摘要:

Approximately half the articles published in medical journals that use statistical methods use hem incorrectly. These errors are so widespread that the present system of peer review has not been able to control them. This article presents a few rules of thumb to help readers identify questionable statistical analysis and estimate what the authors would have concluded had they used appropriate statistical methods. To prevent such errors from appearing, journals should secure review by someone knowledgeable in statistics before accepting a manuscript. In addition, human research committees should insist that an investigator define an appropriate strategy for data analysis before approving a protocol. Such policies should quickly and effectively increase the reliability of the clinical and scientific literature.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The Belgian Heart Disease Prevention Project is a controlled, multifactorial prevention trial involving 19,390 males aged 40–59 years employed by 30 Belgian industries. These industries were paired and randomized into a control or intervention unit. In each intervention factory, the subjects from the two highest deciles of a coronary risk-score distribution curve were given individual advice twice a year. A health education campaign was also organized in each intervention factory. In the control group, 10% of randomly chosen subjects had the same baseline examination as the whole of the intervention group. After 2 years, high-risk subjects and random samples of the control and intervention group were compared regarding the coronary risk profile by means of a multiple logistic function (MLF). In the intervention high-risk group, the MLF showed a decrease of 20%, and in the control group there was an increment of 12.5% (p< 0.001). Comparing the random samples an increment of 25% was found in the control group vs a drop of 2.26 in the intervention group (p< 0.001). The coronary risk profile can be altered in a middle-aged male working population through mass media health education supplemented by face-to-face counseling in high-risk subjects.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We studied the in-hospital mortality and morbidity of 745 patients who had suffered a first myocardial infarction. One hundred twenty-four patients (16.6%) had nontransmural infarction and 621 (83.4%) had transmural infarction. Both groups of patients were similar in the distribution of age, sex, and coronary risk factors. Patients with nontransmural infarction had a significantly lower mortality (3% vs 11%,p< 0.01) and a lower prevalence of premature ventricular complexes (81% vs 88%,p< 0.05). The patients with transmural infarction were distributed evenly among the three subgroups with peak SGOT levels less than 120 units, 120–240 units and more than 240 units (31%, 34% and 35%, respectively), while most patients with nontransmural infarction (60%) had peak SGOT levels less than 120 units (p< 0.0001). When the in-hospital mortality and morbidity were compared between the parallel subgroups, the prognosis of patients with the two types of infarctions was similar. This study shows that the peak SGOT level is more important than the type of infarction in determining the acute mortality and morbidity of first myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The residual fraction – the fraction of tracer extracted and retained by the myocardium after a bolus injection of13IN-labeled ammonia (NH, = NH+) was studied in isolated perfused rabbit hearts under conditions in which flow and cardiac metabolism could be selectively and independently controlled. Residual fraction and clearance (defined as the half-time [t½] required for elimination of sequestered tracer) of this positron-emitting tracer were monitored and quantified by coincident detection. Hearts were perfused with either modified Krebs-Henseleit buffer alone (KH) or KH enriched with washed sheep erythrocytes (KH-RBC) to augment oxygen-carrying capacity. In 13 hearts perfused with KH, the residual fraction (Res Fx) of13IN counts was not altered significantly when flow was decreased by 75% from a control rate of 4.2 ml/g/min (Res Fx = 17.9 ± 2.7%; mean sSEM) to 1.2 ml/g/min (Res Fx = 18.4 ± 1.2%, NS). Clearance of13IN was faster because tl/2 decreased from 36 ± 5 minutes to 15: 3 minutes (p< 0.01). In 12 hearts perfused with KHRBC, Res Fx and tl/2 were not altered despite marked ischemia when flow was diminished by 75% from control flow of 1.4 to 0.3 ml/g/min (control values: Res Fx = 54.6 + 2.4%, tlh = 41 k 6 minutes; low flow values: Res Fx = 58.1 ± 4.4%, tl/2 = 35 ± 10 minutes, NS). In four additional hearts perfused with KH-RBC with 0.02 mg/ml of methionine sulfoximine, a glutamine synthetase inhibitor, myocardial retention of13N counts was reduced by > 60% and myocardial clearance was prolonged compared to pre-inhibition values. The results obtained indicate that the retention and clearance of13N activity by myocardium are influenced to a considerable extent by the metabolic state of the myocardium. Accordingly, relationships between extraction and retention of tracer and flow per se are complex and preclude direct estimation of perfusionm from the amount of tracer sequestered by the myocardium.