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Table 3 Multiple linear regression (stepwise with mixed entry)

From: More severe hypoxemia is associated with better subjective sleep quality in obstructive sleep apnea

Term Coefficient SE Lower 95 % Upper 95 % p-value
Intercept 12.866 2.000 8.913 16.818 <.0001
C-age (years) 0.053 0.023 0.007 0.099 0.025*
C-total sleep time (mins) −0.010 0.005 −0.021 0.001 0.064
PLMI (/hr) 0.618 0.385 −0.142 1.378 0.110
Tendency of depression 2.378 0.636 1.120 3.635 <.0001*
C-lowest 5 % SpO2 (%) −0.263 0.128 −0.516 −0.009 0.042*
Median SpO2-Lowest 5% SpO2 −0.357 0.145 −0.644 −0.070 0.015*
  1. *p < 0.05
  2. Abbreviations: C-age centering of age (age minus the mean of age); C-total sleep time centering of total sleep time (total sleep time minus the mean of total sleep time); C-lowest 5 % SpO2 centering of the averaged value from the lowest 5 % saturation of total sleep time (lowest 5 % SpO2 minus the mean of lowest 5 % SpO2). These centering were performed since collinearity was diagnosed; PLMI periodic leg movements index; tendency of depression was defined as either CES-D ≥15 or HADS-D ≥ 8; median SpO2-lowest 5 % SpO2 difference between median to lowest 5 % of saturation of total sleep time. Median SpO2 minus Lowest 5 % SpO2 was the independent predictor for lower PSQI after adjusting other variables