Tonsillectomy Does Not Reduce Upper Respiratory Infections: A National Cohort Study

Effects of tonsillectomy and adenoidectomy on the immune system

Surgical removal of the tonsils and adenoids, important immune organs, is a frequent and recurrent class of surgery, and currently, there is no consensus on the effects these surgical procedures may have on the immune system. Here, we examine individual studies on tonsillectomy, adenoidectomy, and adenotonsillectomy, discuss their postoperative humoral and cellular immune changes, and explore their effects on the incidence of related diseases. There is evidence that these three surgeries have no negative effects on humoral immunity; however, there has been contrary results. Furthermore, these procedures seem to have no significant effects on cellular immunity, although tonsil and adenoid removal can cause an increased incidence of certain illnesses, especially infectious diseases. Based on this comprehensive review, we conclude that the removal of tonsils and adenoids does not negatively affect cellular and humoral immunity. However, surgery may lead to an increased incidence of related infectious diseases. This finding may inform the surgeon's decision to perform the procedure in a clinical setting.

Long Term Impact of Adeno-tonsillectomy on Immunity Against Respiratory Viral Infections; Evidence Deduced During COVID-19 Pandemic

OBJECTIVES

To evaluate the risk of acquiring COVID-19 infection in patients who have undergone adeno-tonsillectomy (AT) as compared to their siblings.

METHODS

In this bidirectional cohort control study, 36 cohorts, younger than 18 y, who underwent AT, and 27 controls (siblings of the enrolled cohorts, younger than 18 y) were recruited. Incidence of COVID-19 was analyzed by symptoms suggestive of COVID-19 infection, COVID-19 testing, and SARS-CoV-2 specific antibody measurement.

RESULTS

In the cohort group, the overall COVID-19 positivity rate was 80.5% (n = 29/36) and symptomatic COVID-19 positivity rate was 68.9% (n = 20/29). Among the controls, the overall COVID-19 positivity rate was 44% (n = 12/27) and symptomatic COVID-19 positivity rate was 16% (n = 2/12). The cohorts had 1.8 times higher risk of contracting COVID-19 infection and the relative risk of symptomatic COVID-19 infections as compared to controls was 4.14.

CONCLUSIONS

This pilot study indicates that adeno-tonsillectomy poses children at a significantly higher risk of COVID-19 infections and likely other viral upper respiratory tract infections.

Unlocking the Protective Potential of Upper Respiratory Infection Treatment Histories against Alzheimer's Disease: A Korean Adult Population Study

With increasing interest in the inflammation-pathogen infection hypothesis and its potential links to Alzheimer's disease (AD) development, there is growing consideration of using upper respiratory infection (URI) treatments as interventions for AD. This nested case-control study explored the potential association between prior URI histories and AD development in a Korean adult population using the national health screening cohort data (2002-2019). The study included 26,920 AD patients and 107,680 matched control individuals, focusing on those seeking respiratory treatment. Logistic regression analyses assessed the impact of URI histories and treatment on AD risk while adjusting for covariates. Our results revealed that over a 1-year period, individuals with URI histories (≥1, ≥2, or ≥3 instances) exhibited decreasing probabilities of developing AD, with risk reductions of 19%, 15%, and 12%, respectively. Expanding our investigation to a 2-year period consistently showed a 17% reduction in AD risk. This effect remained robust across diverse demographic groups and after adjusting for covariates, encompassing comorbidities, hypertension, hyperlipidemia, blood glucose levels, and lifestyle factors. Subgroup analyses further substantiated this association. In conclusion, our findings cautiously suggest a potential protective role of prior URI treatment histories in mitigating the risk of AD development.

The beneficial effects of an adenotonsillectomy upon upper respiratory tract infections, asthma and rhinitis in children: a national database study in Korea

BACKGROUND

Adenotonsillectomy is the most commonly performed surgery in children.

AIMS

To evaluate the effects of pediatric adenotonsillectomy on health care utilization.

METHODS

From 2006 to 2017, age/sex-matched adenotonsillectomy participants (n = 243.396) and controls (n = 730.188) were selected (62% of male and 38% of female. 47% age≦ 6, 16% 7-9years, 8% 10-12years, 29% 13-18years). The changes in outpatient visits, hospitalization days, and drug prescriptions due to a URI, asthma, and rhinitis before and after the surgery date (from 13 months to 1 month) were compared.

