Insurance Service-National Sample Cohort Database Research Articles

Do statins benefit low-risk population for primary prevention of atherosclerotic cardiovascular disease: A retrospective cohort study.

The reported beneficial effects of statins on cardiovascular outcome based on risk assessment are inconsistent. Therefore, we investigated statin therapy effectiveness for the primary prevention of cardiovascular disease (CVD), according to the Korean Risk Prediction Model (KRPM). Subjects aged 40-79 years with low density lipoprotein cholesterol (LDL-C) of < 190 mg/dL and without CVD history were categorized as statin users or non-users using the National Health Insurance Service-National Sample Cohort (NHIS-NSC) database, Korea, 2002-2015. The 10-year atherosclerotic CVD (ASCVD) risk was calculated using the validated KRPM and categorized as low, borderline, intermediate, or high-risk groups; the incidence of major adverse cardiovascular events (MACEs) was compared over a mean follow-up period of 5.7 years using Cox proportional hazard models. The MACE incidence risk was decreased in statin users [hazard ratio (HR) 0.90, 95% confidence interval (CI) (0.84-0.98)]. However, there was an increased risk of MACE incidence in low-risk statin users [HR 1.80, 95% CI (1.29-2.52)], and no significant relationship was identified between statin use and MACE in the borderline [HR 1.15, 95% CI (0.86-1.54)] and intermediate-risk [HR 0.94, 95% CI (0.85-1.03)] groups. The risk of MACE incidence decreased only in the high CVD risk group among statin users. Statin use is not associated with MACE reduction in low- to intermediate-risk participants. Therefore, individuals with LDL-C level of < 190 mg/dL and low ASCVD risk should consider statin therapy only when CVD risk is proved obvious using an appropriate ASCVD risk tool.

Economic burden of opioid misuse focused on direct medical costs.

Background: Since their development, synthetic opioids have been used to control pain. With increased opioid use, problematic opioid prescription has also increased, resulting in a growing economic burden. However, there is a paucity of research studies on the economic burden of prescription opioid misuse in Asia, especially South Korea. Objectives: To estimate the incremental economic burden of prescription opioid misuse for the South Korean population. Methods: The National Health Insurance Service-National Sample Cohort database, covering 2% of the South Korean population between 2010 and 2015, was analyzed. Outpatients aged 18 or older who took one or more prescription opioids were selected. Based on their opioid prescription patterns, patients were classified into opioid misuse and non-misuse groups. The direct medical costs per person per year (PPPY) and the incremental economic burden of the opioid misuse group were explored using an exponential conditional model with a suitable distribution and log link function. All analyses were performed using SAS® Enterprise Guide version 9.4, and p < 0.05 was considered statistically significant. Results: The number of patients who had ≥1 opioid prescription was 345,020 including 84,648 (24.53%) in the opioid misuse group and 260,372 (75.47%) in the non-misuse group. The adjusted mean direct medical costs PPPY were estimated to be USD 401 for the opioid misuse group, which is 1.49 times significantly higher than that for the non-misuse group (p < 0.0001). The incremental economic burden of the opioid misuse group in the South Korean population was estimated to be approximately USD 0.52 billion for the period 2010-2015. Conclusion: Prescription opioid misuse was significantly associated with the increased economic burden. Along with proper policies for using opioids, it is necessary to monitor opioid prescription patterns to prevent opioid misuse and reduce the related economic burden.

Effects of tiotropium on the risk of coronary heart disease in patients with COPD: a nationwide cohort study

