BACKGROUND AND OBJECTIVES: The incidence and prevalence of hyperthyroidism has been reported to be 0.2-0.9/1000 population/year and 5-10/1000 population in foreign countries, respectively. However, there has been no nationwide survey to evaluate them in Korea. Therefore, this study was conducted to investigate the incidence and prevalence of hyperthyroidism in Korea using medicare claims data provided by the Health Insurance Review and Assessment Service. Preference for its therapeutic modalities and its change were also analyzed. MATERIALS AND METHODS: This study was performed in 308,584 (men 86,460, women 222,124) Korean patients with hyperthyroidism treated from January 2006 to June 2012. Patients with past history of hyperthyroidism were not included. RESULTS: The incidence of hyperthyroidism was 0.72/1000 population/year (men 0.40, women 1.03), and its prevalence was 3.40/1000 population (men 2.09, women 4.70) in Korea. Its peak prevalence was detected between 45 and 49 years of age. Among 177,487 patients with hyperthyroidism treated from 2007 to 2011, anti-thyroid drugs were prescribed in 97.9%, and radioiodine therapy and surgery were finally performed in 8.2% and 0.9%, respectively. The prescription of propylthiouracil (PTU) has been reduced from 63.3% in 2007 to 42.9% in 2011, but the use of methimazole (MMI) increased from 33.9% in 2007 to 54.8% in 2011. Primary physicians preferred PTU to MMI, but physicians in general hospitals preferred MMI to PTU. CONCLUSION: This is the first nationwide report to investigate the incidence and prevalence of hyperthyroidism in Korea.
Female ; Hospitals, General ; Humans ; Hyperthyroidism ; Incidence ; Insurance, Health ; Korea ; Medicare ; Methimazole ; Prescriptions ; Prevalence ; Propylthiouracil

BACKGROUND: Epidemiology studies suggest that oral bisphosphonate may increase the risk of esophageal cancer. The present study aimed to investigate the association between exposure of oral bisphosphonate and risk of esophageal cancer. METHODS: Using the nationwide medical claim database in South Korea, 2,167,955 subjects, who initiated osteoporosis treatment (oral bisphosphonate, intravenous bisphosphonate or raloxifene) or performed dual energy X-ray absorptiometry (DXA) between 2008 and 2012, were analyzed. Diagnosis of esophageal cancer was estimated from medical claim database. Standardized incidence ratio (SIR) was estimated by comparing with incidence in the general population. Cox proportional hazards modeling was used to investigate age-adjusted hazard ratio (aHR) of esophageal cancer. RESULTS: The present study included oral bisphosphonate group (N=1,435,846), comparator group 1 (intravenous bisphosphonate or raloxifene, N=78,363) and comparator group 2 (DXA, N=653,746). Mean age was 65.6+/-8.8 years and mean observation duration was 30.9+/-17.7 months. During 5,503,688 patient-years, 205 esophageal cancer incidences were observed. The annual incidence of esophageal cancer was 3.88, 4.21, and 3.30 for oral bisphosphonate group, comparator group 1 and comparator group 2, respectively. SIR of esophageal cancer was 1.24, 1.38, and 1.40 for oral bisphosphonate group, comparator group 1 and comparator group 2, respectively. Esophageal cancer risk of oral bisphosphonate group was not significantly different from comparator group 1 and comparator group 2 (aHR 0.87; 95% confidence interval [CI] 0.39-1.98 and aHR 0.94; 95% CI 0.68-1.30, respectively). CONCLUSIONS: The use of oral bisphosphonate was not associated with increased risk of esophageal cancer in real clinical practice using large scale nationwide database.
Absorptiometry, Photon ; Diagnosis ; Epidemiology ; Esophageal Neoplasms* ; Incidence ; Korea ; Osteoporosis ; Proportional Hazards Models ; Raloxifene Hydrochloride

