Our results should be interpreted with caution. The diagnoses reported to HIRA might have differed from the actual diagnoses of patients. In our study, only patients who were diagnosed for ischemic stroke during hospitalization were selected as incident cases. This restriction could have increased the reliability of diagnostic accuracy, and could have lowered the incidence of ischemic stroke compared to other studies. A previous validation study compared the diagnoses derived from the HIRA database with the actual diagnoses recorded in patient medical records. The overall positive predictive value of the diagnoses was 83.4% in cases of hospitalized patients. Another point is that although several potential and measurable risk factors were adjusted for, there may have been unmeasured confounders affecting the results. Even though the claims data represent the whole Korean population, the use of administrative data that lacks the most relevant risk factors for stroke, such as depressive symptoms, SES, and blood pressure, warrants a careful interpretation of the results. The use of the propensity score could not control for unmeasured confounders in the study. For example, physician-specific prescribing preferences or genetic factors that we could not measure may have influenced the clinical outcomes. This is a universal problem with all observational studies. Endophytic fungi inhabit asymptomatically and internally within various tissues of host plants during at least one stage of their life cycle. These fungi are found in almost all plants. Although many endophytic fungi have been described and explored from various terrestrial plants, only a limited number have been studied, compared with approximately one million species worldwide. Other plants, particularly those with medical significance tenaciously Chaetocin living under extreme conditions, such as in high-altitude mountainous, Altanserin hydrochloride oceanic, polar, and glacier areas, may harbor unique and diverse endophytic fungi. However, such fungi have been rarely studied. Since the discovery of paclitaxel, which is a powerful anticancer agent from endophytic fungi, such as Taxomyces andreanae and Pestalotia spp., endophytes as novel sources of bioactive metabolites including anticancer, antimicrobial, anti-malarial, and other activities have elicited much attention from researchers worldwide. Consequently, scientists speculate that several horizontal gene transfers occur between endophytes and their host plants and jointly cope with biotic and abiotic stresses, which imply that preference and selectivity exist between host plants and their fungal partners. Although many aspects of biology and interrelatedness of endophytes with their respective hosts have been vastly investigated, novel specific bioactive products and endophytes should be explored from those related pharmaceutical host plants with long history of folk use, which could be remarkably helpful in directing the search for bioactive products.