Rates and incidence rate ratios (IRR) of atrial fibrillation in study cohort by level of thyroid stimulating hormone (TSH) with normal free thyroxine concentration
| Euthyroidism | Subclinical hyperthyroidism | ||||
|---|---|---|---|---|---|
| Normal | High normal | Reduced TSH | Suppressed TSH | ||
| TSH level (mIU/L) | 0.4–5.0 | 0.2–0.4 | 0.1–0.2 | <0.1 | |
| Rate of atrial fibrillation | |||||
| No of events | 15 652 | 623 | 155 | 280 | |
| Time at risk (1000 PY) | 3000.0 | 73.9 | 13.8 | 21.1 | |
| Incidence rate (No/1000 PY): | |||||
| Crude | 4.9 | 8.4 | 11.2 | 13.3 | |
| Age adjusted | 8.0 | 8.8 | 8.9 | 10.3 | |
| Incidence rate ratio (95% CI)* | 1.00 (reference) | 1.12 (1.03 to 1.21) | 1.16 (0.99 to 1.36) | 1.41 (1.25 to 1.59) | |
| Attributable risk percent† | 11 | 14 | 29 | ||
PY=person years. NA=not applicable.
*Risk estimates are adjusted for sex, age, calendar year, Charlson comorbidity index, and socioeconomic status.
†Attributable risk percent = (IRR−1)/IRR×100.