Predictive Value Of Negative Test Research Articles

Cerebrospinal fluid creatine kinase isoenzyme BB levels do not predict the clinical outcome in patients unconscious following cardiac resuscitation.

It has recently been claimed that an increase in creatine kinase isoenzyme BB(CK-BB) in cerebrospinal fluid (CSF) is well correlated with the cerebral outcome in patients resuscitated after cardiac arrest. Twenty-one such patients consecutively admitted from outside this hospital participated in the study. The patients were divided into two groups: 6 survivors and 15 nonsurvivors. The median CSF-CK-BB value was 5 U/L among nonsurvivors and below detection limit among survivors (NS). However, the predictive value of a positive test is limited, since only 6 of 15 nonsurvivors (40%) had an increase in CSF-CK-BB (predictive value of positive test = 67%). The predictive value of a negative test is limited, since 3 of 6 survivors (50%) showed no rise in CSF-CK-BB (predictive value of negative test = 25%). No relationship between cerebral dysfunction and CSF-CK-BB values was revealed. Thus, CSF-CK-BB does not predict the clinical outcome in patients resuscitated after cardiac arrest.

Rapid identification of Staphylococcus epidermidis.

A panel of Minitek sugar disks, consisting of trehalose, mannitol, xylose, and sucrose, was evaluated for its ability to identify blood culture isolates of Staphylococcus epidermidis (SE). Using a heavy suspension of organism in Mueller-Hinton broth, 50 microL was pipetted onto each disk in wells of a flat-bottomed microtiter tray. The tray was covered, incubated in a moist chamber in non-CO2 at 35 degrees C, and examined after 5 and 24 hours. A color change of yellow or orange was positive; no color change (red) was negative. Expected reactions for SE were as follows: negative trehalose, mannitol, and xylose; positive, sucrose. On evaluation of 227 coagulase-negative staphylococci (CNS) at 5 and 24 hours, the panel had a sensitivity of 94 and 96%, specificity of 92 and 89%, predictive value of positive tests of 97 and 96%, and predictive value of negative tests of 84 and 87%. This panel offered an inexpensive and convenient method for differentiating SE from the other CNS in five hours.

Accuracy in Core Biopsy of the Prostate

In this autopsy study the predictive values of positive and negative tests of core biopsies of the prostate were investigated. Core biopsies, which were performed after evisceration, were compared with macroscopic and microscopic findings of the entire prostatic gland. Of 107 investigated patients, 100 contained prostatic tissue in the core biopsies. In 11 patients the core biopsies contained carcinoma. All these patients had carcinoma in the tissue sections from the prostate. In 89 patients the core biopsy did not contain carcinoma. 88 of these patients had no carcinoma in the tissue sections from the entire specimens. However, in 1 patient a highly differentiated acinar adenocarcinoma was found. From these results the predictive value of a positive test is 11/11 = 100%, and the predictive value of a negative test is 88/89 = 98.5%. Core biopsy is a suitable method in diagnosing prostatic diseases and gives a very high accuracy when the core biopsy contains prostatic tissue.

Carpal tunnel syndrome--course and prognosis.

In a retrospective study 157 patients with electrophysiologically proven carpal tunnel syndrome (CTS) were followed up. Of the 85 operatively treated patients, 86% showed clear improvement or cure, as did 32% of the patients not operated upon. Multivariate analysis of variance (MANOVA) and linear discriminant analyses indicated atrophy and length of history as effective predictors of clear improvement. The optimized discriminant point was ascertained in the receiver operator characteristics (ROC) curve. A predictive value of positive test of 0.89 was found for the course form "not cured" and a predictive value of negative test of 0.75 for the course form "cured" with a prevalence of one-third for the good course form. The prognosis was bad if atrophy occurred or the history exceeded 7 months. The determination of distal motor latency is indispensable for diagnosing CTS. For prognosis, however, length of history and clinical findings have been more helpful.

A comparison of three serological tests for the diagnosis of B. owis infection in rams.

The complement fixation test (CFT), the enzyme labelled immunosorbent assay (ELISA) and the gel diffusion precipitin test (GD) were compared, for the diagnosis of Brucellu ovis infection in rams. The sensitivities of the tests in 109 rams which were shedding B. ovis in their semen were: CFT 96.3%; ELISA 97.2%; GD 91.7%. The specificities of the tests in 141 rams from non-infected flocks were: CFI 99.3%; ELISA 98.6%; GD 100%. Predictive values of the three tests were measured in 285 rams from infected flocks. Thirty-eight percent of these rams were shedding B. ovis in their semen. Predictive values of positive tests were: CFT 75.5%; ELISA 66.7%; GD 72.5%. Predictive values of negative tests were: CFI 97.1%; ELISA 97.6%; GD 93.8%.