OBJECTIVE: Adult onset Still s disease is an acute systemic inflammatory disorder. There are no pathognomonic symptoms or specific laboratory abnormalities. In recent reports, serum ferritin concentration is increased in active disease phase and decreased after defervescence. Our purpose was to determine the clinical significance of serum ferritin as an indicator for disease activity. METHODS: Seven patients who were diagnosed as adult onset Still s disease at Samsung Medical Center between October 1994 and March 1997, were reviewed. In these patients we checked leukocyte count, ESR, CRP and serum ferritin concentrations at the time of diagnosis and during follow-up periods and recorded febrile events during follow-up periods. RESULTS: At the time of diagnosis and during febrile periods, the concentrations of ferritin were extremely high(927ng/ml to 96,650ng/ml normal 10-290.8 ng/ml). The values were unrelated to other manifestations of the disease or laboratory findings. The ferritin concentrations decreased rapidly after adequate treatment. Eleven febrile reattacks happened in 7 patients. Serum ferritin concentrations were increased in 8 febrile attacks, while leukocyte count, ESR, and CRP were increased in 5, 5, 6 febrile attacks respectively, There were 10 events of increased serum ferritin concentrations in 7 patients during follow-up periods and 8 events were related with fever. The increases of other laboratory tests were similar. CONCLUSIONS: In all patients, serum ferritin concentrations were increased at the time of diagnosis and closely related to fever. During follow-up periods, serum ferritin concentrations are helpful in monitoring disease activity and guiding decisions about treatment.
Adult* ; Diagnosis ; Ferritins* ; Fever ; Follow-Up Studies ; Humans ; Leukocyte Count ; Still's Disease, Adult-Onset*

BACKGROUND AND OBJECTIVES: The incidence of thyroid cancer has been increasing in Korea as well as in other countries. The majority of thyroid cancers are papillary thyroid carcinomas and follicular thyroid carcinomas, both of which are classified as differentiated thyroid carcinoma (DTC). Total or near-total thyroidectomy followed by administration of radioactive iodine (RAI) constitutes the initial treatment for DTC. This study was conducted to investigate the therapeutic modalities of surgery and RAI for the treatment of DTC in Korea using claims data provided by the Health Insurance Review and Assessment Service. MATERIALS AND METHODS: This study was performed in 170,131 (men 29,002, women 141,129) Korean patients with thyroid cancer treated from January 2008 to December 2012. Patients with past history of thyroid cancer prior to 2008 were not included. RESULTS: Total or near total thyroidectomy was done in 83.4%, lobectomy in 14.4%, and subtotal thyroidectomy in 2.2%. Postoperative RAI treatment was performed in 52.7%. Median 100 mCi of RAI was administered at median 89 days after operation, and it was completed with one dose in 66.0%. Thirty mCi was mostly preferred as an initial dose in 35.6%, and subsequently 150 mCi in 25.7%, 100 mCi in 17.5%, and more than 150 mCi in 10.1%. Median cumulative RAI dose was 130 mCi. RAI treatment rate was decreasing during recent 5 years. CONCLUSION: This is the first nationwide report to investigate the therapeutic modalities of surgery and RAI for the treatment of DTC in Korea.
Adenocarcinoma, Follicular ; Female ; Humans ; Incidence ; Insurance, Health ; Iodine ; Korea ; Thyroid Gland ; Thyroid Neoplasms* ; Thyroidectomy

BACKGROUND: The incidence and prevalence of overt hypothyroidism have been reported to be 2 to 4/1,000 population/year and 8 to 13/1,000 population, respectively, in foreign countries. As there has been no nationwide survey to obtain data in Korea, the present study investigated the incidence and prevalence of overt hypothyroidism in Korea using claims data provided by the Health Insurance Review and Assessment Service. The proportions of causative diseases for hypothyroidism were also analyzed. METHODS: This study was retrospectively performed with 541,969 Korean patients (92,832 men and 449,137 women), with overt hypothyroidism, treated with thyroid hormone between 2008 and 2012. RESULTS: The incidence of overt hypothyroidism in Korea was 2.26/1,000 population/year (0.78 in men and 3.72 in women), and the prevalence was 14.28/1,000 population (4.40 in men and 24.03 in women). When patients with thyroid cancer were excluded, the incidence was 1.56/1,000 population/year (0.54 in men and 2.57 in women). The incidence increased with age, with peaks in and after the late 60s in men and in the early 50s in women. The prevalence peaked in the early 70s in men and in the late 50s in women. CONCLUSION: This is a report of the first nationwide investigation of the incidence and prevalence of overt hypothyroidism in Korea, although it is limited to patients treated with thyroid hormone.
Female ; Humans ; Hypothyroidism* ; Incidence* ; Insurance, Health* ; Korea* ; Male ; Prevalence* ; Retrospective Studies ; Thyroid Gland ; Thyroid Neoplasms

BACKGROUND: Alpha-blocker can result in falling and fractures because of adverse effect such as orthostatic hypotension due to vasodilatory effect. We investigated the association between the alpha-blocker and the risk of osteoporotic hip fractures using a nationwide claim database. METHODS: We identified 1,051,651 men 65 years of age or older who had prescription records of alpha-blocker from nationwide medical claim database, from 2007 to 2012. Alpha-blockers were classified as non-specific general (NSG), non-specific slow-release (NSSR), uro-specific general (USG), and uro-specific slow release (USSR). RESULTS: Total of 6,553 hip fractures were observed. The incidences of hip fracture within 1 year were higher than those of the reference periods in all type of alpha-blocker. Hazard ratio peaked at early period of alpha-blocker, and decreased with time, regardless of type of alpha-blocker. CONCLUSIONS: Use of alpha-blocker is associated with increased risk of hip fracture, especially in early use.
Hip ; Hip Fractures* ; Humans ; Hypotension, Orthostatic ; Incidence ; Male ; Prescriptions ; Registries

PURPOSE: Gallstone formation is one of the most common problems after gastrectomy. This retrospective cohort study used the South Korean nationwide claims database to evaluate the incidence and risk factors of gallstone after gastrectomy for gastric cancer. METHODS: All consecutive patients who underwent gastrectomy for gastric cancer in South Korea in 2008–2010 were identified. Incidence of gallstone formation 5 years after gastrectomy in males and females, in various age groups, and after different types of gastrectomy was determined. Multivariate logistic regression analysis served to identify gallstone risk factors. RESULTS: Of the 47,752 patients, 2,506 (5.2%) developed gallstone during the 5-year follow-up period. At 12, 24, 36, and 48 months, the cumulative incidences were 1.2%, 2.2%, 3.3%, and 4.3%, respectively. Males had a higher incidence than females (5.8% vs. 4.1%, P < 0.001). Older patients (60–89 years) had a higher incidence than younger patients (30–59 years) (6.1% vs. 4.3%, P < 0.001). Gallstone was most common after total gastrectomy (6.6%), followed by proximal gastrectomy (5.4%), distal gastrectomy (4.8%), and pylorus-preserving distal gastrectomy (4.0%) (P < 0.001). Multivariate analysis showed that male sex (odds ratio [OR], 1.39), an older age (OR, 1.44), and total gastrectomy (OR, 1.40 vs. distal gastrectomy) were significant independent risk factors for postgastrectomy gallstone. CONCLUSION: The cumulative incidence of gallstone 5 years after gastrectomy for gastric cancer was 5.2%. Male sex, an older age, and total gastrectomy were significant risk factors. More careful monitoring for gallstone may be necessary in patients with such risk factors.
Cholecystectomy ; Cohort Studies ; Female ; Follow-Up Studies ; Gallstones* ; Gastrectomy ; Humans ; Incidence* ; Korea ; Logistic Models ; Male ; Multivariate Analysis ; Retrospective Studies ; Risk Factors ; Stomach Neoplasms*

