Asthma and Caries: A Systematic Review and Meta-Analysis

Salla Alavaikko 0 1 Maritta S. Jaakkola 0 1 Leo Tja derhane 0 1 Jouni J. K. Jaakkola 0 1 0 Sciences, University of Oulu , Aapistie 1, P.O. Box 5000, 90014 Oulu, Finland ( 1 J. K. Jaakkola); Center for Environmental and Respiratory Health Research, Respiratory Medicine Unit, Institute of Clinical Medicine, University of Oulu , Oulu, Finland (Maritta S. Jaakkola); and Institute of Dentistry, University of Oulu, Oulu University Hospital , Oulu, Finland (Leo Tjaderhane). This work was supported by the Academy of Finland (grant 129419). Conflict of interest: none declared American Journal of Epidemiology The Author 2011. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: . There is inconclusive evidence suggesting a possible association of asthma with increased risk of caries. The authors conducted a systematic review and meta-analysis to synthesize the evidence on the relation between asthma and caries. They performed an Ovid Medline (US National Library of Medicine) database search of literature published from 1950 through May 2010 using the Medical Subject Headings ''asthma'' and ''caries.'' Summary effect estimates were calculated with fixed- and random-effects models, and determinants of heterogeneity were studied in meta-regression analysis. The meta-analysis was based on 11 articles providing estimates of the effect of asthma on primary dentition and 14 articles on permanent dentition. Summary effect estimates for the relation between asthma and caries from the random-effects models were 2.73 (95% confidence interval: 1.61, 4.64) and 2.04 (95% confidence interval: 1.44, 2.89), respectively. Factors identified as determinants of heterogeneity were geographic region for primary dentition and publication year, sample size, asthma definition, and information on the use of asthma medication for permanent dentition. Evidence from this analysis suggests that asthma doubles the risk of caries in both primary and permanent dentition. Publication bias diagnostics and simulation suggested possible overestimation of the summary odds ratio for permanent dentition but not for primary dentition. Physicians and dentists should recommend preventive measures against caries for persons with asthma. asthma; dental caries; meta-analysis; review Abbreviations: CI, confidence interval; dfs, number of decayed and filled surfaces in primary dentition; dft, number of decayed and filled teeth in primary dentition; dmf, number of decayed, missing (due to caries), and filled teeth or surfaces in primary dentition; DMF, number of decayed, missing (due to caries), and filled teeth or surfaces in permanent dentition; dmfs, number of decayed, missing, and filled surfaces in primary dentition; DMFS, number of decayed, missing, and filled surfaces in permanent dentition; dmft, number of decayed, missing, and filled teeth in primary dentition; DMFT, number of decayed, missing, and filled teeth in permanent dentition; NOS, Newcastle-Ottawa Quality Assessment Scale; OR, odds ratio. - Asthma is the most common chronic disease in childhood and is also a major public health problem in adult populations. The basic mechanism of asthma is an inflammatory process in the airways (1). The airway inflammation and airflow limitation cause various symptoms according to the severity of the asthma, which determines the need for asthma medication. Caries is a progressive disease affecting teeth and causing several complications. The prevalence of caries is still high, even in developed countries, and caries is the most common chronic health problem affecting children in the United States. In addition to affecting the quality of life, its treatment is expensive and is needed for the rest of the patients life (2). Thus, prevention of caries is an important public health issue with the potential of substantial economic gains. The role of asthma as a potential determinant of caries risk was first studied in the late 1970s. Since then, several studies have evaluated the effect of asthma severity on caries prevalence (312), and some studies have evaluated the possible cariogenic mechanisms related to use of asthma medications (36, 1318). Most of the studies published to date have provided inconclusive results, mainly because of limitations related to the size of the study population. To throw light on potential mechanisms by which asthma could affect caries, some investigators have measured parameters such as saliva flow, composition, and pH in persons with asthma (3, 5, 1315, 1921). All of these factors might be influenced by asthma medications or the disease itself and may lead to an increased risk of caries (2). According to an Ovid Medline database (US National Library of Medicine) literature search, there have been no previous meta-analyses on the association between asthma and caries. To investigate the relation between asthma and occurrence of caries, as well as factors potentially contributing to such a relation, we conducted a systematic review and meta-analysis. Because several articles provided effect estimates of the relation between asthma and caries for both primary and permanent dentition, these results were analyzed separately. We also conducted stratified meta-analyses and meta-regression in order to analyze potential sources of heterogeneity between the study-specific effect estimates, and we constructed funnel plots to address the possibility of publication bias. MATERIALS AND METHODS Search strategy We conducted a systematic literature search of the Ovid Medline database from 1950 through May 2010 by using the Medical Subject Headings asthma and caries. To ensure that we identified all of the relevant articles, we also conducted a PubMed search with the text terms asthma and caries in the title or abstract. Government reports and conference proceedings were also searched, but information relevant to this meta-analysis was not found in those sources. Inclusion criteria There were 5 criteria for inclusion of a study in this metaanalysis: The study 1) provided relevant and applicable quantitative information on the relation between asthma and caries; 2) was an original study that had an independent study population; 3) was a case-control, cohort, or crosssectional study; 4) had an adequate definition of asthma; and 5) had an adequate definition and measurement of caries. Data extraction The studies fulfilling the inclusion criteria were independently examined and their main characteristics were recorded by two of the authors (S. A., J. J.). The data were collected according to a pilot-tested form including factors such as authors, year of publication, study objective, study design, study population, geographic region, sample size, subjects average birth year, definition of asthma, measurements of oral health, effect estimates, variables adjusted for, and factors matched for. If articles provi (...truncated)