2.2. Study Population
migraine, G43.909, stroke, migraines
MIGRAINE, STROKE, MIGRAINES
We enrolled all participants newly diagnosed with migraines (ICD-9-CM: 346 or ICD-10-CM code: G43.109, G43.501, G43.509, G43.601, G43.609, G43.101, G43.111, G43.119, G43.511, G43.519, G43.611, G43.619, G43.009, G43.011, G43.019, G43.711, G43.719, G43.801, G43.809, G43.A0, G43.B0, G43.C0, G43.D0, G44.001, G44.009, G44.011, G44.019, G44.021, G44.029, G43.811, G43.819, G43.A1, G43.B1, G43.C1, G43.D1, G43.401, G43.409, G43.411, G43.419, G43.701, G43.709, G43.901, G43.909, G44.031, G44.039, G44.041, G44.049, G44.51, G43.911, G43.919), with at least two outpatients or hospitalizations from 1 January 2000, to 31 December 2018, in the LGTD 2005 (n = 123,691). Patients who received acupuncture after the new migraine diagnosis date were defined as acupuncture users, while the remaining patients were defined as acupuncture non-users. In addition, the date of receiving the first acupuncture treatment after the new diagnosis date of the migraine was defined as the index date for the acupuncture cohort. Regarding the index date for the acupuncture non-users, we randomly assigned a month and day to the same index year of the matched acupuncture cases. We excluded subjects aged < 20 years (n = 3540), index date after 31 December 2017 (n = 18,362), and those with a history of stroke (ICD-9-CM 430–438 or ICD-10-CM: I60-I69) before the index date (n = 9976). The 1:1 propensity score method by sex, age, urbanization level, occupation, monthly income, baseline comorbidities, and medication was used to match an equal number of patients in both cohorts. The research process is shown in 