Development of an algorithm for identifying rheumatoid arthritis in the Korean National Health Insurance claims database

A novel method to monitor rheumatoid arthritis prevalence using hospital and medication databases

BACKGROUND

Most estimates of rheumatoid arthritis (RA) prevalence, including all official figures in Australia and many other countries, are based on self-report. Self-report has been shown to overestimate RA, but the 'gold standard' of reviewing individual medical records is costly, time-consuming and impractical for large-scale research and population monitoring. This study provides an algorithm to estimate RA cases using administrative data that can be adjusted for use in multiple contexts to provide the first approximate RA cohort in Australia that does not rely on self-report.

METHODS

Survey data on self-reported RA and medications from 25 467 respondents of the Australian Longitudinal Study on Women's Health (ALSWH) were linked with data from the national medication reimbursement database, hospital and emergency department (ED) episodes, and Medicare Benefits codes. RA prevalence was calculated for self-reported RA, self-reported RA medications, dispensed RA medications, and hospital/ED RA presentations. Linked data were used to exclude individuals with confounding autoimmune conditions.

RESULTS

Of 25 467 survey respondents, 1367 (5·4%) women self-reported disease. Of the 26 840 women with hospital or ED presentations, 292 (1·1%) received ICD-10 codes for RA. There were 1038 (2·8%) cases by the medication database definition, and 294 cases (1·5%) by the self-reported medication definition. After excluding individuals with other rheumatic conditions, prevalence was 3·9% for self-reported RA, 1·9% based on the medication database definition and 0·5% by self-reported medication definition. This confirms the overestimation of RA based on self-reporting.

CONCLUSIONS

We provide an algorithm for identifying individuals with RA, which could be used for population studies and monitoring RA in Australia and, with adjustments, internationally. Its balance of accuracy and practicality will be useful for health service planning using relatively easily accessible input data.

The Relationship between Seropositive Rheumatoid Arthritis and Congestive Heart Failure: A Nationwide Longitudinal Cohort Study in Korea

Objectives: The aim of this nationwide longitudinal cohort study is to determine the risk of congestive heart failure (CHF) associated with a seropositive rheumatoid arthritis (RA) population in Korea. Methods: In this study, National Health Insurance Service-Health Screening Cohort (NHIS-HEALS) data from 2002 to 2003 were used. The cohort was followed up with for 12 years until December of 2015. Seropositive RA was defined as a patient prescribed with a disease-modifying anti-rheumatic drug (DMARD) among patients with the International Classification of Diseases code M05 (seropositive RA). Patients who were diagnosed before 2004 were excluded. The seropositive RA group consisted of 2765 patients, and a total of 13,825 patients were in the control group. The Kaplan-Meier method was used to calculate the 12-year CHF incidence rate for each group. A Cox proportional hazards regression analysis was used to estimate the hazard ratio of CHF. Results: The hazard ratio of CHF in the seropositive RA group was 2.41 (95% confidence interval (CI): 1.40-4.14) after adjusting for age and sex. The adjusted hazard ratio of CHF in the seropositive RA group was 2.50 (95% CI: 1.45-4.30) after adjusting for age, sex, income, and comorbidities. In females aged ≥65 and aged <65, the incidence rates in the non-hypertension, non-diabetes mellitus, and non-dyslipidemia subgroups were significantly higher in the seropositive RA group than in the control group. Conclusions: This nationwide longitudinal cohort study shows an increased risk of CHF in patients with seropositive RA.

Impact of Rheumatoid Arthritis and Seropositivity on the Risk of Non-Cystic Fibrosis Bronchiectasis

BACKGROUND

Despite the coexistence of bronchiectasis and rheumatoid arthritis (RA) and the poor prognosis associated with the combination of conditions, to our knowledge, no longitudinal studies that comprehensively evaluated whether patients with RA have a higher risk of bronchiectasis compared with those without RA have been published. Whether seropositivity is associated with an increased risk of bronchiectasis in RA is the subject of ongoing controversy.

RESEARCH QUESTION

Does RA influence the development of bronchiectasis? Is seropositivity associated with an increased risk of bronchiectasis in RA?

STUDY DESIGN AND METHODS

The incidence of bronchiectasis was compared between individuals with RA (n = 50,651; seropositive rheumatoid arthritis [SPRA]: n = 35,879 and seronegative rheumatoid arthritis [SNRA]: n = 14,772) and 1:5 age- and sex-matched control patients (n = 253,255) enrolled between 2010 and 2017 in the Korean National Health Insurance Service database. The participants were followed from 1 year after RA diagnosis or the corresponding index date to the date of bronchiectasis incidence, censored date, or December 2019.

RESULTS

The cumulative incidence of bronchiectasis at 9 years of follow-up was approximately 7% in participants with RA. During a median follow-up of 4.3 years (interquartile range, 2.6-6.3 years), participants with RA showed a 2.12-fold higher risk of developing bronchiectasis than matched control participants, even after adjusting for potential confounders related to bronchiectasis development (95% CI, 2.00-2.25). In an analysis of RA serologic status using a fully adjusted model, participants with SPRA and those with SNRA showed 2.34-fold (95% CI, 2.20-2.49) and 1.56-fold (95% CI, 1.40-1.73) increased risks, respectively, compared with matched control participants.

INTERPRETATION

Individuals with RA had approximately twice the risk of developing bronchiectasis than matched control individuals, even after adjusting for potential confounders. The increased risk was more evident in individuals with SPRA than in those with SNRA, implying that rheumatic inflammation plays a major role in the development of RA-bronchiectasis overlap.

The Association of Chronic Periodontitis as a Potential Risk Factor with Rheumatoid Arthritis: A Nested Case-Control Study Using a Korean National Health Screening Cohort

Growing research has proposed that rheumatoid arthritis (RA) and chronic periodontitis (CP) share similar pathophysiological mechanisms involving inflammation and tissue destruction. However, the potential correlation of CP as a contributing factor for the occurrence of RA warrants validation in the Korean population, where both diseases are prevalent, especially considering the increasingly aging demographic in Korea. This study examined 5139 RA cases and 509,727 matched controls from a Korean national cohort dataset (2002-2019) by carefully employing propensity score matching to ensure comparability between groups. Baseline characteristics were compared using standardized differences, and logistic regression was employed to estimate the impact of CP history on RA likelihood while controlling for covariates. We fully examined medical records documenting CP occurrences within the two-year period leading up to the index date, conducting comprehensive subgroup analyses. While a 1-year history of CP did not show a significant association with likelihood of RA, a 2-year history of CP increased RA likelihood by 12%, particularly among older adults, females, rural residents, and those with certain comorbidities such as hypercholesterolemia. Interestingly, this association persisted even among individuals with non-smoking habits, normal weight, and infrequent alcohol consumption. These findings suggest that chronic CP exposure for at least 2 years may independently elevate RA risk in Korean adults. The association in certain subgroups appears to suggest a predisposition toward genetic susceptibilities over lifestyle and environmental factors. Predicting RA in CP patients may be challenging, emphasizing the importance of regular RA screening, especially in high-risk subgroups.

Medication utilisation trends during pregnancy and factors influencing adverse pregnancy outcomes in patients with rheumatoid arthritis

OBJECTIVES

We aimed to investigate medication utilisation trends during pregnancy and identify factors associated with adverse pregnancy outcomes (APOs) in patients with rheumatoid arthritis (RA).

METHODS

Female patients with RA aged 20-50 years were identified from the Korean national health insurance database between 2010 and 2020. Pregnancy episodes were divided into two groups according to pregnancy outcome: the delivery group and the APO group (abortion and stillbirth). The characteristics and medication utilisation patterns were compared between the two groups, and multivariable logistic regression analysis was conducted to identify the factors associated with APOs.

RESULTS

A total of 5728 pregnancy episodes were included, comprising 4576 delivery episodes and 1152 APO episodes. The mean maternal age for all pregnancy episodes was 33.7 years; 33.3 years in the delivery group and 33.7 years in the APO group. Hydroxychloroquine was the most commonly used conventional synthetic disease-modifying antirheumatic drug (DMARD) during the preconception period and pregnancy in both groups. The prescription rate of all DMARDs decreased rapidly during pregnancy. In the multivariable analysis, use of methotrexate (adjusted OR (aOR): 2.14, 95% CI 1.57 to 2.92) and leflunomide (aOR: 2.68, 95% CI 1.39 to 5.15) within 3 months before conception was associated with APOs.

CONCLUSION

Methotrexate and leflunomide are associated with an increased possibility of APOs, emphasising the importance of appropriate medication adjustment when planning for pregnancy.

Rheumatoid Arthritis and Risk of Lung Cancer: A Nationwide Cohort Study

INTRODUCTION

There has been an increasing interest in the risk of lung cancer related to rheumatoid arthritis (RA). We investigated the association between RA and the risk of lung cancer with consideration of key confounding factors, including RA serostatus and smoking status.

METHODS

Using a nationwide database, we identified 51,899 patients with newly diagnosed RA between 2010 and 2017, which were matched by sex and age at a 1:5 ratio with 259,495 non-RA population. The association of lung cancer and RA was investigated using Cox regression analyses. Stratified analyses by smoking status, sex, age, and comorbidity of interstitial lung disease were conducted using the same Cox modeling.

RESULTS

During 4.5 years of follow-up, the adjusted hazard ratio of lung cancer in the patients with RA was 1.49 (95% confidence interval: 1.34-1.66). Compared with the patients with seronegative RA, an increased risk of lung cancer was not considerable in the patients with seropositive RA. In the stratified analyses, the increased risk of lung cancer was more prominent in current or previous heavy smokers with RA (interaction p value of 0.046) and male patients (interaction p < 0.001), whereas there was no substantial effect associated with age or interstitial lung disease status.

CONCLUSIONS

Patients with RA had an increased risk of lung cancer compared with the non-RA group, and the risk did not differ by RA serostatus. There is a need for increased awareness of smoking cessation and potentially for regular lung cancer screening with proper risk stratification in patients with RA.