Inhaled long-acting muscarinic antagonist (LAMA) is recommended for the treatment of chronic obstructive pulmonary disease (COPD). However, there is still concern that LAMA may cause cardiovascular adverse events in COPD patients. Therefore, this study aimed to determine whether the administration of tiotropium, the first commercially available LAMA, could increase the risk of coronary heart disease (CHD) in COPD patients through a nationwide cohort study. We used the Korean National Health Insurance Service-National Sample Cohort (NHIS-NSC) database between 2002 and 2014 for the analysis. We applied a washout period of COPD diagnosis during 2002–2003 and excluded the patients who used an inhaler before the diagnosis of COPD. We also excluded patients who were diagnosed with CHD before inhaler use. Among a total of 5787 COPD patients, 1074 patients were diagnosed with CHD. In the Cox regression models with time-dependent tiotropium usage, we found that tiotropium significantly increased the risk of CHD in a subgroup of age ge hspace{0.17em}55 years compared to non-users of tiotropium (adjusted hazard ratio [aHR], 1.24; 95% confidence interval [CI], 1.003–1.54). When analyzed by dividing into tertiles (high/middle/low) according to the cumulative tiotropium exposure, the high tertile exposure group of tiotropium was associated with a higher risk of CHD compared with the low tertile exposure group of tiotropium. Additionally, the risk of CHD was higher in the high tertile exposure group of tiotropium in the age 55 and older group and in the never smoker group. When prescribing tiotropium for COPD patients, particularly those over 55 years of age and never-smokers, it is desirable to evaluate the risk of CHD in advance and closely follow-up for CHD occurrence.

Exposure to Long-Term Air Pollution and Incidence of Peripheral Arterial Disease in the General Population: A Korean National Population-Based Retrospective Cohort Study.

This study aimed to evaluate the causal relationship between long-term outdoor air pollutants and incidence of peripheral arterial disease (PAD) using the Korean National Health Insurance Service-National Sample Cohort (NHIS-NSC) database. We included 292,091 subjects from the general population who had previously not been diagnosed with PAD by the NHIS-NSC between 2008 and 2014. Hourly air pollutant data (particulate and gaseous) and climate data were collected. Correlation analysis of the collected data confirmed the relationship between air pollution and PAD incidence. For 1,836,965.4 person-years, incident cases of PAD were observed in 5243 subjects (285.4/100,000 person-years). In the Cox proportional hazard analysis, exposure to long-term average concentration of sulfur dioxide (SO2) [hazard ratio (HR), 1.686; (95% confidence interval (CI), 1.108-2.565) for .01ppm] and nitrogen dioxide (NO2) [HR, 1.200; (95% CI, 1.077-1.336) for .01 ppm] significantly increased the risk of PAD occurrence after the adjustment for several variables. This study demonstrated that SO2 and NO2 exposure are independent predictors of PAD.

Dyslipidemia Risk in Thyroid Cancer Patients: A Nationwide Population-Based Cohort Study.

ObjectiveThyroid cancer (TC) prevalence has been rapidly increasing. While the relationship between thyroid hormones and lipids has been widely investigated, studies regarding dyslipidemia in patients with TC have been scarce and controversial. We aimed to investigate dyslipidemia risk after TC diagnosis compared to the general population without TC.MethodA population-based prospective study was conducted using data from the Korean National Health Insurance Service-National Sample Cohort Database 2.0 (NHIS-NSC DB 2.0), with health insurance claim data of 1,108,369 subjects between 2002 and 2015. The final study sample comprised 466,735 adult subjects without TC or dyslipidemia diagnoses before the index year, 2009. Bidirectional analyses were performed using prospective and retrospective concepts. In the prospective analysis, Kaplan-Meier estimates were calculated and log-rank tests and univariable and multivariable Cox regression analyses were performed to determine the relationship between TC and dyslipidemia. The retrospective analysis involved 1:5 nested case-control matching based on dyslipidemia status and conditional logistic regression analysis.ResultsNo significant difference in dyslipidemia incidence was observed between TC patients and the control group, in either the prospective matched (log-rank P = 0.483) or non-matched (log-rank P = 0.424) analyses, or the retrospective analysis (P = 0.3724). In the prospective analysis, 193 patients after TC diagnosis showed similar risk of developing dyslipidemia with the 466,542 controls during the median 7 years of follow-up (unadjusted hazard ratio [HR], 1.102; 95% confidence interval [CI], 0.878-1.383; adjusted HR, 0.932; 95% CI, 0.707-1.230). Multiple propensity score-adjusted models showed similar results, and 114 patients and 570 matched controls showed an HR of 0.818 (95% CI, 0.598-1.120). In the retrospective comparison of dyslipidemia risk in 170 patients and 277,864 controls, the odds ratio was 0.822 (95% CI, 0.534-1.266).ConclusionsDyslipidemia risk was not significantly different between patients with TC and the general population, in both prospective and retrospective analyses.

