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Summary Objective This study used the Taiwan Stroke Registry data to evaluate the efficacy and safety of intravenous tissue plasminogen activator (tPA) in treating acute ischemic stroke in patients with renal dysfunction. Design We identified 3525 ischemic stroke patients and classified them into two groups according to the estimated glomerular filtration rate (eGFR) at the emergency department: ≥60, and Results Among patients with eGFR levels of Conclusions tPA for acute ischemic stroke could improve functional outcomes without increasing the risks of upper gastrointestinal bleeding for patients with or without renal dysfunction. The low eGFR was not a significant risk factor for intracerebral hemorrhage among patients receiving tPA treatment.

Background Central venous catheter (CVC) placement is a common procedure used for the treatment of critically ill patients. However, ischemic stroke is a complication after CVC placement. Aim This study investigated the association between CVC placement and ischemic stroke risk in an Asian population. Design Population-based retrospective study. Methods We enrolled 37 623 patients who ever-received CVC placement over 2000–10 and propensity score-matched individuals without CVC placement as the comparison cohort from the Taiwan National Health Insurance Research Database. We determined the cumulative incidence rates and adjusted hazard ratios (aHRs) for ischemic stroke. Results We finally identified and enrolled 34 164 propensity score-matched pairs of individuals. Compared with the comparison group, CVC placement increased the average annual ischemic stroke incidence [19.5 vs. 11.6 per 10 000 person-years; crude HR=1.28, 95%, confidence interval (CI)=1.21–1.35; adjusted subhazard ratio (aSHR)=1.4, 95% CI = 1.33–1.47; P35 years, stroke risk was significantly higher in Conclusion CVC placement increases ischemic stroke risk, particularly in those aged ≤35 years; this trend warrants further investigation.

BackgroundAneurysm of proximal thoracic aorta (pTAA) is an often indolent, yet fatal disease. Although advancements in aneurysmal repair techniques have increased long-term survival rates, studies have proven that there are increases in perioperative risk for stroke incidence after pTAA surgery. Conversely, there is little evidence regarding the long-term stroke incidence in pTAA individuals, which strongly influences the morbidity, mortality, and usage of antithrombotic agents.MethodsUsing the Taiwan National Health Insurance Research Database, a nationwide population-based cohort, we recruited 3013 pTAA survivors hospitalized from 1 January 2000 to 31 December 2012. To ensure study cohort quality, only patients aged 20 years and above who underwent aneurysmal repair surgery are included. The control cohort is identified by matching background features (comorbidities, age, gender) at a 1:4 ratio through the use of frequency matching. The primary outcomes include incidence of ischemic stroke and intracranial hemorrhage one month after aneurysmal repair surgery.ResultsThe mortality of pTAA survivors is nearly twice of the matched controls despite aneurysmal repair (28.5 % vs. 15.2%, p ConclusionsDespite the advancement of aneurysmal repair surgery, this study suggests that pTAA patients may still face an increased risk of hemorrhage stroke. Further investigation is warranted to provide better long-term care for the pTAA population.

Background Aspirin has been found to lower the occurrence rates of some cancers through the inhibition of the cyclooxygenase enzyme. For example, there is a well-known association between aspirin use and the occurrence of hepatocellular carcinoma (HCC) in hepatitis B virus (HBV) carriers. However, the association, if any, between aspirin use and HCC in hepatitis C virus (HCV) carriers is unknown. Therefore, this study compared the occurrence rates of HCC in HCV carriers treated with or without aspirin. Methods The participants in this retrospective cohort study consisted of people newly diagnosed with HCV in Taiwan from 2000 to 2012. Those who were treated with aspirin were defined as the control group, whereas those not treated with aspirin were defined as the comparison cohort. We used a 1:1 propensity score matching by age, sex, comorbidities, drugs, diagnosis year, and index year with covariate assessment. Results Our study sample consisted of 2980 aspirin-treated HCV carriers and 7771 non-aspirin-treated HCV carriers. After propensity score matching, each cohort consisted of 1911 HCV carriers. The adjusted hazard ratio (aHR) of HCC incidence in the aspirin users (aHR = 0.56, 95% CI = 0.43–0.72, p ) was significantly lower than that in the non-aspirin users. A Kaplan-Meier analysis showed that among the HCV carriers, the aspirin users had a lower cumulative incidence rate of HCC over the first 10 years of aspirin treatment (p ). Conclusions The HCC incidence rate was lower in the aspirin-using HCV carriers than in the non- aspirin-using HCV carriers, indicating that the effects of aspirin might occur through inhibition of the cyclooxygenase enzyme pathway. Moreover, protection from HCC was provided by less than a year of aspirin treatment, while treatment with aspirin for 1 to 2 years exhibited the greatest protective effect. We therefore encourage aspirin treatment to prevent HCC in HCV carriers.

Objective: Chinese herbal medicine (CHM) is frequently applied to patients to improve the symptoms and signs associated with anemia. The aim of this study is to use the claims data from the National Health Insurance Research Database (NHIRD) in Taiwan to analyze CHM prescription patterns and to identify the frequency and combinations of CHM commonly used to treat anemia. Materials and methods: A total of 41,028 patients were diagnosed with anemia in Taiwan within the defined study period. After randomly equal matching for age and sex, data from 7682 patients characterized as CHM users and non-users were analyzed. Network analyses of the 30 most frequently applied herbs and formulas were used to indicate CHM combinations in patients with anemia. Results: Those patients with anemia who were older, office workers, and lived in central areas of Taiwan had higher tendencies toward CHM usage. Based on considerations of comorbidities, anemia patients associated with chronic kidney diseases, diabetes mellitus, and hypertensive diseases preferred Western medical management and demonstrated a lesser likelihood of combining treatment with CHM; by contrast, those with coronary artery disease demonstrated a higher tendency for CHM use. Notably, Astragalus membranaceus (AM) and Gui-Pi-Tang (GPT) were the most commonly prescribed CHM single herb and formula, respectively. The core prescription pattern consisted of AM, Salvia miltiorrhiza (SM), Angelica sinensis (AS), GPT, and Si-Wu-Tang (SWT), as indicated by the associations and frequency of CHM utilization by traditional Chinese medicine (TCM) physicians. Conclusion: This study demonstrates that CHM may be applied as an integral element of treatment for patients with anemia. It also provides insight regarding individual therapy and common clinical practices of TCM physicians in the treatment of anemia. Further research is required to explore potential interactions and possible mechanisms at play with CHM management of anemia. Keywords: Chinese herb medicine, Anemia, Cohort study, Prescription pattern

BACKGROUND The purpose of this study was to assess the predictive factors of optic neuropathy among patients with nasopharyngeal carcinoma (NPC). METHODS The analysis included 16 297 patients with NPC and 65 187 controls. Each patient with NPC was randomly frequency-matched with 4 individuals without NPC by age, sex, and index year. Cox proportional hazard models were applied to measure the hazard ratios (HRs) and 95% confidence intervals (CIs) of optic neuropathy development associated with NPC. RESULTS The risk of optic neuropathy was significantly higher in the NPC cohort (adjusted HR [aHR] 3.42; 95% CI 2.85-4.09; P < .001). Independent risk factors for optic neuropathy among patients with NPC included stroke (aHR 1.7; 95% CI 1.07-2.7; P = .03) and receipt of chemotherapy (aHR 1.55; 95% CI 1.17-2.06; P = .002). CONCLUSION The risk of optic neuropathy was significantly higher in patients with NPC than in the general population.

BACKGROUND: Stroke is a severe neurologic complication of dengue fever, described in only a few case reports. The incidence and risk factors for stroke in patients with dengue remain unclear. We conducted a population-based retrospective cohort study to investigate the risk of stroke in patients with dengue. METHODS: Using data from the Taiwan National Health Insurance Research Database, we included a total of 13 787 patients with dengue newly diagnosed between 2000 and 2012. The control cohort consisted of patients who did not have dengue, matched 1:1 by demographic characteristics and stroke-related comorbidities. We calculated the cumulative incidences and hazard ratios (HRs) of stroke in both cohorts using Kaplan–Meier curves and Cox proportional hazards regression. RESULTS: The overall incidence rate of stroke was 5.33 per 1000 person-years in the dengue cohort and 3.72 per 1000 person-years in the control cohort, with an adjusted HR of 1.16 (95% confidence interval [CI] 1.01–1.32). The risk of stroke among patients with dengue was highest in the first 2 months after diagnosis (25.53 per 1000 person-years, adjusted HR 2.49, 95% CI 1.48–4.18). INTERPRETATION: Dengue fever was associated with an increased risk of stroke in the first few months after diagnosis. The effect of dengue on stroke may be acute rather than chronic.

