title: Using individual patient data to adjust for indirectness did not successfully remove the bias in this case of comparative test accuracy.
abstract: OBJECTIVE
  In comparative systematic reviews of diagnostic accuracy, inconsistencies between direct and indirect comparisons may lead to bias. We investigated whether using individual patient data (IPD) can adjust for this form of bias.
  
  
  METHODS
  We included IPD of 3 ovarian reserve tests from 32 studies. Inconsistency was defined as a statistically significant difference in relative accuracy or different comparative results between the direct and indirect evidence. We adjusted for the effect of threshold and reference standard, as well as for patient-specific variables.
  
  
  RESULTS
  Anti-Müllerian hormone (AMH) and follicle stimulation hormone (FSH) differed significantly in sensitivity (-0.1563, P = 0.04). AMH and antral follicle count (AFC) differed significantly in sensitivity (0.1465, P < 0.01). AMH and AFC differed significantly in specificity (-0.0607, P = 0.02). The area under the curve (AUC) differed significantly between AFC and FSH (0.0948, P < 0.01) in the direct comparison but not (0.0678, P = 0.09) in the indirect comparison. The AUCs of AFC and AMH differed significantly (-0.0830, P < 0.01) in the indirect comparison but not (-0.0176, P = 0.29) in the direct comparison. These differences remained after adjusting for indirectness.
  
  
  CONCLUSIONS
  Estimates of comparative accuracy obtained through indirect comparisons are not always consistent with those obtained through direct comparisons. Using IPD to adjust for indirectness did not successfully remove the bias in this case study.
authors.affiliation: Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, PO Box 22700, 1100 DE Amsterdam, The Netherlands.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, PO Box 22700, 1100 DE Amsterdam, The Netherlands.
authors.forename: Patrick
authors.initials: P
authors.lastname: Bossuyt
authors.affiliation: Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, PO Box 22700, 1100 DE Amsterdam, The Netherlands.
authors.forename: Ronald
authors.initials: R
authors.lastname: Geskus
authors.affiliation: Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, PO Box 22700, 1100 DE Amsterdam, The Netherlands.
authors.forename: Aeilko
authors.initials: A
authors.lastname: Zwinderman
authors.affiliation: Department of Reproductive Medicine, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Dolleman
authors.affiliation: Department of Reproductive Medicine, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: Simone
authors.initials: S
authors.lastname: Broer
authors.affiliation: Department of Reproductive Medicine, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Broekmans
authors.affiliation: Department of Obstetrics and Gynaecology, Women's and Children's Hospital, University of Adelaide, 72 King William Road, SA 5006 Adelaide, Australia.
authors.forename: Ben Willem
authors.initials: BW
authors.lastname: Mol
authors.affiliation: Department of Clinical Epidemiology, Biostatistics & Bioinformatics, Academic Medical Center, PO Box 22700, 1100 DE Amsterdam, The Netherlands. Electronic address: m.m.leeflang@amc.uva.nl.
authors.forename: Mariska
authors.initials: M
authors.lastname: Leeflang
mesh_terms: D054304:Anti-Mullerian Hormone / Q000378:metabolism*; D019540:Area Under Curve; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D006801:Humans; D006080:Ovarian Follicle / Q000166:cytology* / Q000378:metabolism; D010053:Ovary / Q000502:physiology*; D010062:Ovulation Induction; D011237:Predictive Value of Tests; D015983:Selection Bias; D012680:Sensitivity and Specificity
chemical_list: D054304:Anti-Mullerian Hormone; D005640:Follicle Stimulating Hormone
keywords: Comparative meta-analysis; Diagnostic test accuracy; Generalized estimating equation; Individual patient data; Receiver operating characteristic; Sensitivity and specificity