Association between outdoor temperature and achilles tendon repair: A 14-years nationwide population-based cohort study

The incidence of achilles tendon rupture varies by gender, age, and seasonal variation. However, there has been no study as yet linking achilles tendon rupture to daily fluctuations in outdoor temperature. The purpose of this study was to investigate the association between outdoor temperature and achilles tendon rupture using a Korea Meteorological Administration database and a Korean National Health Insurance Service-National Sample Cohort database. Between 2002 and 2015, all instances of achilles tendon repair were retrieved from the National Health Insurance Service-National Sample Cohort database to examine sociodemographic factors, specifically sex, age, residential area, and income level. Minimum age requirement was 20 years. Outdoor temperatures recorded at 16 observation points in South Korea were also acquired from the Korea Meteorological Administration data center for analysis. Overall, 850 (0.119%) of 713,456 individuals in the National Health Insurance Service-National Sample Cohort database underwent achilles tendon repair between 2002 and 2015. Yearly procedural totals increased with advancing age, peaking at ages 30–39 years (14.6 per 100,000 persons) and declining thereafter. Minimum, median, and maximum outdoor temperatures were associated with achilles tendon repair (p<0.05), as did household income. In multivariate logistic regression analysis, outdoor temperatures, sex, age, and household income emerged as factors significantly associated with achilles tendon repair. Outcomes of this study confirm an association between incidence of achilles tendon repair and outdoor temperature, the latter denoting a novel index and likely surrogate measure of vigorous physical activity afforded by warmer weather.

Changes in the Frequency of Moderate-to-Vigorous Physical Activity and Subsequent Risk of All-Cause and Cardiovascular Disease Mortality.

We investigated the association of changes in the frequency of moderate-to-vigorous physical activity (MVPA) and the risks of all-cause and cardiovascular disease (CVD) mortality. This study used the nationally representative National Health Insurance Service-National Sample Cohort database. We included 286,402 individuals aged ≥20 years and estimated changes in the frequency of MVPA over a two-year period. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard regression models. The HRs (95% CIs) for the risk of all-cause and CVD mortality for an increased frequency of MVPA from physical inactivity compared with continual physical inactivity were 0.82 and 0.68 (0.73–0.92 and 0.51–0.91) for 1–2, 0.72 and 0.48 (0.62–0.84 and 0.31–0.74) for 3–4, and 0.73 and 0.70 (0.63–0.85 and 0.50–0.98) for ≥5 sessions of MVPA/week. The HRs (95% CIs) for the risk of all-cause and CVD mortality were 1.28 and 1.58 (1.07–1.53 and 1.01–2.46), 1.25 and 2.17 (1.01–1.57 and 1.14–4.12), and 1.43 and 1.44 (1.15–1.77 and 0.84–2.47) for changes from 1–2, 3–4, and ≥5 sessions of MVPA/week to physical inactivity, respectively. This study showed the beneficial effect of increasing physical activity, particularly for those who were physically inactive at baseline, as well as the increased risk of all-cause and CVD mortality after adapting a physically inactive lifestyle regardless of their baseline physical activity status.

Association Between Antihypertensive Use and Hospitalized Pneumonia in Patients With Stroke: A Korean Nationwide Population-Based Cohort Study.

BackgroundWe aimed to examine the association between antihypertensive use and the incidence of hospitalized pneumonia in patients with a history of stroke.MethodsIn this case-crossover study, we obtained data from the Korean National Health Insurance Service–National Sample Cohort database. We included the data of patients with history of stroke who were admitted with a disease code of pneumonia. We analyzed the patients’ exposure to antihypertensives in the 30 (single case period), 90–120, and 150–180 days (2 control periods) before the onset of pneumonia using conditional logistic regression analysis. Additionally, sensitivity analysis and subgroup analysis according to diabetes status, age, and documented disability were performed.ResultsAngiotensin II receptor blocker (ARB) use was associated with a reduced risk of hospitalized pneumonia (adjusted odds ratio [OR] [95% confidence interval; 95% CI]: 0.718 [0.576–0.894]). However, the use of angiotensin converting enzyme inhibitors and other antihypertensives were not associated with a change in hospitalized pneumonia incidence (adjusted OR [95% CI]: 0.902, [0.603–1.350] and 0.788 [0609–1.018], respectively). Subgroup analysis revealed that ARB use was associated with a reduced incidence of hospitalized pneumonia in patients with a history of stroke who were older than 65 years, but not in younger (≤ 65 years) group (adjusted OR [95% CI]: 0.687 [0.536–0.880]).ConclusionARB use is associated with a reduced incidence of hospitalized pneumonia in patients with a history of stroke, especially in older adults.

Effects of early medication treatment and metformin use for cancer prevention in diabetes patients: a nationwide sample cohort study in Korea using extended landmark time analysis.

OBJECTIVESThis study investigated the effectiveness of early medication treatment and metformin use for cancer prevention in type 2 diabetes patients.METHODSPopulation-based cohort data were used from the Korean National Health Insurance Service-National Sample Cohort database (KNHIS-NSC) for 2002–2013. Patient-specific medication prescription status was defined by the landmark time (LMT; a fixed time after cohort entry), considering both pre- and post-LMT prescriptions to control methodological biases in observational research. The LMT was set to 2 years. Logistic regression analysis with multivariable adjustment was conducted to analyze cancer incidence by patient-specific medication prescription status.RESULTSOnly 33.4% of the subjects were prescribed medication early (before the LMT) with compliance. Cancer incidence in individuals with early prescription and compliance was 25% lower (odds ratio [OR], 0.75; 95% confidence interval [CI], 0.67 to 0.84) than in those without. As early-prescribed medications, metformin monotherapy and metformin combination therapy were associated with 34% (OR, 0.66; 95% CI, 0.51 to 0.83) and 25% (OR, 0.75; 95% CI, 0.64 to 0.88) lower cancer risk than non-use, respectively. Patients who were prescribed late (post-LMT) but did not comply with the prescription had a 24% (OR, 1.24; 95% CI, 0.97 to 1.58) higher cancer incidence than non-users. Among patients who started monotherapy early without changes throughout the entire follow-up period, those who started on metformin had a 37% (OR, 0.63; 95% CI, 0.41 to 0.99) lower risk of cancer than non-metformin users.CONCLUSIONSDoctors must prescribe antidiabetic medication early, and patient compliance is required, regardless of the prescription time, to prevent cancer. Metformin monotherapy or combination therapy is recommended as an early prescription.

Risk of fracture in antidepressant users with concurrent use of benzodiazepines: A self-controlled case-series analysis.

Despite the fracture risk associated with both antidepressant (AD) medication and benzodiazepines (BDZs), they are commonly prescribed simultaneously. However, studies elucidating the effects of concurrent use of BDZs and ADs on the risk fracture are scant. The objective of this study was to evaluate the risk of fracture associated with concurrent use of BDZs in AD users, using a self-controlled case-series analysis. A self-controlled case-series analysis, in which the participants act as their own control, was conducted using the Korean National Health Insurance Service-National Sample Cohort database (2002-2015). We studied AD users who were prescribed BDZs and diagnosed with a fracture. The risk periods were subdivided into consecutive periods (1-30, 31-60, and>60days) after receiving a BDZ. A 2-week pre-exposure period and a 2-week post-exposure period were also included. The incidence rate ratio (IRR) was estimated after adjusting for age and use of co-medications. A total of 3020 patients were identified during the study period. There was an increased fracture risk in the first 30days following BDZ use (IRR: 1.88, 95% confidence interval [CI] 1.66-2.12), in the 31-60-day period (1.73, 95% CI 1.48-2.02), and beyond the 60-day period (IRR: 1.68, 95% CI 1.47-1.91). The risks of fracture were greater in men and older patients. The concomitant use of BDZs and ADs was related to a significant increase in fracture risk. AD users should be aware of the fracture risk with concomitant BDZ use, especially for first-time BDZ users and for elderly patients.

Risk of Stroke or Acute Myocardial Infarction in Subconjunctival Hemorrhage: A Nationwide Cohort Study

ABSTRACT Purpose To investigate whether subconjunctival hemorrhage (SCH) raises the risk of subsequent stroke or acute myocardial infarction (AMI) in the general population. Methods Using the National Health Insurance Service-National Sample Cohort database records from 2002 to 2013. Of 1,025,340 individuals in the database, we included 703,090 aged ≥ 20 years old without any history of SCH, cerebrovascular diseases, and ischemic heart diseases in the analyses. Of these, we identified 46,251 cases of incident SCH and regarded it as a time-varying covariate. We performed sensitivity analyses using 1:4 propensity score (PS)-based matched controls. To adjust for potential confounders, we investigated Cox regression models using defined demographic information, comorbidities, co-medications, and the Charlson Comorbidity Index score. Results The SCH group showed higher incidence probability of stroke or AMI than the general population (3.17% versus 2.71%, respectively; p < .001); however, when compared to the PS-based matched controls, there was no difference (3.17% versus 3.03%, respectively; p = .76). Time-varying covariate Cox regression analyses without adjusting for confounders showed that SCH was associated with increased risk of subsequent stroke or AMI; however, after adjusting for confounders, SCH did not increase the risk of stroke or AMI. Conclusion This population-based cohort study showed that SCH itself is not a risk factor for stroke or AMI. Clinicians could reassure patients with SCH that it would not increase the risk for stroke or AMI. We recommend attentive evaluation of underlying diseases for patients with SCH for identifying risk factors of stroke or AMI.

CLINICAL IMPACT OF HORMONE REPLACEMENT THERAPY ON LONE ATRIAL FIBRILLATION IN POSTMENOPAUSAL WOMEN: A NATIONWIDE COHORT STUDY

Individuals with atrial fibrillation (AF), especially women, have an increased risk of stroke and death. Hormone replacement therapy (HRT) is widely used to control symptoms of menopause and treat osteoporosis in postmenopausal women. However, the association between HRT use and AF risk has been scarcely explored. Thus, we aimed to investigate the association between various types of HRT and lone AF in a national cohort of Korean menopausal women. In total, 21,023 women enrolled in the Korean National Health Insurance Service-National Sample Cohort database were included. Participants were aged 45–60 years and were free from cardiovascular disease and AF at baseline. For analysis, participants were classified into groups of HRT never users, past users, and current users, and subgroup analysis was performed according to the specific type of HRT. In the overall population, 13,458 (64.02%) women never received HRT, 5,685 (27.04%) had received HRT previously, and 1,880 (8.94%) were currently receiving HRT. In multivariable analysis, the relative hazards for AF were higher among HRT current users (hazard ratio [HR]: 1.86; 95% confidence interval [CI]: 1.26-2.75; p=0.002) and significantly lower among HRT past users (HR: 0.73; 95% CI: 0.56-0.95; p=0.021). For current users, an increased AF risk was observed for all HRT users except for estradiol-only HRT users (HR: 1.25, 95% CI: 0.40-3.90, p=0.703). For past users, reduced AF risk was observed in estradiol plus progestin HRT (comparison: HRT never users) after adjusting for covariates (HR: 0.62; 95% CI: 0.39-0.97; p=0.038). We observed that ongoing HRT posed an increased risk of AF. The degree of AF risk varied based on the specific type of estrogen and whether progestins were co-administered. These data support the assertion that HRT containing estradiol is more beneficial than other types of HRT in terms of AF risk.

