Table 3.
Threshold Effect Analysis of Sensitivity to Thyroid Hormone Indices on DR Using the Two-Piecewise Linear Regression Model with Sex Differences
| Sex | Male (OR, 95% CI, P) | Female (OR, 95% CI, P) | Total (OR, 95% CI, P) |
|---|---|---|---|
| Exposure TSHI | |||
| Fitting model by standard linear regression | P-interaction: <0.001 | ||
| 0.96 (0.54, 1.70) 0.88 | 1.69 (0.85, 3.35) 0.13 | 1.20 (0.79, 1.83) 0.39 | |
| Fitting model by two-piecewise linear regression | P-interaction: 0.017 | ||
| Inflection point of thyroid hormone Index | 3.28 | 2.05 | 3.54 |
| < Inflection point | 1.31 (0.66, 2.60) 0.43 | 11.61 (0.23, 582.05) 0.22 | 1.45 (0.91, 2.31) 0.12 |
| > Inflection point | 0.05 (0.00, 1.09) 0.06 | 1.32 (0.59, 2.95) 0.49 | 0.06 (0.00, 1.64) 0.09 |
| Log likelihood ratio | 0.022 | 0.197 | 0.008 |
| Exposure TT4RI | |||
| Fitting model by standard linear regression | P-interaction: 0.012 | ||
| 1.00 (0.98, 1.02) 0.87 | 1.02 (0.99, 1.04) 0.13 | 1.01 (0.99, 1.02) 0.47 | |
| Fitting model by two-piecewise linear regression | P-interaction: 0.106 | ||
| Inflection point of thyroid hormone Index | 55.95 | 14.29 | 11.67 |
| < Inflection point | 1.00 (0.98, 1.02) 0.99 | 1.18 (0.84, 1.65) 0.34 | 1.34 (0.95, 1.89) 0.09 |
| > Inflection point | 0.96 (0.85, 1.10) 0.58 | 1.01 (0.99, 1.04) 0.28 | 1.00 (0.99, 1.02) 0.88 |
| Log likelihood ratio | 0.004 | 0.30 | 0.092 |
| Exposure TFQI | |||
| Fitting model by standard linear regression | P-interaction: <0.001 | ||
| 1.14 (0.41, 3.17) 0.79 | 2.33 (0.76, 7.18) 0.14 | 1.41 (0.69, 2.91) 0.35 | |
| Fitting model by two-piecewise linear regression | P-interaction: 0.012 | ||
| Inflection point of thyroid hormone Index | 0.09 | 0.26 | 0.23 |
| < Inflection point | 4.10 (0.97, 17.31) 0.05 | 3.75 (0.91, 15.49) 0.07 | 3.19 (1.24, 8.17) 0.02 |
| > Inflection point | 0.06 (0.00, 0.73) 0.03 | 0.39 (0.01, 11.42) 0.58 | 0.11 (0.01, 0.93) 0.04 |
| Log likelihood ratio | 0.003 | 0.263 | <0.001 |
Notes: Crude model was adjust for: None, Adjusted model was adjust for: Sex; Age; BMI; Duration of diabetes; HbA1c; HDL-C; FT3; FT4, P value < 0.05 was considered significant.
Abbreviations: OR Odds ratios, CI Confidence, Ref Reference; BMI, body mass index; HDL-C, high-density lipoprotein cholesterol; HbA1c, glycated hemoglobin; FT3, free triiodothyronine; FT4, free thyroxine; TSHI, TSH Index; TT4RI, TSH T4 resistance index; TFQI, Thyroid Feedback Quantile-based Index; DR, diabetic retinopathy.