection of IDA, from 41% (ferritin alone) to 92% (ferritin, sTfR, sTfR Index). Use of sTfR and the sTfR Index improves detection of IDA, particularly in situations where routine markers provide equivocal results. Findings demonstrate a significant advantage in the simultaneous determination of ferritin, sTfR and sTfR Index. Obtaining a ferritin level alone may delay diagnosis of combined IDA and ACD.

Analytical performance of a standardized single-platform MHC tetramer assay for the identification and enumeration of CMV-specific CD8+ T lymphocytes.

Major histocompatibility complex (MHC) multimers that identify antigen-specific T cells, coupled with flow cytometry, have made a major impact on immunological research. HLA Class I multimers detect T cells directed against viral, tumor, and transplantation antigens with exquisite sensitivity. This technique has become an important standard for the quantification of a T cell immune response. The utility of this method in multicenter studies, however, is dependant on reproducibility between laboratories. As part of a clinical study using a standardized two-tube three-color single-platform method, we monitored and characterized performance across multiple sites using tetramers against the T cell receptors (TCR) specific for MHC Class I, A*0101--VTEHDTLLY, A*0201--NLVPMVATV and B*0702--TPRVTGGGAM CMV peptides. We studied the analytical performance of this method, focusing on reducing background, maximizing signal intensity, and ensuring that sufficient cells are enumerated to provide meaningful statistics. Inter and intra-assay performance were assessed, which included inherent variability introduced by shipping, type of flow cytometer used, protocol adherence, and analytical interpretation across a range of multiple sample levels and specificities under routine laboratory testing conditions. Using the described protocol, it is possible to obtain intra- and interlab CV's of <20%, with a functional sensitivity for absolute tetramer counts of 1 cell/microL and 0.2% tetramer+ percent for A*0101, A*0201, and B*0702 alleles. The standardized single-platform MHC tetramer assay is simple, rapid, reproducible, and useful for assessing CMV-specific T cells, and will allow for reasonable comparisons of clinical evaluations across multiple centers at clinically relevant thresholds (2.0-10.0 cells/microL).

Use of blood biomarkers to screen for obstructive sleep apnea.

PURPOSE: Obstructive sleep apnea (OSA) is a highly prevalent disorder associated with increased risk for cardiovascular disease, diabetes, and other chronic conditions. Unfortunately, up to 90% of individuals with OSA remain without a diagnosis or therapy. We assess the relationship between OSA and blood biomarkers, and test the hypothesis that combinations of markers provide a characteristic OSA signature with diagnostic screening value. This validation study was conducted in an independent cohort in order to replicate findings from a prior feasibility study. PATIENTS AND METHODS: This multicenter prospective study consecutively enrolled adult male subjects with clinically suspected OSA. All subjects underwent overnight sleep studies. An asymptomatic control group was also obtained. Five biomarkers were tested: glycated hemoglobin (HbA1c), C-reactive protein (CRP), uric acid, erythropoietin (EPO), and interleukin-6 (IL-6). RESULTS: The study enrolled 264 subjects. The combination of HbA1c+CRP+EPO (area under the curve 0.78) was superior to the Epworth Sleepiness Scale (ESS; 0.53) and STOP-Bang (0.70) questionnaires. In non-obese subjects, the combination of biomarkers (0.75) was superior to body mass index (BMI; 0.61). Sensitivity and specificity results, respectively, were: HbA1c+CRP+EPO (81% and 60%), ESS (78% and 19%), STOP-Bang (75% and 52%), BMI (81% and 56%), and BMI in non-obese patients (81% and 38%). CONCLUSION: We verify our hypothesis and replicate our prior feasibility findings that OSA is associated with a characteristic signature cluster of biomarker changes in men. Concurrent elevations of HbA1c, CRP, and EPO levels should generate a high suspicion of OSA and may have utility as an OSA screening tool. Biomarker combinations correlate with OSA severity and, therefore, may assist sleep centers in identifying and triaging higher risk patients for sleep study diagnosis and treatment.

Blood biomarkers of endocrine, immune, inflammatory, and metabolic systems in obstructive sleep apnea.

