Study Subjects
We identified patients diagnosed with a common cold as the primary diagnosis in December 2018 using the KCD-7 code (J00). If there was more than one record of common cold per patient, only the first one was counted. We selected patients aged 20 years and older who visited a primary care clinic. Patients diagnosed with GI disorders (KCD-7 code: K20, K21, K22, K23, K25, K26, K27, K28, K29, and K30) within the 90 days before the diagnosis of colds and patients without any drug prescribed for a common cold were excluded (Appendix I and III).