Statistical analysis
The standardized mean difference (SMD) in Table 1 provides a
quantitative assessment of the imbalance between the study and control
groups. In general, if the SMD value is less than 0.1, no imbalance
exists between the two groups. To assess the relationship between OSA
and incident BVFL, Cox proportional hazard regression analysis were
used. Unadjusted hazard ratios (HR) were not adjusted in Table 2, but
adjusted HR were adjusted for eight clinical factors. Further
10000-person year (PYs) is defined as the number of new disease cases in
one year in the population at risk of disease occurrence.