Methods
Creators: name: Botero, Javier Enrique
Publisher: name: OSF Registries
Year: 2023

description: This systematic review will be conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA).PECO question Population: pregnant women without restrictions of age, ethnicity, race with and without low birth weight/preterm delivery Exposure: periodontitis Comparator: without periodontitis Outcome: frequency women with periodontitis in each group What is the association between periodontitis and low birth weight/preterm delivery in pregnant women?
Population, exposure and comparator:
The population of interest will include pregnant women regardless of age, ethnicity, or race with and without pregnancy complications such as low birth weight or preterm delivery. The exposure of interest is the presence of periodontitis, determined by clearly established periodontal clinical parameters or by means of periodontal indices. The comparison group consists of the absence of periodontitis, determined by clearly established periodontal clinical parameters or by means of periodontal indices.
Outcomes:
The primary outcome of interest is the prevalence of periodontitis associated with the presence of low birth weight or preterm delivery. As a measure of effect size, the odds ratio (Odds Ratio; 95% confidence interval) will be calculated. As secondary outcomes, the means of probing depth (PD) and periodontal attachment level (AL) will be evaluated.
Search strategy:
A comprehensive search will be performed from inception to May 2023 in the following electronic databases: PubMed/MEDLINE and Scopus. The search strategy will include appropriate combinations of free keywords and relevant controlled vocabulary (e.g. Medical Subject Headings-MeSH) terms related to 'low birth weight', 'preterm birth' and 'periodontitis'. Keywords will be searched in English, Spanish and Portuguese. In addition to the electronic database search, to identify any potentially eligible studies snowballing and screening of relevant reference lists of included studies, as well as grey literature search, will be performed through Google Scholar and SciELO.
Study selection process:
Only human, case-control, cohort, and cross-sectional studies that focused on evaluating the presence of periodontitis in women with pregnancy complications will be included. Intervention studies, animal studies, previous systematic reviews, conference proceedings, and case reports will be excluded.
The inclusion language is limited to English, Spanish and Portuguese.
Initial screening of titles and abstracts will be performed by two independent reviewers based on pre-determined eligibility criteria. Full text articles will be retrieved for potentially eligible studies. Two independent reviewers will then assess the full-text articles for final eligibility based on the inclusion and exclusion criteria. Any discrepancies will be resolved by discussion or consultation with a third reviewer.
Data extraction:
A standardized data extraction form was developed to collect relevant data from the included studies. The following data elements will be extracted: study characteristics (author, year, study design), participant characteristics, sample size, exposure details, comparison details, outcome measures, and statistical results. Two independent reviewers wil perform data extraction. Extracted data will be checked for accuracy and any discrepancies will be resolved by discussion or consultation with a third reviewer.
Risk of Bias (RoB):
The methodological quality and risk of bias of the included studies will be assessed using appropriate tools, such as the Newcastle-Ottawa scale for cohort and case-control studies. The quality result is rated as (7-9) Low risk, (4-6) Moderate risk and (0-3) High risk.
For cross-sectional studies, the National Heart, Lung, and Blood Institute (NHLBI-NIH) Quality Assessment Tool for Observational Cohort and Cross-sectional Studies will be used. The guide is not intended to be a checklist, but rather a tool to identify potential issues that could introduce bias. The quality of each study will be rated as low, medium or high (good).
Meta-analysis:
Heterogeneity between included studies will be assessed using statistical tests, such as Cochran's Q test and the I^2 statistic. As substantial heterogeneity (I^2 &gt; 50%) is anticipated, a random effects model will be used for meta-analysis. Sensitivity and subgroup analysis will be performed to explore potential sources of heterogeneity, including study design, participant characteristics, and methodological quality.
Publication bias:
A visaul inspection of funnel plots and statistical tests such as Egger's regression test will be used to assess for publication bias to detect any potential reporting bias.
Quality of evidence and strength of recommendation:
The quality of the evidence will be assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The GRADE framework assesses the quality of evidence based on factors such as study design, risk of bias, inconsistency, indirectness, imprecision, and publication bias. Based on the overall quality of the evidence, the strength of the association between periodontitis and pregnancy complications will be determined and graded as high, moderate, low, or very low.