Table 1. Characteristic of studies included in the meta-analysis.
| Study | Year | Country | Study design | No. of subjects | No. of patients | Sex | Age,Median(Range),yrs | Flouride exposure (yrs) | Follow-up(yrs) | Adjustment for covariates |
|---|---|---|---|---|---|---|---|---|---|---|
| Simonen O | 1985 | Finland | Cohort study | 133,398 | 395 | F and M | NA(≥50) | 19 | 11 | Unadjust |
| Sowers MF | 1991 | United States | A prospective cohort study | 506 | 7 | F | NA(20–80) | NA | 5 | Adjusted for age and body size |
| Danielson C | 1992 | United States | Ecological cohort | 6,049 | 246 | F and M | NA(≥65) | 20 | 7 | Unadjust |
| Jacobsen SJ | 1992 | United States | Cohort study | 70,000,000 | 218,951 | F and M | NA(≥65) | NA | 4 | Adjusted for age |
| Jacobsen SJ | 1993 | United States | A retrospective-prospective cohort | NA | 751 | F and M | NA(≥50) | 20 | 10 | Adjusted for age. |
| Cauley JA | 1995 | United States | A prospective cohort study | 2,076 | 41 | F | NA(≥65) | 12.7 ± 8.0 | 6.1 | Adjusted for age, BMI, total calcium intake (diet plus supplements), history of osteoporosis, surgical menopause. history of kills in past year, drinks per week, education, current estrogen use. current thiazidc diuretic use, ever used bottled water. |
| Karagas MR | 1996 | United States | A retrospective cohort study | 444,000 | 28,194 | F and M | NA(65–89) | NA | 4 | Unadjust |
| Lehmann R | 1998 | Germany | A retrospective cohort | 623,602 | 1,198 | F and M | NA(≥35) | 7–17 | 2 | Unadjust |
| Kurttio P | 1999 | Finland | A retrospective cohort study | 144,627 | 4,449 | F and M | NA(50–80) | NA | 13 | Adjusted for age and area |
| Phipps KR | 2000 | United States | Multicentre prospective cohort study | 7,129 | 231 | F | 74.2(≥65) | 44 | 7 | Adjusted for age, weight, education, muscle strength, surgical menopause, calcium intake, drinks/week, current oestrogen use, current thiazide use, noninsulin dependent diabetes, current thyroid hormone use, walking for exercise, and smoking status |
| Hillier S | 2000 | United Kingdom | Case-control study | 1,041 | 514 | F and M | NA(≥50) | NA | NA | Adjusted for age and gender、all potential confounders |
| Li Y | 2001 | china | Cohort study | 8266 | 56 | F and M | 62.8(NA) | >25 | NA | Unadjust |
| Park EY | 2008 | Korean | Cohort study | 1,567,397 | 3,842 | F and M | NA(≥65) | NA | 7 | Unadjust |
| Näsman P | 2013 | Sweden | Cohort study | 473,277 | 60,733 | F and M | 62.8(44.0–87.0) | NA | 16.8 | Adjusted for gender, age group, county of residence, calendar group |
F, female; M, male; NA, not available.