Background and purpose: Lung cancer has high global incidence and mortality rates. Chronic obstructive pulmonary disease (COPD) is strongly associated with lung cancer and is an independent risk factor for lung cancer with or without smoking. Chinese herbal medicines (CHMs) are used to treat COPD. This study sought to determine whether CHM treatment effectively decreases the incidence of lung cancer in COPD patients receiving conventional Western medical treatment.Methods: Records obtained from the National Health Insurance Research Database (NHIRD) were used to identify 81,780 adults aged ≥18 years newly diagnosed with COPD in Taiwan between 2000 and 2010. Among them, 11,180 received CHMs after COPD diagnosis and 23,319 did not (non-CHM). After excluding patients with missing basic demographic information, each group consisted of 2,682 patients. Statistical methods analyzed the baseline characteristics for both groups and we performed a Cox proportional hazard regression analysis to examine the incidence of lung cancer. The cumulative incidence of lung cancer in COPD patients with or without CHM treatment was calculated by the Kaplan-Meier method. The association between herbs and formulas was examined by NodeXL to perform a network analysis of CHM.Results: COPD patients using CHM had a lower risk for lung cancer (adjusted hazards ratio [aHR] = 0.36, 95% confidence interval [CI] = 0.24–0.53, p < 0.001). Older age was associated with a higher risk of lung cancer: patients aged 40–59 years (aHR = 5.32, 95% CI = 2.19–12.94, p < 0.001) and those aged ≥60 years (aHR = 16.75, 95% CI = 7.54–37.23, p < 0.001) were at significantly greater risk compared with patients aged 18–39 years. CHM use was associated with a trend for a lower cumulative incidence of lung cancer compared with non-CHM use (p < 0.001). Among the 10 most commonly used single herbs and formulas used to decrease the risk of lung cancer in COPD patients, Fritillariae thunbergii was the most commonly used single herb and Xiao Qing Long Tang the most commonly used formula.Conclusion: The findings from this nationwide retrospective cohort study indicate that CHM as adjunctive therapy in COPD treatment regimens may reduce the risk of lung cancer in this vulnerable patient population.

Objectives Much epidemiological evidence links diabetes mellitus (DM) to the development of multiple cancers and, in particular, the development of hepatocellular carcinoma (HCC). The aim of this study was to investigate whether Chinese herbal medicine (CHM) reduces the incidence of HCC in patients receiving Western antidiabetic drugs. Interventions and main outcome measures This retrospective cohort study used data from the National Health Insurance Research Database involving 81,105 diabetic patients, including 5122 CHM users and 25,966 non-CHM users. Analyses of treatment effects were adjusted for covariates including gender, age, comorbidities, antidiabetic drugs and liver medications. NodeXL software performed a network analysis to identify the 50 most commonly used CHM herbs and formulas. Results In Cox proportional hazards models adjusted for demographic and clinical characteristics, DM patients exposed to adjuvant CHM therapy were significantly less likely to develop HCC compared with non-CHM users (adjusted hazard ratio [aHR] 0.59; 95 % confidence interval [CI], 0.41-0.87; p = 0.01). Kaplan-Meier analysis revealed a lower 10-year cumulative risk of HCC among CHM users compared with non-CHM users. Amongst the 10 individual CHM herbs and herbal formulas most commonly prescribed for DM, the most frequent were Salvia miltiorrhiza (Dan Shen) and Liu Wei Di Huang Wan, respectively. Conclusion This nationwide retrospective cohort study from Taiwan provides some valuable insights into the prescribing characteristics of CHM treatment in patients with DM. Compared with use of Western antidiabetic medications alone, use of adjuvant CHM effectively reduces the incidence of HCC in patients with DM.

