Table 3.
Stepwise multiple linear regression analysis
| Regression analysis results | ||||
|---|---|---|---|---|
| Dependent variable | Significant variable | r2 | Standardized β coefficients | P |
| ΔHR (bpm) | SpO2% | 0.15 | 0.387 | 0.042 |
| 30:15 index | AHI (/h) | 0.21 | −0.454 | 0.015 |
| AHI (/h) | 0.23 | 0.804 | < 0.001 | |
| ΔSBP (mm Hg) | SBP centile | 0.39 | 0.408 | 0.020 |
| SpO2% | 0.55 | −0.361 | 0.044 | |
| Valsalva ratio | AHI (/h) | 0.24 | −0.490 | 0.008 |
ΔHR (bpm), Highest and lowest heart rate changes during first 30 sec of tilt test; 30:15 index, RR interval at 15th and at 30th beats after tilt (normal value > 1.04); ΔSBP (mm Hg), systolic blood pressure changes during first 3 min of tilt test; Valsalva Ratio, the longest RR interval after maneuver and the shortest RR interval during manoeuvres (normal value more than 1.21); AHI, apnea-hypopnea index (events/hour); SpO2%, overnight arterial oxygen saturation.
Model 1 (ΔHR) excluded variables: age (years), sex, BMI centile, AHI (/h), basal HR (bpm), SBP centile and DBP centile, ODI oxygen desaturation index (events/h), mean oxygen desaturation (%)
Model 2 (30:15 index) excluded variables: age (y), sex, BMI centile, SpO2 (%), basal HR (bpm), SBP centile and DBP centile, ODI oxygen desaturation index (events/h), mean oxygen desaturation (%)
Model 3 (ΔSBP) excluded variables: age (y), sex, BMI centile, basal HR (bpm) and DBP centile, ODI oxygen desaturation index (/h), mean oxygen desaturation (%)
Model 4 (Valsalva ratio) excluded variables: age (y), sex, BMI centile, SpO2 (%), basal HR (bpm), SBP centile and DBP centile, ODI oxygen desaturation index (/h), mean oxygen desaturation (%).