[Predictive model for prostate cancer in patients with biopsy indication].

OBJECTIVE Attemp to determine the probability of developing prostate carcinoma taking into acc age, digital rectal examination and PSA once a transrectal biopsy has been indicated, so that both doctors and patients have mor information to face such pathology. MATERIAL AND METHODS Retrospective study of 633 biopsies, taken into acc the patient's age, digital rectal examination, PSA level and histology. The data were included in a database created with Access and were put a logistic regression by mens the software program SPSS. RESULTS Once the biopsy is indicated, digital rectal examination is the parameter offesing a higher discriminatory valuer with an odd ratio of 5.9 (CI 95%, 3.9-8.9). The mathematical model obtained shows a sensitivity level of 57% and a level of specificity of 84%. Pre-test probability is 36%, the probability post-test increasing up to 70%, and a negative predictive value of 77% and a positive predictive value of 67%. CONCLUSIONS The mathematical model obtained individually determines the probability of suffering from prostatic carcinoma. Moreover, using this model the probabilities obtained re more precise than those derived from the fact of fulfilling the criteria for a prostatic biopsy. Once a biopsy is indicated, the rectal examination becomes the parameter with a higher predictive value of PC, irrespective of PSA and age. The PPV of the model is higher than of the PSA or the digital recta examination used separately.