title: [Fuzzy logic and logistic regression in the decision making for parathyroid scintigraphy study].
abstract: OBJECTIVE
  To develop and compare two mathematical models, the first one based on logistic regression and the second one on fuzzy sets theory, aiming at defining a laboratory testing-based measure of indication for submitting patients to parathyroid scintigraphy.
  
  
  METHODS
  One-hundred and ninety-four patients with serum calcium and parathyroid hormone available were identified from the data registry of parathyroid scintigraphy of a diagnostic laboratory in São Paulo, Southern Brazil, in the period between January 2000 and December 2004. The logistic regression model was developed using SPSS and the fuzzy model was developed using MatLab software programs. The performances of both models were compared using ROC curves.
  
  
  RESULTS
  The performance of both models were statistically different (p=0.026). The area under the ROC curves were 0.862 (95% CI: 0.811-0.913) for the logistic regression model and 0.887 (95% CI: 0.840-0.933) for the fuzzy model. The latter had the advantage of allowing to making decisions based on parathyroid hormone information within a non-discriminating range of calcium values.
  
  
  CONCLUSIONS
  The mathematical model based on fuzzy sets theory seemed to be more useful than the logistic model in the decision making for scintigraphy indication. However, inferences can be made only regarding model comparison and not for parathyroid scintigraphy itself since the data analyzed was not representative of any population.
authors.affiliation: Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, Avenida Dr. Arnaldo 715, São Paulo, SP, Brasil.
authors.forename: Clóvis Arlindo de
authors.initials: CA
authors.lastname: Sousa
authors.forename: Paulo Schiavom
authors.initials: PS
authors.lastname: Duarte
authors.forename: Júlio Cesar Rodrigues
authors.initials: JC
authors.lastname: Pereira
mesh_terms: D002118:Calcium / Q000097:blood; D003661:Decision Support Techniques; D005260:Female; D017143:Fuzzy Logic; D006801:Humans; D016015:Logistic Models; D008297:Male; D010280:Parathyroid Glands / Q000000981:diagnostic imaging*; D010281:Parathyroid Hormone / Q000097:blood; D012372:ROC Curve; D011877:Radionuclide Imaging; D017678:Sex Distribution
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium