The symptoms of organic disease vary widely among patients with the same tissue abnormality, because the experience of a symptom is shaped by the patient's perceptual and cognitive style. Thus, the ...relationship between myocardial ischemia and chest pain is variable in that many patients experience pain without ischemia and many others exhibit ischemia without pain-termed "silent" or "asymptomatic ischemia." Although the nature of the ischemic event may be important in determining the degree of associated pain, we suggest more study of the individual who perceives the event. Myocardial ischemia may not generate a spontaneous report of chest pain because the patient is generally hyposensitive to visceral sensation; because he or she is coping with the threat of heart disease by denying the evidence of it--ie, denying the pain to deny the disease; or because the patient misunderstands the cause and significance of a vague or ambiguous cardiac sensation, normalizing the symptom and misattributing it to a nonpathologic cause.
Two cases of calf muscle arteriovenous malformation in young women, presenting clinically as deep venous thrombosis, were initially detected by Tc-99m erythrocyte venography and later confirmed by ...arteriography. The role of this technique in the investigation of venous thrombosis is discussed, emphasizing the importance of the lateral calf view.
Biochemical failure, defined here as a rise in the serum prostate specific antigen (PSA) concentration to >0.3 ng/mL or the initiation of adjuvant therapy, is thought to be an adverse prognostic ...factor for men who undergo radical prostatectomy (RP) as definitive treatment for clinically localized cancer of the prostate (CAP). We have developed an artificial neural network (ANN) to predict biochemical failure that may benefit clinicians and patients choosing among the definitive treatment options for CAP.
Clinical and pathologic data from 196 patients who had undergone RP at one institution between 1988 and 1999 were utilized. Twenty-one records were deleted because of missing outcome, Gleason sum, PSA, or clinical stage data. The variables from the 175 remaining records were analyzed for input variable selection using principal component analysis, decision tree analysis, and stepped logistic regression. The selected variables were age, PSA, primary and secondary Gleason grade, and Gleason sum. The records were randomized and split into three bootstrap training and validation sets of 140 records (80%) and 35 records (20%), respectively.
Forty-four percent of the patients suffered biochemical failure. The average duration of follow up was 2.5 years (range 0-11.5 years). Forty-two percent of the patients had pathologic evidence of non-organ-confined disease. The average area under the receiver operator characteristic (ROC) curve for the validation sets was 0.75 +/- 0.07. The ANN with the highest area under the ROC curve (0.80) was used for prediction and had a sensitivity of 0.74, a specificity of 0.78, a positive predictive value of 0.71, and a negative predictive value of 0.81.
These results suggest that ANN models can predict PSA failure using readily available preoperative variables. Such predictive models may offer assistance to patients and physicians deciding on definitive therapy for CaP.
A number of new predictive modeling techniques have emerged in the past several years. These methods can be used independently or in combination with traditional modeling techniques to produce useful ...tools for the management of prostate cancer. Investigators should be aware of these techniques and avail themselves of their potentially useful properties. This review outlines selected predictive methods that can be used to develop models that may be useful to patients and clinicians for prostate cancer management.
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