Plasma 25-hydroxyvitamin D level and the risk of frailty among Chinese community-based oldest-old: evidence from the CLHLS study

Table 3 Threshold effect analysis of 25(OH) D (nmol/L) using the piece-wise regression model

Variables	Crude ^a OR (95% CI)	Adjusted ^b OR (95% CI)
Continuous	0.967 (0.960, 0.975) ^***	0.975 (0.965, 0.984) ^***
Cutoff
≤ 33.96	0.948 (0.929, 0.967) ^***	0.963 (0.939, 0.988) ^***
> 33.96	0.978 (0.966, 0.989) ^***	0.981 (0.966, 0.996) ^*
p-value of log-likelihood ratio test	0.032	0.317

^a Crude: no adjustment
^b Adjusted for socio-demographics (age, sex, marital status, residence, education level, and co-residence), health characteristics (smoking, drinking, and regular exercise, hypertension, diabetes mellitus, heart diseases, cerebrovascular diseases, and respiratory diseases) and confounding biomarkers (CRP, ALB, CHO, CREA, HDLC, LDLC, TG, SOD, MDA, WBC, and HGB)
^* < 0.05, ^** < 0.01, ^*** < 0.001

ISSN: 1471-2318