Validation of claims-based algorithms for rheumatoid arthritis in Japan: Results from the VALIDATE-J study

AIM

Validity of Algorithms in Large Databases: Infectious Diseases, Rheumatoid Arthritis, and Tumor Evaluation in Japan (VALIDATE-J) study examined algorithms for identifying rheumatoid arthritis (RA) in Japanese claims data.

METHODS

VALIDATE-J was a multicenter, cross-sectional retrospective study. Disease-identifying algorithms were used to detect RA diagnosed between January 2012 and December 2016 using claims data from two Japanese hospitals. An RA diagnosis was confirmed using one of four gold standard definitions. Positive predictive values (PPVs) were calculated for prevalent (regardless of baseline RA-free period) and incident (preceded by a 12-month RA-free period) cases.

RESULTS

Of patients identified using claims-based algorithms, a random sample of 389 prevalent and 134 incident cases of RA were included. Cases identified by an RA diagnosis, no diagnosis of psoriasis, and treatment with any disease-modifying antirheumatic drugs (DMARDs) resulted in the highest PPVs versus other claims-based treatment categories (29.0%-88.3% [prevalent] and 41.0%-78.2% [incident]); cases identified by an RA diagnosis, no diagnosis of psoriasis, and glucocorticoid-only treatment had the lowest PPVs. Across claims-based algorithms, PPVs were highest when a physician diagnosis or decision by adjudicators (confirmed and probable cases) was used as the gold standard and were lowest when American College of Rheumatology/European Alliance of Associations for Rheumatology 2010 criteria were applied. PPVs of claims-based algorithms for RA in patients aged ≥66 years were slightly higher versus a USA Medicare population (maximum PPVs of 95.0% and 88.9%, respectively).

CONCLUSION

VALIDATE-J demonstrated high PPVs for most claims-based algorithms for diagnosis of prevalent and incident RA using Japanese claims data. These findings will help inform appropriate RA definitions for future claims database research in Japan.

Long-Term Survival Analysis of 5619 Total Ankle Arthroplasty and Patient Risk Factors for Failure

BACKGROUND

Total ankle arthroplasty (TAA) has higher complication and failure rates compared to other surgical joint replacement procedures despite technological advances. This study aimed to find the long-term survivability of the TAA procedure and identify the patient risk factors for failure with one of the largest cohorts of patients in the literature.

METHODS

This retrospective cohort study involving cases between 2007 and 2018 analyzed patients who received an index primary TAA procedure in Korea. A total of 5619 cases were included in the final analysis. The TAA failure was defined as either a case with revision arthroplasty or a case with TAA implant removal and arthrodesis performed after primary TAA.

RESULTS

During the study period, the 5-year survival rate was 95.4% (95% CI, 94.7-96.1%), and the 10-year survival rate was 91.1% (95% CI, 89.1-93.1%). A younger age (<55 years, adjusted hazard ratio [AHR], 1.725; 55-64 years, AHR, 1.812; p < 0.001 for both), chronic pulmonary disease (AHR, 1.476; p = 0.013), diabetes (AHR, 1.443; p = 0.014), and alcohol abuse (AHR, 1.524; p = 0.032) showed a significantly high odds ratio for primary TAA failure in Cox regression analysis.

CONCLUSION

The 10-year TAA survivorship rate was 91.1%. A younger age, chronic pulmonary disease, diabetes, and heavy alcohol consumption are risk factors for TAA.

A Decline in Overutilization of Transfusion after Total Knee Arthroplasty Using Pharmacological Agents for Patient Blood Management in South Korea: An Analysis Based on the Korean National Health Insurance Claims Database from 2008 to 2019

Background

This study aimed to evaluate the annual trends of transfusion rates and utilization of blood management agents in total knee arthroplasty (TKA) based on the operation type and to analyze the risk factors of transfusion after TKA.

Methods

Using the Korean National Insurance claims database of 797,106 primary and revision TKAs between January 2008 and October 2019, data on the patients' characteristics, comorbidities, utilization of transfusion, and blood management agents were collected. The patients were categorized into three groups based on the operation type: primary, revision, and simultaneous bilateral TKA. The transfusion rate and utilization of blood management agents (intraoperative tranexamic acid [TXA] and preoperative iron supplements) were compared, and the risk factors for transfusion were evaluated.

Results

After excluding the inaccurate data, 730,554 arthroplasties (636,292 primary, 10,540 revision, and 41,861 simultaneous bilateral TKAs) were identified. The transfusion rates of primary, revision, and simultaneous bilateral TKAs in 2019 were 64.0%, 67.7%, and 68.9%, respectively, which were significantly decreased compared with 83.2%, 88.0%, and 92.5% in 2008, respectively (p < 0.001). Conversely, the utilization of intraoperative TXA and preoperative iron supplements was significantly increased from 4.6% and 13.8%, respectively, in 2008 to 52.4% and 27.0%, respectively, in 2019 (p < 0.001). The utilization of intraoperative TXA and preoperative iron supplements significantly lowered the risk of transfusion after TKA (odds ratio [OR], 0.20; p < 0.001 and OR, 0.71; p < 0.001).

Conclusions

The transfusion rate after TKA decreased gradually from 83.5% to 64.5% between 2008 and 2019 in South Korea corresponding with the increased utilization of blood management agents. Therefore, consistent attention to patient blood management should be emphasized to reduce the transfusion rate after TKA.

Performance of Cardiovascular Risk Prediction Models in Korean Patients With New-Onset Rheumatoid Arthritis: National Cohort Study

BACKGROUND

This study aimed to compare the performance of established cardiovascular risk algorithms in Korean patients with new-onset rheumatoid arthritis.

METHODS AND RESULTS

This retrospective cohort study identified patients newly diagnosed with rheumatoid arthritis without a history of cardiovascular diseases between 2013 and 2019 using the National Health Insurance Service database. The cohort was followed up until 2020 for the development of the first major adverse cardiovascular event. General cardiovascular risk prediction algorithms, such as the systematic coronary risk evaluation model, the Korean risk prediction model for atherosclerotic cardiovascular diseases, the American College of Cardiology/American Heart Association pooled equations, and the Framingham Risk Score, were used. The discrimination and calibration of cardiovascular risk prediction models were evaluated. Hazard ratios were estimated using Cox proportional hazards regression. A total of 611 patients among 24 889 patients experienced a major adverse cardiovascular event during follow-up. The median 10-year atherosclerotic cardiovascular diseases risk score was significantly higher in patients with major adverse cardiovascular events than those without. The C-statistics of risk algorithms ranged between 0.72 and 0.74. Compared with the low-risk group, the actual risk of developing major adverse cardiovascular events increased significantly in the intermediate- and high-risk groups for all algorithms. However, the risk predictions calculated from all algorithms overestimated the observed cardiovascular risk in the middle to high deciles, and only the systematic coronary risk evaluation algorithm showed comparable observed and predicted event rates in the low-intermediate deciles with the highest sensitivity.

CONCLUSIONS

The systematic coronary risk evaluation model algorithm and the general risk prediction models discriminated patients with rheumatoid arthritis appropriately. However, overestimation should be considered when applying the cardiovascular risk prediction model in Korean patients.

Association of Tumor Necrosis Factor Inhibitors with the Risk of Nontuberculous Mycobacterial Infection in Patients with Rheumatoid Arthritis: A Nationwide Cohort Study

Tumor necrosis factor inhibitors (TNFi) are proposed as a risk factor for nontuberculous mycobacteria (NTM) infection. Limited research investigates NTM infection risk in rheumatoid arthritis (RA) patients treated with TNFi compared to conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), considering other concurrent or prior non-TNFi antirheumatic drugs. We aimed to evaluate the NTM infection risk associated with TNFi using a real-world database. Patients with RA treated with TNFi or csDMARDs between 2005 and 2016 were identified utilizing the Korean National Health Insurance Service database. To minimize potential bias, we aligned the initiation year of csDMARDs for both TNFi and csDMARD users and tracked them from their respective treatment start dates. The association of TNFi with NTM infection risk was estimated in a one-to-one matched cohort using a multivariable conditional Cox regression analysis. In the matched cohort (n = 4556), the incidence rates of NTM infection were 2.47 and 3.66 per 1000 person-year in TNFi and csDMARD users. Compared to csDMARDs, TNFi did not increase the risk of NTM infection (adjusted hazard ratio (aHR) 0.517 (95% confidence interval, 0.205-1.301)). The TNFi use in RA patients was not associated with an increased risk of NTM infection compared to csDMARDs. Nevertheless, monitoring during TNFi treatment is crucial.

Exploring patient medication adherence and data mining methods in clinical big data: A contemporary review

BACKGROUND

Increasingly, patient medication adherence data are being consolidated from claims databases and electronic health records (EHRs). Such databases offer an indirect avenue to gauge medication adherence in our data-rich healthcare milieu. The surge in data accessibility, coupled with the pressing need for its conversion to actionable insights, has spotlighted data mining, with machine learning (ML) emerging as a pivotal technique. Nonadherence poses heightened health risks and escalates medical costs. This paper elucidates the synergistic interaction between medical database mining for medication adherence and the role of ML in fostering knowledge discovery.

METHODS

We conducted a comprehensive review of EHR applications in the realm of medication adherence, leveraging ML techniques. We expounded on the evolution and structure of medical databases pertinent to medication adherence and harnessed both supervised and unsupervised ML paradigms to delve into adherence and its ramifications.

RESULTS

Our study underscores the applications of medical databases and ML, encompassing both supervised and unsupervised learning, for medication adherence in clinical big data. Databases like SEER and NHANES, often underutilized due to their intricacies, have gained prominence. Employing ML to excavate patient medication logs from these databases facilitates adherence analysis. Such findings are pivotal for clinical decision-making, risk stratification, and scholarly pursuits, aiming to elevate healthcare quality.

CONCLUSION

Advanced data mining in the era of big data has revolutionized medication adherence research, thereby enhancing patient care. Emphasizing bespoke interventions and research could herald transformative shifts in therapeutic modalities.

Risk of venous thromboembolism in Korean patients with rheumatoid arthritis treated with Janus kinase inhibitors: A nationwide population-based study

OBJECTIVE

There was a safety concern about an increased risk of thromboembolic events in patients with rheumatoid arthritis (RA) treated with Janus kinase inhibitors (JAKis). This study aimed to determine the risk of venous thromboembolism (VTE) in Korean patients with RA treated with JAKis compared with tumour necrosis factor (TNF) inhibitors.

METHODS

Using the National Health Insurance Service database between 2015 and 2019, patients with prevalent RA who started JAKi or TNF inhibitor were selected as the study population. All participants were naïve to targeted therapy. Patients that had experienced any VTE event or used anticoagulant agents within 30 days were excluded. Demographic and clinical characteristics were all balanced by stabilised inverse probability of treatment weighting (sIPTW) using propensity score. The Cox proportional hazard model considering death as a competing risk was used to evaluate the risk of VTE in JAKi users compared with TNF inhibitor users.

RESULTS

A total of 4,178 patients were included: 871 JAKi users and 3,307 TNF inhibitor users were followed up for 1,029.2 person-years (PYs) and 5,940.3 PYs, respectively. With a balanced sample after sIPTW, the incidence rates (IR) of VTE were 0.06 per 100 PYs (95% confidence interval [CI] 0.00-1.23) in JAKi users and 0.38 per 100 PYs (95% CI 0.25-0.58) in TNF inhibitor users. The hazard ratio was 0.18 (95% CI 0.01-3.47) after adjusting for unbalanced variables after performing sIPTW.

CONCLUSION

There is no increased risk of VTE in RA patients treated with JAKis compared with TNF inhibitors in Korea.

Rheumatoid Arthritis and Risk of Parkinson Disease in Korea

Importance

Although it has been postulated that chronic inflammation caused by rheumatoid arthritis (RA) contributes to the development of Parkinson disease (PD), the association between these 2 conditions has yet to be determined.

Objective

To evaluate the association between RA and subsequent PD risk.

Design, Setting, and Participants

This retrospective cohort study used the Korean National Health Insurance Service database to collect population-based, nationally representative data on patients with RA enrolled from 2010 to 2017 and followed up until 2019 (median follow-up, 4.3 [IQR, 2.6-6.4] years after a 1-year lag). A total of 119 788 patients who were first diagnosed with RA (83 064 with seropositive RA [SPRA], 36 724 with seronegative RA [SNRA]) were identified during the study period and included those who underwent a national health checkup within 2 years before the RA diagnosis date (64 457 patients). After applying exclusion criteria (eg, age <40 years, other rheumatic diseases, previous PD), 54 680 patients (39 010 with SPRA, 15 670 with SNRA) were included. A 1:5 age- and sex-matched control group of patients without RA was also included for a total control population of 273 400.

Exposures

Rheumatoid arthritis as defined using International Classification of Diseases, Tenth Revision codes M05 for SPRA and M06 (except M06.1 and M06.4) for SNRA; prescription of any disease-modifying antirheumatic drug; and enrollment in the Korean Rare and Intractable Diseases program.

Main Outcomes and Measures

The main outcome was newly diagnosed PD. Data were analyzed from May 10 through August 1, 2022, using Cox proportional hazards regression analyses.

Results

From the 328 080 individuals analyzed (mean [SD] age, 58.6 [10.1] years; 74.9% female and 25.1% male), 1093 developed PD (803 controls and 290 with RA). Participants with RA had a 1.74-fold higher risk of PD vs controls (95% CI, 1.52-1.99). An increased risk of PD was found in patients with SPRA (adjusted hazard ratio [aHR], 1.95; 95% CI, 1.68-2.26) but not in patients with SNRA (aHR, 1.20; 95% CI, 0.91-1.57). Compared with the SNRA group, those with SPRA had a higher risk of PD (aHR, 1.61; 95% CI, 1.20-2.16). There was no significant interaction between covariates on risk of PD.

Conclusions and Relevance

In this study, RA was associated with an increased risk of PD, and seropositivity of RA conferred an augmented risk of PD. The findings suggest that physicians should be aware of the elevated risk of PD in patients with RA and promptly refer patients to a neurologist at onset of early motor symptoms of PD without synovitis.

Association of Oral Health with Risk of Rheumatoid Arthritis: A Nationwide Cohort Study

Periodontitis and rheumatoid arthritis (RA) are inflammatory diseases that share many similarities. We aimed to investigate the associations of periodontitis and oral hygiene status and behaviors with RA in a nationwide general population cohort. Participants from the National Health Screening cohort database of Korea who underwent oral health screening by dentists between 2003 and 2004 were included. The occurrence of RA was analyzed according to the presence of periodontitis, oral health examination findings, and behaviors. Overall, 2,239,586 participants were included. During a median of 16.7 years, RA occurred in 27,029 (1.2%) participants. The risk for incident RA was higher when participants had periodontitis (hazard ratio (HR) 1.2, 95% confidence interval (CI), 1.08-1.24) and an increased number of missing teeth (HR 1.5, 95% CI, 1.38-1.69). In contrast, better oral hygiene behaviors, such as a higher frequency of daily tooth brushing (HR 0.76, 95% CI 0.73-0.79, p for trend <0.001) and a recent history of dental scaling (HR 0.96, 95% CI 0.94-0.99), were associated with a lower occurrence of RA. Periodontitis and increased missing teeth were associated with an increased risk of RA. Maintaining good oral hygiene through frequent tooth brushing and regular dental scaling may reduce the risk of RA occurrence.

Association of immune-mediated inflammatory diseases with depression and anxiety in patients with type 2 diabetes: A nationwide population-based study

Objective

Patients with type 2 diabetes (T2DM) are at a high risk of developing depression and anxiety. To better stratify the risk, we aimed to assess whether the presence of immune-mediated inflammatory diseases (IMIDs) confers a higher risk of depression and anxiety in these patients.

Methods

Patients with T2DM without prior depression or anxiety who underwent national health examination between 2009 and 2012 (n = 1,612,705) were enrolled from the nationwide health check-up data from Korean National Health Insurance Service. The outcome events were incident depression and anxiety, defined as International Classification of Diseases, 10th Revision codes F32-F33 and F40-F41, respectively. Multivariable Cox proportional hazard regression analyses were conducted to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) according to the existence of IMIDs.

Results

Over an average follow-up time of 6.4 years, existence of gut IMIDs was associated with a higher risk of depression (aHR: 1.28 [95% CI: 1.08-1.53]) and anxiety (1.22 [1.06-1.42]). Existence of joint IMIDs was associated with a higher risk of depression (1.34 [1.31-1.37]) and anxiety (1.31 [1.29-1.34]). Existence of skin IMID was associated with a higher risk of depression (1.18 [1.14-1.23]) and anxiety (1.13 [1.09-1.16]). The effect sizes of IMIDs on depression and anxiety were larger in those with ≥ 2 IMIDs (1.42 [1.19-1.69] and 1.49 [1.29-1.72], respectively) than in those with one IMID (1.30 [1.27-1.32] and 1.26 [1.24-1.28], respectively).

Conclusion

In patients with T2DM, presence of IMIDs was associated with a higher risk of depression and anxiety. More stringent attention and screening for anxiety and depression should be encouraged in patients with T2DM and comorbid IMIDs due to clinical implications of psychological distress on patient-reported outcomes and prognosis.

The prevalence of rheumatoid arthritis in Western Australia

BACKGROUND

Rheumatoid arthritis (RA) is the most common form of autoimmune arthritis, but the prevalence in Australia is unknown. We estimated RA period prevalence and identified factors associated with frequent RA hospitalisations, using linked administrative health and state-specific Australian Pharmaceutical Benefits Scheme (PBS) datasets in Western Australia (WA) from 1995 to 2014.

METHODS

This was a longitudinal population-based cohort study using two independent datasets to identify prevalent RA patients. RA prevalence was calculated per 1000 hospital separations and biological therapy users. RA patients were identified in the WA linked health dataset using ICD codes 714.0-714.9 and M05.00-M06.99. Dispensing data on biological therapy for RA were obtained from PBS records and converted to defined daily doses /1000 population/day. Multivariable logistic regression was used to analyse factors associated with frequent RA hospitalisations (> 2/year), controlling for sex, age, and geographic locations. Potential interactions were assessed using logistic regression in a stepwise approach.

RESULTS

A total of 17,125 RA patients had 50,353 hospital separations between 1995 and 2014, averaging three hospitalisations per patient over 20 years. The RA period prevalence was 3.4 per 1000 separations (0.34%; 95% CI 0.33-0.34), while the RA period prevalence based on biological therapy use was 0.36% (95% CI 0.35-0.37). The corrected RA prevalence based on biological therapy usage was 0.36% (95% CI 0.35-0.37) for the 2005-2009 and increased to 0.72% (95% CI 0.70-0.74) in 2010-2014 period. Associated factors for frequent RA hospitalisations were being female [1.21 (95% CI 1.15-1.26)], aged 60-69 years [4.45 (95% CI 3.74-5.30)], living in rural areas [1.12 (95% CI 1.02-1.24)]. The odd ratio of interaction between these associated factors was 1.34 (95% CI 1.16-1.55).

CONCLUSION

The minimal prevalence of RA in Western Australia is 0.34-0.36%, which falls within the literature range. Older female RA patients in rural were more likely to be hospitalised, suggesting unmet primary care for needs.

Association between malignancy risk and Janus kinase inhibitors versus tumour necrosis factor inhibitors in Korean patients with rheumatoid arthritis: a nationwide population-based study

OBJECTIVE

To determine the risk of malignancy in Korean patients with rheumatoid arthritis (RA) receiving Janus kinase inhibitors (JAKis) compared with tumour necrosis factor inhibitors (TNFis).

METHODS

A retrospective cohort of patients with RA initiating their first JAKi or TNFi was established using the Korean National Health Insurance database between 2015 and 2019. They were followed up from treatment initiation to the occurrence of malignancy, drug discontinuation, death or until December 2019. Baseline features of the patients were balanced through inverse probability of treatment weighting (IPTW) using a propensity score. A Cox proportional hazard model was established to estimate the HR for malignancy risk in JAKi users compared with TNFi users.

RESULTS

A total of 4929 patients (1064 JAKi-treated and 3865 TNFi-treated patients) were included, and the observation periods were 1288.6 person-years (PYs) for JAKi users and 6823.8 PYs for TNFi users. The incidence rates of overall malignancy were 0.54 per 100 PYs (95% CI 0.26 to 1.14) in JAKi users and 0.85 per 100 PYs (95% CI 0.66 to 1.10) in TNFi users. In IPTW analysis with a balanced sample (4101 JAKi-treated and 5131 TNFi-treated patients), HR was 0.83 (95% CI 0.55 to 1.27) for overall malignancy: 0.77 (95% CI 0.50 to 1.19) for solid malignancy and 2.86 (95% CI 0.41 to 20.00) for haematological malignancy.

CONCLUSION

Malignancy risk in Korean patients with RA was not increased with JAKi use compared with TNFi use.

Associations between Cardiovascular Outcomes and Rheumatoid Arthritis: A Nationwide Population-Based Cohort Study

Despite a growing burden posed by cardiovascular disease (CVD) in rheumatoid arthritis (RA) patients, large-scale studies on the association between the characteristics of RA patients and CVD risks and studies adjusted for various confounding factors are lacking. In this large-scale nationwide cohort study, we aimed to investigate the association between CVD risk and RA and factors that may increase CVD risk using a dataset provided by the Korean National Health Insurance Service (NHIS). We enrolled 136,469 patients with RA who participated in national health examinations within two years of RA diagnosis between 2010 and 2017 and non-RA controls matched by age and sex (n = 682,345). The outcome was the occurrence of myocardial infarction (MI) or stroke. MI was defined as one hospitalization or two outpatient visits with ICD-10-CM codes I21 or I22. Stroke was defined as one hospitalization with ICD-10-CM codes I63 or I64 and a claim for brain imaging (CT or MRI). The Cox proportional hazard model and Kaplan-Meier curve were used for analysis. The mean follow-up duration was 4.7 years, and the incidence rate of CVD was higher in the RA group than the control group (MI: 3.20 vs. 2.08; stroke: 2.84 vs. 2.33 per 1000 person-years). The risk of MI and stroke was about 50% and 20% higher, respectively, in RA patients. The association between RA and CVD was prominent in females after adjusting for confounding variables. The association between RA and risk of MI was significant in individuals without DM. Therefore, appropriate screening for CVD is important in all RA patients including females and younger patients.

Operational Definition Identifying Osteoporotic Vertebral Fractures in the Claims Database

BACKGROUND

We analyzed the International Classification of Diseases, 10th edition (ICD-10) diagnostic codes, procedure codes, and radiographic image codes for vertebral fracture (VF) used in the database of Health Insurance Review and Assessment Service (HIRA) of Korea to establish a validated operational definition for identifying patients with osteoporotic VF in claims data.

METHODS

We developed three operational definitions for detecting VFs using 9 diagnostic codes, 5 procedure codes and 4 imaging codes. Medical records and radiographs of 2,819 patients, who had primary and subordinated codes of VF between January 2016 and December 2016 at two institutions, were reviewed to detect true vertebral fractures. We evaluated the sensitivity and positive predictive value (PPV) of the operational definition in detecting true osteoporotic VF and obtained the receiver operating characteristic (ROC) curve.

RESULTS

Among the 2,819 patients who had primary or secondary diagnosis codes for VF, 995 patients satisfied at least one of the criteria for the operational definition of osteoporotic VF. Of these patients, 594 were judged as having true fractures based on medical records and radiographic examinations. The sensitivity and PPV were 62.5 (95% confidence interval [CI], 59.4-65.6) and 59.7(95% CI, 56.6-62.8) respectively. In the receiver operating characteristic analysis, area under the curve (AUC) was 0.706 (95% CI, 0.688-0.724).

CONCLUSION

Our findings demonstrate the validity of our operational definitions to identify VFs more accurately using claims data. This algorithm to identify VF is likely to be useful in future studies for diagnosing osteoporotic VF.

The risk of newly diagnosed cancer in patients with rheumatoid arthritis by TNF inhibitor use: a nationwide cohort study

Background

Tumor necrosis factor (TNF) inhibitors use in patients with rheumatoid arthritis (RA) has raised safety concerns about cancer risk, but study results remain controversial. This largest nationwide study to date compared cancer risk in TNF inhibitor users to non-biologic disease-modifying anti-rheumatic drug (nbDMARD) users in Korean patients with RA.

Methods

Data on all the eligible patients diagnosed with RA between 2005 and 2016 were retrieved from the Korean National Health Information Database. The one-to-one matched patients consisted of the matched cohort. The risks for developing all-type and site-specific cancers were estimated using incidence and incidence rate (IR) per 1000 person-years. Adjusted hazard ratio (HR) and 95% confidence interval (CI) were estimated using a Cox regression model.

Results

Of the 22,851 patients in the before matching cohort, 4592 patients were included in the matched cohort. Treatment with TNF inhibitors was consistently associated with a lower risk of cancer than in the nbDMARD cohort (IR per 1000 person-years, 6.5 vs. 15.6; adjusted HR, 0.379; 95% CI, 0.255–0.563). The adjusted HR (95% CI) was significantly lower in the TNF inhibitor cohort than the nbDMARD cohort for gastrointestinal cancer (0.432; 0.235–0.797), breast cancer (0.146; 0.045–0.474), and genitourinary cancer (0.220; 0.059–0.820).

Conclusions

The use of TNF inhibitors was not associated with an increased risk of cancer development, and rather associated with a lower cancer incidence in Korean patients with RA. Cautious interpretation is needed not to oversimplify the study results as cancer-protective effects of TNF inhibitors. A further study linking claims and clinical data is needed to confirm our results.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02868-w.

Incident and recurrent herpes zoster for first-line bDMARD and tsDMARD users in seropositive rheumatoid arthritis patients: a nationwide cohort study

BACKGROUND

There is limited information regarding disease-modifying antirheumatic drug (DMARD)-dependent risks of overall, incident, and recurrent herpes zoster (HZ) during first-line biologic DMARD (bDMARD) or targeted synthetic DMARD (tsDMARD) treatment among patients with seropositive rheumatoid arthritis (RA) in terms of HZ risk.

METHODS

A total of 11,720 patients with seropositive RA who were prescribed bDMARD or tofacitinib between January 2011 and January 2019 from the Korean Health Insurance Review & Assessment Service database were studied. A multivariate Cox proportional hazards regression model was adopted to evaluate the adjusted hazard ratio (aHR) with 95% confidence interval (CI) for the risk of HZ dependent on the choice of first-line bDMARDs or tsDMARD, including etanercept, infliximab, adalimumab, golimumab, tocilizumab, rituximab, tofacitinib, and abatacept.

RESULTS

During the 34,702 person-years of follow-up, 1686 cases (14.4%) of HZ were identified, including 1372 (11.7%) incident and 314 (2.7%) recurrent HZs. Compared with that of the abatacept group, tofacitinib increased the overall risk (aHR, 2.46; 95% CI, 1.61-3.76; P<0.001), incidence (aHR, 1.99; 95% CI, 1.18-3.37; P=0.011), and recurrence (aHR, 3.69; 95% CI, 1.77-7.69; P<0.001) of HZ. Infliximab (aHR, 1.36; 95% CI, 1.06-1.74; P=0.017) and adalimumab (aHR, 1.29; 95% CI, 1.02-1.64; P=0.032) also increased the overall HZ risk. Moreover, a history of HZ was found to be an independent risk factor for HZ (aHR, 1.54; 95% CI, 1.33-1.78; P<0.001).

CONCLUSIONS

HZ risk is significantly increased in RA patients with a history of HZ after the initiation of bDMARDs or tsDMARD. The risk of incident and recurrent HZ was higher after tofacitinib treatment in patients with RA than that after treatment with bDMARDs. Individualized characteristics and history of HZ should be considered when selecting bDMARDs or tsDMARD for RA patients considering HZ risks.

Potential Cancer Risk in Patients with Rheumatoid Arthritis: A Longitudinal Korean Population-Based Analysis

The potential link between rheumatoid arthritis (RA) and cancer incidence needs to be validated due to inconsistent results between Asian and Western countries. We explored the long-term association of RA with the overall and organ-specific cancer incidence using nationwide population data. This longitudinal follow-up study (2002–2015) included 3070 patients with RA and 12,280 controls (1:4 propensity score-matched for sex, age, residence, and income) from the Korean National Health Insurance Service-Health Screening Cohort database. A Cox proportional hazard model estimated the hazard ratio for malignancy following adjusting for covariates. Despite the similar overall cancer incidence between RA and control groups, differences in the incidence of organ-specific cancers were noted: the RA group had a 1.63-fold greater likelihood for lung cancer (95% confidence interval 1.11–2.40). In the sex-stratified subgroup analyses, the male RA patients exhibited higher odds of lung and thyroid cancer but a lower probability for colorectal cancer; no such associations were detected in either female patients with RA or age subgroups. In summary, the higher likelihood for lung cancer in Korean RA patients, especially thyroid and lung cancer in male RA patients, seems to be characteristic, which needs to be carefully monitored.

Incident Rheumatoid Arthritis Following Statin Use: From the View of a National Cohort Study in Korea

Safety issues regarding the potential risk of statins and incident rheumatoid arthritis (RA) have been raised, but the existing data are largely based on Caucasian populations, and continue to have biases and require further validation in Asian populations. Here, we aimed to verify the risk of RA depending on the duration of previous statin use and statin types using a large-scale, nationwide database. This study enrolled 3149 patients with RA and 12,596 matched non-RA participants from the national health insurance database (2002−2015), and investigated their statin prescription histories for two years before the index date. Propensity score overlap-weighted logistic regression was applied after adjusting for multiple covariates. The prior use of any statins and, specifically, the long-term use of lipophilic statins (>365 days) were related to a lower likelihood of developing RA ((odds ratio (OR) = 0.73; 95% confidence intervals (CI) = 0.63−0.85, p < 0.001) and (OR = 0.71; 95% CI = 0.61−0.84, p < 0.001), respectively). Subgroup analyses supported these preventive effects on RA in those with dyslipidemia, independent of sex, age, smoking, alcohol use, hypertension, and hyperglycemia. Hydrophilic statin use or short-term use showed no such associations. Our study suggests that prior statin use, especially long-term lipophilic statin use, appears to confer preventive benefits against RA.

Association of particulate matter with autoimmune rheumatic diseases among adults in South Korea

OBJECTIVE

The primary objective of this study was to investigate adverse effects of ambient particulate matter of various sizes on the incidence of the prevalent autoimmune rheumatic diseases (AIRDs): RA, AS and SLE.

METHODS

We investigated 230 034 participants in three metropolitan cities of South Korea from the National Health Insurance Service-National Sample Cohort (NHIS-NSC). Starting from January 2010, subjects were followed up until the first event of prevalent AIRDs, death, or December 2013. The 2008-2009 respective averages of particulate matter2.5 (<2.5 μm) and particulate mattercoarse (2.5 μm to 10 μm) were linked with participants' administrative district codes. Adjusted hazard ratios (aHRs) and 95% CIs were estimated using Cox regression analysis in one- and two-pollutant models.

RESULTS

Adjusted for age, sex, region, and household income, in the two-pollutant model, RA incidence was positively associated with the 10 μg/m³ increment of particulate matter2.5 (aHR = 1.74, 95% CI: 1.06, 2.86), but not with particulate mattercoarse (aHR = 1.27, 95% CI: 0.87, 1.85). In the one-pollutant model, the elevated incidence rate of RA was slightly attenuated (particulate matter2.5 aHR = 1.61, 95% CI: 0.99, 2.61; particulate mattercoarse aHR = 1.13, 95% CI: 0.80, 1.61), with marginal statistical significance for particulate matter2.5. The RA incidence was also higher in the 4th quartile group of particulate matter2.5 compared with the first quartile group (aHR = 1.83, 95% CI: 1.07, 3.11). Adverse effects from particulate matter were not found for AS or SLE in either the one- or two-pollutant models.

CONCLUSION

The important components of particulate matter10 associated with RA incidence were the fine fractions (particulate matter2.5); no positive association was found between particulate matter and AS or SLE.

Validation of an Operational Definition to Identify Distal Radius Fractures in a National Health Insurance Database

PURPOSE

To develop and validate identification criteria for distal radius fractures (DRFs) and their treatment using a national health insurance database.

METHODS

Patients who had at least 1 wrist radiograph taken in 2018 were recruited from a single academic referral hospital. After excluding patients who lacked immobilization code for wrist pathology, we collected data on the overall population. Because some patients might have undergone wrist radiography at another institution or had DRFs without an immobilization code, we additionally included patients who had a DRF diagnosis code at our institution. Reviews of medical records and wrist radiographs were considered for the diagnosis of DRF. We evaluated the sensitivity, specificity, and positive predictive value (PPV) of 3 operational definitions of fractures that were based on a single primary or secondary diagnosis code; all diagnosis codes, including primary and secondary codes; and all diagnosis and procedure codes.

RESULTS

Among 768 patients included in the study, true DRFs were confirmed in 305. The sensitivity, specificity, and PPV for definition 1 were 91.5% (95% CI, 88.3%-94.6%), 97.5% (95% CI, 95.9%-99.1%), and 96.9% (95% CI, 94.9%-98.9%), respectively. Although the sensitivity of definition 2 was higher (92.1%; 95% CI, 89.1%-95.2%), its specificity and PPV were lower (96.4% [95% CI, 94.4%-98.3%] and 95.6% [95% CI, 93.2%-97.9%], respectively). The sensitivity of definition 3 was the lowest (88.2%; 95% CI, 84.6%-91.8%), but its specificity and PPV were the highest among the 3 definitions (98.6% [95% CI, 97.4%-98.8%] and 98.2% [95% CI, 96.6%-99.8%], respectively).

CONCLUSIONS

Patients with DRFs can be identified from claims databases with high accuracy using an operational definition based on DRF diagnosis and procedure codes, including codes for surgical and nonoperative methods.

CLINICAL RELEVANCE

Verified operational definitions will increase the consistency of results in future national health insurance database studies related to DRFs.

Association between previous rheumatoid arthritis and COVID-19 and its severity: a nationwide cohort study in South Korea

OBJECTIVES

The prevalence of rheumatoid arthritis (RA) among patients with COVID-19 and the association between RA and the outcome of COVID-19 remain unclear. We aimed to compare the prevalence of RA between participants with and without COVID-19; we then analysed the association between the presence of RA and the severity of COVID-19.

DESIGN

A cross-sectional study.

SETTING

Data from a nationwide COVID-19 cohort database by the Korea National Health Insurance Corporation were used.

PARTICIPANTS AND INTERVENTIONS

A total of 8070 patients with COVID-19 (1 January 2020 through 4 June 2020) were matched with 32 280 control participants with regard to age, sex and income. Patients with COVID-19 were confirmed by SARS-CoV-2 PCR and controls were collected from the database. RA was confirmed using the diagnostic code (International Classification of Disease, Tenth Revision) and medication claim codes. Conditional/unconditional logistic regression was applied to analyse the association between RA and COVID-19.

PRIMARY OUTCOME AND SECONDARY OUTCOME

Laboratory confirmation of SARS-CoV-2 infection was defined as the primary outcome. The secondary outcome was severe COVID-19 defined as a history of intensive care unit admission, invasive ventilation or death.

RESULTS

The prevalence of RA in the COVID-19 (0.4%, 35/8070) and control (0.4%, 121/32,280) groups did not differ (p=0.446). After adjusting for underlying diseases, no association between RA and COVID-19 was observed (adjusted OR=1.14, 95% CI: 0.78 to 1.67) and COVID-19 severity was not associated with RA (adjusted OR=0.62, 95% CI: 0.14 to 7.29). The overall mortality rate was 2.9% (237/8070) and RA was not significantly associated with mortality (adjusted OR=1.64, 95% CI: 0.33 to 8.15).

CONCLUSION

We did not find an association between the presence of RA and COVID-19. In addition, RA was not associated with the severity of COVID-19.

Risk of reoperation and infection after percutaneous endoscopic lumbar discectomy and open lumbar discectomy : a nationwide population-based study

AIMS

Open discectomy (OD) is the standard operation for lumbar disc herniation (LDH). Percutaneous endoscopic lumbar discectomy (PELD), however, has shown similar outcomes to OD and there is increasing interest in this procedure. However despite improved surgical techniques and instrumentation, reoperation and infection rates continue and are reported to be between 6% and 24% and 0.7% and 16%, respectively. The objective of this study was to compare the rate of reoperation and infection within six months of patients being treated for LDH either by OD or PELD.

METHODS

In this retrospective, nationwide cohort study, the Korean National Health Insurance database from 1 January 2007 to 31 December 2018 was reviewed. Data were extracted for patients who underwent OD or PELD for LDH without a history of having undergone either procedure during the preceding year. Individual patients were followed for six months through their encrypted unique resident registration number. The primary endpoints were rates of reoperation and infection during the follow-up period. Other risk factors for reoperation and infection were also evalulated.

RESULTS

Out of 549,531 patients, 522,640 had undergone OD (95.11%) and 26,891 patients had undergone PELD (4.89%). Reoperation rates within six months were 2.28% in the OD group, and 5.38% in the PELD group. Infection rates were 1.18% in OD group and 0.83% in PELD group. The risk of reoperation was lower for patients with OD than for patients with PELD (adjusted hazard ratio (HR) 0.38). The risk of infection was higher for patients with OD than for patients undergoing PELD (HR, 1.325).

CONCLUSION

Compared with the OD group, the PELD group showed higher reoperation rates and lower infection rates. Cite this article: Bone Joint J 2021;103-B(8):1392-1399.

Effects of diabetes mellitus on the rate of carpal tunnel release in patients with carpal tunnel syndrome

The objective of this study was to evaluate the effects of diabetes mellitus (DM) on the rate of carpal tunnel release (CTR) using a large nationwide cohort in Korea and to identify risk factors, including comorbidities and socioeconomic status (SES), associated with CTR. Patients with a primary or secondary diagnosis of carpal tunnel syndrome (CTS; ICD-10 code: G560) were selected and divided into two groups according to the presence of DM. A Cox proportional hazard model was used to assess the rate of CTR between the two groups. To evaluate the influence of demographic factors, comorbidities, and SES on CTR, multivariate Cox proportional hazard regression models were used to adjust for confounding variables. In total, 12,419 patients with CTS were included in the study: 2487 in DM cohort and 9932 in non-DM cohort. DM duration was negatively related with the rate of CTR (HR = 0.89, 95% CI 0.87–0.91) in CTS patients with DM. The rate of CTR was decreased in patients with DM compared to those without DM in the unadjusted model; however, after adjusting for comorbidities, DM had no significant effect on the rate of CTR. Female sex (HR = 1.50, 95% CI 1.36–1.67) correlated with the rate of CTR, and an inverse relationship between the number of comorbidities and CTR was found (p < 0.001) irrespective of DM. Diabetic polyneuropathy (DPN) was not associated with CTR, and we did not find any factors correlating with CTR in DPN patients. We found that CTS patients with more comorbidities or combined with a longer duration of DM were undertreated in real-word practice. Actual outcomes of CTR in CTS patents with various comorbidities should be investigated in future studies for optimal management of CTS.

The risk of serious infection in rheumatoid arthritis patients receiving tocilizumab compared with tumor necrosis factor inhibitors in Korea

OBJECTIVES

To examine the risk of serious infections (SIs) among patients with rheumatoid arthritis (RA) treated with tocilizumab compared with tumor necrosis factor inhibitor (TNFi) in Korea.

METHODS

We conducted a retrospective cohort study using the Korean National Health Insurance data. The study cohort included patients ≥18 years with RA who were initiated with tocilizumab or TNFi between January 2013 and June 2018. The primary outcome was a composite endpoint of SIs, defined as an infection resulting in intravenous antimicrobial therapy or hospitalization. Secondary outcomes were organ-specific SIs. To control for confounders, we used inverse probability of treatment weighting (IPTW) using propensity score. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using a multivariable Cox regression model.

RESULTS

A total of 8794 patients were identified: 1395 and 7399 patients initiated with tocilizumab and TNFi, respectively. The mean follow-up durations were 1.2 years for tocilizumab initiators and 1.0 year for TNFi initiators. After IPTW and adjustment, no increased risk of SIs was observed in tocilizumab versus TNFi (HR, 1.00; 95%CI, 0.90-1.11). In the secondary analysis, tocilizumab was associated with a higher risk of skin and subcutaneous tissue infections (HR, 1.26; 95%CI, 1.02-1.54) and a lower risk of urological and gynecological infections (HR, 0.65; 95%CI, 0.49-0.87) compared to TNFi.

CONCLUSION

In this population-based cohort of RA patients in Korea, tocilizumab was not associated with a higher risk of SI compared to TNFi. However, tocilizumab should be carefully used for patients at high risk for skin-related infections.

Comparison of healthcare resource utilization and medical costs between patients with seropositive and seronegative rheumatoid arthritis

Objectives:

To compare healthcare utilization and medical costs between patients with seronegative (SN) and seropositive (SP) rheumatoid arthritis (RA).

Methods:

We conducted a nationwide population study using the Korean health insurance claims database in 2016. We divided patients with RA into SN and SP groups and compared healthcare utilization including medications, medical utilization, and direct medical costs for 1 year between the groups in a cross-sectional analysis. Differences in costs between patients with SPRA and SNRA were assessed using the quantile regression model. We performed longitudinal analysis using data from 2012 and 2016 to examine changes over time.

Results:

A total of 103,815 SPRA and 75,809 SNRA patients were included in the analyses. The SPRA group used significantly more methotrexate (73.2% versus 30.3%) and biologic agents (7.9% versus 2.9%) than the SNRA group. The number of RA-related outpatient visits [6.0 ± 3.7 versus 4.4 ± 4.0 times/year, standardized difference (SD) = 0.41] and annual medical costs per patient ($1027 versus $450/year, SD = 0.25) were higher in the SPRA group than the SNRA group. Quantile regression results indicated that the incremental cost of seropositivity on total medical costs of RA patients gradually increased as medical costs approached the upper quantile. The annual direct medical costs for each patient between 2012 and 2016 increased in both groups: by 25.1% in the SPRA group and 37.6% in the SNRA group.

Conclusion:

Annual RA-related direct medical costs and RA-related healthcare utilization per patient are higher in patients with SPRA than those with SNRA.

Bidirectional association between migraine and rheumatoid arthritis: two longitudinal follow-up studies with a national sample cohort

OBJECTIVE

To investigate the bidirectional association between migraine and rheumatoid arthritis (RA).

DESIGN

Two longitudinal follow-up studies.

SETTING

Data collected from a national cohort between 2002 and 2013 by the Korean National Health Insurance Service-Health Screening Cohort.

PARTICIPANTS

In cohort 1, matching resulted in the inclusion of 31 589 migraine patients and 126 356 control I participants. In cohort 2, matching resulted in the inclusion of 9287 RA patients and 37 148 control II participants.

PRIMARY AND SECONDARY OUTCOME MEASURES

The HRs for RA in patients with migraine (cohort 1) and migraine in patients with RA (cohort 2) were analysed using stratified Cox proportional hazard models after adjusting for autoimmune disease, Charlson Comorbidity Index scores without rheumatoid diseases, obesity (body mass index), smoking and history of alcohol intake. Subgroup analyses stratified by age, sex, income and region of residence were also performed.

RESULTS

The incidence of RA in the migraine group (2.0% (640/31 589)) was higher than that in the control I group (1.4% (1709/126 356), p<0.001). The adjusted HR for RA in the migraine without aura group was 1.48 (95% CIs=1.34 to 1.63, p<0.001).The incidence of migraine in the RA group (6.4% (590/9287)) was higher than that in the control II group (4.6% (1721/37 148), p<0.001). The adjusted HR for migraine without aura in the RA group was 1.35 (95% CI=1.23 to 1.49, p<0.001).

CONCLUSION

Migraine increases the risk of RA, and RA is also associated with an increased risk of migraine.

Association of first, second, and third-line bDMARDs and tsDMARD with drug survival among seropositive rheumatoid arthritis patients: Cohort study in A real world setting

OBJECTIVES

To determine the association of first, second, and third-line biologic disease-modifying antirheumatic drugs (bDMARDs) and tofacitinib with drug survival among seropositive rheumatoid arthritis (RA) patients.

METHODS

The study population was composed of 8,018 seropositive RA patients who were prescribed bDMARDs or tofacitinib between January 2014 and January 2019 from the Korean Health Insurance Review and Assessment Service database. First, second, and third-line choice of tumor necrosis factor inhibitors (TNFi) including etanercept, infliximab, adalimumab, and golimumab, as well as non-TNFi including tocilizumab, rituximab, tofacitinib, and abatacept were assessed. Multivariate Cox proportional hazards regression was used to determine the adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for drug failure according to bDMARD or tofacitinib choice starting from the initial prescription date.

RESULTS

Compared to first etanercept users, patients with first tocilizumab (aHR 0.56, 95% CI 0.46-0.68), tofacitinib (aHR 0.27, 95% CI 0.18-0.42), or abatacept (aHR 0.83, 95% CI 0.69-0.99) had lower risk of drug failure. Second choice of tocilizumab (aHR 0.38, 95% CI 0.25-0.55), tofacitinib (aHR 0.23, 95% CI 0.15-0.37), or abatacept (aHR 0.54, 95% CI 0.35-0.84) was associated with lower drug failure risk compared to second etanercept users. Finally, third choice of tocilizumab (aHR 0.32, 95% CI 0.16-0.62) or tofacitinib (aHR 0.35, 95% CI 0.19-0.63) was associated with lower drug failure risk compared to third TNFi users.

CONCLUSION

First and second-line tocilizumab, tofacitinib, or abatacept may lead to improved drug survival. Third-line use of tocilizumab or tofacitinib may be beneficiary in reducing drug failure risk among seropositive RA patients.

Association between ischemic stroke and seropositive rheumatoid arthritis in Korea: A nationwide longitudinal cohort study

The purpose of this longitudinal follow-up study was to investigate the risk of ischemic stroke nationwide in patients with seropositive rheumatoid arthritis (RA) and controls who were matched in age and sex. Patient data were collected from the National Health Insurance Service (NHIS) Health Screening (HEALS) cohort. Using the International Classification of Diseases code M05 (seropositive RA), with a prescription of any disease-modifying anti-rheumatic drug (DMARD), RA was identified. A total of 2,765 patients and 13,825 control subjects were included in our study. The 12-year incidence of ischemic stroke in each group was calculated using the Kaplan–Meier method. The risk ratio of ischemic stroke was estimated using Cox proportional hazards regression. Sixty-four patients (2.31%) in the seropositive RA group and 512 (3.70%) in the control group experienced ischemic stroke (P < 0.001) during the follow-up period. The hazard ratio of ischemic stroke in the seropositive RA group was 1.32 (95% confidence interval (CI), 1.02–1.73) after adjusting for age and sex. The adjusted hazard ratio of ischemic stroke in the seropositive RA group was 1.40 (95% CI, 1.07–1.82) after adjusting for demographics and comorbid medical disorders. According to the subgroup analysis, the hazard ratios of ischemic stroke risks in the female and hypertensive subgroups were 1.44 (95% CI, 1.05–1.97) and 1.66 (95% CI, 1.16–2.38), respectively. In the non-diabetes and non-dyslipidemia subgroups, the corresponding hazard ratios of ischemic stroke were 1.47 (95% CI, 1.11–1.95) and 1.43 (95% CI, 1.07–1.91). Seropositive RA patients have an increased risk of ischemic stroke. In female, hypertension, non-diabetes, and non-dyslipidemia RA subgroups, even without the traditional risk factors for stroke (except for hypertension), increased the risk, which could be potentially attributed to RA.

Epidemiology of Rheumatoid Arthritis in Korea

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterised by symmetrical involvement of the joints, associated extra-articular manifestations and functional disability. In Korea, several epidemiologic studies reporting prevalence and incidence rates of RA have been conducted using large databases such as claims databases, national surveys, prospective cohort databases or electronic health records; according to these data sources, the estimated prevalence ranged from 0.27% to 1.85%. The prevalence of extra-articular manifestations such as interstitial lung disease (ILD) and Sjögren's syndrome (SS) were also reported, but an issue of external validity of the study results persisted. In this review, we detail the epidemiology of Korean RA patients, focusing on the prevalence of RA and the frequency of systemic extra-articular manifestations including ILD and SS reported in previous studies. In addition, we discuss the current methodological issues which are inherent in Korean epidemiologic studies for patients with RA with understanding of the characteristics of each database.

Trends in Meniscal Allograft Transplant in the Republic of Korea, 2010-2018: An Analysis Based on the Korean National Health Insurance Claims Database

Background:

Analyzing the current trends in meniscal allograft transplant (MAT) is important. However, no recent descriptive epidemiological study based on a national registry database has been reported.

Purpose:

To assess serial trends in the incidence of MAT in the Republic of Korea between 2010 and 2018, stratified by age and sex.

Study Design:

Descriptive epidemiology study.

Methods:

The number of MAT procedures between 2010 and 2018 was assessed using the Korean National Health Insurance claims database. We used code N0825 for isolated MAT and code N0820 for MAT combined with other procedures, such as ligament reconstruction, realignment surgery, and cartilage procedures. The incidence of MAT was calculated using the general population data of the Republic of Korea, and Poisson log-linear regression analysis was used to assess statistical serial trends.

Results:

A total of 369 patients underwent MAT in 2010 and 774 in 2018, with an increase of 47.6%. The incidence of MAT per 100,000 person-years in the Republic of Korea increased significantly during the period studied, from 0.75 in 2010 to 1.50 in 2018 (annual relative risk = 1.09; 95% CI, 1.08-1.10; P < .001), whereas the rate of MAT combined with other procedures increased from 5.1% in 2014 to 16.0% in 2018. MAT was mostly performed in men in their early 20s. Most MAT procedures were performed in the summer and winter, with distinct seasonal variances.

Conclusion:

In the Republic of Korea, the incidence of MAT in 2018 was 1.50 per 100,000 person-years, with an average annual increase of 10% since 2010. MAT was mostly performed in men in their early 20s, and the rate of MAT combined with other procedures has increased since 2014.

Psoriasis is associated with an increased risk of osteoporosis: follow-up and nested case-control studies using a national sample cohort

A total of 25,306 psoriasis participants were matched to 101,224 controls, and the occurrence of osteoporosis was analyzed. Additionally, 79,212 osteoporosis patients were matched to 79,212 controls and a previous history of psoriasis was analyzed. Psoriasis increased the risk of osteoporosis among participants aged ≥ 40 years.

INTRODUCTION

The aim of the present study was to evaluate the association between psoriasis and osteoporosis using two different studies.

METHODS

Data from the Korean National Health Insurance Service-Health Screening Cohort of participants aged ≥ 40 years were collected from 2002 to 2013. Psoriasis and osteoporosis were included using International Classification of Diseases (ICD)-10 codes. In study I (a follow-up study), a total of 25,306 psoriasis participants were matched to 101,224 controls with respect to age, sex, income, and region of residence, and the occurrence of osteoporosis was analyzed. Crude (simple) and adjusted hazard ratios (HRs) were analyzed using a stratified Cox proportional hazard model. In study II (a nested case-control study), a total of 79,212 osteoporosis patients were matched to 79,212 controls and a previous history of psoriasis was analyzed. Crude and adjusted odds ratios (ORs) were analyzed using a conditional logistic regression analysis. Subgroup analyses were conducted according to age group and sex.

RESULTS

The adjusted HR of osteoporosis was 1.09 (95% confidence interval [CI] = 1.05-1.13, P < 0.001) in study I. In the subgroup analysis according to age and sex, the results were consistent except for ≥ 60-year-old women. The adjusted OR of psoriasis was 1.21 (95% CI = 1.16-1.27, P < 0.001) in study II. All subgroups demonstrated high adjusted ORs of osteoporosis for psoriasis.

CONCLUSIONS

Psoriasis increased the risk of osteoporosis among participants aged ≥ 40 years in Korea.

The accuracy of administrative health data for identifying patients with rheumatoid arthritis: a retrospective validation study using medical records in Western Australia

The use of administrative health datasets is increasingly important for research on disease trends and outcome. The Western Australian (WA) Rheumatic Disease Epidemiological Registry contains longitudinal health data for over 10,000 patients with rheumatoid arthritis (RA). Accurate coding for RA is essential to the validity of this dataset. Investigate the diagnostic accuracy of International Classification of Diseases (ICD)-based discharge codes for RA at WA's largest tertiary hospital. Medical records for a sample of randomly selected patients with ICD-10 codes (M05.00-M06.99) in the hospital discharge database between 2008 and 2020 were retrospectively reviewed. Rheumatologist-reported diagnoses and ACR/EULAR classification criteria were used as reference standards to determine accuracy measures. Medical chart review was completed for 87 patients (mean (± SD) age 64.7 ± 17.2 years), 67.8% female). A total of 80 (91.9%) patients had specialist confirmed RA diagnosis, while seven patients (8%) had alternate clinical diagnoses. Among 87 patients, 69 patients (79.3%) were fulfilled ACR/EULAR classification criteria. The agreement between the reference standards was moderate (Kappa 0.41). Based on rheumatologist-reported diagnoses and ACR/EULAR classification criteria, primary diagnostic codes for RA alone had a sensitivity of (90% vs 89.8%), and PPV (90.9% vs 63.6%), respectively. A combination of a diagnostic RA code with biologic infusion codes in two or more codes increased the PPV to 97.9%. Hospital discharge diagnostic codes in WA identify RA patients with a high degree of accuracy. Combining a primary diagnostic code for RA with biological infusion codes can further increase the PPV.

Risk of New-Onset Acute Coronary Syndrome and Atrial Fibrillation in Patients With Rheumatoid Arthritis Compared With a Risk-Set and Propensity Score-Matched Cohort - A Nationwide Cohort Study

BACKGROUND

Rheumatoid arthritis (RA) has extra-articular manifestations of cardiovascular diseases and is associated with a high mortality rate in Western populations. This study aimed to investigate the risk of acute coronary syndrome (ACS) and atrial fibrillation (AF) associated with RA in a Korean population.Methods and Results:Patients were selected from a senior cohort from the Korean National Health Insurance Service in 2002, and followed until 31 December 2015. Patients with newly developed ACS and AF were identified and compared with controls for a 10-year period using time-dependent propensity and risk-set matching. A total of 4,217 incident RA patients and their 8,432 controls comprised the incident RA and matched cohorts, respectively. ACS was identified during 24,642 person-years [incidence rate (IR) 402 per 10,000 person-years, 95% confidence interval (CI) 330-489] among the RA cohort. In the matched cohort, 141 ACS patients were identified during 50,011 person-years (IR 282 per 100,000 person-years, 95% CI 239-333). RA patients were 1.43-fold more likely to develop ACS than the matched controls [hazard ratio (HR) 1.43, 95% CI 1.10-1.84], but showed similar occurrence risk of AF (HR 1.06, 95% CI 0.83-1.35).

CONCLUSIONS

A higher risk for ACS and a similar risk for AF were found by risk-set matched analysis in a senior RA cohort compared with the control, using Korean nationwide long-term data.

Assessment of the Accuracy of Using ICD-10 Codes to Identify Systemic Sclerosis

Importance

With the increased use of data from electronic medical records for research, it is important to validate in-patient electronic health records/hospital electronic health records for specific diseases identification using International Classification of Diseases, Tenth Revision (ICD-10) codes.

Objective

To assess the accuracy of using ICD-10 codes to identify systemic sclerosis (SSc) in the French hospital database.

Design Setting and Participants

Electronic health record database analysis. The setting of the study's in-patient database was the Toulouse University Hospital, a tertiary referral center (2880 beds) that serves approximately 2.9 million inhabitants. Participants were patients with ICD-10 discharge diagnosis codes of SSc seen at Toulouse University Hospital between January 1, 2010, and December 31, 2017.

Main Outcomes and Measures

The main outcome was the positive predictive value (PPV) of discharge diagnosis codes for identifying SSc. The PPVs were calculated by determining the ratio of the confirmed cases found by medical record review to the total number of cases identified by ICD-10 code.

Results

Of the 2766 hospital stays, 216 patients were identified by an SSc discharge diagnosis code. Two hundred were confirmed as SSc after medical record review. The overall PPV was 93% (95% CI, 88-95%). The PPV for limited cutaneous SSc was 95% (95% CI, 85-98%).

Conclusions and Relevance

Our results suggest that using ICD-10 codes alone to capture SSc is reliable in The French hospital database.

Comparative risk of osteoporotic fracture among patients with rheumatoid arthritis receiving TNF inhibitors versus other biologics: a cohort study

In this population-based cohort study on comparative osteoporotic fracture risks between different biologic disease-modifying drugs among patients with rheumatoid arthritis (RA), we did not find a significant difference in the risk of osteoporotic fractures between RA patients receiving TNF inhibitors versus abatacept or tocilizumab.

INTRODUCTION

We aimed to investigate the comparative risk of osteoporotic fractures between rheumatoid arthritis (RA) patients who initiated TNF inhibitors (TNFis) versus abatacept or tocilizumab.

METHODS

Using the Korea National Health Insurance Service datasets from 2002 to 2016, RA patients who initiated TNFis, abatacept, or tocilizumab were identified. The primary outcome was a composite end point of non-vertebral fractures and hospitalized vertebral fractures; secondary outcomes were two components of the primary outcome and fractures occurring at the humerus/forearm. Propensity score (PS) matching with a variable ratio up to 10 TNFi initiators per 1 comparator drug initiator was used to adjust for > 50 baseline confounders. We estimated hazard ratios (HRs) and 95% confidence interval (CI) of fractures comparing TNFi initiators to abatacept and to tocilizumab by Cox proportional hazard models stratified by a matching ratio.

RESULTS

After PS-matching, 2307 TNFi initiators PS-matched on 588 abatacept initiators, and 2462 TNFi initiators on 640 tocilizumab initiators were included. A total of 77 fractures occurred during a mean follow-up of 454 days among TNFi and abatacept initiators and 83 fractures during 461 days among TNFi and tocilizumab initiators. The PS-matched HR (95% CI) was 0.91 (0.48-1.71) comparing TNFi versus abatacept initiators, and 1.00 (0.55-1.83) comparing TNFi versus tocilizumab initiators. Analysis on vertebral and non-vertebral fractures showed similar results.

CONCLUSIONS

In this nationally representative cohort, we did not find a significant difference in the risk of fractures between TNFi initiators versus abatacept or tocilizumab among RA patients.

Prevalence of patients with rheumatoid arthritis and age-stratified trends in clinical characteristics and treatment, based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan

AIM

To estimate the prevalence and age-stratified treatment trends and clinical characteristics of rheumatoid arthritis (RA) in Japan.

METHOD

Using 7 RA definitions, the prevalence of RA in those aged ≥16 years was estimated using the National Database of Health Insurance Claims and Specific Health Checkups of Japan in the fiscal year 2017. We analyzed age-stratified trends in characteristics and treatments.

RESULTS

Of 1 116 122 patients aged ≥16 years with at least 1 RA-related International Classification of Diseases-10 code, 825.7 thousand patients (women, 76.3%) were assessed as having RA with an estimated prevalence of 0.65%. The highest age-stratified prevalence was 1.63% in patients aged 70-79 years. Overall, 60.8% and 7.0% of patients with RA were aged ≥65 years and ≥85 years, respectively. Methotrexate use was most frequent in patients aged 50-59 years (73.0%) and least frequent in patients aged ≥85 years (38.2%). Biologic disease-modifying antirheumatic drugs use was 50.9% in patients aged 16-19 years and decreased to 13.7% in those aged ≥85 years. Preference for the use of tumor necrosis factor inhibitors versus abatacept decreased from 24.0:1 to 1.7:1 in patients aged 16-19 years and ≥85 years, respectively. The prevalence of cardiovascular disease was 3.5% in patients aged 60-69 years and 12.1% in those aged ≥85 years. Overall RA-related orthopedic surgeries were most prevalent in patients aged 70-79 years.

CONCLUSION

The estimated prevalence of patients with RA in Japan was 0.65%. Age-stratified treatment trends and clinical characteristics have been described in a super-aged society for the first time.

Increased Risk of Temporomandibular Joint Disorder in Patients with Rheumatoid Arthritis: A Longitudinal Follow-Up Study

We evaluated the incidence of temporomandibular disorder (TMD) in patients with rheumatoid arthritis (RA) and examined the association between TMD and RA, through longitudinal follow-up. Population data from the Korean National Health Insurance Service-Health Screening Cohort from 2002 to 2015 was used. From 514,866 subjects, 3122 with RA were matched with 12,488 controls in a 1:4 ratio. The crude and adjusted models (for obesity, smoking, alcohol consumption, blood pressure, blood glucose, total cholesterol, and Charlson Comorbidity Index scores) were calculated. Chi-square tests, Kaplan-Meier (KM) analysis, and two-tailed analyses were used for statistical analysis. Stratified Cox proportional hazard models were used to assess the hazard ratios (HR) and 95% confidence intervals (CI) for TMD in the RA group, compared to those in the control group. The adjusted HR for TMD in RA was 2.52 (95% CI = 1.70–3.74), compared to the control group. The results were consistent with the subgroup analyses, according to age and sex, except in men older than 60 years of age. KM analysis showed similar results. Hence, we found that patients with RA have a higher risk of TMD, and should be observed for symptoms of the initial stage of TMD to prevent the risk of aggravation.

Bidirectional association between GERD and rheumatoid arthritis: two longitudinal follow-up studies using a national sample cohort

Several previous studies have suggested a relationship between GERD and RA. However, no study has investigated the bidirectional relationship between GERD and RA. This study aimed to evaluate the causal relationships between rheumatoid arthritis (RA) and gastroesophageal reflux disease (GERD). Participants aged ≥ 20 years old in the Korean Health Insurance Review and Assessment Service-National Sample Cohort from 2002 to 2013 were enrolled. In study I, 132,140 GERD participants were 1:2 matched with 264,280 control I participants. In study II, 6615 RA participants were 1:4 matched with 26,460 control II participants. Both control I and control II groups were matched with their study groups for age, sex, income, and region of residence. The occurrence of RA (study I) and GERD (study II) were followed up in both the study and control groups. The hazard ratios (HRs) of GERD for RA (study I) and of RA for GERD (study II) were analysed using stratified Cox-proportional hazards models. In study I, 0.8% (1,034/132,140) of the GERD group and 0.5% (1,290/264,280) of the control I group had RA (P < 0.001). The GERD group demonstrated a 1.49-fold higher adjusted HR than did the control I group (95% confidence interval (95% CI) = 1.37-1.62, P < 0.001). In study II, 22.5% (1,490/6,615) of the RA group and 15.2% (4,034/26,460) of the control II group had GERD (P < 0.001). The RA group showed a 1.46-fold higher adjusted HR than did the control II group (95% CI = 1.38-1.55, P < 0.001). GERD and RA have bidirectional associations in Korean adult population. Key Points • Several previous studies have suggested a relationship between gastroesophageal reflux disease (GERD) and rheumatoid arthritis (RA). • However, no study has investigated the bidirectional relationship between GERD and RA. • This is the first study to present a bidirectional relationship between GERD and RA. • GERD and RA have bidirectional relations with each other.

Risk factors associated with initiation of a biologic disease modifying anti-rheumatic drug in patients with rheumatoid arthritis: A nested case-control study on 34,925 patients

OBJECTIVE

To identify risk factors of biological disease-modifying anti-rheumatic drugs (bDMARDs) initiation in patients with rheumatoid arthritis (RA).

METHODS

Using the 2002-2016 Korea National Health Insurance database, we conducted a nested case-control study on seropositive RA patients. Cases (bDMARD users) and controls (users of conventional synthetic DMARDs only) were 1:4 matched on the calendar year/month of RA diagnosis and index dates (bDMARD initiation dates). Potential risk factors from two time periods, 1-year post-RA-diagnosis and 1-year pre-index, were separately assessed on the association with bDMARD initiation by conditional logistic regression analyses.

RESULTS

The study included 6985 cases and 27,940 controls. Older age, female gender, use of methotrexate (MTX), leflunomide, or tacrolimus as a first csDMARD, higher initial MTX dose, and initial csDMARD combination during 1-year post-diagnosis were negatively associated with later bDMARD initiation, while use of sulfasalazine as a first csDMARD, corticosteroid therapy, and higher maximal MTX dose were positively associated. Among covariates from 1-year period before bDMARD initiation, use of leflunomide, sulfasalazine, or tacrolimus, parenteral MTX, higher maximal MTX dose, corticosteroid, and csDMARD combination were positively associated with subsequent bDMARD initiation. Effects of comorbidities on bDMARD initiation were heterogenous across involved systems.

CONCLUSION

In this population-based nationwide study, we identified period-specific risk factors of bDMARD initiation among RA patients in Korea. Overall, initial aggressive RA treatment after diagnosis was associated with less use of later bDMARD, while highly intensive therapy observed just before bDMARD initiation rather reflects refractory nature of RA during this period, and did not prevent bDMARD use.

Introducing big data analysis using data from National Health Insurance Service

Among the different providers of health care big data in Korea, the data provided by the National Health Insurance Database include the medical information of all the citizens who have subscribed to medical insurance. As such, the data have representativeness and completeness. In order to conduct research using these National Health Insurance Database data, it is necessary to understand the characteristics of the claim data to avoid various biases, and to control confounding variables when making various operational definitions in the planning stage of the research. Moreover, without a proper understanding of the big data, it is possible during the analysis and data interpretation to mistakenly interpret the correlation between variables as a causal relationship. Therefore, in order to help advanced medical science, which reflects the medical reality such as medical expenses and number of hospital visits by clearly recognizing and analyzing the characteristics and limitations of health care big data, this author has dealt with the use of data sharing services provided by the National Health Insurance Database.

Pregnancy outcomes in women with inflammatory bowel disease: a 10-year nationwide population-based cohort study

BACKGROUND

Data relating to the association between inflammatory bowel disease (IBD) and pregnancy outcomes are lacking in Korea.

AIMS

To determine the incidence rates of pregnancy outcomes in women with IBD.

METHODS

A nationwide population study was performed using the Korean National Health Insurance claims database. A total of 2058 women with IBD consisting of ulcerative colitis (UC, n = 1469) and Crohn's disease (CD, n = 589) were pregnant between 2007 and 2016. We compared their incidence of pregnancy outcomes with 20 580 age-matched controls without IBD. We also stratified the patients into those with quiescent to mild and moderate to severe IBD and compared the outcomes between them.

RESULTS

The pregnancy rate of women with IBD was lower than that of women without (25.7% vs 32.3%, P < 0.001). Caesarean section (46.5% vs 38.8%, odds ratio [OR] 1.43, 95% confidence interval [CI]: 1.17-1.75), and intrauterine growth retardation (IUGR) (3.0% vs 1.0%, OR 2.89, 95% CI: 1.59-5.26) were increased in CD patients than the controls. In regards to disease severity, there were no significant differences in pregnancy outcomes between patients with quiescent to mild IBD and the controls. However, the live birth rate of patients with moderate to severe IBD was lower than that of the controls (65.0% vs 69.9%, OR 0.79, 95%CI: 0.66-0.94). In addition, moderate to severe IBD was significantly associated with spontaneous abortion (14.9% vs 11.9%, OR 1.33, 95% CI: 1.04-1.68), caesarean section (46.4% vs 38.8%, OR 1.41, 95% CI: 1.14-1.74) and IUGR (3.4% vs 1.0%, OR 3.20, 95% CI: 1.75-5.84).

CONCLUSIONS

With the exception of moderate to severe disease, the incidences of adverse pregnancy outcomes in women with IBD are similar to that of the general population.

The association between Bell's palsy and rheumatoid arthritis: A longitudinal study

This study aimed to evaluate the relationship between Bell's palsy and rheumatoid arthritis in a national sample cohort from Korea.Data were collected for individuals ≥20 years old from 2002 to 2013 in the Korean National Health Insurance Service-National Sample Cohort. We extracted data for patients with rheumatoid arthritis (n = 7628) and 1:4-matched controls (n = 30,512) and analyzed the occurrence of Bell's palsy in both groups. Matching was performed based on age, sex, income, and region of residence. Rheumatoid arthritis was diagnosed according to International Classification of Disease-10 (ICD-10) codes (M05-M06) and the prescription of biological agents and/or disease-modifying antirheumatic drugs. Bell's palsy patients were diagnosed according to ICD-10 code H912 and treatment ≥2 times with steroids. Adjusted hazard ratios (HRs) were calculated using stratified Cox proportional hazard models for the Charlson comorbidity index and 95% confidence intervals (CIs). Subgroup analyses based on age and sex were also performed.The rates of Bell's palsy were similar between the rheumatoid arthritis group (0.5% [38/7628]) and the control group, with no significant difference (0.4% [124/30,512], P = .270). The adjusted HR for Bell's palsy was 1.12 (95% CI, 0.78-1.62) in the rheumatoid arthritis group (P = .540). In the subgroup analyses according to age and sex, the relationship between Bell's palsy and rheumatoid arthritis did not reach statistical significance.The risk of Bell's palsy was not increased in patients with rheumatoid arthritis.