Association between pacifier use and breast-feeding, sudden infant death syndrome, infection and dental malocclusion

[Truncated abstract] ObjectiveTo critically review all literature related to pacifier use for full-term healthyinfants and young children.The specific review questions addressed are:What is the evidence of adverse and/or positive outcomes of pacifier use in infancy andchildhood in relation to each of the following subtopics:• breast-feeding;• sudden infant death syndrome;• infection;• dental malocclusion.Inclusion criteriaSpecific criteria were used to determine which studies would beincluded in the review: (i) the types of participants; (ii) the types of research design; and(iii) the types of outcome measures. To be included a study has to meet all criteria.Types of participantsThe participants included in the review were healthy term infantsand healthy children up to the age of 16 years. Studies that focused on preterm infants,and infants and young children with serious illness or congenital malformations wereexcluded. However, some total population studies did include these children.Types of research designIt became evident early in the review process that very fewrandomised controlled trials had been conducted. A decision was made to includeobservational epidemiological designs, specifically prospective cohort studies and, in thecase of sudden infant death syndrome research, case–control studies. Purely descriptiveand cross-sectional studies were excluded, as were qualitative studies and all other formsof evidence.148 A Callaghanet al.A number of criteria have been proposed to establish causation in the scientific andmedical literature. These key criteria were applied in the review process and aredescribed as follows: (i) consistency and unbiasedness of findings; (ii) strength ofassociation; (iii) temporal sequence; (iv) dose–response relationship; (v) specificity;(vi) coherence with biological background and previous knowledge; (vii) biologicalplausibility; and (viii) experimental evidence.Studies that did not meet the requirement of appropriate temporal sequencing ofevents and studies that did not present an estimate of the strength of associationwere not included in the final review.Types of outcome measuresOur specific interest was pacifier use related to:• breast-feeding;• sudden infant death syndrome;• infection;• dental malocclusion.Studies that examined pacifier use related to procedural pain relief were excluded.Studies that examined the relationship between pacifier use and gastro-oesophagealreflux were also excluded as this information has been recently presented as asystematic review.Search strategyThe review comprised published and unpublished researchliterature. The search was restricted to reports published in English, Spanish andGerman. The time period covered research published from January 1960 to October2003. A protocol developed by New Zealand Health Technology Assessment wasused to guide the search process. The search comprised bibliographic databases,citation searching, other evidence-based and guidelines sites, government documents,books and reports, professional websites, national associations, hand search,contacting national/international experts and general internet searching.Assessment of qualityAll studies identified during the database search wereassessed for relevance to the review based on the information provided in the title,abstract and descriptor/MeSH terms, and a full report was retrieved for all studiesthat met the inclusion criteria. Studies identified from reference list searches wereassessed for relevance based on the study title. Keywords included: dummy,dummies, pacifier(s), soother(s), comforter(s), non-nutritive sucking, infant, child,infant care.Initially, studies were reviewed for inclusion by pairs of principal investigators.Authorship of articles was not concealed from the reviewers. Next, the methodologicalquality of included articles was assessed independently by groups of three ormore principal investigators and clinicians using a checklist. All 20 studies thatwere accepted met minimum set criteria, but few passed without somemethodological concern.Data extractionTo meet the requirements of the Joanna Briggs Institute, reasonsfor acceptance and non-acceptance at each phase were clearly documented.An assessment protocol and report form was developed for each of the three phasesof review. The first form was created to record investigators’ evaluations of studiesincluded in the initial review. Those studies that failed to meet strict inclusion criteriawere excluded at this point. A second form was designed to facilitate an in-depthcritique of epidemiological study methodology. The checklist was pilot tested andadjustments were made before reviewers were trained in its use. When reviewersOutcomes of pacifier use in infants 149could not agree on an assessment, it was passed to additional reviewers anddiscussed until a consensus was reached. At this stage, studies other than cohort,case–control and randomised controlled trials were excluded. Issues of clarificationwere also addressed at this point. The final phase was that of integration. This phase,undertaken by the principal investigators, was assisted by the production of dataextraction tables. Through a process of trial and error, a framework was formulatedthat adequately summarised the key elements of the studies. This information was tabulated under the following headings: authors/setting, design, exposure/outcome, confounders controlled, analysis and main findings...