title: Lesion size affects diagnostic performance of IOTA logistic regression models, IOTA simple rules and risk of malignancy index in discriminating between benign and malignant adnexal masses.
abstract: OBJECTIVE
  To estimate the ability to discriminate between benign and malignant adnexal masses of different size using: subjective assessment, two International Ovarian Tumor Analysis (IOTA) logistic regression models (LR1 and LR2), the IOTA simple rules and the risk of malignancy index (RMI).
  
  
  METHODS
  We used a multicenter IOTA database of 2445 patients with at least one adnexal mass, i.e. the database previously used to prospectively validate the diagnostic performance of LR1 and LR2. The masses were categorized into three subgroups according to their largest diameter: small tumors (diameter < 4 cm; n = 396), medium-sized tumors (diameter, 4-9.9 cm; n = 1457) and large tumors (diameter ≥ 10 cm, n = 592). Subjective assessment, LR1 and LR2, IOTA simple rules and the RMI were applied to each of the three groups. Sensitivity, specificity, positive and negative likelihood ratio (LR+, LR-), diagnostic odds ratio (DOR) and area under the receiver-operating characteristics curve (AUC) were used to describe diagnostic performance. A moving window technique was applied to estimate the effect of tumor size as a continuous variable on the AUC. The reference standard was the histological diagnosis of the surgically removed adnexal mass.
  
  
  RESULTS
  The frequency of invasive malignancy was 10% in small tumors, 19% in medium-sized tumors and 40% in large tumors; 11% of the large tumors were borderline tumors vs 3% and 4%, respectively, of the small and medium-sized tumors. The type of benign histology also differed among the three subgroups. For all methods, sensitivity with regard to malignancy was lowest in small tumors (56-84% vs 67-93% in medium-sized tumors and 74-95% in large tumors) while specificity was lowest in large tumors (60-87%vs 83-95% in medium-sized tumors and 83-96% in small tumors ). The DOR and the AUC value were highest in medium-sized tumors and the AUC was largest in tumors with a largest diameter of 7-11 cm.
  
  
  CONCLUSIONS
  Tumor size affects the performance of subjective assessment, LR1 and LR2, the IOTA simple rules and the RMI in discriminating correctly between benign and malignant adnexal masses. The likely explanation, at least in part, is the difference in histology among tumors of different size.
authors.affiliation: Department of Obstetrics and Gynecology, Catholic University, Rome, Italy. alessia.dilegge@virgilio.it
authors.forename: A
authors.initials: A
authors.lastname: Di Legge
authors.forename: A C
authors.initials: AC
authors.lastname: Testa
authors.forename: L
authors.initials: L
authors.lastname: Ameye
authors.forename: B
authors.initials: B
authors.lastname: Van Calster
authors.forename: A A
authors.initials: AA
authors.lastname: Lissoni
authors.forename: F P G
authors.initials: FP
authors.lastname: Leone
authors.forename: L
authors.initials: L
authors.lastname: Savelli
authors.forename: D
authors.initials: D
authors.lastname: Franchi
authors.forename: A
authors.initials: A
authors.lastname: Czekierdowski
authors.forename: D
authors.initials: D
authors.lastname: Trio
authors.forename: C
authors.initials: C
authors.lastname: Van Holsbeke
authors.forename: E
authors.initials: E
authors.lastname: Ferrazzi
authors.forename: G
authors.initials: G
authors.lastname: Scambia
authors.forename: D
authors.initials: D
authors.lastname: Timmerman
authors.forename: L
authors.initials: L
authors.lastname: Valentin
mesh_terms: D000291:Adnexal Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018394:CA-125 Antigen / Q000097:blood; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D012306:Risk; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D018394:CA-125 Antigen