Chronic kidney disease (CKD) is a serious complication affecting patients with chronic hepatitis. The effectiveness of CHM for the prevention of CKD in hepatitis patients remains unclear. Therefore, we conducted a retrospective cohort study to investigate the effectiveness of CHM in preventing the development of CKD in hepatitis patients. From a subdataset of the Taiwan National Health Insurance Research Database (NHIRD), we included 19,409 patients newly diagnosed with hepatitis B and hepatitis C between the years 2000 and 2010. After exclusion criteria and 1 : 1 propensity score matching process, we compared demographic factors, comorbidities, and correlated drugs between the CHM and non-CHM cohorts. Statistical analysis was applied to evaluate the differences in characteristic distributions and to compare the cumulative incidence of CKD between the CHM and non-CHM cohorts. This study showed that the patients suffering from hepatitis C with CHM treatment more than 90 days as an adjuvant therapy combined with western medical treatment modalities exhibited a decreased risk of developing CKD (hazard ratio (HR) = 0.40, 95% confidence interval (CI) = 0.21–0.76, p value p value = 0.004) for the CHM cohort. For further reference, we herein offer the ten most frequently prescribed single herbs and herbal formulas; as such, Salviae miltiorrhizae and Jia-Wei-Xiao-Yao-San were the most commonly prescribed single herb and formula, respectively. This nationwide retrospective cohort study provides evidence that CHM is an effective adjuvant treatment to decrease the risk of developing CKD in hepatitis C patients.

Type 2 diabetes mellitus (T2DM) is a progressive disease. After metformin failure, the addition of insulin or sulfonylureas might increase the risk of hypoglycemia and cardiovascular (CV) morbidity. Here, the risk of all-cause mortality was compared between early insulin treatment and glimepiride use in T2DM patients with background metformin therapy.We conducted a 9-year retrospective cohort study from the population-based National Health Insurance Research Database in Taiwan. A total of 2054 patients with T2DM under insulin or glimepiride treatment were enrolled during 2004 to 2012. Overall event rates of all-cause mortality were compared between 1027 insulin users and 1027 matched glimepiride users.After the propensity score matching, the mortality rates were 72.5 and 4.42 per 1000 person-years for insulin users and glimepiride users. The adjusted hazard ratio of mortality was 14.47 (95% CI: 8.64-24.24; P value

Both ischemic heart disease (IHD) and stroke are major causes of death worldwide. We investigated the effects of combined Traditional Chinese medicine (TCM) and western medicine (WM) on stroke risk in IHD patients.Taiwanese patients with IHD were enrolled in the TCM study during their outpatient visit. Stroke events after TCM or non-TCM treatment were examined. Chi-square tests and Student t-tests were used to examine differences between patients using and not using TCM. The Cox proportional hazards regression model was used to estimate hazard ratios (HRs). Sex, age, and comorbidities were included in a multivariable Cox model to estimate the adjusted HR (aHR). The survival probability and the probability free of stroke were calculated by the Kaplan-Meier method.There were 733 IHD patients using TCM and 733 using non-TCM treatment, with the same proportion of sex and age within each cohort. Using single Chinese herb such as Dan Shen, San Qi, or Chuan Xiong would have lower stroke events and lower aHR than non-TCM in IHD patients. There was 0.3-fold lower stroke risk in IHD patients with combination TCM and non-TCM treatment (95% CI = 0.11-0.84, P = .02). Moreover, the survival rate was higher (P < .001) and the incidence of hemorrhagic stroke was significantly lower (P = .04) in IHD patients with TCM treatment.IHD patients using combined TCM and WM had a higher survival rate and lower risk of new onset stroke, especially hemorrhagic stroke than those who did not use TCM treatment.

Background and purpose: Chinese herbal medicine (CHM) is frequently applied in conjunction with western pharmacotherapy to relieve symptoms in patients with CKD. However, evidence-based research into the effectiveness of CHM use as applied to treat CKD is limited and warrants further investigation. The aim of this study is to assess whether adjunctive treatment with CHM affected survival rate of CKD patients undergoing conventional western medical management.Methods: A total of 14,718 CKD patients, including 6,958 CHM users and 7,760 non-CHM users, were recruited from the Longitudinal Health Insurance Database 2000, a sub-dataset of the National Health Insurance Research Database, to conduct this study. Demographic characteristics, including sex, age, job type, residential area, and comorbidity were considered as covariates to adjust the analysis. A network analysis of treatments, including with herbal formulas and single herbs, was performed to investigate the core patterns of CHM use for the treatment of CKD patients. The Kaplan-Meier method was used to determine the survival rate between CHM and non-CHM groups.Results: After matching for sex and age, there were 550 subjects in both the CHM and non-CHM cohorts. Other than presence of diabetes (adjusted OR = 0.57, p < 0.001) and urinary tract infection (adjusted OR = 0.69, p < 0.05), sex, age, job type, area of residence, and other comorbidities indicated no special preference for CHM use among subjects. Salvia miltiorrhiza Bunge (SM) and Ji-Sheng-Shen-Qi-Wan (JSSQW) were the most frequent single herb and formula, respectively, prescribed for patients with CKD. The most frequent CHM combination between herbs and formulas was JSSQW, associated with Rheum officinale Baill. (RO), SM and Astragalus membranaceus (Fisch.) Bunge (AM). The long-term survival rate demonstrated significant benefits for CHM users within a 12-year follow-up period (P < 0.004).Conclusion: This nationwide retrospective cohort study provides valuable insight into the characteristics and prescription patterns of CHM usage in CKD patients. JSSQW associated with RO, SM, and AM is the most common CHM prescription. CHM improves long-term survival in patients with CKD, suggesting that CHM is an effective adjuvant therapy for CKD.

Benign prostatic hyperplasia (BPH) is a common disorder in the aging male population. Despite evidence that thyroid status impacts the prostate, the objective of this study was to examine whether patients with hyperthyroidism were at a greater risk for BPH. This study is a retrospective nationwide population-based cohort study of the Chinese population. Data for this study were retrieved from the Taiwan National Health Insurance Research Database (NHIRD). Overall, 1032 male patients aged 40 years or older with hyperthyroidism diagnosed between 2000 and 2006 were included in the hyperthyroidism group, and 4128 matched controls without hyperthyroidism were included in the non-hyperthyroidism group. Both groups were monitored until the end of 2011. A Cox proportional hazards regression model was used to compute and compare the risk of BPH between study participants with and those without hyperthyroidism. Patients with hyperthyroidism exhibited a greater incidence of BPH (18.51% vs 15.53%) than did the controls. Furthermore, the hazard ratio (HR) of the hyperthyroidism group was 1.24 times that of the control group [95% confidence interval (95% CI 1.05–1.46)] signifying that there is a significant 24% increase in the risk of BPH with the presence of hyperthyroidism. This increased risk of BPH with hyperthyroidism, however, failed to remain significant (adjusted HR = 1.11, 95% CI = 0.94–1.3) after adjusting for covariates of age (adjusted HR = 2.72, 95% CI = 2.32–3.2), diabetes (adjusted HR = 1.4, 95% CI = 1.17–1.68), hypertension (adjusted HR = 1.74, 95% CI = 1.49–2.03), hyperlipidemia (adjusted HR = 1.25, 95% CI = 1.03–1.53), neurogenic bladder, cystitis (adjusted HR = 1.23, 95% CI = 0.58–2.59), urethral stricture (adjusted HR = 2.01, 95% CI = 0.28–14.47), urethritis (adjusted HR = 1.52, 95% CI = 0.72–3.21), and urinary tract infection (adjusted HR = 1.77, 95% CI = 1.31–2.39). After adjustment for comorbidities and covariates, hyperthyroidism was not found to be a significant risk factor of BPH in our male study subjects. Further research is warranted to validate our results and elucidate the association of the pathophysiology of these 2 diseases.

Salvia miltiorrhiza Bunge (Danshen), a common medicinal plant in traditional Chinese medicine, has been tested effectively to prevent urolithiasis in animals; nevertheless, the clinical application for urolithiasis remains unclear. We thus investigated the clinical effect of Danshen by analyzing the database from the Taiwan National Institute of Health. The cohort “Danshen-users” was prescribed Chinese herb medicine Danshen after the initial diagnosis of calculus. The control group (non-Danshen-users) was not given Danshen after the initial diagnosis of calculus. The date of first using Danshen after new diagnosis date of calculus was considered as index date. The outcome variables were categorized into two categories: the first category included calculus surgical treatment, including extracorporeal shock wave lithotripsy, ureteroscopy, percutaneous nephrostomy with fragmentation, and ureterolithotomy; the second category included any bleeding disorders, including gastrointestinal bleeding, intracranial hemorrhage, and blood transfusions. The incidence of calculus surgical treatment in the Danshen-users was less than that in the non-Danshen-users: 1.071% in 1,000 person-years (200 people followed up for 5 years) and 3.142% in 1,000 person-years, respectively. The adjusted hazard ratio for calculus surgical treatment in the Danshen-users was 0.34 (95% confidence intervals: 0.31–0.38) as compared to the non-Danshen-users. When stratified by sex, the incidence of calculus surgical treatment in Danshen-users was 0.685% in 1,000 person-years and 1.575% in 1,000 person-years for women and men, respectively, which was lower than that in non-Danshen-users. Danshen decreased the ratio of subsequent stone treatment after the first treatment in the study population; there was no increased bleeding risk due to long-term Danshen use.

Background. Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB) share many risk factors. Evidence suggests that metabolic risk factors are important to AD; however, their association with DLB is unclear. The risk of cardiovascular diseases (CVD) associated with AD and DLB is also uncertain. Thus, this nationwide, population-based study was designed to evaluate the metabolic and CVD risks in AD and DLB. Materials and Methods. Data were obtained from the Taiwan National Health Insurance Research Database. AD patients, DLB patients, and normal control (NC) individuals from 1996 to 2013 were enrolled for risk assessment. Results. In total, 7544 NC individuals, 1324 AD patients, and 562 DLB patients were enrolled. Participants with one or more metabolic risk factors had significantly higher odds of AD or DLB. No significant differences in metabolic risk factors were observed between DLB and AD patients. AD patients had a lower risk of CVD (aHR = 0.67, 95% CI = 0.59–0.76, p value p value p value Conclusion. Metabolic risk factors are important in AD and DLB. Patients with AD might have a lower risk of CAD and ischemic strokes. Patients with DLB might have a higher risk of ischemic stroke.

We conducted a National Health Insurance Research Database-based Taiwanese nationwide population-based cohort study to evaluate whether Chinese herbal medicine (CHM) treatment decreased the incidence of chronic hepatitis in breast cancer patients receiving chemotherapy and/or radiotherapy. A total of 81171 patients were diagnosed with breast cancer within the defined study period. After randomly equal matching, data from 13856 patients were analyzed. Hazard ratios of incidence rate of chronic hepatitis were used to determine the influence and therapeutic potential of CHM in patients with breast cancer. The patients with breast cancer receiving CHM treatment exhibited a significantly decreased incidence rate of chronic hepatitis even across the stratification of age, CCI score, and treatments. The cumulative incidence of chronic hepatitis for a period of seven years after initial breast cancer diagnosis was also reduced in the patients receiving CHM treatment. The ten most commonly used single herbs and formulas were effective in protecting liver function in patients with breast cancer, where Hedyotis diffusa and Jia-Wei-Xiao-Yao-San were the most commonly used herbal agents. In conclusion, our study provided information that western medicine therapy combined with CHM as an adjuvant modality may have a significant impact on liver protection in patients with breast cancer.

Background/purposeLimited evidence has been obtained on varicella-zoster virus (VZV) infection in patients with breast cancer as a complication related to adjuvant radiotherapy. We conducted a cohort study aimed to assess the risk of VZV infection in this patient setting.Materials and methodsWe used the National Health Insurance Research Database to identify 65,981 patients with breast cancer in Taiwan who underwent breast surgery between 2000 and 2011. After a 1:1 propensity score match was obtained between patients with and without radiotherapy, a competing risk regression model was constructed to estimate the hazard ratios and the incidence rate difference (IRD) of VZV infection in the patients with breast cancer receiving radiotherapy and those not receiving radiotherapy.ResultsAfter adjusting for covariates, the radiotherapy cohort showed a 1.51-fold higher risk (95% confidence interval = 1.06-5.16, p = 0.02, IRD = 4.98/10000 person-years) of subsequent VZV infection than the nonradiotherapy cohort. Furthermore, VZV infection risk was 3.85-fold higher among patients aged >65 years who received radiotherapy than among those of the same age who did not receive radiotherapy (95% confidence interval = 1.1-13.4, p < 0.05, IRD = 11.09/10000 person-years). The risk increased with adjusted hazard ratio of 6.6 (95% confidence interval I = 1.51-28.8, p < 0.05, IRD = 32.01/10,000 person-years) and 7.08 (95% confidence interval = 1.64-30.5, p < 0.01, IRD = 35.72/10,000 person-years) in follow-up period less than 3 months and 3-5 months respectively.ConclusionRadiotherapy was associated with an increased risk of VZV infection among patients with breast cancer. The risk was significantly higher in older patient (>65 years old) and/or those who received chemotherapy. Regular clinical follow-up and additional serological testing in the first 5 months after radiotherapy are recommended.