Table 3.
Subgroup sensitivity analyses
| Events per 1000 patient years* |
Hazard ratio (95% CI) brand vs. generic | P-value for interaction | |||
|---|---|---|---|---|---|
| Outcomes | Subgroup | Brand T4 | Generic T4 | ||
|
| |||||
| Atrial fibrillation | 0.95 | 0.98 | 0.96 (0.58, 1.60) | ||
| Age < 65 (N = 68,751) | 0.68 | 0.81 | 0.82 (0.46, 1.48) | 0.33 | |
| Age ≥ 65 (N = 2583) | 8.80 | 5.88 | 1.47 (0.52. 4.13) | ||
| With thyroid cancer (N = 2108) | 1.03 | 1.06 | 1.02 (0.06, 16.01) | 1.00 | |
| Without thyroid cancer (N = 69,226) | 0.95 | 0.97 | 0.96 (0.57, 1.61) | ||
| Dose < 100 mcg (N = 51,611) | 0.61 | 0.62 | 0.98 (0.46, 2.08) | 0.92 | |
| Dose ≥ 100 mcg (N = 19,723) | 1.74 | 1.87 | 0.92 (0.46, 1.82) | ||
| With thyroid surgery (N = 1968) | 0 | 1.54 | NA | ||
| Without thyroid surgery (N = 69,366) | 0.97 | 0.96 | 0.99 (0.60, 1.66) | ||
| Myocardial infarction | 0.72 | 1.08 | 0.66 (0.39, 1.14) | ||
| Age < 65 | 0.68 | 0.88 | 0.76 (0.43, 1.37) | 0.23 | |
| Age ≥ 65 | 1.93 | 7.09 | 0.27 (0.06, 1.29) | ||
| With thyroid cancer | 1.04 | 1.13 | 0.85 (0.05, 14.20) | 0.81 | |
| Without thyroid cancer | 0.71 | 1.07 | 0.65 (0.38, 1.14) | ||
| Dose < 100 mcg | 0.51 | 0.84 | 0.61 (0.29, 1.28) | 0.75 | |
| Dose ≥ 100 mcg | 1.20 | 1.66 | 0.71 (0.33. 1.56) | ||
| With thyroid surgery | 1.59 | 1.66 | 0.94 (0.05, 16.08) | 0.79 | |
| Without thyroid surgery | 0.70 | 1.06 | 0.65 (0.38, 1.13) | ||
| Congestive heart failure | 1.11 | 0.85 | 1.30 (0.78, 2.16) | ||
| Age < 65 | 0.91 | 0.75 | 1.22 (0.70, 2.12) | 0.63 | |
| Age ≥ 65 | 6.77 | 3.97 | 1.71 (0.51, 5.77) | ||
| With thyroid cancer | 0 | 0 | NA | 0.32 | |
| Without thyroid cancer | 1.15 | 0.87 | 1.31 (0.79, 2.17) | ||
| Dose < 100 mcg | 0.98 | 0.83 | 1.17 (0.63, 2.18) | 0.58 | |
| Dose ≥ 100 mcg | 1.41 | 0.88 | 1.59 (0.66, 3.81) | ||
| With thyroid surgery | 0 | 0 | NA | ||
| Without thyroid surgery | 1.14 | 0.86 | 1.30 (0.79, 2.16) | ||
| Stroke | 1.44 | 1.98 | 0.72 (0.49, 1.06) | ||
| Age < 65 | 1.29 | 1.66 | 0.77 (0.51, 1.17) | 0.39 | |
| Age ≥ 65 | 5.79 | 11.95 | 0.48 (0.18, 1.28) | ||
| With thyroid cancer | 2.07 | 2.33 | 0.90 (0.13, 6.42) | 0.83 | |
| Without thyroid cancer | 1.42 | 1.97 | 0.71 (0.48, 1.06) | ||
| Dose < 100 mcg | 1.36 | 1.76 | 0.77 (0.47, 1.24) | 0.67 | |
