title: Multivariate analysis of clinical, demographic, and laboratory data for classification of disorders of calcium homeostasis.
abstract: Parathyroid hormone (PTH) nomograms combine total calcium and intact PTH (iPTH) measurements to classify disorders of calcium homeostasis. Our objective was to determine if using a combination of laboratory, demographic, and clinical parameters improves the accuracy of classification of these disorders. Chart data were collected for 236 patients with physician-ordered iPTH and total calcium tests. Classification was done using 3 approaches: (1) PTH nomogram plotting total calcium and iPTH results against known cases; (2) review of all available chart data ("gold standard"); and (3) multivariate model (classification and regression tree [CART] or logistic regression) using 24 variables. The CART model was developed using the gold standard patient classification and validated using leave-one-out cross-validation. The CART model was significantly (P = .002) more accurate (80.6%) than the PTH nomogram (59.7%) and logistic regression (66.2%) at classifying calcium homeostasis disorders. The CART model used 6 of 24 variables (iPTH, calcium, creatinine, renal transplantation, percentage of females, and urea nitrogen) and had a misclassification error rate of 0.194 (27/139). Classification of disorders of calcium homeostasis based on the PTH nomogram can be improved by using the CART model developed in this study.
authors.affiliation: Dept of Pathology and Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, 27599-7525, USA.
authors.forename: Stacey S
authors.initials: SS
authors.lastname: O'Neill
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Gordon
authors.forename: Ruixin
authors.initials: R
authors.lastname: Guo
authors.forename: Hongtu
authors.initials: H
authors.lastname: Zhu
authors.forename: Christopher R
authors.initials: CR
authors.lastname: McCudden
mesh_terms: D000368:Aged; D002118:Calcium / Q000097:blood*; D002965:Classification / Q000379:methods; D003663:Decision Trees; D005260:Female; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000145:classification* / Q000175:diagnosis; D006996:Hypocalcemia / Q000097:blood / Q000145:classification* / Q000175:diagnosis; D007037:Hypothyroidism / Q000097:blood / Q000145:classification* / Q000175:diagnosis; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D049451:Nomograms; D010281:Parathyroid Hormone / Q000097:blood*; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium