Clinical variables
In all, eight variables were created: four for demographics, three for
comorbidities, and one for OSA surgery history. We separated each age
group into three subgroups (40-60 years old, Others). Economic status
was classified according to income quantiles; the top 30% had high
economic status, while the bottom 70% had poor economic status.
Residential areas were divided into three subgroups (Seoul,
Metropolitan, and Rural). The ICD-10 code for diagnosis and medicine
prescribing was used to describe comorbidities such as hypertension
(HTN), diabetes (DM), and chronic kidney disease (CKD). OSA surgical
history was characterized among OSA patients as those with Q2196, Q2197,
Q2195, Q2280, Q2281, Q2300, or Q2310 insurance code records prior to
BVFL records.