Liver function tests before treatment showed abnormalities of liver function tests during treatment, while 15(68. 2%) of 22 patients who had abnormal liver function tests before treatment showed abnormalities during treatment. In 12 of the 25 patients who showed abnormalities of liver function tests during treatment with allopurinol, allopurinol was stopped and all patients showed improvement of liver function tests. In remaining 13 patients, 10 patients were improved and other 2 patients showed only mild abnormalities of liver function tests despite of continuing allopurinol and 1 patient was lost during follow-up. CONCLUSION: Abnormalities of liver function tests were common during treatment with allopurinol. Most patiensts who had mild abnormalities of liver functions tests during treatment with allopurinol were improved regardless of continuing allopurinol.
Allopurinol* ; Follow-Up Studies ; Gout* ; Humans ; Liver Function Tests* ; Liver*

Background: The occurrence of hepatocellular carcinoma (HCC) is a major concern during antiviral therapy for chronic hepatitis B. There are conflicting opinions regarding the effects of entecavir (ETV) and tenofovir disoproxil fumarate (TDF) on HCC prevention. We assessed these two antiviral medications for preventing HCC in treatment-naïve patients with chronic hepatitis B. Methods: We conducted a retrospective cohort study using nationwide claims data from the Korea Health Insurance Review and Assessment Service. We included 55,473 treatmentnaïve adult cases where ETV or TDF treatment was started between 2013 and 2017 (cohort 1).The ETV and TDF groups were matched 1:2 based on age, sex, comorbidities, hospital type, and index date year. Patients were followed up until December 2018. The outcome was the development of HCC. Subgroup analyses were conducted according to sex, age, hospital type and the presence of cirrhosis. We also compared the outcomes of patients who had started antiviral therapy during the 2012–2014 period (cohort 2). Results: The matched participants (18,491 in the ETV and 36,982 in the TDF groups) were a part of the study for, on average, 41.2 months. The incidence of HCC did not differ significantly between the ETV (1.46 per 100 patient-years) and the TDF (1.36 per 100 patient-years) treatments (hazard ratio, 0.93; 95% confidence interval, 0.86–1.01; P = 0.081). By contrast, HCC incidence was significantly higher in the ETV group than tenofovir group of cohort 2. Conclusion In patients with chronic hepatitis B, the ETV treatment did not result in a higher rate of HCC than the TDF treatment.

Background: The occurrence of hepatocellular carcinoma (HCC) is a major concern during antiviral therapy for chronic hepatitis B. There are conflicting opinions regarding the effects of entecavir (ETV) and tenofovir disoproxil fumarate (TDF) on HCC prevention. We assessed these two antiviral medications for preventing HCC in treatment-naïve patients with chronic hepatitis B. Methods: We conducted a retrospective cohort study using nationwide claims data from the Korea Health Insurance Review and Assessment Service. We included 55,473 treatmentnaïve adult cases where ETV or TDF treatment was started between 2013 and 2017 (cohort 1).The ETV and TDF groups were matched 1:2 based on age, sex, comorbidities, hospital type, and index date year. Patients were followed up until December 2018. The outcome was the development of HCC. Subgroup analyses were conducted according to sex, age, hospital type and the presence of cirrhosis. We also compared the outcomes of patients who had started antiviral therapy during the 2012–2014 period (cohort 2). Results: The matched participants (18,491 in the ETV and 36,982 in the TDF groups) were a part of the study for, on average, 41.2 months. The incidence of HCC did not differ significantly between the ETV (1.46 per 100 patient-years) and the TDF (1.36 per 100 patient-years) treatments (hazard ratio, 0.93; 95% confidence interval, 0.86–1.01; P = 0.081). By contrast, HCC incidence was significantly higher in the ETV group than tenofovir group of cohort 2. Conclusion In patients with chronic hepatitis B, the ETV treatment did not result in a higher rate of HCC than the TDF treatment.