RESULTS

Outpatient visits decreased more in the surgery group than the control group (mean change, 3.24 ± 8.61 d and 1.16 ± 6.57 d for URI, 2.07 ± 8.63 d and 0.51 ± 6.47 d for rhinitis, and 0.72 ± 4.81 d and 0.42 ± 3.91 d for asthma, p < .001 for all). Hospitalizations also showed greater decreases in the surgery group (mean change, 0.31 ± 2.96 d and 0.04 ± 1.70 d for URI, 0.13 ± 2.40 d and 0.02 ± 1.48 d for rhinitis, 0.11 ± 2.32 d and 0.04 ± 1.83 d for asthma, p < .001 for all). The prescription of antihistamines, leukotriene modulators, oral antibiotics, oral steroids, and expectorants, cough suppressants and oral bronchodilators was also decreased after surgery.

CONCLUSIONS

The adenotonsillectomy group showed a greater decrease in post-operative outpatients visits, hospital days and drug prescriptions associated with URI, rhinitis and asthma than the control group.

Tonsillectomy in Adults over 40 Years of Age Does Not Increase the Risk of Pneumonia: A Three-Year Longitudinal Follow-Up Study

To evaluate the effect of tonsillectomy on the subsequent risk of pneumonia in an adult population, a longitudinal follow-up case control study was conducted using a national health screening cohort dataset between 2003 and 2012. A total of 1005 tonsillectomy participants were 1:4 matched with 4020 control participants for age, sex, income, and region of residence. The number of pneumonia diagnoses were counted from the index date (ID) to the date after the first-year (post-ID 1y), second-year (post-ID 2y), and third-year (post-ID 3y) periods. Simple linear regression and multiple linear regression were conducted to calculate estimated values (EVs) and 95% confidence intervals for each post-ID pneumonia and compared between the two groups. Subgroup analyses were performed according to age, sex, and the number of pneumonia cases during the year prior to the ID (pre-ID 1y). In the simple linear regression model, post-ID pneumonia did not show a significant correlation with tonsillectomy (post-ID 1y: EV = 0.003; post-ID 2y: EV = 0.007; post-ID 3y: EV = 0.013; all p > 0.05). In the multiple regression model, post-ID pneumonia also did not show a significant correlation with tonsillectomy (post-ID 1y: EV = 0.001; post-ID 2y: EV = 0.006; post-ID 3y: EV = 0.011; all p > 0.05). In the subgroup analyses, tonsillectomy did not show a significant correlation with post-ID pneumonia in either the simple linear regression or multiple linear regression models (all p > 0.05). Tonsillectomy performed in the adult population did not show any effect in increasing the incidence of pneumonia during the first three postoperative years.

Adenotonsillectomy Does not Alter the Risk of Upper Airway Infections in Children

OBJECTIVE

Given the conflicting evidence regarding adenotonsillectomy and the risk of upper airway infections (UAIs), including acute pharyngitis (APT), rhinosinusitis (ARS), and otitis media (AOM), we evaluated the risk of developing UAIs following adenotonsillectomy in a childhood population.

METHODS

In this population-based follow-up study, we used data from the National Health Insurance Service-National Sample Cohort. The adenotonsillectomy group (n = 2,377) included patients aged <10 years who underwent an adenotonsillectomy. For every patient with APT (n = 2,309), ARS (n = 2,308), and AOM (n = 2,207) who had an adenotonsillectomy, four participants were randomly selected for the control groups (n = 9,204, n = 9,196, and n = 8,788, respectively) using propensity score matching. The number of postoperative hospital visits for UAIs was recorded for 1 to 9 years, and the equivalence test was used to compare the number of visits between the adenotonsillectomy and control groups.

RESULTS

There were no significant differences in the incidence of APT, ARS, or AOM at the margin of equivalence of difference (-0.5 < 95% confidence interval of difference < 0.5) between the two groups from postoperative year 1 to year 9. The hospital visits for these diseases gradually decreased over time in both groups. There was a significant decrease in the number of visits for APT, ARS, and AOM in the 5-9 years age group when compared with those in the <4 years age group (P < .01).