OBJECTIVE/BACKGROUND: Obstructive sleep apnea (OSA) is a common disorder, affecting over 100 million adults. Untreated OSA leads to serious health consequences and perturbations in endocrine, immune, inflammatory, and metabolic systems. Study objectives are to evaluate the association between OSA and biomarkers, and to test the hypothesis that a combination of markers may be useful in screening for OSA. PATIENTS/METHODS: A multicenter trial was conducted enrolling symptomatic male patients with suspected OSA. All subjects underwent in-laboratory overnight polysomnography. A non-symptomatic control group was also obtained. Eleven biomarkers were tested: HbA1c, CRP, EPO, IL-6, uric acid, cortisol, hGH, prolactin, testosterone, DHEA (Beckman Coulter UniCel DxC 600i Synchron® Access® Clinical Systems), IGF-1. RESULTS: 73 male subjects were enrolled; 26 had moderate/severe OSA. ROC curve analysis showed HbA1c, CRP, EPO, IL-6, and Uric Acid (AUCs: 0.76, 0.73, 0.65, 0.65, 0.61) were superior to the Epworth Sleepiness Scale (AUC: 0.52). Concurrent elevation of HbA1c and CRP provide even greater predictive power. A combination of elevated HbA1c, CRP, and EPO provided 0.08 increase in AUC (0.84 [0.75 - 0.94]) over individual markers (p<0.05), with high sensitivity (85%), and specificity (79%) for moderate/severe OSA. CONCLUSIONS: OSA induces characteristic endocrine, immune, inflammatory, and metabolic disturbances that can be detected with blood biomarkers. These biomarkers are superior to standard screening questionnaires. Various clusters of these biomarkers have an even greater association with OSA and thus may represent physiologic signatures of the disorder that may have value in initial screening for OSA as well as for follow-up of therapy response.

Absolute and relative changes (delta) in troponin I for early diagnosis of myocardial infarction: Results of a prospective multicenter trial.

OBJECTIVES: We investigated absolute and relative cardiac troponin I (TnI) delta changes, optimal sampling protocols, and decision thresholds for early diagnosis of myocardial infarction (MI). Serial cardiac biomarker values demonstrating a rise and/or fall define MI diagnosis; however the magnitude of change, timing, and diagnostic accuracy of absolute versus relative (percentage) deltas remains unsettled. METHODS: We prospectively measured TnI (AccuTnI+3™, Beckman Coulter) at serial time intervals in 1929 subjects with chest pain or equivalent symptoms of acute coronary syndrome at 14 medical centers. Diagnosis was adjudicated by an independent central committee. RESULTS: Elevated TnI above a threshold of 0.03ng/mL demonstrated significant diagnostic efficacy (AUC 0.96). For patients with TnI<0.03ng/mL and symptom onset≥8h, 99.1% (NPV) were diagnosed with conditions other than MI. Absolute delta performed significantly better than relative delta at 1-3h (AUC 0.84 vs 0.69), 3-6h (0.85 vs 0.73), and 6-9h (0.91 vs 0.79). Current recommendations propose ≥20% delta within 3-6h; however, results were optimized using an absolute delta of 0.01 or 0.02ng/mL. Sensitivity results for absolute delta at 1-3h and 3-6h (75.8%, 78.3%) were superior to relative delta (48.0%, 61.3%). NPV (rule out) was 99.6% when baseline TnI<0.03ng/mL and absolute delta TnI<0.01ng/mL. CONCLUSIONS: Absolute delta performed significantly better than relative delta at all time intervals. Baseline TnI and absolute delta may be used in conjunction to estimate probability of MI. Consensus recommendations are supported for sampling on admission and 3h later, repeated at 6h in patients when clinical suspicion remains high.

Diagnostic performance of cardiac Troponin I for early rule-in and rule-out of acute myocardial infarction: Results of a prospective multicenter trial.

OBJECTIVES: To compare emergency department TnI serial sampling intervals, determine optimal diagnostic thresholds, and report representative diagnostic performance characteristics for early rule-in and rule-out of MI. METHODS: We prospectively measured TnI (AccuTnI+3™, Beckman Coulter) at serial time intervals in 1929 subjects with chest pain or equivalent ischemic symptoms suggestive of acute coronary syndromes at 14 medical centers. Diagnosis was adjudicated by an independent central committee. RESULTS: TnI ≥0.03ng/mL provided 96.0% sensitivity and 89.4% specificity at 1-3h after admission, and 94.9% sensitivity and 86.7% specificity at 3-6h. NPV (rule-out, non-MI) was 99.5% at 1-3h, and 99.0% at 3-6h when TnI is <0.03ng/mL. NPV was 99.1% when TnI is <0.03ng/mL and time of symptom onset is ≥8h. Approximately 50-58% (PPV) of patients with TnI ≥0.03ng/mL were diagnosed with MI, depending upon time from onset or admission; PPVs emphasize the importance of serial samples and delta TnI (rising or falling pattern) when low cutoffs are used. Nevertheless, even a single elevated TnI value increased the risk of MI. As TnI values rose, the probability of MI increased. Values ≥0.20ng/mL were associated with nearly 90% probability of MI. CONCLUSIONS: We report a large multicenter prospective adjudicated trial assessing troponin for early rule-in and rule-out using the Universal Definition of MI and conducted in primary care hospital-associated emergency departments. Our study demonstrates high diagnostic accuracy at early observation times, and reinforces consensus recommendations for sampling on admission and 3h later, repeated at 6h when clinical suspicion remains high.

