Table 1.
Baseline Characteristics of Individuals in the Included Studies (n = 43 598)
| Study, Year (Reference) | Description of Study Sample | n | Median Age (Range), ya | Women, n, % | Thyroid Medication at Baseline, n, %b | Thyroid Medication at Follow-Up n, %c | TSH, Median (IQR) | FT4 Mean (SD)d | Follow-Up Median (IQR) | Person-Years |
|---|---|---|---|---|---|---|---|---|---|---|
| 4D Study, 1998 (18) | Trial of atorvastatin in type 2 diabetes and hemodialysis patients, Germany | 841 | 66 (30–83) | 368 (43.8) | 0 | 11 (1.3) | 1.10 (0.77–1.60) | 13.90 pmol/L (2.92) | 1.5 (0.2–3.6) | 1666 |
| Birmingham Study, 1988 (20) | CDAs aged ≥60 y from primary care practice in Birmingham, England | 1015 | 69 (60–94) | 550 (54.2) | 0 | NA | 1.60 (1.10–1.20) | NA | 10.2 (5.7–10.6) | 8301 |
| Brazilian Thyroid Study, 1999 (41) | Adults from Japanese descent living in São Paulo, Brazil | 890 | 56 (30–92) | 459 (51.6) | 0 | NA | 1.40 (0.90–2.20) | 1.07 ng/dL (0.18) | 7.3 (7.1–7.5) | 6274 |
| Busselton Health Study, 1981 (25) | Adults in Busselton, Western Australia | 1902 | 50 (18–90) | 912 (47.9) | 0 | 11 (0.6) | 1.42 (1.00–1.96) | 16.35 pmol/L (2.89) | 20.0 (19.9–20.0) | 33 825 |
| Cardiovascular Health Study, 1989 (17) | CDAs with Medicare eligibility in four US communities | 2526 | 71 (64–100) | 1488 (58.9) | 0 | 52 (2.1) | 2.05 (1.45–2.89) | NA | 14.1 (8.6–16.4) | 31 099 |
| EPIC-Norfolk Study, 1995 (24) | Adults living in Norfolk, England | 11 986 | 58 (40–78) | 6365 (53.1) | 0 | NA | 1.70 (1.20–2.30) | 12.58 pmol/L (3.17) | 13.4 (12.6–14.3) | 153 766 |
| Health ABC Study, 1997 (21) | CDAs with Medicare eligibility in two US communities | 2170 | 74 (69–81) | 1033 (47.6) | 0 | 37 (1.7) | 2.00 (1.37–2.72) | NA | 11.8 (7.5–12.2) | 21 057 |
| InCHIANTI Study, 1998 (35) | Adults aged 20–102 y living in Chianti geographic area, Italy | 1049 | 71 (21–102) | 575 (54.8) | 11 (1.0) | NA | 1.38 (0.96–1.98) | 1.42 ng/dL (0.29) | 9.1 (8.2–9.2) | 8435 |
| Leiden 85-plus Study, 1997 (36) | Adults aged 85 y living in Leiden, The Netherlands | 452 | 85 (NA) | 290 (60.4) | 0 | 6 (1.3) | 1.65 (1.15–2.31) | 14.5 pmol/L (2.26) | 5.2 (2.5–8.5) | 2555 |
| MrOS Study, 2000 (34) | Community-dwelling US men aged ≥65 y | 1410 | 73 (65–99) | 0 | 83 (5.9) | NA | 1.97 (1.36–2.72) | 0.99 ng/dL (0.15) | 12.0 (8.5–12.7) | 14 541 |
| Nagasaki Adult Health Study, 1984 (19) | Atomic bomb survivors in Nagasaki, Japan | 2342 | 57 (38–92) | 1419 (60.6) | 27 (1.2) | NA | 2.60 (2.00–3.40) | 1.45 ng/dL (0.46) | 13.0 (12.3–13.7) | 28 574 |
| Pisa cohort, 2000 (38) | Patients admitted to cardiology department in Pisa, Italye | 2695 | 63 (19–92) | 840 (31.2) | 0 | 0 | 1.53 (1.02–2.30) | 1.19 ng/dL (0.24) | 2.6 (1.6–3.8) | 7326 |
| PREVEND Study, 1997 (37) | Adults living in Groningen, The Netherlands | 2493 | 46 (28–75) | 1255 (50.3) | 0 | 4 (0.2) | 1.37 (0.99–1.90) | 12.81 pmol/L (2.25) | 10.9 (10.6–11.1) | 24 621 |
| PROSPER trial, 1997 (28) | Trial on the benefits of pravastatin vs placebo in adults | 4953 | 75 (69–83) | 2403 (48.5) | 0 | 28 (0.6) | 1.80 (1.26–2.51) | NA | 3.3 (3.0–3.5) | 15 937 |
| Rotterdam Study, 1989 (40) | Adults ≥55 y living in Rotterdam, The Netherlands | 1577 | 68 (55–93) | 934 (59.2) | 0 | NA | 1.54 (1.06–2.26) | 16.29 pmol/L (2.93) | 17.0 (11.2–18.9) | 23 217 |
| SHIP Study, 1997 (39) | Adults in West Pomerania, northeast of Germany | 2977 | 47 (20–81) | 1476 (49.6) | 0 | 90 (3.0) | 0.79 (0.61–1.07) | 12.67 pmol/L (3.42) | 11.3 (10.6–11.8) | 32 238 |
| Whickham Survey, 1974 (27)f | Adults living in and near Newcastle upon Tyne, England | 2320 | 46 (18–92) | 1213 (52.3) | 92 (4.0) | 54 (2.3) | 2.10 (1.20–3.00) | 8.41 pmol/L (1.95) | 19.0 (15.8–20.0) | 37 252 |
| Overall | 43 598 | 64.9 (18–102) | 21 580 (49.6) | 213 (0.5) | 293 (1.4) | 1.65 (1.10–2.40) | 13.6 pmol/L (2.6) | 11.6 (5.1–13.9) | 450 684 |
Abbreviations: CDA, community-dwelling adult; 4D, Die Deutsche Diabetes Dialyze; IQR, interquartile range (25th-75th percentile); MrOS, Osteoporotic Fractures in Men; NA, not applicable; SHIP, Study of Health in Pomerania.
Participants younger than 18 years of age were not included.
Participants with missing information on thyroid medication at baseline: Health ABC Study, seven; MrOs Study, 59; Rotterdam Study, 463; and Whickham Survey, three.
Participants with missing information on thyroid medication at follow-up: Whickham Survey 1430.
Measure of 1 pmol/L is 0.0777 ng/dL.
Excluded patients with acute coronary syndrome or severe illness.
The Whickham Survey used a first-generation assay for the measurement of TSH and did not measure FT4 but total T4.