Sensitivity, specificity, positive predictive value, and negative predictive value of the dipyridamole sestamibi stress test in predicting graft occlusion or > or = 50% new native coronary artery disease in men versus women and in patients aged > or = 65 years versus < 65 years who had prior coronary artery bypass grafting

The sensitivity, specificity, positive predictive value, and negative predictive value of the dipyridamole sestamibi stress test (DSST) in predicting graft obstruction or > or = 50% new native coronary artery disease (CAD) in 88 men compared with 56 women with prior coronary artery bypass surgery were 96% and 94% (p = NS), 30% and 67% (p = NS), 91% and 96 % (p = NS), 50% and 57% (p = NS), respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of the DSST in predicting graft obstruction or > or = 50% new native CAD in 92 patients aged < 65 years were 95% and 95% (p = NS), 50% and 40% (p = NS), 96% and 87% (p = NS), and 43% and 67% (p = NS), respectively.     

Comparison of sensitivity, specificity, positive predictive value, and negative predictive value of stress testing versus 64-multislice coronary computed tomography angiography in predicting obstructive coronary artery disease diagnosed by coronary angiography

Sixty-four-multislice coronary computed tomographic angiography (CTA) and coronary angiography were performed in 145 patients (mean age 67 +/- 10 years), and stress testing was performed in 47 of these patients to determine the sensitivity, specificity, positive predictive value, and negative predictive value of coronary CTA and of stress testing in diagnosing obstructive coronary artery disease (CAD) in patients with suspected CAD. In 145 patients, coronary CTA had 98% sensitivity, 74% specificity, 90% positive predictive value, and 94% negative predictive value in diagnosing obstructive CAD. In 47 patients, stress testing had 69% sensitivity, 36% specificity, 78% positive predictive value, and 27% negative predictive value for diagnosing obstructive CAD, whereas coronary CTA had 100% sensitivity, 73% specificity, 92% positive predictive value, and 100% negative predictive value for diagnosing obstructive CAD. In conclusion, coronary CTA has better sensitivity, specificity, positive predictive value, and negative predictive value than stress testing in diagnosing obstructive CAD.     

Introduction to biostatistics: Part 3, Sensitivity, specificity, predictive value, and hypothesis testing

Diagnostic tests guide physicians in assessment of clinical disease states, just as statistical tests guide scientists in the testing of scientific hypotheses. Sensitivity and specificity are properties of diagnostic tests and are not predictive of disease in individual patients. Positive and negative predictive values are predictive of disease in patients and are dependent on both the diagnostic test used and the prevalence of disease in the population studied. These concepts are best illustrated by study of a two by two table of possible outcomes of testing, which shows that diagnostic tests may lead to correct or erroneous clinical conclusions. In a similar manner, hypothesis testing may or may not yield correct conclusions. A two by two table of possible outcomes shows that two types of errors in hypothesis testing are possible. One can falsely conclude that a significant difference exists between groups (type I error). The probability of a type I error is alpha. One can falsely conclude that no difference exists between groups (type II error). The probability of a type II error is beta. The consequence and probability of these errors depend on the nature of the research study. Statistical power indicates the ability of a research study to detect a significant difference between populations, when a significant difference truly exists. Power equals 1-beta. Because hypothesis testing yields "yes" or "no" answers, confidence intervals can be calculated to complement the results of hypothesis testing. Finally, just as some abnormal laboratory values can be ignored clinically, some statistical differences may not be relevant clinically.     

Chronic pancreatitis: sensitivity, specificity and predictive value of the pancreolauryl test

Assessment of the clinical value of the pancreolauryl test (PLT) in the literature range from "useless" to a specifity of 95% and a sensitivity of 98%. In this work, our own data are presented in relation to various reference methods. The results are derived from the largest collective investigated to data, comprising 40 controls and 391 patients (108 with chronic pancreatitis and 283 with other gastrointestinal disorders). The specifity of the the PLT varies between 81% and 95% according to the "quality" of the control collective. The PLT is particularly frequently pathological in patients with diseases in the region of the gallbladder/bile duct and the gastrointestinal tract. The sensitivity of the PLT for chronic pancreatitis varies between 68% and 100%, depending on 9 different reference methods employed. Based on the prevalence of chronic pancreatitis with exocrine insufficiency in various patient collectives, the predictive value of the PLT for the presence of this disorder can be calculated using our data.     

