Table 3.
Rates and incidence rate ratios (IRR) of atrial fibrillation in study cohort by thyroid status
| Thyroid status | |||||
|---|---|---|---|---|---|
| Overt hypothyroidism | Subclinical hypothyroidism | Euthyroidism | Subclinical hyperthyroidism | Overt hyperthyroidism | |
| All subjects (n=586 460) | |||||
| No of events | 42 | 402 | 16 275 | 435 | 183 |
| Time at risk (1000 PY) | 9.7 | 67.5 | 3100 | 34.9 | 23.7 |
| Incidence rate (No/1000 PY): | |||||
| Crude | 4.3 | 6.0 | 5.2 | 12.5 | 7.7 |
| Age and sex adjusted | 4.4 | 5.7 | 6.4 | 8.4 | 9.1 |
| Incidence rate ratio (95% CI)* | 0.67 (0.50 to 0.92) | 0.88 (0.79 to 0.97) | 1.00 (reference) | 1.30 (1.18 to 1.43) | 1.41 (1.22 to 1.63) |
| Attributable risk percent† | NA | NA | — | 23 | 30 |
| All women (n=355 505) | |||||
| No of events | 27 | 303 | 8466 | 319 | 141 |
| Time at risk (1000 PY) | 7.9 | 55.4 | 1900 | 26.8 | 18.9 |
| Incidence rate (No/1000 PY): | |||||
| Crude | 3.4 | 5.5 | 4.4 | 11.9 | 7.4 |
| Age adjusted | 3.6 | 5.3 | 6.2 | 8.1 | 8.9 |
| Incidence rate ratio (95% CI)* | 0.58 (0.40 to 0.85) | 0.86 (0.77 to 0.97) | 1.00 (reference) | 1.35 (1.20 to 1.51) | 1.44 (1.22 to 1.70) |
| Attributable risk percent† | NA | NA | — | 26 | 31 |
| Women aged <65 years (n=277 856) | |||||
| No of events | 3 | 33 | 1467 | 33 | 22 |
| Time at risk (1000 PY) | 5.3 | 34.9 | 1500 | 14.2 | 13.7 |
| Crude incidence rate (No/1000 PY) | 0.6 | 0.9 | 1.0 | 2.3 | 1.6 |
| Incidence rate ratio (95% CI)* | 0.51 (0.16 to 1.57) | 0.76 (0.54 to 1.07) | 1.00 (reference) | 1.89 (1.34 to 2.67) | 1.60 (1.05 to 2.43) |
| Attributable risk percent† | NA | NA | — | 47 | 38 |
| Women aged ≥65 years (n=77 649) | |||||
| No of events | 24 | 270 | 6999 | 286 | 119 |
| Time at risk (1000 PY) | 2.7 | 20.4 | 457.2 | 12.6 | 5.3 |
| Crude incidence rate (No/1000 PY) | 9.0 | 13.2 | 15.3 | 22.7 | 22.5 |
| Incidence rate ratio (95% CI)* | 0.58 (0.39 to 0.87) | 0.86 (0.76 to 0.97) | 1.00 (reference) | 1.27 (1.13 to 1.43) | 1.40 (1.17 to 1.68) |
| Attributable risk percent† | NA | NA | — | 21 | 29 |
| All men (n=230 955) | |||||
| No of events | 15 | 99 | 7809 | 116 | 42 |
| Time at risk (1000 PY) | 1.6 | 11.4 | 1200 | 7.6 | 4.3 |
| Incidence rate (No/1000 PY): | |||||
| Crude | 9.1 | 8.6 | 6.7 | 15.3 | 9.8 |
| Age and sex adjusted | 10.8 | 10.4 | 10.8 | 13.7 | 14.5 |
| Incidence rate ratio (95% CI)* | 0.95 (0.57 to 1.58) | 0.94 (0.77 to 1.14) | 1.00 (reference) | 1.20 (0.99 to 1.44) | 1.32 (0.97 to 1.78) |
| Attributable risk percent† | NA | NA | — | 17 | 24 |
| Men aged <65 (n=182 690) | |||||
| No of events | 3 | 27 | 2542 | 26 | 21 |
| Time at risk (1000 PY) | 1.1 | 7.7 | 883.8 | 4.1 | 3.1 |
| Crude incidence rate (No/1000 PY) | 2.7 | 3.5 | 2.9 | 6.3 | 6.7 |
| Incidence rate ratio (95% CI)* | 0.81 (0.26 to 2.50) | 1.20 (0.81 to 1.75) | 1.00 (reference) | 1.73 (1.18 to 2.56) | 2.34 (1.52 to 3.59) |
| Attributable risk percent† | NA | NA | — | 42 | 57 |
| Men aged ≥65 (n=48 265) | |||||
| No of events | 12 | 72 | 5267 | 90 | 21 |
| Time at risk (1000 PY) | 0.5 | 3.8 | 272.8 | 3.5 | 1.1 |
| Crude incidence rate (No/1000 PY) | 22.7 | 19.0 | 19.3 | 25.8 | 18.8 |
| Incidence rate ratio (95% CI)* | 1.03 (0.58 to 1.81) | 0.88 (0.70 to 1.22) | 1.00 (ref.) | 1.14 (0.92 to 1.40) | 0.93 (0.60 to 1.42) |
| Attributable risk percent† | NA | NA | — | 12 | NA |
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.