Background
Methods
Search strategy
Study selection
Methodological quality assessment
Data collection
Data analysis
Results
Literature search
Study | The setting (center) | PCI categorization | Design | Comparison groups | No of participants | Study Duration | Outcomes |
---|---|---|---|---|---|---|---|
Burke 2011 [14] | Maternity Unit, University Maternity Hospital, Limerick, Ireland | Gross examination | Prospective cohort | MCI, VCI vs. normal PCI | 727 | not specified | SGA, Em CD |
Boulis 2013 [24] | Obstetrics Dept, LIJ School of Medicine, Long Island, New York, USA | Existing data | Retrospective cohort | MCI, VCI vs. CDC database | 122 | 2002–2012 | PTB, SGA, Em CD, IUFD |
Brouillet 2014 [25] | Obstetrics Dept, Grenoble University Hospital, France | Existing data | Retrospective cohort | Central PCI vs. Peripheral (MCI, VCI and paracentral PCI) | 528 | Aug 2006 - Dec 2006 | SGA |
Carbone 2008 [23] | Obstetrics Dept, Hartford Hospital, Connecticut, USA | Existing data | Case-control | MCI vs. normal PCI | 282 | Nov 2005 – Feb 2008 | PTB |
Ebbing 2013 [6] | Medical Birth Registry of Norway | Existing data | Retrospective cohort | VCI vs. non-VCI, MCI vs. non-MCI | 634,741 | 1999–2009 | PTB, SGA, Low BW, Em CD, IUFD |
Eddleman 1992 [10] | Obstetrics Dept, The Mount Sinai School of Medicine, New York, USA | Existing data | Retrospective cohort | VCI vs. non-VCI | 15,942 | Jan 1985 - Dec 1988 | PTB, SGA, Low BW |
Esakoff 2015 [7] | California Birth Statistics | Existing data | Retrospective cohort | VCI vs. non-VCI | 482,812 | Jan 2006 - Dec 2006 | PTB, SGA, Em CD, IUFD |
Feldman 2004 [17] | Obstetrics Dept, Hartford Hospital, Connecticut, USA | Sonography | Case-control | MCI vs. normal PCI | 75 | Jan 2002 - Dec 2003 | PTB, Low BW, |
Hasegawa 2009 [19] | Obstetrics Dept, Showa University Hospital, Tokyo, Japan | Existing data | Retrospective cohort | MCI, VCI vs. normal PCI | 556 | June 2005 - Dec 2006 | Em CD |
Hasegawa 2006 [18] | Obstetrics Dept, Showa University Hospital, Tokyo, Japan | Sonography | prospective cohort | MCI, VCI vs. normal PCI | 3446 | Sept 2002 - June 2004 | Em CD |
Heinonen 1996 [20] | Obstetrics Dept, University Hospital of Kuopio, Finland | Existing data | Retrospective cohort | VCI vs. non-VCI | 12,750 | July 1989 - Dec 1993 | PTB, SGA, Low BW, Em CD, IUFD |
Pinar 2014 [15] | Perinatal Pathology, Women and infants Hospital, Rhode Island, USA | Gross examination | Case-control | VCI vs. non-VCI | 1718 | Mar 2006 - Sept 2008 | IUFD |
Raisanen 2012 [8] | Obstetrics Dept, University Hospital of Kuopio, Finland | Existing data | Retrospective cohort | VCI vs. non-VCI | 26,849 | 2000–2011 | PTB, SGA, Low BW, Em CD, IUFD |
Suzuki 2015 [21] | Obstetrics Dept, Japanese Red Cross Katsushika Maternity Hospital, Tokyo | Existing data | Prospective cohort | VCI vs. non-VCI | 16,965 | 2002–2011 | PTB, SGA, Em CD |
Tantbirojn 2009 [16] | Pathology Dept, Brigham and Women’s Hospital, Boston, MA, USA | Gross examination | Case-control | MCI, VCI vs. normal PCI | 541 | 1987–2007 | IUFD |
Uyanwah-Akpom 1977 [9] | Pathology Dept, St Mary’s Hospital, Manchester, UK | Existing data | Prospective cohort | Normal PCI vs. Peripheral PCI | 1000 | not specified | SGA, IUFD |
Yerlikaya 2016 [22] | Obstetrics Dept, Medical University of Vienna, Austria | Existing data | Case-control | VCI vs. non-VCI | 216 | Jan 2003 - Dec 2013 | IUFD |
Study characteristics
Methodological quality
Study | Year | Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertainment of exposure | Demonstration that outcome of interest was not present at the start of study | Comparability of cohorts on the basis of the design or analysis | Assessment of outcome |
---|---|---|---|---|---|---|---|
Burke et al. | 2011 | * | * | * | * | * | |
Boulis et al | 2013 | * | * | * | |||
Brouillet et al | 2014 | * | * | * | * | * | * |
Carbone et al | 2008 | * | * | * | * | ||
Ebbing et al | 2013 | * | * | * | * | * | * |
