Table 4.

Threshold effect analysis of serum 25(OH)D concentrations on all-cause and CVD mortality in OA patients

	Adjusted HR (95% CI), P-value
All-cause mortality
Fitting by the standard linear model	1.00 (0.99, 1.00) 0.31
Fitting by the two-piecewise linear model
Inflection point	54.40 nmol/L
25(OH)D concentrations < 54.40 nmol/L	0.98 (0.96, 0.99) < 0.01
25(OH)D concentrations ≥ 54.40 nmol/L	1.00 (1.00, 1.01) 0.40
P for Log-likelihood ratio	0.02
CVD mortality
Fitting by the standard linear model	1.00 (0.99, 1.01) 0.84
Fitting by the two-piecewise linear model
Inflection point	27.70 nmol/L
25(OH)D concentrations < 27.70 nmol/L	0.83 (0.72, 0.95) < 0.01
25(OH)D concentrations ≥ 27.70 nmol/L	1.00 (0.99, 1.02) 0.56
P for log-likelihood ratio	0.02

Adjusted for age, sex, race/ethnicity, survey cycle, education level, PIR, BMI, smoking status, alcohol consumption, disease duration of OA, and history of hypertension or diabetes