Table 5 Threshold effect analysis of serum parathyroid hormone levels on trabecular bone score by using two-piecewise linear regression.
Trabecular bone score | Adjusted ß (95% CI), p-value |
|---|---|
Total Serum PTH level | |
Fitting by standard linear model | − 0.0034 (− 0.0050, − 0.0017) < 0.0001 |
Fitting by two-piecewise linear model | |
Inflection point | 6.71 |
PTH < 6.71 (pmol/L) | − 0.0102 (− 0.0130, − 0.0073) < 0.0001 |
PTH > 6.71 (pmol/L) | 0.0022 (− 0.0003, 0.0048) 0.0820 |
Log likelihood ratio | < 0.001 |
Gender | |
Male | |
Fitting by standard linear model | − 0.0030 (− 0.0051, − 0.0008) 0.0076 |
Fitting by two-piecewise linear model | |
Inflection point | 7.7 |
PTH < 7.7 (pmol/L) | − 0.0072 (− 0.0106, − 0.0038) < 0.0001 |
PTH > 7.7 (pmol/L) | 0.0017 (− 0.0019, 0.0053) 0.3572 |
Log likelihood ratio | 0.002 |
Female | |
Fitting by standard linear model | − 0.0038 (− 0.0061, − 0.0015) 0.0014 |
Fitting by two-piecewise linear model | |
Inflection point | 11.5 |
PTH < 11.5 (pmol/L) | − 0.0144 (− 0.0195, − 0.0092) < 0.0001 |
PTH > 11.5 (pmol/L) | 0.0011 (− 0.0021, 0.0042) 0.5031 |
Log likelihood ratio | < 0.0001 |
Age | |
< 60 year | |
Fitting by standard linear model | − 0.0036 (− 0.0057, − 0.0016) 0.0006 |
Fitting by two-piecewise linear model | |
Inflection point | 5.61 |
PTH < 5.61 (pmol/L) | − 0.0096 (− 0.0135, − 0.0056) < 0.0001 |
PTH > 5.61 (pmol/L) | 0.0004 (− 0.0027, 0.0034) 0.8087 |
Log likelihood ratio | < 0.001 |
≥ 60 year | |
Fitting by standard linear model | 0.0002 (− 0.0020, 0.0025) 0.8363 |
Fitting by two-piecewise linear model | |
Inflection point | 2.64 |
PTH < 2.64 (pmol/L) | 0.0776 (0.0387, 0.1165) < 0.0001 |
PTH > 2.64 (pmol/L) | − 0.0006 (− 0.0029, 0.0016) 0.5794 |
Log likelihood ratio | < 0.001 |
Race | |
Mexican American | |
Fitting by standard linear model | − 0.0193 (− 0.0553, 0.0167) 0.2932 |
Fitting by two-piecewise linear model | |
Inflection point | 7.45 |
PTH < 7.45 (pmol/L) | − 0.0893 (− 0.1445, − 0.0342) 0.0016 |
PTH > 7.45 (pmol/L) | 0.0632 (0.0021, 0.1243) 0.0429 |
Log likelihood ratio | < 0.001 |
Non-Hispanic Black | |
Fitting by standard linear model | − 0.0327 (− 0.0562, − 0.0092) 0.0065 |
Fitting by two-piecewise linear model | |
Inflection point | 8.75 |
PTH < 8.75 (pmol/L) | − 0.0905 (− 0.1252, − 0.0558) < 0.0001 |
PTH > 8.75 (pmol/L) | 0.0469 (0.0046, 0.0892) 0.0298 |
Log likelihood ratio | < 0.001 |