Effect of patient age on early detection of prostate cancer with serum prostate-specific antigen and digital rectal examination.

This study was designed to determine the effects of age by decade on the efficacy of digital rectal examination (DRE) and serum prostate-specific antigen (PSA) for early detection of prostate cancer in men aged fifty and over. A prospective multicenter clinical trial was conducted at six university centers. All 6,630 male volunteers underwent a serum PSA (Hybritech, Tandem) determination and DRE. Quadrant biopsies of the prostate were performed if PSA was > 4 ng/mL or DRE suspicious. A total of 1,167 biopsies were performed, and 264 cancers were detected. The cancer detection rate increased from 3 percent in men aged fifty to fifty-nine to 14 percent in men eighty years or older (p < 0.0001). PSA detected significantly more of the total cancers than DRE at all age ranges (p < 0.05). The positive predictive values (PPV) for PSA were 32 percent (50-59 years), 30 percent (60-69 years), 34 percent (70-79 years), and 38 percent (80+ years). The corresponding PPVs for DRE were 17 percent, 21 percent, 25 percent, and 38 percent. Eighteen percent of the cancers were detected solely by DRE, whereas 45 percent of cancers were detected solely by PSA. Thus, the use of both tests in combination provided the highest rate of detection in all age groups. One hundred-sixty patients underwent radical prostatectomy and pathologic staging. Cancer was organ-confined in 74 percent (25/34) of men aged fifty to fifty-nine, 76 percent (65/86) of men aged sixty to sixty-nine, and 60 percent (24/40) of men aged seventy or over (chi 2, < 70 vs. > or = 70, p < 0.05). Early detection programs yield a lower, yet still substantial, cancer detection rate in younger men, and there is a greater likelihood for detection of organ-confined disease in this age range. Younger men have the longest projected life expectancy and, therefore, the most to gain from early prostate cancer detection.

Prospective evaluation of pregnancy-associated plasma protein-a and outcomes in patients with acute coronary syndromes.

OBJECTIVES: This study sought to investigate whether pregnancy-associated plasma protein-A (PAPP-A) is useful for risk assessment in non-ST-segment elevation acute coronary syndrome (NSTE-ACS). BACKGROUND: PAPP-A is a high molecular weight, zinc-binding metalloproteinase that is associated with vulnerable plaque and may be a predictor of cardiovascular disease and mortality. METHODS: We measured PAPP-A at baseline in 3,782 patients with non NSTE-ACS randomized to ranolazine or placebo in the MERLIN-TIMI 36 (Metabolic Efficiency With Ranolazine for Less Ischemia in Non-ST Elevation Acute Coronary Syndromes) trial and followed for an average of 1 year. A cut point of 6.0 µIU/ml was chosen from pilot work in this cohort. RESULTS: PAPP-A >6.0 µIU/ml at presentation was associated with higher rates of cardiovascular death (CVD) or myocardial infarction (MI) at 30 days (7.4% vs. 3.7%, hazard ratio [HR]: 2.01; 95% confidence interval [CI]: 1.43 to 2.82; p < 0.001) and at 1 year (14.9% vs. 9.7%, HR: 1.63; 95% CI: 1.29 to 2.05; p < 0.001). PAPP-A was also associated with higher rates of CVD (HR: 1.94; 95% CI: 1.07 to 3.52, p = 0.027) and myocardial infarction (HR: 1.82; 95% CI: 1.22 to 2.71, p = 0.003) individually at 30 days. There was no difference in the risk associated with PAPP-A stratified by baseline cardiac troponin I [Accu-TnI >0.04 µg/l], p interaction = 0.87). After adjustment for cardiac troponin I, ST-segment deviation, age, sex, diabetes, smoking, hypertension, and coronary artery disease, PAPP-A was independently associated with CVD/myocardial infarction at 30 days (adjusted HR: 1.62, 95% CI: 1.15 to 2.29; p = 0.006) and 1 year (adjusted HR: 1.35, 95% CI: 1.07 to 1.71; p = 0.012). PAPP-A also improved the net reclassification for CVD/MI (p = 0.003). There was no significant interaction with ranolazine. CONCLUSIONS: PAPP-A was independently associated with recurrent cardiovascular events in patients with NSTE-ACS. This finding supports PAPP-A as a candidate prognostic marker in patients with ACS and supports investigation of its therapeutic implications.

Accuracy of digital rectal examination and transrectal ultrasonography in localizing prostate cancer.

