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Table 2 Summary of cohort studies included in the meta-analysis

From: Tooth loss as a risk factor for dementia: systematic review and meta-analysis of 21 observational studies

Author /Year Country Sample size Study design Age, yr Main exposure definition Exposure cut-off point Accessment of cognitive function Effect size and crude association results with 95%CI highest vs. lowest category Effect size and adjusted association results with 95%CI highest vs. lowest category Adjustment Follow- up, yr Quality scores
Takeuchi et al (2017) [30] Japan 1566 Cohort ≥60 Number of teeth present ≥20,
10–19,
1–9,
0
DSM-III R 3.83 (2.47–5.93) 1.63 (0.95–2.80) Sex, age, occupation, education, hypertension, diabetes mellitus, history of stroke, alcohol intake, tooth brushing frequency, regular visits to the dentist, and denture use. 5 16
Stewart et al (2015) [31] Sweden 697 Cohort 70–92 Number of teeth present ≥25,
21–24,
9–20,
0–8,
DSM-III R 1.62 (0.84–3.11) Age, education, social class, and vascular risk factors 37 13
Batty et al (2013) [30] 20 Countries 11,140 Cohort 55–88 Number of teeth present ≥22,
1–21,
0
MMSE 1.48 (1.24–1.78) Age, sex, socio-economic CVD risk factors, treatment allocation and ethnicity 5 14
Yamamoto et al (2012) [32] Japan 4425 Cohort ≥65 Number of teeth present ≥20,
≤19,
0
Standardized questionnaire 3.42 (1.05–11.08) 1.41 (0.42–4.70) Age, adjusted household income, BMI, present illness, alcohol consumption, exercise, and forgetfulness 4 15
Paganini-Hill et al (2012) [33] USA 5468 Cohort 52–105 Number of teeth present 26–32,
16–25,
1–15,
0
MMSE 0.84 (0.67–1.06) 18 13
Arrivé et al (2011) [34] France 405 Cohort. 66–80 Number of teeth missing < 11
≥11
DSM-III R 1.35 (0.81–2.25) 15 12
Kim et al. (2007) [35] Korea 686 Cohort ≥65 Number of teeth present ≥28
25–27, 15–24,
1–14,
0
DSM-IV 1.38 (1.12–1.69) 1.26 (1.00–1.59) Age, gender and education, reported diet, vascular disease/risk, BMI and MAC, albumin and cholesterol 2.4 14
Stein et al (2007) [26] USA 101 Cohort 75–98 Number of teeth present 10–28,
0–9
MMSE 2.69 (1.07–6.73) 2.20 (1.10–4.50) Age, education, and apolipoprotein E4 allele 12 13
Shimazakil et al (2001) [36] Japan 517 Cohort study ≥65 Number of teeth present >20,
1–19,
0
Historical diagnosis information from medical records 5.20 (2.00–13.10) 2.40 (0.90–6.50) Age, and classification of institution, physical health status, and cerebrovascular disorder 6 13
  1. Notes: BMI Body mass index, CI Confidence interval, CVD Cardiovascular disease, DSM-IV The Diagnostic and Statistical Manual of Mental Disorders Fourth Edition, DSM-III R Diagnostic and Statistical Manual of Mental Disorders Third Edition, Revised, MAC Mid arm circumference, MMSE The Mini-Mental State Examination