title: Comprehensive chromosome screening improves embryo selection: a meta-analysis.
abstract: OBJECTIVE
  To study whether preimplantation genetic screening with comprehensive chromosome screening (PGS-CCS) improves clinical implantation rates (IR) and sustained IR (beyond 20 weeks) compared with routine care for embryo selection in IVF cycles.
  
  
  METHODS
  Meta-analysis of randomized controlled trials (RCTs) and observational studies (OSs).
  
  
  METHODS
  University-affiliated teaching hospital.
  
  
  METHODS
  Infertile couples undergoing IVF.
  
  
  METHODS
  PGS-CCS with the use of different genetic platforms performed on polar body (PB), cleavage embryo, or blastocyst following embryo biopsy.
  
  
  METHODS
  Clinical IR and sustained IR in RCTs as well as OSs comparing PGS-CCS and routine care were determined after a complete review of the literature. Pooled estimates of risk ratios (RRs) with their 95% confidence intervals (CIs) according to a fixed-effects model with the use of the Mantel-Haenszel method were calculated after the meta-analysis. Forest plots are provided for comparative purposes.
  
  
  RESULTS
  Out of 763 citations identified, 29 articles met initial eligibility criteria and were further analyzed. Of these, only three RCTs and eight OSs met full inclusion criteria, allowing direct comparison of PGS-CCS and routine IVF care based on embryo morphology selection. In the RCTs, all embryo biopsies were performed on day 5-6 of embryo development. In the OSs, biopsies were performed on different stages of embryo development, including PB, day 3, or day 5-6. Meta-analysis of the RCTs (3 studies; n = 659) showed that PGS-CCS was associated with a significantly higher clinical IR, with a pooled RR of 1.29 (95% CI 1.15-1.45), as well as a significantly higher sustained IR, with a pooled RR of 1.39 (95% CI 1.21-1.60). Similar findings were shown in the OSs, where the pooled RR for clinical IR was 1.78 (95% CI 1.60-1.99; 7 studies; n = 2,993) and for sustained IR was 1.75 (95% CI 1.48-2.07; 4 studies; n = 1,124). Statistical heterogeneity (I(2)) was minimal for RCTs and substantial among OSs.
  
  
  CONCLUSIONS
  PGS with the use of CCS technology increases clinical and sustained IRs, thus improving embryo selection, particularly in patients with normal ovarian reserve. Results from ongoing RCTs conducted on different patient populations (e.g., decreased ovarian reserve) and different embryo stage biopsy (e.g., PB, day 3) may further clarify the role of this technology.
authors.affiliation: Assisted Reproduction Center, CHU Sainte-Justine, University of Montreal, Montreal, Quebec, Canada; PROCREA Clinics, Montreal, Canada; Department of Obstetrics and Gynecology, University of Montreal, Montreal, Canada. Electronic address: elias.dahdouh@umontreal.ca.
authors.forename: Elias M
authors.initials: EM
authors.lastname: Dahdouh
authors.affiliation: Department of Obstetrics and Gynecology, University of Montreal, Montreal, Canada.
authors.forename: Jacques
authors.initials: J
authors.lastname: Balayla
authors.affiliation: Instituto Valenciano de Infertilidad (IVI) Madrid and Rey Juan Carlos University, Madrid, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: García-Velasco
mesh_terms: D001706:Biopsy; D001755:Blastocyst / Q000473:pathology*; D016009:Chi-Square Distribution; D002869:Chromosome Aberrations; D003362:Cost-Benefit Analysis; D046149:Embryo Culture Techniques; D004624:Embryo Transfer; D047108:Embryonic Development; D005307:Fertilization in Vitro / Q000009:adverse effects* / Q000191:economics; D005820:Genetic Testing / Q000191:economics; D017048:Health Care Costs; D006801:Humans; D064887:Observational Studies as Topic; D016017:Odds Ratio; D011237:Predictive Value of Tests; D019836:Preimplantation Diagnosis / Q000191:economics / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D013997:Time Factors
keywords: Preimplantation genetic screening; comprehensive chromosome screening; elective single embryo transfer; embryo selection