Table 2 Subgroup analyses of the association between vitamin D and OSA in this meta-analysis
From: The association between serum vitamin D and obstructive sleep apnea: an updated meta-analysis
Subgroup | No. of studies | Sample | Mean difference (95% CI) | P for Heterogeneity | I-squared Value | P Value between groups | |
|---|---|---|---|---|---|---|---|
Experiment | Control | ||||||
Ethnic | |||||||
 Caucasian | 16 | 3547 | 1707 | − 0.59[− 0.9, − 0.27] | 0.0003 | 93% | P < 0.00001 |
 Asian | 10 | 662 | 382 | − 1.28[− 1.92, − 0.64] | P < 0.0001 | 94% | P < 0.00001 |
BMI | |||||||
 Normal range | 3 | 176 | 129 | − 1.66[− 2.73, − 0.59] | 0.002 | 93% | P < 0.00001 |
 Overweight | 4 | 1983 | 1186 | − 1.33[− 2.55, − 0.1] | 0.03 | 98% | P < 0.00001 |
 Obesity | 17 | 1981 | 634 | − 0.57[− 0.93, − 0.21] | 0.002 | 92% | P < 0.00001 |
PSG degree | |||||||
 I | 19 | 3750 | 1833 | − 0.55[− 0.85, − 0.26] | 0.0002 | 93% | P < 0.00001 |
 II | 4 | 277 | 157 | − 1.4[− 2.21, − 0.58] | 0.0008 | 91% | P < 0.00001 |
 III | 3 | 182 | 99 | − 1.93[− 2.28, − 1.58] | P < 0.00001 | 21% | 0.28 |
Study quality | |||||||
 High/A | 18 | 3640 | 1769 | − 0.61[− 0.92, − 0.31] | P < 0.0001 | 93% | P < 0.00001 |
 Medium/B | 8 | 569 | 320 | − 1.37[− 2.07, − 0.66] | 0.0001 | 95% | P < 0.00001 |
Study latitude | |||||||
 Low latitude | 4 | 336 | 117 | − 1.24[− 2.25, − 0.23] | 0.02 | 94% | P < 0.00001 |
 Middle latitude | 22 | 3873 | 1972 | − 0.8[− 1.11, − 0.49] | P < 0.00001 | 95% | P < 0.00001 |