| Dose ≥ 100 mcg | 1.63 | 2.54 | 0.64 (0.33, 1.22) | ||
| With thyroid surgery | 4.73 | 1.63 | 2.92 (0.30, 28.73) | 0.21 | |
| Without thyroid surgery | 1.37 | 1.99 | 0.68 (0.46, 1.01) | ||
| Pneumonia | 2.06 | 2.41 | 0.85 (0.61, 1.19) | ||
| Age < 65 | 1.69 | 2.23 | 0.75 (0.52, 1.08) | 0.11 | |
| Age ≥ 65 | 12.63 | 7.71 | 1.66 (0.69, 3.99) | ||
| With thyroid cancer | 3.11 | 2.17 | 1.44 (0.23, 9.02) | 0.56 | |
| Without thyroid cancer | 2.03 | 2.41 | 0.83 (0.59, 1.17) | ||
| Dose < 100 mcg | 1.87 | 2.20 | 0.85 (0.56, 1.28) | 0.98 | |
| Dose ≥ 100 mcg | 2.50 | 2.92 | 0.86 (0.49, 1.50) | ||
| With thyroid surgery | 4.72 | 3.32 | 1.54 (0.24, 9.79) | 0.56 | |
| Without thyroid surgery | 2.01 | 2.39 | 0.83 (0.59, 1.17) | ||
| Spine fractures | 0.33 | 0.37 | 0.87 (0.38, 1.99) | ||
| Age < 65 | 0.30 | 0.35 | 0.85 (0.35, 2.03) | 0.92 | |
| Age ≥ 65 | 0.97 | 0.97 | 1.00 (0.06, 15.53) | ||
| With thyroid cancer | 0 | 0 | NA | ||
| Without thyroid cancer | 0.34 | 0.38 | 0.87 (0.38, 2.00) | ||
| Dose < 100 mcg | 0.47 | 0.39 | 1.18 (0.48, 2.85) | ||
| Dose ≥ 100 mcg | 0 | 0.32 | 1.86E–16 (6.00E–17, 5.78E–16) | ||
| With thyroid surgery | 0 | 0 | NA | ||
| Without thyroid surgery | 0.33 | 0.38 | 0.86 (0.38, 1.99) | ||
| Hip fractures | 0.16 | 0.19 | 0.86 (0.26, 2.82) | ||
| Age < 65 | 0.14 | 0.16 | 0.83 (0.22, 3.09) | 0.92 | |
| Age ≥ 65 | 0.97 | 1.00 | 0.94 (0.06, 14.50) | ||
| With thyroid cancer | 0 | 0 | NA | ||
| Without thyroid cancer | 0.17 | 0.19 | 0.87 (0.27, 2.83) | ||
| Dose < 100 mcg | 0.19 | 0.26 | 0.71 (0.20, 2.47) | ||
| Dose ≥ 100 mcg | 0.11 | 0 | 7.02E + 14 (9.88E + 13, 4.98E + 15) | ||
| With thyroid surgery | 0 | 0 | NA | ||
| Without thyroid surgery | 0.17 | 0.19 | 0.87 (0.26, 2.82) | ||
| Falls | 0.07 | 0.06 | 1.02 (0.14, 7.32) | ||
| Age < 65 | 0.07 | 0.06 | 1.02 (0.14, 7.35) | 0.98 | |
| Age ≥ 65 | 0 | 0 | NA | ||
| With thyroid cancer | 0 | 0 | NA | ||
| Without thyroid cancer | 0.07 | 0.06 | 1.02 (0.14, 7.37) | ||
| Dose < 100 mcg | 0.09 | 0.09 | 1.04 (0.14, 7.57) | 0.97 | |
| Dose ≥ 100 mcg | 0 | 0 | NA | ||
| With thyroid surgery | 0 | 0 | NA | ||
| Without thyroid surgery | 0.07 | 0.06 | 1.02 (0.14, 7.34) | ||
*
Censored on end of coverage, 30 days after end of treatment, event or brand to generic, generic to brand switch or switch to other thyroid medications