Sensitivity, specificity, and predictive value of abdominal fat aspiration for the diagnosis of amyloidosis

Samples of abdominal fat aspirates from 73 patients were sent to us for staining and interpretation. Ten samples were positive for amyloid. We calculated the sensitivity, specificity, and predictive value of the procedure based on the findings and the clinical information and other biopsy data about these patients. Using the results from more traditional biopsies as the "gold standard," sensitivity was 57%, specificity was 100%, and the predictive value was 100% for positive findings in the abdominal fat aspirate. Although the sample size in this study was relatively small, the procedure was found to be a minimally invasive test of high clinical utility.     

Sensitivity, specificity and predictive values of the secretin infusion test in the diagnosis of gastrinoma

From 1974 to 1981, 55 patients, 18 with Zollinger-Ellison syndrome (ZES) histologically confirmed and 37 patients with duodenal ulcer (DU) without pylorostenosis were followed for a minimal period of 5 years. The diagnostic values of a) basal acid output (BAO mEq/h); b) 60 min acid output after secretin infusion, 3 CU-GIH/kg, (MAO-SE mEq/h); c) basal serum gastrin (BSG pg/ml: mean of 4 gastrin determinations) and d) serum gastrin after secretin (SG-SE pg/ml: mean of 4 gastrin determinations during secretin infusion) were calculated. Cut off point values of 100 p. 100 specificity (i. e. no DU patient reached these values) with a positive predictive value of 100 p. 100 (i. e. probability for gastrinoma when this cut off point was attained) were BAO greater than 26 mEq/h, MAO-SE greater than 18 mEq/h, BSG greater than 221 pg/ml, SG-SE greater than 186 pg/ml. The sensitivities of these parameters (i. e. percent of ZES which reached the given cut off point) were respectively (p. 100): 39, 78, 72 and 94. Ranking these parameters according to their own discriminative value expressed by R2 (square correlation coefficient) gave SG-SE, R2 = 0.559; BSG, R2 = 0.508; MAO-SE, R2 = 0.456; BAO, R2 = 0.414. The most discriminative association of 2 variables was SG-SE and MAO-SE (R2 = 0.650). Association of SG-SE, MAO-SE and BAO or BSG (or BAO and BSG) did not increase significantly the discrimination between ZES and DU (R2 = 0.672).     

The predictive value of a strongly positive stress test in patients with minimal symptoms

The ability of a strongly positive stress test to predict left main coronary artery disease in people with suspected coronary artery disease but with minimal or no angina was investigated in 40 such patients. Nine had a history of myocardial infarction but no angina. Thirty-one had mild angina or a history of mild angina. The stress electrocardiograms were analyzed according to criteria known to be associated with left main coronary artery disease in moderately or severely symptomatic patients; (1) early S-T segment changes (stage I or II of exercise), (2) 2 mm or more S-T segment depression, (3) downsloping S-T segments, (4) associated exercise-induced hypotension, (5) prolonged S-T segment changes after the test (≥8 minutes) and (6) anterior and inferior S-T segment depression. The prevalence of left main coronary artery disease was 35 percent and that of any severe coronary artery disease 75 percent. The criterion of anterior and inferior electrocardiographic changes with exercise was most predictive of left main coronary artery disease (P < 0.01 by χ²). Exercise electrocardiography is useful in the prediction of left main or other severe coronary artery disease even when performed in patients who have minimal angina or in those who are asymptomatic after myocardial infarction.     

Sensitivity, specificity, and predictive values of closed pleural biopsy

To determine the clinical value of a nonspecific pleural biopsy specimen and fluid in malignant neoplasm and tuberculosis, we retrospectively reviewed records of all patients with pleural effusions undergoing the procedure at three community hospitals over six years. Two hundred eleven patients underwent biopsies. Adequate tissue was obtained in 207. The results were compared with the ultimate clinical and pathologic outcome by follow-up for 12 to 72 months. The initial procedure was diagnostic of malignant neoplasm in 54 patients and granulomatous disease in ten. A nonspecific or normal result was found in 143 (68%). Malignant neoplasms or tuberculosis was eventually established in 30 and excluded in 101 of the 143 patients. In 12 patients, no diagnosis was made. The procedure's sensitivities were 65% (malignant neoplasm) and 90% (tuberculosis). One false-positive result occurred in a patient with nontuberculous granulomatous pleuritis. The specificity and positive predictive value were 99% and 98%, respectively. The negative predictive value was 77%. Closed pleural biopsy with simultaneous fluid analysis is a valuable diagnostic procedure in community hospital patients, but a nonspecific result does not exclude malignant disease.     

