How strong is the link between periodontitis and stroke?

Data sources PubMed, Scopus, Web of Science, The Cochrane Library, LILACS, OpenGrey and Google Scholar. No language restriction applied; studies conducted until September 2018. Study selection Observational studies in humans exposed and not exposed to periodontitis, in which the primary outcome was the risk of cerebrovascular accident, including haemorrhagic and ischaemic attacks (transient ischaemic attack and ischaemic stroke). Data extraction and synthesis Three examiners conducted a literature search. Duplicates, opinion articles, technical articles, guides and animal studies were excluded. Quality assessment was carried out followed by assessment of risk of bias. The extracted data were analysed using RevMan software. The meta-analysis looked for odds ratio (OR) in case-control studies and risk ratio (RR) in cohort studies as well as their 95% confidence intervals. Results Ten studies were included, all showing low risk of bias. The number of patients ranged from 80 to 15,792 with follow-up duration from 0 to 15 years. The studies showed variable heterogeneity. For stroke in case-control studies (seven studies), the overall heterogeneity was considerable (I2 = 77%). For ischaemic stroke in case-control studies (five studies), the overall heterogeneity was considerable (I2 = 72%), but after an outlying study was removed (I2 = 78%), it reduced significantly (I2 = 4%). For stroke in cohort studies (three studies), null heterogeneity was observed (I2 = 0%). The meta-analysis informed the three main outcomes: 1) individuals with periodontitis were twice as likely to suffer stroke (OR 2.31 [1.39, 3.84], p = 0.001, I2 = 77%); 2) individuals with periodontitis were twice as likely to suffer ischaemic stroke (OR 2.72 [2.00, 3.71], p <0.00001, I2 = 4%); and 3) individuals with periodontitis had a higher risk of experiencing stroke (RR 1.88 [1.55, 2.28], p <0.00001). Overall, the authors found that stroke events were associated with periodontitis. Conclusions The meta-analysis suggests an association between risk of stroke and periodontal disease. However, there is a need for prospective studies to ascertain the relationship between periodontal disease severity and stroke severity; whether there is an impact of periodontal treatment and to review whether periodontal disease impacts on stroke survival.