title: Relative operating characteristic analysis in reproductive medicine: comparison of progesterone and human chorionic gonadotropin doubling time as predictors of early gestational normalcy.
abstract: OBJECTIVE
  To directly compare the ability of serum P and hCG doubling time to predict early gestational complications.
  
  
  METHODS
  We analyzed differences in P concentrations and hCG doubling times between spontaneously conceived normal and abnormal pregnancies (abortions and tubal pregnancies) during the first 49 days of pregnancy. Multiple 2 x 2 contingency tables were constructed that compared pregnancy outcome within discriminatory serum P concentrations or hCG doubling time. From these tables relative operating characteristic curves were generated for P concentration and hCG doubling times. The area under the curves were estimated and compared by the critical z score.
  
  
  RESULTS
  Calculation of the areas under the curve for hCG doubling time and P concentration yielded values of 0.799 +/- 0.056 and 0.780 +/- 0.051 (mean +/- SEM), respectively. Critical z testing did not reveal a significant difference between the two curves.
  
  
  CONCLUSIONS
  Serum P and hCG doubling times equally predict early gestational normalcy. Thus, a single serum P may be just as valuable in estimating risks of early pregnancy complications as repeated hCG measurements.
authors.affiliation: Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson.
authors.forename: J D
authors.initials: JD
authors.lastname: Isaacs
authors.forename: N S
authors.initials: NS
authors.lastname: Whitworth
authors.forename: B D
authors.initials: BD
authors.lastname: Cowan
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood*; D005260:Female; D006801:Humans; D009994:Osmolar Concentration; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011374:Progesterone / Q000097:blood*; D012372:ROC Curve; D012016:Reference Values
chemical_list: D006063:Chorionic Gonadotropin; D011374:Progesterone