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The predictive value of induration 24 hours after administration of purified protein derivative (PPD) was examined. Altogether 1082 healthy schoolchildren were tested using 5 tuberculin units of PPD. Induration was measured at 24, 48, and 72 hours. At 24 hours, induration of any size had a relatively low positive predictive value (63%), although indurations > 5 mm had a higher (86%) positive predictive value.
As a predictor of pregnancy induced hypertension (PIH) the roll over test (ROT) has conflicting predictive values in the literature, possibly as a result of sample size, composition or methodology. In this study the roll over test was performed on 600 African women in their first pregnancy and at 26-32 weeks. The test was positive in 15% of women and had a positive predictive value of only 20%. It is concluded that the roll over test is of no value in the prediction of PIH.
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OBJECTIVES: To assess the nature of pulmonary dysfunction in type 1 diabetes and the relationship of pulmonary function tests to diabetic factors and complication. SUBJECTS AND METHODS: Sixteen type 1 diabetic patients and 26 control subjects matched for age and sex were studied. We performed spirometry measurements and measured pulmonary diffusing capacity (DL(CO)) in sitting and supine position by the single-breath method corrected by alveolar volume (VA). Glycosylated hemoglobin (HbA(Ic)), retinopathy and microalbuminuria were included as parameters of metabolic control and diabetic complications. RESULTS: Diabetic patients showed a significant reduction of the following pulmonary function tests (% predicted value) as compared with control subjects: total lung capacity (TLC, 92.6 +/- 14.5 vs. 113.9 +/- 17.5, p < 0.001), lung diffusing capacity in sitting position (DL(CO), 90.4 +/- 21.1 vs. 107.7 +/- 15.6, p = 0.004), lung diffusing capacity in supine position (DL(CO), 88.3 +/- 19.3 vs. 111.9 +/- 19.9, p = 0.001). The differences in diffusing capacity corrected by alveolar volume in sitting and supine position (DL(CO)/VA) were not significant. By changing the posture from sitting to supine position both diabetic patients and control subjects significantly increased DL(CO)/VA (103.4 +/- 17.7 vs. 112.7 +/- 22.3, p = 0.046 and 99.5 +/- 13.4 vs. 114.4 +/- 13, p < 0.001, respectively). There was no correlation between pulmonary function tests and diabetic complications. CONCLUSION: These data indicate that type 1 diabetic patients showed reduced TLC and DL(CO), features of pulmonary restrictive dysfunction. There was no correlation between abnormal pulmonary function and the presence of other diabetic complications.
BACKGROUND: The American Thoracic Society recommends using the lower limit of normal (LLN) method to diagnose obstructive lung disease. However, few studies have investigated the clinical relevance of these recommendations. We compared the LLN derived from available data sets to a fixed ratio (FEV1/FVC, < 75% or 70%) and also to the FEV1/FVC percent predicted ratio to determine the impact of changing the FEV1/FVC "cutoff" on the spirometric diagnosis of obstructive lung disease. METHODS: FEV1, FVC, FEV1/FVC ratio, age, race, sex, height, and weight were recorded from 1,503 pulmonary function tests. Predicted values were calculated using the Third National Health and Nutrition Examination Study data set (Hankinson), and reference values from studies by Crapo, Knudson, and Morris. In addition, the LLN of the FEV1/FVC ratio was calculated for the Hankinson and Crapo reference values. RESULTS: The number of studies interpreted as obstructed varied from 37% using the Hankinson data set to 55% using the 75% fixed ratio method. Comparing the LLN method vs the 70% fixed ratio method resulted in 7.5% (Hankinson LLN vs 70% fixed) and 6.9% (Crapo LLN vs 70% fixed), which were discordant results. Age was the strongest predictor of discordance, and 16% of subjects > 74 years of age had discordant results comparing Hankinson values to the 70% fixed method. CONCLUSION: At the extremes of age and height, a large number of spirometry test results will be interpreted as showing an obstructive defect if a 70% fixed ratio method is used for interpretation compared with the LLN derived from the Hankinson data set.
A study of 116 patients with histologically proven uveal malignant melanoma suggested that hepatic metastases were present at the same time that the ocular tumor was diagnosed in 15 patients (13%) by serum gamma-glutamyl transpeptidase assay. The average pretherapy gamma-glutamyl transpeptidase levels were statistically higher (P less than .01) in the 28 patients who developed metastases compared with those in 88 patients who have remained clinically free of metastases for a follow-up period of at least two years. The predictive value test indicated that pretherapy gamma-glutamyl transpeptidase levels greater than or equal to 22 IU/ml were increased in patients developing metastasis. With this upper-normal limit, 15 (54%) of the 28 patients who later developed clinical evidence of metastasis had increased pretherapy levels. In comparison, only 12 (14%) of the 88 patients who remained tumor-free for at least two years had increased pretherapy levels. Although not all patients who developed metastases had increased pretherapy levels, most developed increases at some time during the course of their disease. Because the gamma-glutamyl transpeptidase assay can detect hepatic metastases before other liver function assays, it should be included as a routine liver function study for patients with uveal malignant melanoma.
Of 197 patients referred for colposcopy who underwent repeat Pap smears and colposcopic biopsies (when indicated), histologic evidence of human papillomavirus (HPV) infection involving the endocervix, cervix, or vagina or all three sites was documented in 109 biopsies. Sixty-six (61%) had normal Pap smears at the time of colposcopy. Despite a specificity of 92% for detecting HPV, the Pap smear demonstrated a low sensitivity (39%), with a positive and negative predictive test value of 88% and 50%, respectively. In patients with biopsies revealing HPV infection without associated dysplasia, false negative Pap smears were found most often in women with strictly vaginal HPV (74%) (P less than 0.05), followed by those with coexistent cervical and vaginal HPV (65%), and then by those with solely cervical HPV (51%). We question the use of the Pap smear for the detection of lower genital tract HPV, particularly in patients with only vaginal involvement, especially when the smear is repeated at the time of colposcopy. Benefits and disadvantages of other screening tests for HPV are discussed.
Urinary hydroxyproline (HP) excretion has been estimated without prior dietary restriction in 33 patients with carcinoma of the prostate and expressed as either 24-h HP output or as the hydroxyproline/creatinine (HP/Cr) ratio in 24-h urine sample, an early morning urine sample or a spot urine sample. The early morning urine hydroxyproline/creatinine ratio (EMU HP/Cr) appears to be the most accurate and avoids the disadvantages of formal dietary restriction and prolonged urine collection. The rest is useful in monitoring the responses to treatment of a patient with bony metastatic disease and relapse of a patient when his tumour ceases to be hormone sensitive. Furthermore, changes in EMU HP/Cr occur earlier than changes in other clinical or investigative variables, giving the test predictive value.
OBJECTIVE: To examine the clinical course of age-associated memory impairment (AAMI) and to evaluate the value of neuropsychological tests in predicting cognitive decline in AAMI subjects in a follow-up period of more than 3 years. DESIGN: Prospective cohort study. SETTING: The outpatient Memory Research Unit of the Department of Neurology at the University of Kuopio in Eastern Finland. PARTICIPANTS: A sample of 229 subjects (mean age 71.7 years) identified in two screening studies as having AAMI. MEASUREMENTS: A battery of neuropsychological tests and a structured inquiry for health status and subjective memory complaints were performed at baseline and follow-up to diagnose AAMI according to the criteria proposed by a National Institute of Mental Health work group. RESULTS: Of the 229 subjects, 176 (76.9%) participated in the follow-up for, on average, 3.6 years after the baseline. Of the participants, 104 (59.1%) still met the AAMI criteria. Other subjects were classified into five subgroups: (1) subjects showing decline in cognition meeting dementia diagnosis (16, 9.1% (13 of them AD)); (2) subjects with mild cognitive decline meeting neither dementia nor AAMI criteria (13, 7.4%); (3) subjects with memory performance now superior to AAMI criteria (17, 9.7%); (4) subjects having a disease classified as exclusion in the criteria (15, 8.5%); (5) subjects not now reporting subjective memory loss in everyday life (9, 5.1%). Two subjects (1.1%) were not classified because of incomplete data. Neuropsychological tests predicted which subjects would develop dementia during the follow-up period. The best discriminators between these subjects and those who remained AAMI were memory and verbal fluency tests. CONCLUSION: The study suggests that, in general, AAMI is nonprogressive, but the AAMI population also includes subjects with early dementia and subjects without genuine memory loss. However, these subjects can be differentiated with a more detailed neuropsychological evaluation.
OBJECTIVE: The purpose of this study was to evaluate levels of lipoprotein(a) as a marker of family history of cardiovascular risk. PATIENTS AND METHODS: We have studied 673 six-year old children. Lipoprotein(a) was determined and previous family history of cardiovascular risk (hypercholesterolemia and cardiovascular disease under 55 years) was collected. RESULTS: Of the children studied, 7.42% had positive antecedents of cardiovascular risk in the parents, 51.8% in grandparents and 9.21% in parents and grandparents. The lipoprotein(a) levels were higher in these groups than in those without any family history of cardiovascular risk. Likewise, the percentage of children with lipoprotein(a) levels higher than 30 mg/dl was 15.69% in the group without a family history of problems and 25.8% and 25.69%, in the group with hypercholesterolemia antecedents and cardiovascular disease, respectively. The sensitivity, specificity and positive predictive value test did not prove that a positive family history could be used to detect the majority of children with lipoprotein higher than 30 mg/dl. CONCLUSIONS: Lipoprotein(a) levels in children are higher in those with a family history of cardiovascular disease or hypercholesterolemia, but these antecedents cannot be used as a determinant factor to detect the majority of children with lipoprotein(a) higher than 30 mg/dl.
The results are reported of the first round of a biennial mammographic screening of women aged 50-64 years started in the Health District of Leno (Brescia, Italy) in December 1985. A total of 7662 women are invited and 5235 attended the programme (68.3%), 87 underwent biopsy or surgery and 39 were found to have a malignant tumor (positive predictive test value: 44.8%; detection rate: 7.5%). The series of 39 cancers found at screening included 4 carcinoma in situ (10.3%); of the invasive tumors, 8 were less than or equal to 10 mm (20.5%); 20 were 11-20 mm in greatest diameter (51.3%) and 7 were 21-40 mm (17.9%). Twenty-four cases showed no axillary lymph node involvement (61.5%), and none of them had metastasis at the time of diagnosis. On the basis of pTNM, 69.2% of cases was classified stage I, 17.9% stage II, none stage III and 2.6% stage IV.
A computer model simulating the electrical activity of the heart is described. The model is designed for use in clinical cardiological research. Its implementation is based on the methods of discrete process simulation. The simulation program is written in FORTRAN, has approximately 12,000 lines and requires 160 kilobytes of memory to run. The whole heart is modelled, including a realistic description of the conduction system and a 'hollow shell' structure with a central plane representing the atrial, ventricular and septal components of the cardiac musculature. The myocardium itself is represented by simple hexagonal elements, which are pieced together to form the 'hollow shell'. The ideas used to develop the model are briefly described, but emphasis is given to clinical applications. The model is first validated by examining its output under well-known pathological conditions. Clinical applications, including predictive value, testing of hypotheses, and evaluation of pacemaker function, are then described, results being presented in the form of orthogonal lead projections.
To study to prognostic capabilities of the exercise electrocardiogram (ECG) in a fit, healthy, middle-aged population, 548 members of the U.S. Navy's "1000 Aviator" cohort were exercised to 85% predicted maximum heart rate in 1969 and then followed-up in 1977 for the development of clinically evident coronary artery disease (CAD). Of these subjects, 23 (4.2%) had significant ST depression during their exercise test in 1969. At the end of the 8-year follow-up period, 38 of the 548 subjects (6.9%) had developed clinically evident CAD. The sensitivity (percent of disease predicted by an abnormal test) and predictive value (percent of abnormal tests predictive of disease) of an abnormal exercise test were 15.7% and 26%, respectively. We conclude that even in a carefully screened aviator population with a low risk for CAD, a single normal exercise ECG does not exclude the presence of latent CAD. Furthermore, in this population, a single abnormal exercise ECG should not be a disqualifying defect without further work-up.
If a proper gold standard is not available, then the predictive value of a test cannot be estimated. In this paper the concept of etiologic predictive value (EPV) is introduced. It is a quantity that will yield the predictive value of a test to predict presence of a specified disease in situations for which no proper gold standard is available. This is achieved by using information obtained from a healthy control population. This quantity requires that the marker in our test is present in all individuals having the specified disease, as in the case where the marker is the aetiologic factor for the specified disease. Furthermore this quantity requires that asymptomatic carriers are present. This means that not all individuals with the marker has the specified disease. EPV is developed with special reference to the evaluation of bacterial cultures, or rapid tests to detect a bacterium, but the quantity might be used in other circumstances as well. EPV is applied to an example in which conventional throat culture is evaluated. Further information concerning EPV can be found at http://www.infovice.se/fou/epv.
In primary hyperaldosteronism, discriminating bilateral adrenal hyperplasia (BAH) from an aldosterone-producing adenoma (APA) is important because adrenalectomy, which is usually curative in APA, is seldom effective in BAH. We analyzed the results from our most recent 7-yr series to evaluate the predictive value of preoperative noninvasive tests compared with adrenal vein sampling (AVS). Forty-eight patients with hypertensive hyperaldosteronism underwent bedside testing, computed tomography (CT) imaging, and AVS. Those in whom the results of AVS indicated APA underwent adrenalectomy. Twelve (30%) and 14 (34%) of 41 patients with APA had paradoxical falls with ambulation in plasma aldosterone concentration (PAC) and 18-hydroxycorticosterone (18-OH-B), respectively. Twenty-nine (70%) and 26 (65%) APA patients had a rise in PAC and 18-OH-B, respectively, as did all 8 BAH patients. Significant identifiers of BAH were supine PAC values less than 15 ng/dL (P: = 0.04), an increase greater than 60% (P: = 0.02) in PAC with ambulation, and supine 18-OH-B values less than 60 ng/dL (P: = 0.04). CT imaging alone was not predictive for BAH or APA. In our population, patients with a positive bedside test result (e.g. a fall in PAC and/or 18-OH-B) and a unilateral adrenal nodule on CT (10 of 41 patients) could have proceeded directly to adrenalectomy for APA. However, a positive bedside test result with a negative CT or a negative bedside test result regardless of CT findings required AVS to confirm the diagnosis and site of disease.
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Azostix-reagent-tests(R) strips (Ames, Miles, Inc., Diagnostic Division, Elkhart, IN) were used to measure blood urea nitrogen values in blood samples from 125 dogs and cats at the North Carolina State University, College of Veterinary Medicine. Results of the tests were compared with standard serum urea nitrogen results. Sensitivity, specificity, and negative predictive values were high (86.4, 90.3, and 96.5%, respectively). Positive predictive value was low, 65.5% of the dogs and cats with elevated blood urea nitrogen values were correctly classified as abnormal The test performs well when the prevalence of abnormal values is near 50%.
The purpose of this prospective, controlled study was to estimate the prevalence of immune-mediated (autoimmune) inner ear disease in a high-risk patient population, in order to determine the predictive value of a positive lymphocyte transformation test. The high-risk group was defined as any dizzy patient with unilateral or bilateral-asymmetric sensorineural hearing loss, who had not previously received immunotherapy. From more than 400 consecutive patients with a chief complaint of dizziness, 58 were entered into the study over an 8-month period. The control group consisted of 15 normal volunteers. Thirteen patients (22%) one control (7%) had positive lymphocyte transformation tests. The data suggest that positive results in "high-risk" patients are more common than previously believed. Assuming test sensitivity is 96%, specificity 93%, and disease prevalence 22% in high-risk patients, the predictive value of a positive lymphocyte transformation test using inner ear membranes is 79%. That is, approximately three fourths of all positive results are true positives. Positive results in suspected patients, therefore, should be considered true positives, and treatment recommended. Future research should attempt to refine the putative antigen(s), further define "high risk" patients, and prospectively verify these preliminary results.