Table 4.
The results of subgroup analyses.
| Subgroup | No. of study and patients | Heterogeneity | SMD | |||||
|---|---|---|---|---|---|---|---|---|
| Chi2 | p | I 2 (%) | SMD | 95% CI | Z | p | ||
| Age | ||||||||
| ≤50 | 3/80 | 22.70 | ≤0.001 | 91 | -0.64 | -1.76 to 0.48 | 1.12 | 0.26 |
| >50 | 3/190 | 4.93 | 0.09 | 59 | 0.18 | -0.26 to 0.63 | 0.81 | 0.42 |
| BMI | ||||||||
| <35 | 3/203 | 32.64 | ≤0.001 | 94 | -0.56 | -1.65 to 0.53 | 1.00 | 0.32 |
| ≥35 | 3/67 | 5.54 | 0.06 | 64 | 0.15 | -0.43 to 0.73 | 0.51 | 0.61 |
| Daily duration | ||||||||
| <4 h | 2/39 | 0.09 | 0.76 | 0 | -0.01 | -0.45 to 0.44 | 0.03 | 0.97 |
| ≥4 h | 3/211 | 31.97 | ≤0.001 | 94 | -0.63 | -1.64 to 0.38 | 1.22 | 0.22 |
| CPAP duration | ||||||||
| ≤3 month | 3/190 | 4.93 | 0.09 | 59 | 0.18 | -0.26 to 0.63 | 0.81 | 0.42 |
| >3 month | 3/80 | 22.70 | ≤0.001 | 91 | -0.64 | -1.76 to 0.48 | 1.12 | 0.26 |
| Gender | ||||||||
| Women | 2/163 | 0.21 | 0.65 | 0 | 0.00 | -0.22 to 0.22 | 0.02 | 0.99 |
| Male | 5/107 | 37.43 | ≤0.001 | 89 | -0.25 | -1.12 to 0.62 | 0.57 | 0.57 |
| Sample size | ||||||||
| ≤30 | 4/87 | 5.57 | 0.13 | 46 | 0.12 | -0.29 to 0.53 | 0.58 | 0.56 |
| >30 | 2/183 | 31.96 | ≤0.001 | 97 | -0.87 | -2.64 to 0.91 | 0.96 | 0.34 |
| Study design | ||||||||
| SCT | 4/100 | 36.98 | ≤0.001 | 92 | -0.29 | -1.33 to 0.75 | 0.55 | 0.58 |
| RCT | 2/170 | 0.07 | 0.79 | 0 | 0.01 | -0.21 to 0.22 | 0.05 | 0.96 |
AHI: apnea-hypopnea index, BMI: body mass index, SMD: standardized mean difference, CI: confidence interval, SCT: self-control trials, RCT: randomized controlled trials.