Table 1.
Baseline Characteristics of Individuals in Included Studies
| Source | Description of Study Sample | No. of Participants | Age, Median (Range), ya | No. (%)
|
Follow-upd
|
||||
|---|---|---|---|---|---|---|---|---|---|
| Women | Endogenous Subclinical Hyperthyroidismb | Thyroid Medication During Follow-upc | Start | Duration, Median (IQR) | Person-years | ||||
| United States | |||||||||
| Cardiovascular Health Study10 | Community-dwelling adults with Medicare eligibility in 4 US communities | 2569 | 71 (64–100) | 1516 (59.0) | 43 (1.7) | 57 (2.2) | 1989–1990 | 14.0 (8.6–16.4) | 31 599 |
| Health, ABC Study38 | Community-dwelling adults with Medicare eligibility in 2 US communities | 2212 | 74 (70–79) | 1062 (48.0) | 43 (1.9) | 43 (1.9) | 1997 | 8.1 (7.2–8.3) | 15 772 |
| Europe | |||||||||
| Birmingham Study6 | Community-dwelling adults aged ≥60 y from primary care practice in Birmingham, England | 1075 | 69 (60–94) | 586 (54.5) | 60 (5.6) | 5 (0.5) | 1988 | 10.2 (5.5–10.6) | 8688 |
| EPIC-Norfolk Study23 | Adults living in Norfolk, England | 12 341 | 58 (40–78) | 6596 (53.4) | 360 (2.9) | NA | 1995–1998 | 13.4 (12.6–14.3) | 158 227 |
| HUNT Study27 | Adults living in Nord-Trøndelag County, Norway | 24 291 | 55 (41–98) | 16 506 (68.0) | 381 (1.6) | NA | 1995–1997 | 8.3 (7.9–8.9) | 197 935 |
| Leiden 85-Plus Study7 | All adults aged 85 y living in Leiden, the Netherlands | 470 | 85 | 301 (64.0) | 20 (4.3) | 12 (2.6) | 1997–1999 | 5.2 (2.6–8.5) | 2650 |
| Pisa cohort8 | Patients admitted to the cardiology department in Pisa, Italy e | 2903 | 63 (19–92) | 927 (31.9) | 208 (7.2) | 0 | 2000–2005 | 2.6 (1.6–3.8) | 7966 |
| SHIP39 | Adults living in Western Pomerania, Germany | 3883 | 49 (20–81) | 1891 (48.7) | 934 (24.1) | 140 (3.6) | 1997–2001 | 10.1 (9.3–10.7) | 37 532 |
| Australia | |||||||||
| Busselton Health Study22 | Adults living in Busselton, Western Australia | 1950 | 51 (18–90) | 933 (47.8) | 49 (2.5) | 12 (0.6) | 1981 | 20.0 (20.0–20.0) | 34 676 |
| South America | |||||||||
| Brazilian Thyroid Study40 | Adults of Japanese descent living in São Paulo, Brazil | 980 | 57 (30–92) | 510 (52.0) | 90 (9.2) | NA | 1999–2000 | 7.3 (7.0–7.5) | 6877 |
| Overall | 52 674 | 59 (18–100) | 30 828 (58.5) | 2188 (4.2) | 269 (0.5) | 1981–2005 | 8.8 (7.9–12.4) | 501 922 | |
Abbreviations: EPIC, European Prospective Investigation of Cancer; Health ABC Study, Health Aging and Body Composition Study; HUNT, Nord-Trøndelag Health Study; IQR, interquartile range (25th–75th percentiles); NA, data not available; SHIP, Study of Health in Pomerania.
Participants younger than 18 years were excluded.
We used a common definition of subclinical hyperthyroidism, thyrotropin level lower than 0.45 mIU/L, and normal free thyroxine level, whereas thyrotropin cutoff values varied among the previous reports from each cohort, resulting in different numbers from previous reports. For endogenous subclinical hyperthyroidism, 216 participants of Health ABC Study, 9 of Leiden 85-Plus Study, 258 of SHIP, and 14 of Busselton Health Study were excluded because of thyroid medication use at baseline.
Data on thyroid medication use (thyroxine, antithyroid drugs) were not available for 8 participants of the Health ABC Study at baseline, for 1006 participants of Birmingham Study during follow-up, and for all participants during follow-up in EPIC-Norfolk Study, HUNT Study, and Brazilian Thyroid Study.
For all cohorts, we used the maximal follow-up data that were available, which might differ from previous reports for some cohorts.
Patients with acute coronary syndrome or severe illness were excluded from the Pisa cohort.