Eddleman et al | 1992 | * | * | * | * | * | * |
Esakoff et al | 2015 | * | * | * | * | * | |
Feldman et al | 2004 | * | * | * | * | * | |
Hasegawa et al | 2006 | * | * | * | * | * | |
Hasegawa et al | 2009 | * | * | * | * | * | |
Heinonen et al | 1996 | * | * | * | * | * | |
Pinar et al | 2014 | * | * | * | |||
Raisanen et al | 2012 | * | * | * | * | * | |
Suzuki et al | 2015 | * | * | * | * | * | * |
Tantbirojn et al | 2009 | * | * | * | |||
Uyanwah-Akpom et al | 1977 | * | * | * | * | * | |
Yerlika et al | 2016 | * | * | * | * | * | * |
Profile of individual studies | Comments | |
---|---|---|
Number of studies | 4 | |
Number of participants | 637, 438 | • 632, 978 participants are from Ebbing et al. [6] |
Total number of VCI | 9566 | |
Total number of Abnormal PCI | 49,141 | |
Total number of Normal PCI | 578, 731 | |
Univariable results | ||
Number of significant effect estimates > 1 | 3 | |
Number of non-significant effect estimates | 0 | |
Number of significant effect estimates < 1 | 1 | • Reference: [19] |
Not reported | 0 | |
Multivariable results | ||
Number of significant effect estimates > 1 | 2 | |
Number of non-significant effect estimates | 0 | |
Number of significant effect estimates < 1 | 0 | |
Not reported | 2 | |
Risk of diagnostic ascertainment bias | ||
Very high | 0 | |
High | 0 | |
Medium | 0 | |
Low | 4 | |
Statistical heterogeneity across studies: I
2
= 44% (for abnormal PCI) and I
2
= 74% (for VCI) | ||
GRADE assessment a
| Comments | |
Phase of investigation | Phase 2 (high) | • A ‘high’ rating was assigned before applying other GRADE criteria. All studies used cohort designs and sought to confirm the independent association between abnormal PCI with emergency CD. |
GRADE criteria (based on meta-analysis) | ||
Study limitations: • Downgrade by −1 if most evidence is from studies with moderate or unclear risk of bias for most bias domains (serious limitations). • Downgrade by −2 if most evidence is from studies with high risk of bias for almost all bias domains (very serious limitations). | • All four studies had low risk of diagnostic ascertainment bias. • No change. | |
Inconsistency: unexplained heterogeneity or variability in results across studies • Downgrade by −1 when estimates of the risk factor association with the outcome vary in direction (for example, some effects appear protective whereas others show risk) and the confidence intervals show no, or minimal overlap. | • See Forest plot. There is some heterogeneity in results across studies, (I2 = 44% for abnormal PCI and 74% for VCI). • The confidence intervals of the four studies overlap with no change in direction noted (the CI of one study included 1 [19]). • No change. | |
Indirectness: the study sample, the prognostic factor, and/or the outcome in the primary studies do not accurately reflect the review question • Downgrade by −1 when: (1) the final sample only represents a subset of the population of interest; (2) when the complete breadth of the prognostic factor that is being considered in the review question is not well represented in the available studies; or (3) when the outcome that is being considered in the review question is not broadly represented. | • No change. | |
Imprecision: • Downgrade by −1 if the evidence is generated by a few studies involving a small number of participants and most of the studies provide imprecise results. | • No change. | |
Publication bias: • Downgrade by −1 unless the value of the risk/protective factor in predicting the outcome has been repetitively investigated, ideally by phase 2 and 3 studies. | • No change. | |
Moderate/large effect size: • Upgrade by +1 if moderate or large similar effect is reported by most studies. | • Three out of four studies had few events resulting in wide confidence intervals for effect size. • No change. | |
GRADE: OVERALL QUALITY OF EVIDENCE (+, very low; ++, low; +++, moderate; ++++, high) | +++ Moderate |