CONCLUSION

Our results suggest that adenotonsillectomy does not alter the frequency of UAIs in children.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2021.

Increased risk of ischemic stroke in patients with Bell's palsy: A longitudinal follow-up study using a national sample cohort

OBJECTIVE

To investigate the association between Bell's palsy and stroke according to the different types of stroke, using a sample cohort based on the national Korean population.

METHODS

Individuals aged ≥ 20 years were collected from the Korean National Health Insurance Service National Sample Cohort between 2002 and 2013. We extracted the data for Bell's palsy patients (n = 3658) and 1:4 matched controls (n = 14,632) and analyzed the occurrence of hemorrhagic or ischemic stroke in both groups. Matching was performed on the basis of age, gender, income, and region of residence. For Bell's palsy, we included only participants who received the diagnosis (ICD-10 code, G510) 2 or more times via ambulatory visits for the same episode with steroid treatment. Patient admission histories were used to identify occurrences of hemorrhagic stroke (I60, I61 and I62) and ischemic stroke (I63). Adjusted hazard ratios were calculated using stratified Cox proportional hazard models for the Charlson comorbidity index and 95% confidence intervals (CIs). For the subgroup analyses, we divided the participants by age, sex, and each time period after the onset of Bell's palsy (≤1 year, 1 to 2 years, 2 to 3years, > 3years).

RESULTS

The risk of ischemic stroke was significantly increased in Bell's palsy patients compared to that in the controls (adjusted HR = 1.74, 95% CI = 1.38-2.19, P < 0.001). In the subgroup analyses, a significant association between two clinical disorders was observed in patients aged ≥ 50 years old, regardless of gender. The risk of ischemic stroke was significantly increased, especially within 2 years after Bell's palsy. In contrast, the risk of hemorrhagic stroke was not significantly increased.

CONCLUSION

There is an association of Bell's palsy with ischemic stroke but not with hemorrhagic stroke.

Association of adenotonsillectomy with asthma and upper respiratory infection: A nationwide cohort study

Adenotonsillectomy is a common paediatric surgery for treating obstructed breathing or recurrent inflammation; however, the long-term health consequences on the developing immune system are unknown. This study investigated the potential association between adenotonsillectomy and the development of asthma and upper respiratory infections (URI). This propensity score-matched retrospective cohort study utilized data from the National Sample Cohort 2002–2013. In the asthma cohort, we used a Cox-proportional hazards model to analyze the hazard ratio (HR) of adenotonsillectomy for asthma events. In the URI cohort, equivalence testing of postoperative visits for URI was performed. The margin of equivalence of the difference was set at -0.5–0.5. Asthma incidence was 66.97/1000 person-years in children who underwent adenotonsillectomy and 30.43/1000 person-years in those who did not. Adjusted asthma HRs were 2.25 (95% confidence interval, 1.96–2.57) in the adenotonsillectomy vs. non-adenotonsillectomy groups. In a subgroup analysis, children aged 5–9 years living in metropolitan areas showed a higher incidence of subsequent asthma than those of other ages and areas. However, any significant difference between the groups in terms of URI events in the 1–11-year postoperative period was not identified. Adenotonsillectomy in children is associated with an increased incidence of asthma, with no significant impact on postoperative visits for URI.

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.

Appendectomy and rheumatoid arthritis: A longitudinal follow-up study using a national sample cohort

The present study evaluated the association between appendectomy and rheumatoid arthritis (RA) using a national sample cohort of the Korean population. In this cohort study, the Korean National Health Insurance Service-National Sample Cohort of individuals ≥20 years old was collected from 2002 to 2013. A total of 14,995 appendectomy participants were 1:4 matched with 59,980 control subjects for age, group, sex, income group, region of residence, hypertension, diabetes, and dyslipidemia. We analyzed the occurrence of RA in both the appendectomy and control groups. Appendectomies were identified using operation codes for appendicitis only. RA was defined by International Classification of Disease-10 codes (M05 or M06) and medication histories. Crude and adjusted hazard ratios (HRs) were analyzed using a stratified Cox proportional hazard model. Subgroup analyses were performed on groups stratified by age and sex. The adjusted HR for RA was 1.02 (95% confidence interval = 0.76-1.38) in the appendectomy group (P = .883). In all of the subgroup analyses according to age and sex, the adjusted HRs for RA were not higher in the appendectomy group than those in the control group. We could not identify any significant relationship between appendectomy and RA.

Rheumatoid arthritis and neurodegenerative dementia: a nested case-control study and a follow-up study using a national sample cohort

OBJECTIVES

The present study evaluated the associations between rheumatoid arthritis (RA) and neurodegenerative dementia using a Korean national sample cohort.

METHODS

We designed two studies using the Korean National Health Insurance Service-National Sample Cohort from 2002 to 2013. Study I included participants with dementia matched 1:4 with controls and analyzed the participants' history of RA. Study II included participants with RA matched 1:4 with controls and analyzed the occurrence of dementia. RA was defined by the presence of relevant ICD-10 codes (M05 or M06) and medication histories. Neurodegenerative dementia was defined using ICD-10 codes (G30 or F00). Crude and adjusted odds ratios (ORs) were analyzed using conditional logistic regression analyses. Crude and adjusted hazard ratios (HRs) were analyzed using the stratified Cox proportional hazard model. Subgroup analyses were performed on groups stratified by age and sex.

RESULTS

The adjusted ORs for RA were 0.96 (95% CI = 0.78-1.16, P = 0.644) in the dementia group in study I. The adjusted HRs for dementia were 0.91 (95% CI = 0.76-1.10, P = 0.319) in the RA group in study II. No subgroup analysis reached the statistical significance level.

CONCLUSION

We could not identify any significant relationship between RA and dementia.Key Points• Two studies were conducted to identify the relationship between rheumatoid arthritis and dementia using national cohort data.• Neither study showed any association between rheumatoid arthritis and dementia.

Association between Herpes Zoster and Osteoporosis: A Nested Case-Control Study Using a National Sample Cohort

Objectives

Chronic inflammatory disease might affect osteoporosis; however, few studies have reported the association between herpes zoster and osteoporosis. The goal of this study was to estimate the association between herpes zoster and osteoporosis in Korean residents.

Methods

The Korean National Health Insurance Service-National Sample Cohort, which includes individuals aged ≥ 50 years, was assessed from 2002 to 2013. In total, 68,492 osteoporosis participants were matched with 68,492 control participants at a ratio of 1:1 by age, sex, income, and region of residence. We assayed the prior histories of herpes zoster in the osteoporosis and control groups. The diagnoses of herpes zoster and osteoporosis were based on ICD-10 codes and claim codes. Crude and adjusted models of odds ratios (ORs) were explored using conditional logistic regression analyses, and the 95% confidence intervals (CIs) were computed. The participants were stratified according to age, sex, income, and region of residence. Subgroup analyses were performed to investigate the role of age and sex.

Results

The rate of herpes zoster in the osteoporosis group (5.1% [3,487/68,492]) was higher than that in the control group (4.0% [2,738/68,492]). The adjusted OR of herpes zoster in the osteoporosis group was 1.17 (95% CI = 1.11-1.24). In the subgroup analyses, the adjusted OR was 1.34 (95% CI = 1.01-1.78) among males aged < 65 years, 1.20 (95% CI = 1.12-1.29) among females aged < 65 years, and 1.19 (95% CI = 1.04-1.36) among males aged ≥ 65 years.

Conclusion

The ORs of herpes zoster were increased among the osteoporosis patients. This correlation was reliable in all subgroups by age and sex except group of women ≥ 65 years old.

Increased risk of psoriasis in patients with chronic rhinosinusitis without nasal polyps: a longitudinal follow-up study using Korean national sample cohort

PURPOSE

Focal chronic inflammation or infection is thought to be one of the causes of psoriasis. Few reports on the association between chronic rhinosinusitis (CRS) and psoriasis exist, thus it is poorly defined. This study seeks to investigate the incidence of psoriasis in patients with CRS with reference to a matched control group.

METHODS

This national cohort study relies on data from Korean Health Insurance Review and Assessment Service-National Sample Cohort (HIRA-NSC), which were entered from 2002 to 2013. A total of 34,219 patients with CRS without nasal polyps was matched with 136,976 controls. The Cox proportional hazard model was used to analyze the crude (simple) and adjusted hazard ratios (HRs) of psoriasis. For subgroup analysis, participants were grouped by age and sex.

RESULTS

The risk of psoriasis was higher in the CRS group than in the control group (adjusted HR 1.28, 95% CI 1.12-1.47, P < 0.001). Children, adolescents below 19 years regardless of sex, and old adult men above 60 years are at significantly higher risk for subsequent psoriasis after CRS diagnosis.

CONCLUSION

CRS may increase the risk of psoriasis.

Association between chronic rhinosinusitis and osteoporosis: a case-control study using a national sample cohort

BACKGROUND

The purpose of this study was to further clarify the relationship between chronic rhinosinusitis (CRS) and osteoporosis in a Korean population.

METHODS

The Korean National Health Insurance Service-National Sample Cohort, with subjects ≥50 years old, was assessed for the time period 2002-2013. In total, 68,459 osteoporosis participants were matched with 68,459 control participants at a ratio of 1:1 with respect to age, sex, income group, region of residence, hypertension, diabetes, and dyslipidemia. We analyzed previous histories of CRS with/without nasal polyp in the osteoporosis and control groups. CRS and osteoporosis were included using codes from the International Classification of Diseases-tenth edition and claim codes. Crude and adjusted odds ratios (ORs) were analyzed using conditional logistic regression analyses. The 95% confidence intervals (CIs) were then calculated. Subgroup analyses were performed according to age and sex.

RESULTS

The rate of CRS with/without nasal polyp was higher in the osteoporosis group (3.0% [2078 of 68,459]) compared with the control group (2.0% [1344 of 68,459]) (p < 0.001). The adjusted OR of CRS with/without nasal polyp was 1.47 (95% CI, 1.37-1.58; p < 0.001) in the osteoporosis group. The results of the subgroup analyses were consistent.

CONCLUSION

The ORs of CRS were increased in osteoporosis participants. This relation was consistent in all age and sex groups.

Association between cholelithiasis and sialolithiasis: Two longitudinal follow-up studies

This study aimed to evaluate the association between cholelithiasis and sialolithiasis using a national sample cohort in Korea.The Korean National Health Insurance Service-National Sample Cohort (patients ≥20 years old) was collected from 2002 to 2013. In study I, we extracted cholelithiasis patients (n = 21,170) and 1:4 matched control I subjects (n = 84,680) and analyzed the occurrence of sialolithiasis. In study II, we extracted sialolithiasis patients (n = 761) and 1:4 matched control II subjects (n = 3044) and analyzed the occurrence of cholelithiasis. Hazard ratios (HRs) were determined using the stratified Cox proportional hazard model.The HR for sialolithiasis was 1.49 (95% CI = 0.88-2.52) in the cholelithiasis group (P = .14), and the HR for cholelithiasis was 1.18 (95% CI = 0.53-2.59) in the sialolithiasis group (P = .69).We did not find an association between cholelithiasis and sialolithiasis.

Increased risk of appendectomy due to appendicitis after tonsillectomy in women: A longitudinal follow-up study using a national sample cohort

The purpose of this study was to evaluate the risk of appendectomy due to appendicitis after tonsillectomy in Koreans using national cohort data. Using the national cohort study from the Korean Health Insurance Review and Assessment Service, 1:4 matched tonsillectomy participants (9015) and control participants (36,060) were selected. The Cox-proportional hazard model was used. In this analysis, a crude and adjusted model for age, sex, income, region of residence, and the past medical histories of hypertension, diabetes mellitus, and dyslipidemia were used. For the subgroup analyses, the participants were divided as follows: children (≤14 years old) vs adolescents and adults (≥15 years old) and men vs women. The adjusted hazard ratio (HR) of tonsillectomy for appendectomy was 1.06 (95% confidence interval, CI = 0.89-1.27, P = .517). In the subgroup analysis, the HR was 1.03 (95% CI = 0.82-1.30, P = .804) in children and 1.10 (95% CI = 0.84-1.47, P = .468) in adolescents and adults. In another subgroup analysis, the HR was 0.89 (95% CI = 0.70-1.12, P = .314) in men and 1.39 (95% CI = 1.06-1.83, P = .018) in women. The risk of appendectomy was higher in the tonsillectomy group but only in women.

Increased risk of gallstones after gastrectomy: A longitudinal follow-up study using a national sample cohort in korea

This study sought to evaluate the association between gastrectomy and the occurrence of gallstones using a national sample cohort from Korea.Data from 2002 to 2013 were collected for individuals ≥20 years of age in the Korean National Health Insurance Service-National Sample Cohort (NHIS-NSC). We extracted data for patients who had undergone gastrectomy (n = 1998) and a 1:4 matched control group (n = 7992) and then analyzed the occurrence of gallstones. The patients were matched according to age, sex, income, region of residence, hypertension, diabetes mellitus, and history of dyslipidemia. Gastrectomies were identified using operation codes (Q2533-Q2537, Q2594-Q2596, and Q2598). Gallstones were diagnosed if the corresponding International Classification of Disease-10 code (K80) was reported ≥2 times. Crude (simple) and adjusted hazard ratios (HRs) were analyzed using Cox proportional hazard models, and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed based on age and sex.The adjusted HR for gallstones was 1.77 (95% CI = 1.34-2.35, P < .001) in the gastrectomy group compared to control. Consistent HRs were found in the analyses of all of the subgroups determined using age and sex.The occurrence of gallstones was increased in the patients who had undergone gastrectomy compared to their matched control group.

Risk of ischaemic stroke in patients with migraine: a longitudinal follow-up study using a national sample cohort in South Korea

OBJECTIVE

Accumulating evidence has supported the association between migraine and stroke, but the causative association remains unclear. We aimed to investigate the risks of different types of stroke in patients with migraine.

DESIGN

A longitudinal follow-up study.

SETTING

Data collected from a national cohort between 2002 and 2013 by the South Korea Health Insurance Review and Assessment.

PARTICIPANTS

We extracted the data from patients with migraine (n=41 585) and 1:4 matched controls (n=1 66 340) and analysed the occurrence of ischaemic and haemorrhagic strokes. The migraine group included participants treated for migraine (International Classification of Disease-10 (ICD-10): G43)≥2 times. Haemorrhagic stroke (I60-I62) and ischaemic stroke (I63) were determined based on the admission histories. The crude and adjusted HRs were calculated using Cox proportional hazard models, and the 95% CI were determined. Subgroup analyses stratified by age and sex were also performed.

RESULTS

Higher rates of ischaemic stroke were observed in the migraine group (2.3% [964/41,585]) than in the control group (2.0% [3294/166 340], P<0.001). The adjusted HR for ischaemic stroke was 1.18 (95% CI=1.10 to 1.26) in the migraine group (P<0.001). Compared with control subjects, participants who reported migraine with aura and migraine without aura had increased adjusted HRs of 1.44 (95% CI=1.09 to 1.89) and 1.15 (95% CI=1.06 to 1.24), respectively, for ischaemic stroke, but no increased risk of haemorrhagic stroke. In our subgroup analysis, a strong association between migraine and ischaemic stroke was observed in young patients, specifically young women. The contribution of migraine to the occurrence of ischaemic stroke was also observed in middle-aged women and old women (each P<0.05). The risk of haemorrhagic stroke did not reach statistical significance in any age group.

CONCLUSION

Migraine is associated with an increased risk of ischaemic stroke, but not haemorrhagic stroke.

Bidirectional association between gallstones and renal stones: Two longitudinal follow-up studies using a national sample cohort

The present study evaluated the associations between gallstones and renal stones using a national sample cohort of the Korean population. The Korean National Health Insurance Service-National Sample Cohort was collected from 2002 to 2013. We designed two different longitudinal follow-up studies. In study I, we extracted gallstone patients (n = 20,711) and 1:4-matched control I subjects (n = 82,844) and analyzed the occurrence of renal stones. In study II, we extracted renal stone patients (n = 23,615) and 1:4-matched control II subjects (n = 94,460) and analyzed the occurrence of gallstones. Matching was performed for age, sex, income, region of residence, and history of hypertension, diabetes mellitus, and dyslipidemia. Crude and adjusted hazard ratios (HRs) were calculated using a Cox proportional hazards model, and the 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed according to age and sex. The adjusted HR of renal stones was 1.93 (95% CI = 1.75–2.14) in the gallstone group (P < 0.001). The adjusted HR of gallstones was 1.97 (95% CI = 1.81–2.15) in the renal stone group (P < 0.001). The results were consistent in all subgroup analyses. Gallstones increased the risk of renal stones, and renal stones increased the risk of gallstones.

Nephrolithiasis predicts ischemic stroke: A longitudinal follow-up study using a national sample cohort

This study sought to evaluate associations between nephrolithiasis and hemorrhagic and ischemic stroke using a national sample cohort from Korea. Data from 2002 to 2013 were collected for individuals ≥ 20 years of age in the Korean National Health Insurance Service (NHIS)-National Sample Cohort. We extracted nephrolithiasis patients (n = 22,636) and 1:4 matched controls (n = 90,544) and analyzed the occurrence of stroke. Matching was performed based on age, sex, income, region of residence, hypertension, diabetes mellitus, and dyslipidemia history. Crude and adjusted hazard ratios (HRs) were calculated using Cox proportional hazard models, and 95% confidence intervals (CIs) were determined. We performed subgroup analyses according to age, sex, and follow-up period. The adjusted HR of ischemic stroke was 1.13 (95% CI = 1.06-1.21) in the nephrolithiasis group (P < 0.001). The relationship between nephrolithiasis and ischemic stroke remained present for the young women and middle-aged men as well as during a follow-up period of ≤ 1 year. The HR for hemorrhagic stroke did not reach statistical significance. The risk of ischemic stroke was higher in the nephrolithiasis patients.

Gastroesophageal reflux disease increases the risk of chronic rhinosinusitis: a nested case-control study using a national sample cohort

BACKGROUND

The purpose of this study was to evaluate the relations between gastroesophageal reflux disease (GERD) and chronic rhinosinusitus (CRS) in a Korean population.

METHODS

Subjects from the Korean National Health Insurance Service-National Sample Cohort, all ≥20 years old, were assessed from 2002 to 2013. In total, 23,489 CRS participants were matched with 93,956 controls at a ratio of 1:4 with respect to age, group, sex, income group, region of residence, hypertension, diabetes, and dyslipidemia. We analyzed previous history of GERD in the CRS and control groups. The CRS group included patients identified using International Classification of Diseases 10th edition (ICD-10) codes (J32) who had treated their CRS ≥2 times and had undergone head and neck computed tomography (CT). The GERD group included patients identified using the ICD-10 (K21) code who had treated their GERD ≥2 times and had taken a proton pump inhibitor (PPI) for ≥2 weeks. Crude and adjusted odds ratios (ORs) were analyzed using unconditional logistic regression analyses. The 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed according to age and sex.

RESULTS

The rate of GERD was higher in the CRS group (17.1% [4020 of 23,489]) than in the control group (9.1% [8522 of 93,956]; p < 0.001). The adjusted OR of GERD was 2.04 (95% CI, 1.96-2.13; p < 0.001) in the CRS group. The results of the subgroup analyses were consistent.

CONCLUSION

The ORs of GERD were increased in CRS participants. This relationship was consistent in all age and sex groups.

Increased risk of appendectomy in patients with gastroesophageal reflux disease: A nested case-control study using a national sample cohort

The purpose of this study is to confirm and complement previous data regarding an association between gastroesophageal reflux disease and appendectomy.The Korean National Health Insurance Service-National Sample Cohort includes data from people ≥ 20 years old collected from 2002 to 2013. A total of 13,484 participants who received an appendectomy were matched with 53,936 controls at a 1:4 ratio. We analyzed the previous histories of gastroesophageal reflux disease (GERD) in the appendectomy and control groups. Appendectomies were identified using operation codes (Q2860-Q2863) exclusive for appendicitis (International Classification of Disease-10 (ICD-10): K35). GERD was defined using the ICD-10 (K21), and patients who were treated ≥ 2 times and were prescribed a proton pump inhibitor (PPI) for ≥ 2 weeks were included. Crude (simple) and adjusted odds ratios (ORs) for GERD and appendectomy were analyzed using conditional logistic regression analyses.A higher GERD rate was detected in the appendectomy group (11.4% [1,713/15,062]) than in the control group (8.2% [4,947/60,248], P < .001). Adjusted ORs for GERD were 1.37 (95% confidence interval [CI] = 1.30-1.45) (P < .001). Subgroup analyses stratified according to age and sex revealed consistent findings. The adjusted OR for GERD in participants prescribed PPIs for ≥ 30 days was 1.31 (95% CI = 1.20-1.43), and the adjusted OR for GERD in participants prescribed PPIs for ≥ 60 days was 1.30 (95% CI = 1.15-1.48).The Odds for GERD were higher in the appendectomy group than in the control group.

Bidirectional association between gastroesophageal reflux disease and depression: Two different nested case-control studies using a national sample cohort

The purpose of this study is to evaluate the associations between gastroesophageal reflux disease (GERD) and depression using a national sample cohort of the Korean population. Data were collected from individuals ≥20 years old in the Korean National Health Insurance Service-National Sample Cohort between 2002 and 2013. We designed two different nested case-control studies. In study I, 60,957 participants with depression were matched at a 1:4 ratio with 243,828 controls, and their previous histories of GERD were analyzed. In study II, 133,089 participants with GERD were matched at a 1:2 ratio with 266,178 controls, and their previous histories of depression were analyzed. Crude and adjusted odds ratios (ORs) were analyzed using unconditional logistic regression analyses, and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed according to age and sex. The adjusted OR for GERD was 2.01 (95% CI = 1.96–2.07) in the patients with depression (study I). The adjusted OR for depression was 1.48 (95% CI = 1.43–1.52) in the patients with GERD (study II). The results of the subgroup analyses were consistent. GERD and depression displayed bidirectional associations.

Tonsillectomy increases the risk of retropharyngeal and parapharyngeal abscesses in adults, but not in children: A national cohort study

Objectives

The purpose of this study is to evaluate the risk of retropharyngeal and parapharyngeal abscesses (deep neck infection) after tonsillectomy in Koreans using national cohort data.

Methods

Using the national cohort study from the Korean Health Insurance Review and Assessment Service, participants who had undergone a tonsillectomy (5,299) and control participants (21,196) were selected and matched 1:4 (for age, sex, income, region of residence, and pre-operative upper respiratory infection visits). The Cox-proportional hazard model was used. A crude model and an adjusted model for age, sex, income, region of residence, hypertension, diabetes, and dyslipidemia were used in this analysis. For the subgroup analyses, the participants were divided into 2 groups: children (≤ 14 years old) and adolescents and adults (≥ 15 years old).

Results

The adjusted hazard ratio of deep neck infection after tonsillectomy was 1.43 (95% confidence interval, CI = 1.18–1.72, P < 0.001). In subgroup analysis, this ratio was 1.12 (95% CI = 0.86–1.47, P = 0.390) in children and 1.87 (95% CI = 1.43–2.45, P < 0.001) in adolescents and adults. The crude hazard ratios were almost the same as the adjusted ratios.

Conclusion

The risk of deep neck infection was higher in the tonsillectomy group. The subgroup analysis showed a similar finding in the adolescent and adult group but not in the child group.

Visual impairment and risk of depression: A longitudinal follow-up study using a national sample cohort

The association of visual impairment and depression has been investigated in several studies based on a cross-sectional design, which cannot delineate temporal relationships. In the present study, we evaluated the influence of visual impairment on depression in all age groups using a longitudinal database of a national sample cohort from 2002 to 2013 provided by the Korean National Health Insurance Service. Of a total of 1,025,340 subjects, 5,846 participants who were registered as visually impaired persons without a previous diagnosis of depression were enrolled at a 1:4 ratio with 23,384 control participants matched for age, sex, income, and region of residence. The crude and adjusted (age, sex, income, region of residence, hypertension, diabetes, and dyslipidemia) hazard ratios (HRs) for the development of depression between the visually impaired and control groups were analyzed using a Cox proportional hazards model. Visual impairment increased the risk of depression after adjusting for age, sex, income, region of residence, hypertension, diabetes, and dyslipidemia (adjusted HR = 1.19, P = 0.002). The risk of depression increased significantly in both the non-blindness visual impairment (adjusted HR = 1.15, P = 0.036) and blindness subgroups (adjusted HR = 1.31, P = 0.016), with a higher HR in the blindness subgroup.