Trends in Dental Sedation of Korean Children and Adolescents

The purpose of this study was to investigate trends in dental sedation of Korean children and adolescents. A retrospective study was conducted on patients under 20 years of age who received dental treatment under sedation using National Health Insurance Service-National Sample Cohort Database from 2002 to 2015. Based on the 1 million standard data, there were 436 cases of dental treatment under sedation in 2002, but 4002 cases in 2015, showing a trend increasing every year. The 3 - 5 year old group accounted for the largest portion (54.2%), while the 6 - 8 year old group increased recently. Nitrous oxide inhalation sedation is the most commonly used, accounting for 45.9% in 2002, but increased to 89.5% in 2015. Combination of nitrous oxide inhalation sedation, chloralhydrate and hydroxyzine was the most common, accounting for 5.7% in 2002, but decreased to 2.9% in 2015. There is a trend to use the sedation method more safely and in a way that reduces side effects.

Exposure to air pollution and incidence of atopic dermatitis in the general population: A national population-based retrospective cohort study

To date, little evidence is available to determine whether atopic dermatitis (AD) can be caused by exposure to air pollutants, including gases and particulate matter. We aimed to evaluate the relationship between air pollutants and incidence of AD using the National Health Insurance Service-National Sample Cohort database. We included 209,168 subjects from the general population previously not diagnosed with AD between 2008 and 2013. Long-term average concentration of air pollutants before diagnosis was calculated for each subject. For 1,030,324 person-years, incident cases of AD were observed in 3203 subjects. There was a significant positive association between incidence of AD and long-term average concentration of particulate matter smaller than 2.5μm in diameter (hazard ratio [HR], 1.420; 95% CI, 1.392-1.448; for 1μg/m3), particulate matter smaller than 10μm in diameter (HR, 1.333, 95% CI, 1.325-1.341; for 1μg/m3), sulfur dioxide (HR, 1.626; 95% CI, 1.559-1.695; for 1parts per billion), nitrogen dioxide (HR, 1.200; 95% CI, 1.187-1.212; for 1parts per billion), and carbon monoxide (HR, 1.005; 95% CI, 1.004-1.005; for 1parts per billion) after adjusting for age, sex, income, comorbid diseases, and meteorologic variables. The National Health Insurance Service database lacks detailed information on individual subjects. This study demonstrated that long-term exposure to air pollutants, including gases and particulate matter, is an independent risk factor for developing AD.

Risk of Fractures in Older Adults with Chronic Non-cancer Pain Receiving Concurrent Benzodiazepines and Opioids: A Nested Case-Control Study.

The aim of this study was to investigate the relationship between the concurrent use of benzodiazepines and opioids and the risk of fractures in older patients with chronic non-cancer pain. Patients with osteoarthritis or low back pain (≥ 65 years of age) included in the Korean National Health Insurance Service-National Sample Cohort database of Korea and with an incident diagnosis of hip, humeral, or forearm fracture between 2011 and 2015 were identified as cases. For each case, four controls were matched for age (within 5 years), sex, and year of cohort entry. We estimated the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for fractures associated with concurrent use of benzodiazepines and opioids usinga conditional logistic regression analysis, adjusting for comorbidities and comedications. The aOR (95% CI) for the concurrent use of benzodiazepines and opioids was 1.45 (1.22-1.71), compared with those of non-use within 30 days before the index date. The aOR was 1.65 (1.22-2.23) in patients who were continuously receiving benzodiazepines and were newly initiated with concurrent opioids. The aORs for concurrent use were 1.95 (1.39-2.74) and 1.27 (1.03-1.56) in the case of hip fracture and forearm fracture, respectively. The concurrent use of benzodiazepines and opioids was associated with an increased risk of fractures in older patients with chronic non-cancer pain. Therefore, patients continuously receiving benzodiazepines in whom opioids are newly initiated need careful monitoring, and such combined therapy should be limited to the shortest duration possible.

