Methods
This review adhered to principles outlined in guidance published by
PRISMA (Preferred Reporting Items for Systematic Reviews and
Meta-analysis) and CHARMS (CHecklist for critical Appraisal and data
extraction for systematic Reviews of prediction Modelling Studies). The
protocol for this review has been published by PROSPERO and is available
online.
A literature search was conducted during May 2018 of the following
databases: Medline, Embase, CINAHL and the Cochrane Library. To inform
the full search strategy a limited search of Medline was first conducted
followed by an extensive search of the literature of the aforementioned
databases. A copy of the search strategy for Medline and Embase is
available in Table S1. The main search terms were ‘predict$’,
‘risk score’ and ‘postpartum haemorrhage’ with the appropriate synonyms
adopted.
Inclusion criteria and exclusion criteria for this review are outlined
in Table 1 . Titles and abstracts were independently screened by
two reviewers (CN and SN) with any disagreements resolved by a third
reviewer (MB).
Data extraction and quality assessment (at study level) were conducted
independently in accordance with the CHARMS checklist (Table S2 )
to allow identification of potential bias in primary studies and
identify limitations to applicability of the results. Items extracted
were as follows: source of data; participants; outcome to be predicted;
candidate predictors (or index tests); sample size; missing data; model
development; model performance; model evaluation; results and
interpretation (including whether authors deemed their model fit for
purpose or nature of further research required before using). The
findings were tabulated and a narrative synthesis performed. The
findings address the baseline characteristics of the studies, the type
of models included, evaluation of the models and the applicability of
the models to clinical practice.