Table 2.
Subgroup analysis of included studies to identify the association of thyroid hormone level with mortality.
| Characteristics | Mortality, T3 | Mortality, T4 | ||||||
|---|---|---|---|---|---|---|---|---|
| N | T3, SMD (95% CI) | P value for heterogeneity | I2, % | N | T4, SMD (95% CI) | P value for heterogeneity | I2, % | |
| ALL | 6 | −2.31(−4.10, −0.52) | P < 0.00001 | 97 | 5 | −2.40(−3.89, −0.91) | <0.00001 | 94 |
| Male(%) | ||||||||
| ≥70 | 3 | −2.43(−5.54, 0.68) | <0.00001 | 99 | 3 | −2.18(−4.18, −0.17) | <0.00001 | 93 |
| <70 | 3 | −2.16(−4.23, −0.09) | <0.00001 | 93 | 2 | −2.73(−5.01,−0.46) | <0.00001 | 95 |
| Sample size | ||||||||
| ≥80 | 2 | −2.81(−7.36, 1.74) | <0.00001 | 99 | 1 | −3.86(−4.35, −3.37) | — | — |
| <80 | 4 | −2.01(−3.45, −0.58) | <0.00001 | 90 | 4 | −2.00(−3.38, −0.62) | <0.00001 | 89 |
| Study quality | ||||||||
| Low | 2 | −1.41(−1.97, −0.84) | 0.48 | 0 | 2 | −1.07(−1.90, −0.24) | 0.13 | 56 |
| High* | 4 | −2.74(−5.45, −0.03) | <0.00001 | 98 | 3 | −3.29(−4.67, −1.92) | 0.0006 | 87 |
| Mortality(%) | ||||||||
| ≥40 | 3 | −2.48(−4.32, −0.64) | <0.00001 | 91 | 3 | −2.11(−3.99, −0.22) | <0.00001 | 93 |
| <40 | 3 | −2.10(−5.30, 1.10) | <0.00001 | 99 | 2 | −2.84(−4.49, 0.75) | 0.0003 | 93 |
| Measurement techniques | ||||||||
| RIA | 3 | −2.48(−4.32, −0.64) | <0.00001 | 91 | 3 | −2.11(−3.99, −0.22) | <0.00001 | 93 |
| others(2 NR/1 ECLIA) | 3 | −2.10(−5.30, 1.10) | <0.00001 | 99 | 2 | −2.84(−4.94, −0.75) | 0.0003 | 93 |
Abbreviations: 95% CI, 95% confidence interval; ECLIA, electro-chemiluminescence immunoassay; N, the number of studies; NR, not reported; RIA, radioimmunoassay; SMD, standard mean difference; T3, Triiodothyronine; T4, thyroxine. *High-quality studies were those that achieved >4.5 points in quality assessment.