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Purpose Non-vitamin K antagonist oral anticoagulants (NOACs) are widely used in patients with atrial fibrillation (AF) because of their effectiveness in preventing stroke and their better safety, compared with warfarin. However, there are concerns for an increased risk of bleeding associated with concomitant use of non-steroidal anti-inflammatory drugs (NSAIDs) or selective serotonin reuptake inhibitors (SSRIs) with NOACs. In this study, we aimed to evaluate the risk of bleeding events in individuals taking concomitant NSAIDs or SSRIs with NOACs after being diagnosed with AF. Materials and Methods A nested case-control analysis to assess the safety of NSAIDs and SSRIs among NOAC users with AF was performed using data from Korean National Health Insurance Service from January 2012 to December 2017. Among patients who were newly prescribed NOACs, 1233 cases hospitalized for bleeding events were selected, and 24660 controls were determined. Results The risk of bleeding events was higher in patients receiving concomitant NSAIDs [adjusted odds ratio (aOR) 1.41; 95% confidence interval (CI) 1.24–1.61] or SSRIs (aOR 1.92; 95% CI 1.52–2.42) with NOACs, compared to no use of either drug, respectively. The risk of upper gastrointestinal bleeding was higher in patients receiving concomitant NSAIDs or SSRIs without proton pump inhibitors (PPIs) (NSAIDs: aOR 2.47; 95% CI 1.26–4.83, SSRI: aOR 10.8; 95% CI 2.41–2.48) compared to no use. Conclusion When NSAIDs or SSRIs are required for NOAC users with AF, physicians need to monitor bleeding events and consider the use of PPIs, especially for combined use of both drugs or when initiating NOACs treatment.

The purpose of this study was to examine the association between bisphosphonate exposure and osteonecrosis of the jaw (ONJ) in Korean patients with osteoporosis. A nested case-control study was performed using the claims database during 2002 to 2010 provided by the National Health Insurance Service. We identified a cohort of individuals with diagnosis of osteoporosis during 2002 to 2010. Cases and controls were identified during 2004 to 2010, and the date of potential cases of ONJ was defined as the index date. Bisphosphonate exposure was evaluated during 2 y prior to the index date. The association between bisphosphonate exposure and ONJ was tested by performing a conditional logistic regression analysis for matched data, and odds ratios (ORs) with 95% confidence intervals (CIs) were presented. Subjects were classified as nonuser, recent user, past user, or continuous user, depending on the prescription of bisphosphonates in 2 periods (1 to 2 y and 0 to 1 y prior to the index date). Continuous users were defined as patients who were exposed to bisphosphonate in both periods. We also examined the impact of bisphosphonate medication compliance by measuring the cumulative duration of exposure (CDE) on the risk of ONJ. A total of 212 cases with ONJ and 2,120 controls matched by sex, age, income level, and insurance type were identified among 109,787 patients with osteoporosis out of 1,025,340 enrollees in the sample cohort. The odds of having ONJ after adjusting for patient comorbidities significantly increased in continuous users of bisphosphonates (OR, 3.9; 95% CI, 2.4 to 6.2) compared to nonusers. Increased odds of ONJ were observed as CDE increased. The adjusted OR in patients with 1.5 y < CDE ≤ 2 y prior to the index date was 7.8 (95% CI, 4.0 to 15.5) versus nonusers. Our study results support significantly increased occurrences of potential ONJ in patients with osteoporosis who were exposed to bisphosphonates compared to those without exposure.

We conducted a case-crossover study to evaluate the comparative risk of ischemic stroke associated with the use of risperidone, quetiapine and olanzapine in geriatric patients using the Korean Health Insurance Review and Assessment Service database. Cases included elderly patients >64 years old who had experienced their first ischemic stroke (International Classification of Disease, Tenth Revision (ICD-10), I63) hospitalization from July 2005 to June 2006 and who had been without prior cerebrovascular diseases (ICD-10, I60-I69), or transient ischemic attack (ICD-10, G45). Exposures to risperidone, quetiapine and olanzapine were assessed during the 30 days prior to the stroke episode. We set two control periods with lengths which were the same as the hazard periods. Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were estimated by conditional logistic regression. A total of 1601 cases of ischemic stroke with a mean age of 75.6 (±6.7) years were identified, among which 933 (58.3%) were female. An increased risk of ischemic stroke was associated with the use of risperidone (aOR=3.5, 95% CI 3.3-4.6) and quetiapine (aOR=2.7, 95% CI 2.0-3.6) during the 30 days prior to stroke: however, no significant risk was observed with olanzapine (aOR=1.2, 95% CI 0.7-2.0). The increased stroke risk in demented patients, assessed within 30 days after exposure, was also observed with olanzapine. However, the sample of olanzapine users was small and underpowered.

Spermatogonial stem cells (SSCs) are germline stem cells that serve as the foundation of spermatogenesis to maintain fertility throughout a male’s lifetime. To treat male infertility using stem cell banking systems and transplantation, it is important to be able to preserve SSCs for long periods of time. Therefore, this study was conducted to develop an optimal cryopreservation protocol for SSCs using antioxidants and apoptosis inhibitors in freezing medium. No differences were observed compared to controls when SSCs were cryopreserved in the presence of apoptosis inhibitors by themselves. However, mouse germ cells cryopreserved in basal medium containing the antioxidant hypotaurine (14 mM) resulted in significantly greater proliferation potential and mitochondrial activity. Furthermore, treatment groups with combinations containing 200 mM trehalose and 14 mM hypotaurine showed higher proliferation rates compared to controls. In addition, several serum free conditions were evaluated for SSC cryopreservation. Treatment media containing 10% or 20% knockout serum replacement resulted in similar cryopreservation results compared to media containing FBS. SSC transplantation was also performed to confirm the functionality of SSCs frozen in 14 mM hypotaurine. Donor SSCs formed normal spermatogenic colonies and sperm in the recipient testis. These data indicate that inclusion of 14 mM hypotaurine in cryopreservation media is an effective way to efficiently cryopreserve germ cells enriched for SSCs and that knockout serum replacement can replace FBS in germ cell cryopreservation media.

An increasing number of studies are using healthcare claims databases to assess healthcare intervention utilization patterns or outcomes in real-world clinical settings. However, methodological issues affecting study design or data analysis can make conducting and reporting these types of studies difficult. This review presents an overview of the types of information contained in claims data, describes some advantages and limitations of using claims data for research purposes, and outlines steps for utilizing the Korea Health Insurance Review and Assessment and National Health Insurance Service databases. The study also reviews epidemiological approaches utilizing healthcare claims databases (including cross-sectional, case-control, case-crossover, and cohort designs) with respect to protocol development, analysis, and reporting of results, and introduces relevant guidelines and checklists, including the Guidelines for Good Pharmacoepidemiology Practices, the Strengthening the Reporting of Observational Studies in Epidemiology checklist, and the Risk of Bias in Nonrandomized Studies of Interventions tool.

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