2.3. Statistical Analysis
strokes
REGRESSIONS, STROKES
Differences in baseline characteristics between both groups were examined using the standardized mean difference (SMD). A standardized mean difference of 0.1 or less indicates a negligible difference. The incidence density rates of strokes were calculated for both acupuncture and non-acupuncture cohorts. Univariable and multivariable Cox proportional hazard regressions were performed to evaluate the hazard ratios (HRs) with 95% confidence intervals (CIs) for strokes. The Kaplan–Meier method was used to estimate the differences in the cumulative incidence of strokes between the two cohorts by the log-rank test. A 