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Different exercise ECG lead systems were evaluated for the detection of multivessel coronary disease in 118 male survivors of a transmural myocardial infarction. Patients were classified according to the location of myocardial infarction and angina functional class and test results were correlated with angiographic findings. The ECG criteria for a positive test in any lead were horizontal or downsloping ST-segment depression ≥ 1 mm for 0.08 second, and a slow, upsloping ST segment depressed ≥ 1.5 mm at 0.08 second after the J point compared with the rest tracing.The sensitivity of the test for multivessel disease was greater using 14 ECG leads (72%) or leads CC5, CM, and V, (64%) than lead V5alone (50%) (p< 0.05). Sensitivity was less when the site of infarction was anterior (64%) vs inferior (77%). The predictive value of a positive test ranged from 50–100% and that of a negative test from 24–80%, depending on angina functional class and lead positivity during exercise. Leads CC5, CM5and V5gave data similar to data from 14 ECG leads. The maximum diagnostic value of exercise testing after infarction was for patients in angina class 0 or 1. A positive test in this subset increased the likelihood of multivessel disease from 50–55% to 80–100%, and a negative test reduced the risk of three-vessel disease to less than 10%. In patients with more severe angina, the post-test risk was only slightly more than the prevalence of multivessel disease, and false-negative tests were common. A positive test predicted multivessel disease more frequently when the site of infarction was inferior (89%) than anterior (73%). Exercise-induced chest pain, the number of positive ECG leads, ST-segment elevation, treadmill work time and maximum depth of ST-segment depression provided additional diagnostic information.We conclude that probability statements for multivessel disease from exercise test results after infarction are most useful in patients with few or no symptoms and that satisfactory results can be obtained by recording leads CC5, CM5, and V5,.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To evaluate the diagnostic potential and hemodynamic significance of exercise-induced multiple- lead QRS changes, we studied exercise test responses in 230 patients with chest pain syndromes undergoing Bruce protocol exercise tests. When increases in the R waves of multiple ECG leads (ΣR) plus ST segment change > 1 mm were present, 74 of 75 patients (99%) had coronary disease; this was a higher percentage than that achieved with either measurement alone or when ST change was combined with increase in R in a single lead. Sixty-four of the 75 patients (85%) had multivessel disease, the most severe form of coronary artery disease. Left ventricular end-diastolic pressure (both at rest and after left ventriculography), presence and degree of resting ventricular asynergy, and ejection fraction were all significantly more abnormal in patients whose ΣR increased, regardless of ST-segment change. Further, in patients who stopped exercise because of cardiac symptoms, exercise duration and the product of heart rate times blood pressure were significantly lower when ΣR increased. Thus, the mechanism for the increase in ΣR with exercise in patients with coronary artery disease appears to be related to abnormalities in left ventricular function.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To determine the effect of exercise on the in vivo formation of circulating platelet aggregates in patients with severe coronary artery disease (CAD), platelet aggregate ratios (PAR) (normal 0.8–1.1) were measured immediately before and after treadmill exercise and 30 minutes after exercise in 17 CAD patients (group 1, mean age 55 years), 12 age-matched normal subjects (group 2), and 13 young normals (mean age 27 years, group 3). Coronary patients had lower resting PAR than group 3 (0.79 ± 0.05 vs 0.98 ± 0.03;p< 0.01), while group 2 had an intermediate value 0.86 4- 0.04 (p> 0.05 vs CAD and group 3). Immediately after exercise, group I PAR declined from 0.79 ± 0.05 to 0.53 ± 0.04 (p< 0.001), while groups 2 and 3 were unchanged (p> 0.05; bothp< 0.001 vs group 1); 30 minutes after exercise, PAR in group 1 rose to 0.66 ± 0.05 (p< 0.05 vs pre- and immediately postexercise); groups 2 and 3 remained unchanged vs pre- and immediately postexercise (p> 0.05; bothp< 0.001 vs group 1). Six group 1 patients received 1300 mg aspirin daily for 10 days and repeated the protocol. Resting PARs were unchanged (p> 0.05) from resting values without aspirin. The exercise-induced decline in PAR was attenuated by aspirin: without aspirin, 0.73 ± 0.02 preexercise to 0.54 ± 0.04 postexercise; with aspirin, 0.73 ± 0.03 to 0.82 ± 0.03 (p< 0.05 vs no aspirin). These data indicate that platelet aggregation occurs with exercise in CAD. In addition, these data suggest that aspirin exerts a significant inhibitory effect on exercise-induced platelet aggregation in CAD patients.

ISSN:0009-7322    

出版商:OVID    

年代:1980

数据来源: OVID