Not all prostate cancers are sonographically hypoechoic or palpable on digital rectal examination, and suspicious areas on transrectal prostatic ultrasonography or digital rectal examination often are not cancer. We present quadrant biopsy results from a multicenter prostate cancer screening study in which men were evaluated with prostate specific antigen (PSA) and digital rectal examination. If the PSA level was elevated (greater than 4.0 ng./ml., Hybritech Tandem assay) or digital rectal examination was suspicious quadrant biopsies were performed. Biopsy specimens were labeled separately, and histological findings were correlated by quadrant with the findings on ultrasonography and digital rectal examination. Of the 6,630 subjects enrolled into the study 16% were biopsied. Of 1,002 quadrants that were suspicious on digital rectal examination 110 (11%) had cancer, while 308 of 418 quadrants containing cancer (74%) were not suspicious on digital rectal examination. Of 855 quadrants that were sonographically suspicious 153 (18%) had cancer, while 282 of 435 quadrants containing cancer (65%) were not sonographically suspicious. Of 225 patients with cancer 137 (61%) would have been missed if only the exact site of the palpable induration had been biopsied. Of 251 patients with cancer 131 (52%) would have been missed if only the exact site of the hypoechoic lesion had been biopsied. We conclude that digital rectal examination and transrectal ultrasonography have limited accuracy in identifying and localizing prostate cancer. Our study emphasizes the importance of obtaining systematic biopsies if the PSA level is elevated, even in the absence of digital rectal examination or ultrasound anomalies.

Comparison of digital rectal examination and serum prostate specific antigen in the early detection of prostate cancer: results of a multicenter clinical trial of 6,630 men.

To compare the efficacy of digital rectal examination and serum prostate specific antigen (PSA) in the early detection of prostate cancer, we conducted a prospective clinical trial at 6 university centers of 6,630 male volunteers 50 years old or older who underwent PSA determination (Hybritech Tandem-E or Tandem-R assays) and digital rectal examination. Quadrant biopsies were performed if the PSA level was greater than 4 micrograms/l or digital rectal examination was suspicious, even if transrectal ultrasonography revealed no areas suspicious for cancer. The results showed that 15% of the men had a PSA level of greater than 4 micrograms/l, 15% had a suspicious digital rectal examination and 26% had suspicious findings on either or both tests. Of 1,167 biopsies performed cancer was detected in 264. PSA detected significantly more tumors (82%, 216 of 264 cancers) than digital rectal examination (55%, 146 of 264, p = 0.001). The cancer detection rate was 3.2% for digital rectal examination, 4.6% for PSA and 5.8% for the 2 methods combined. Positive predictive value was 32% for PSA and 21% for digital rectal examination. Of 160 patients who underwent radical prostatectomy and pathological staging 114 (71%) had organ confined cancer: PSA detected 85 (75%) and digital rectal examination detected 64 (56%, p = 0.003). Use of the 2 methods in combination increased detection of organ confined disease by 78% (50 of 64 cases) over digital rectal examination alone. If the performance of a biopsy would have required suspicious transrectal ultrasonography findings, nearly 40% of the tumors would have been missed. We conclude that the use of PSA in conjunction with digital rectal examination enhances early prostate cancer detection. Prostatic biopsy should be considered if either the PSA level is greater than 4 micrograms/l or digital rectal examination is suspicious for cancer, even in the absence of abnormal transrectal ultrasonography findings.

Selection of optimal prostate specific antigen cutoffs for early detection of prostate cancer: receiver operating characteristic curves.

A prospective clinical trial of prostate cancer screening was conducted at 6 university centers including 6,630 men 50 years old or older who underwent a serum prostate specific antigen (PSA) determination and digital rectal examination. Biopsies were performed if the PSA level was greater than 4.0 ng./ml. (Hybritech Tandem assay) or digital rectal examination was suspicious for cancer. We evaluated the effect on biopsy rate and cancer detection if the cutoff value was shifted from 4.0 to age-specific reference ranges recommended in the literature. In men 50 to 59 years old with normal digital rectal examination findings a decrease from 4.0 to 3.5 ng./ml. would have resulted in a 45% increase in the number of biopsies (39 of 87) and a projected 15% increase in cancer detection. An increase from 4.0 to 4.5 ng./ml. in men 60 to 69 years old would result in 15% fewer biopsies (35 of 238) and would miss 8% of the organ confined tumors (2 of 25). Increasing the cutoff to 6.5 ng./ml. in men 70 years old or older would result in 44% fewer biopsies (70 of 159) and would miss 47% of the organ confined cancers (7 of 15). The number of biopsies performed for each cancer detected with a PSA level of greater than 4.0 ng./ml. remains constant across age groupings, which suggests that the cutoff of 4.0 ng./ml. does not need to be altered in the older men, since it is apparently unaffected by the simultaneously increasing prevalence of benign prostatic hyperplasia and cancer with age. We conclude that a serum PSA concentration of 4.0 ng./ml. should be used as a general guideline for biopsy in all age groups.