Association between Meniere\u2019s disease and air pollution in South Korea

Meniere’s disease is thought to be a disorder of the inner ear function, affected by genetic and environmental factors. Several recent studies have shown that air pollution could affect middle and inner ear diseases. The purpose of this study was to investigate the relationship between the Meniere’s disease occurrence and air pollution status in Korea. This study used a time-stratified case-crossover design. Hospital visit data by Meniere’s disease were collected from the Korea National Health Insurance Service-National Sample Cohort (NHIS-NSC) database. Daily air pollution data for sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and particulate matter (PM10: ≤ 10 μm in diameter, and PM2.5: ≤ 2.5 μm in diameter) were collected from the National Ambient air quality Monitoring Information System (NAMIS) database. We used two-stage analysis to assess the association between degree of air pollution and the occurrence of Meniere’s disease. In the first stage, region-specific analysis was conducted to estimate the odds ratios (ORs) of Meniere’s disease risk associated with each air pollutant exposure by using conditional logistic regression for matched case–control sets in 16 regions. In the second stage, region-specific ORs from the first stage were combined and the pooled effect estimates were derived through fixed and random effect meta-analysis. Subgroup analysis was conducted for age, sex, seasonality, and urbanization of residence. In total, 29,646 (32.1% males and 67.9% females) Meniere’s disease cases were identified from Korea NHIS-NSC database between 2008 and 2015. Overall, SO2, NO2, CO, and PM10 showed significant correlation with Meniere’s disease risk at immediate lags, and weaker correlation at delayed lags, whereas O3 showed slightly negative correlation at the immediate lag (lag0) and PM2.5 did not show strong correlation (SO2: 1.04 [95% confidence interval: 1.01, 1.06]; NO2: 1.08 [1.06, 1.11]; CO: 1.04 [1.02, 1.06]; O3: 0.96 [0.93, 0.99]: statistically significant ORs at lag0 are listed). These positive and negative associations between Meniere’s disease and each air pollutant were generally stronger in the age of 40–64, female, summer (June–August) season, and urban subgroups. Our results showed that hospital visits for Meniere’s disease were associated with the measured concentrations of ambient air pollutants SO2, NO2, CO, and PM10. Further studies are required to confirm these associations and find their mechanisms.

Association between Skin Cancer and Systemic and Ocular Comorbidities in South Korea.

Background: In this study, we investigated the associations between various systemic and ocular comorbidities and skin cancer, in a nationwide cohort of South Koreans. Method: We reviewed the data of 1,103,302 individuals in the South Korean National Health Insurance Service-National Sample Cohort database from 2002 to 2015. Of these, 1202 individuals diagnosed with skin cancer from 2004 were included in the study group. The control group was matched in a 1:5 ratio based on propensity scores. Results: The prevalence rates of melanoma and non-melanoma skin cancer increased from 2004 to 2015. Multivariate logistic regression analysis revealed that, among the various systemic conditions, hypertension was significantly associated with skin cancer, while among ocular comorbidities, macular degeneration showed a significant association with skin cancer. Conclusions: This is the first study to demonstrate associations between skin cancer and various systemic and ocular comorbidities. The results suggest that hypertension and macular degeneration may increase the risk of skin cancer development, or vice versa. Further studies are needed to evaluate the causal relationships between these conditions.

Impact of comorbidity assessment methods to predict non-cancer mortality risk in cancer patients: a retrospective observational study using the National Health Insurance Service claims-based data in Korea

BackgroundCancer patients’ prognoses are complicated by comorbidities. Prognostic prediction models with inappropriate comorbidity adjustments yield biased survival estimates. However, an appropriate claims-based comorbidity risk assessment method remains unclear. This study aimed to compare methods used to capture comorbidities from claims data and predict non-cancer mortality risks among cancer patients.MethodsData were obtained from the National Health Insurance Service-National Sample Cohort database in Korea; 2979 cancer patients diagnosed in 2006 were considered. Claims-based Charlson Comorbidity Index was evaluated according to the various assessment methods: different periods in washout window, lookback, and claim types. The prevalence of comorbidities and associated non-cancer mortality risks were compared. The Cox proportional hazards models considering left-truncation were used to estimate the non-cancer mortality risks.ResultsThe prevalence of peptic ulcer, the most common comorbidity, ranged from 1.5 to 31.0%, and the proportion of patients with ≥1 comorbidity ranged from 4.5 to 58.4%, depending on the assessment methods. Outpatient claims captured 96.9% of patients with chronic obstructive pulmonary disease; however, they captured only 65.2% of patients with myocardial infarction. The different assessment methods affected non-cancer mortality risks; for example, the hazard ratios for patients with moderate comorbidity (CCI 3–4) varied from 1.0 (95% CI: 0.6–1.6) to 5.0 (95% CI: 2.7–9.3). Inpatient claims resulted in relatively higher estimates reflective of disease severity.ConclusionsThe prevalence of comorbidities and associated non-cancer mortality risks varied considerably by the assessment methods. Researchers should understand the complexity of comorbidity assessments in claims-based risk assessment and select an optimal approach.