Sensitivity, specificity, and predictive values of bronchoscopy in neoplasm metastatic to lung

Bronchoscopic examination to diagnose lung metastases has not been as rewarding as in primary lung cancer. Despite a lower expected yield, we believe the procedure has value in certain patients, ie, those with clinical findings of endobronchial disease. To determine better the value of bronchoscopy in this population, we retrospectively reviewed records of patients at five community teaching hospitals over a 66-month period. These patients all underwent fiberoptic bronchoscopy. They had a history of prior nonpulmonary malignancy and an abnormal chest roentgenogram suspicious for recurrent malignant disease, or they presented with abnormal chest roentgenographic findings and further evaluation showed the lung disease to be metastatic. Bronchoscopy for metastatic lung disease was most likely diagnostic in patients with primary colorectal cancer (79 percent) and breast cancer (57 percent), and least likely in patients with genitourinary tract cancer (33 percent). Hemoptysis, signs of local airway obstruction, or a roentgenogram showing either atelectasis or diffuse lung disease especially favored a positive biopsy. Bronchoscopy is a valuable diagnostic procedure in selected patients with metastatic lung disease.     

Diagnostic studies for systemic necrotizing vasculitis. Sensitivity, specificity, and predictive value in patients with multisystem disease

Forty patients with multisystem disease and suspected systemic necrotizing vasculitis were evaluated with a protocol designed to confirm the diagnosis with sequential testing. All patients underwent initial laboratory testing. Subsequent studies were individualized to the patient starting with "safe" tests (skin, muscle, rectal biopsies) and progressing to "invasive" tests (arteriography, kidney and lung biopsies). No single laboratory study was found to have adequate predictive value. Skin biopsy, rectal biopsy, and arteriography were insensitive, nonspecific, or had poor predictive values. Muscle biopsy was the most valuable safe procedure (sensitivity, 50%; specificity, 100%; predictive value, 100%; predictive value of negative biopsy, 76%; efficiency, 64%). A diagnostic approach to the patient with possible systemic necrotizing vasculitis is described.     

Tuberculin skin test: estimation of positive and negative predictive values from routine data.

OBJECTIVE: To estimate, using routinely available data, the predictive values of tuberculin testing with 2TU RT23 for detection of latent tuberculosis infection (LTBI) in the Dutch population as a basis for recommendations on cut-off values at various levels of infection prevalence. DESIGN: Smoothed distributions of TST reactions among 312 tuberculosis patients and 2848 healthy non-BCG-vaccinated persons were used to estimate the sensitivity and specificity at various cut-off values. RESULTS: Sensitivity was 98.9% at 5 mm, 95.4% at 10 mm and 79.8% at 15 mm cut-off. Specificity with the corresponding cut-offs was 95.3%, 96.3% and 97.1% before and 98.0%, 98.8% and 99.6% after adjustment for presumed LTBI. At 10 mm, the positive predictive value (PPV) was > 75% if the infection prevalence in the tested population was at least 10%, but strongly declined with lower prevalences. For lower prevalences a cut-off of 15 mm was proposed, as this results in a higher PPV without greatly affecting the negative predictive value. CONCLUSION: Estimation of the predictive values of the TST from routine data can be useful for establishing cut-off values for detection of LTBI in different populations with different tuberculin preparations.     

Effect of serum uric acid on the positive predictive value of dobutamine stress echocardiography

