Table 1. Characteristics of the included studies.
| First author year | Study population | Study design (Duration) | Country | Sample size (PCa cases) | Age (years) | Follow-up period (years) | PD ascertainment | PD therapy | Adjustments | Dental/smoking status (severity) |
|---|---|---|---|---|---|---|---|---|---|---|
| Arora, et al. 2010 (11) | The Swedish Twin Registry | Prospective cohort (1963-2004) | Sweden | 15.333 (604) | 38-77 | 27 | Self-report | Unreported | Age, education, employment, number of siblings, smoking status, smoking status of partner, alcohol status, body mass index, and diabetes | PD |
| Dizdar, et al. 2017 (12) | The Hacettepe University Dentistry and Oncology hospitals in Ankara | Retrospective cohort (2001-2010) | Turkey | 1.250 (3 cases with CP) | 49.6 | 12 | Clinical and radiographic parameters | Included | Age | CP (moderate or severe) |
| Güven, et al. 2019 (13) | The Hacettepe University Dentistry and Oncology hospitals in Ankara | Retrospective cohort (2007-2012) | Turkey | 5.199 (40 cases with PD) | 57.7 | 7.2 | Clinical and radiographic parameters | Unreported | Age | PD |
| Hujoel, et al. 2003 (20) | The NHANES I Epidemiologic Follow-up Study (NHEFS) | Prospective cohort (1971/1975-1992) | USA | 11.328 (67) | 25-74 | 10 | Clinical diagnosis | Unreported | Age, poverty index, education, race, smoking, vitamin A and C consumption, and alcohol consumption | Periodontitis Gingivitis |
| Hwang, et al. 2014 (21) | Taiwan National Health Insurance (NHI) system | Retrospective cohort (1996-2010) | Taiwan | 38.902 (250 cases with PD) | 43.1±13.6 | NA | Clinical diagnosis | Unreported | Age, occupation, type 2 diabetes mellitus, hypertension, and hyperlipidemia | PD |
| Lee, et al. 2017 (22) | National Health Insurance Service-Health Examinee Cohort (NHIS-HEC) | Retrospective cohort (2002-2013) | Korea | 187.934 (934) | ≥40 | NA | Clinical and radiographic parameters | Unreported | Age, household income, insurance status, residence area, hypertension, diabetes mellitus, cerebral infarction, angina pectoris, myocardial infarction, smoking status, alcohol intake, and regular exercise | PD Current smokers |
| Michaud, et al. 2016 (23) | The Health Professionals Follow-up Study (HPFS) | Prospective cohort (1986-2012) | USA | 19.933 (696) | 40-75 | 26 | Self-report | Unreported | Age, race, alcohol use, physical activity, history of diabetes, body mass index, geographical location, height, and NSAID use | PD |
| Michaud, et al. 2018 (24) | Atherosclerosis Risk in Communities study cohort (ARIC) | Prospective cohort (1987-2012) | USA | 7.466 (375) | 44-66 | 14.7 | Self-report | Included | Age, field center, education level, smoking status, smoking duration, drinking status, body mass index, and diabetes status | Periodontitis (Moderate) |
| Wen, et al. 2014 (25) | Taiwan National Health Insurance (NHI) system | Retrospective cohort (1997-2010) | Taiwan | 153.566 (384) | 45.2± 14.8 | NA | Clinical diagnosis | Included | Age, diabetes, hypertension and hyperlipidemia | PD |
CP = chronic periodontitis; NA = not applicable; NSAID = nonsteroidal anti-inflammatory drug; PCa = prostate cancer; PD = periodontal disease