Risk of early mortality and cardiovascular disease according to the presence of recently diagnosed diabetes and requirement for insulin treatment: A nationwide study.

Aims/IntroductionWe estimated the hazards of cardiovascular diseases (CVDs) and early all‐cause mortality in Korean adults according to the presence of recently diagnosed type 2 diabetes (type 2 diabetes for <5 years) and insulin use.Materials and MethodsWe used the Korean National Health Insurance Service–National Sample Cohort database (2002–2015) for this longitudinal population‐based study. Among adults aged ≥40 years without baseline CVD, individuals without diabetes or with recently diagnosed type 2 diabetes were selected (N = 363,919). The hazard ratios (HRs) for myocardial infarction (MI), stroke, and all‐cause mortality during follow‐up were analyzed according to three groups categorized by the presence of type 2 diabetes and insulin use.ResultsWithin a mean 7.8 years, there were 5,275 MIs, 7,220 strokes, and 15,834 deaths. The hazards for outcomes were higher in the insulin‐treated type 2 diabetes group than in the non‐diabetes group [HR (95% CI): 2.344 (1.870–2.938) for MI, 2.420 (1.993–2.937) for stroke, and 3.037 (2.706–3.407) for death], higher in the non‐insulin‐treated type 2 diabetes group than in the non‐diabetes group [HR (95% CI): 1.284 (1.159–1.423) for MI, 1.435 (1.320–1.561) for stroke, and 1.135 (1.067–1.206) for death], and higher in the insulin‐treated type 2 diabetes group than in the non‐insulin‐treated type 2 diabetes group [HR (95% CI): 1.914 (1.502–2.441) for MI, 1.676 (1.363–2.060) for stroke, and 2.535 (2.232–2.880) for death].ConclusionsRecently diagnosed type 2 diabetes patients showed increased risks of incident CVDs and premature mortality, and insulin‐treated group demonstrated an additional increase in the risks of these outcomes in adults with recently diagnosed type 2 diabetes, suggesting the need for intensified cardio‐protective interventions for adults with insulin‐treated type 2 diabetes.

Prevalence of Intracranial Aneurysm in Patients With Aortic Disease in Korea: A Nationwide Population-Based Study.

BackgroundPatients with aortic disease (AD) might have a higher prevalence of intracranial aneurysm (IA). The present study evaluated the prevalence of IA in patients with AD and identified potential risk factors of IA using nationwide representative cohort sample data.Methods and ResultsWe defined AD as both aortic dissections and aortic aneurysms. This study used a nationwide representative cohort sample from the Korea National Health Insurance Service–National Sample Cohort database from 1.1million patients. Using χ 2 or Fisher’s exact tests, the prevalence of the IA in patients with AD and potential risk factors for their concurrence were analyzed. The prevalence of IA in patients with AD was 6.8% (155/2285). The adjusted odds ratios (OR) for having concurrent IA in patients with AD was 3.809 (95% CI, 3.191–4.546; P<0.01). Patients with AD and hypertension were >19 times more likely to be affected by IA (adjusted OR, 18.679; 95% CI, 16.555–21.076; P<0.01). Patients with AD and diabetes mellitus, old age (>60 years), and male sex were >4, 3, and 2 times more likely to be affected by IA, respectively (adjusted OR, 4.291, 3.469, and 1.983, respectively; 95% CI, 3.914–4.704, 3.152–3.878, and 1.779–2.112, respectively). Subgroup analysis with socioeconomic status or disability revealed that the prevalence of IA was significantly higher in all groups.ConclusionsIn the current population‐based study, the prevalence of IA in patients with AD was quadrupled compared with that in the general population. Early IA screening might be considered among patients with AD for appropriate management.