There is controversial data regarding the relationship between uric acid (UA) and coronary artery disease and cardiovascular events. Despite the deleterious effects of hyperuricemia on endothelial function, the effect of UA on myocardial ischemia has not been previously studied. We aimed to investigate the relationship between UA and myocardial ischemia that was identified using dobutamine stress echocardiography (DSE). In this retrospective study, the laboratory and DSE reports of 548 patients were reviewed. The patients were divided into two groups based on the presence of ischemia and further subdivided into three groups according to the extent of ischemia (none, ischemia in 1–3 segments, ischemia in >3 segments). Serum UA levels were compared. Determinants of ischemia were assessed using a regression model. UA was increased in patients with ischemia and was correlated with the number of ischemic segments (p < 0.001). A cutoff value of UA > 5 mg/dl had 63.9 % sensitivity, 62.0 % specificity, 42.5 % positive predictive value (PPV), and 79.6 % negative predictive value for ischemia. When the positive DSE exams were further sorted according to the UA cutoff, the PPV of DSE increased from 80.2 to 94.0 %. Uric acid (odds ratio 1.51; 95 % CI 1.14–1.99), diabetes mellitus, HDL and glomerular filtration rate were found to be independent determinants of myocardial ischemia in DSE. Increased UA is associated with both the presence and extent of DSE-identified myocardial ischemia. A UA cutoff may be a good method to improve the PPV of DSE.     

Sensitivity, specificity and predictive value of two-dimensional echocardiography in detecting coronary artery aneurysms in patients with Kawasaki disease

Seventy-seven patients with Kawasaki disease were prospectively evaluated from 1978 to 1983 to determine the sensitivity, specificity and predictive value for detecting coronary artery aneurysms with two-dimensional echocardiography. Seventy (91%) underwent selective coronary arteriography and are included in this report. The study was divided into two periods because of increased experience and the use of a systematic approach with two-dimensional echocardiography in the second period as compared with the first. Aneurysms were demonstrated in nine patients (13%). The coronary artery system was divided into six regions: proximal third of the main right coronary artery, distal right coronary artery, left main coronary artery, left anterior descending coronary artery, circumflex coronary artery and distal left coronary artery. The sensitivity and specificity were high when imaging the proximal regions, and improved from the first period to the second. Both sensitivity and specificity were lower for the more distal regions of the right and left coronary arteries. Overall, the sensitivity of two-dimensional echocardiography was 100% because there were no patients in our study who had isolated distal coronary artery aneurysms. Two-dimensional echocardiography is a sensitive and specific test for detecting aneurysms in the proximal portions of both the right and left coronary arteries, and is useful in selecting patients for invasive investigation with selective coronary arteriography.     

Sensitivity and positive predictive value of medicare part B physician claims for rheumatologic diagnoses and procedures

Objective. To examine the sensitivity and positive predictive value of Medicare physician claims for select rheumatic conditions managed in rheumatology specialty practices. Methods. Eight rheumatologists in 3 states abstracted 378 patient office records to obtain information on diagnosis and office procedures. The Medicare Part B physician claims for these patient visits were obtained from the Health Care Financing Administration. The sensitivity of the claims data for a specific diagnosis was calculated as the proportion of all patients whose office records for a particular visit documented that diagnosis and who also had physician claims for that visit which identified that diagnosis. The positive predictive value was evaluated in a separate sample of 331 patient visits identified in Medicare physician claims. The positive predictive value of the claims data for a specific diagnosis was calculated as the proportion of patients with that diagnosis coded in the claims for a particular visit who also had the diagnosis documented in the medical record for that visit. Results. Ninety percent of abstracted office medical records were matched successfully with Medicare physician claims. The sensitivity of the Medicare physician claims was 0.90 (95% confidence interval [CI] 0.85–0.95) for rheumatoid arthritis (RA), 0.85 (95% CI 0.73–0.97) for systemic lupus erythematosus (SLE), and 0.85 (95% CI 0.78–1.0) for aspiration or injection procedures. The sensitivity for osteoarthritis (OA) of the hip or knee was ≤0.50 if 5-digit codes specifying anatomic site were required. The sensitivity for fibromyalgia (FM) was 0.48 (95% Cl 0.28–0.68). The positive predictive values were at least 0.90 for RA, SLE, and aspiration or injection procedures. Positive predictive values for FM and the 5-digit site-specific codes for OA of the knee were 0.83 (95% CI 0.66–1.0) and 0.88 (95% CI 0.75–1.0), respectively, while the positive predictive value of the 5-digit site-specific codes for OA of the hip was zero (95% CI 0–0.26). The positive predictive value of OA at any site was 0.83 (95% CI 0.76–0.90). Conclusion. In specialty practice, Medicare physician claims had high sensitivity and positive predictive value for RA, SLE, OA without specification of anatomic site, and injection or aspiration procedures. The claims had lower sensitivity and predictive value for FM and for OA of the hip. The accuracy of Medicare physician claims for other conditions and in the primary care setting requires further investigation.