Familial Risk of Appendicitis: A Nationwide Population Study.

OBJECTIVE: To investigate the familial risk of appendicitis in the general population. STUDY DESIGN: A nationwide, cross-sectional study consisting of 24 349 599 Taiwan National Health Insurance beneficiaries in 2015 was conducted. Among them, 788 042 individuals had at least 1 first-degree relative with appendicitis. The familial relative risks (RRs) of appendicitis and familial transmission were estimated. RESULTS: The overall RR (95% CI) of appendicitis in individuals with any affected first-degree relatives was 1.67 (1.64-1.71) compared with the general population. The RRs for individuals with an affected twin, sibling, offspring, and parent were 3.40 (2.66-4.35), 1.98 (1.92-2.04), 1.55 (1.51-1.59), and 1.54 (1.50-1.58), respectively. The RRs for individuals with 1, 2, 3 or more affected first-degree relatives were 1.65 (1.62-1.68), 2.63 (2.37-2.91), and 6.70 (4.22-10.63), respectively. Furthermore, there was an age-dependent trend of the RRs, with the greatest RR in the youngest group. The estimated familial transmission (genetic plus shared environmental contribution to the total phenotypic variance of appendicitis) was 23.2%. CONCLUSION: Individuals with a family history of appendicitis have an increased risk of appendicitis. This risk is age-dependent and related to the genetic distance and numbers of affected relatives.

Risk of Appendicitis among Children with Different Piped Water Supply: A Nationwide Population-Based Study.

Appendicitis is a common surgical condition for children. However, environmental effects, such as piped water supply, on pediatric appendicitis risk remain unclear. This longitudinal, nationwide, cohort study aimed to compare the risk of appendicitis among children with different levels of piped water supply. Using data from Taiwan Water Resource Agency and National Health Insurance Research Database, we identified 119,128 children born in 1996⁻2010 from areas of the lowest piped water supply (prevalence 51.21% to 63.06%) as the study cohort; additional 119,128 children of the same period in areas of the highest piped water supply (prevalence 98.97% to 99.63%) were selected as the controls. Both cohorts were propensity-score matched by baseline variables. We calculated the hazard ratios (HRs) and 95% confidence intervals (CIs) of appendicitis in the study cohort compared to the controls by Cox proportional hazards regression. The study cohort had a raised overall incidence rates of appendicitis compared to the control cohort (12.8 vs. 8.7 per 10,000 person-years). After covariate adjustment, the risk of appendicitis was significantly increased in the study cohort (adjusted HR = 1.46, 95% CI: 1.35, 1.58, p < 0.001). Subgroup and sensitivity analyses showed consistent results that children with low piped water supply had a higher risk of appendicitis than those with high piped water supply. This study demonstrated that children with low piped water supply were at an increased risk of appendicitis. Enhancement of piped water availability in areas lacking adequate, secure, and sanitized water supply may protect children against appendicitis.

Increased risk of autoimmune diseases in dengue patients: A population-based cohort study.

OBJECTIVE: To investigate the risk of autoimmune diseases in dengue patients. METHODS: We conducted a population-based cohort study by the Taiwan National Health Insurance Research Database, including a total of 12,506 newly diagnosed dengue patients and 112,554 control subjects between 2000 and 2010, matched by gender, age, income, urbanization, and comorbidities. Both cohorts were followed for a 3-year period to examine the incidence of autoimmune diseases. A Cox proportional hazards regression analysis was applied to calculate the risk of autoimmune diseases between both groups. RESULTS: The dengue group showed an overall increased risk for 21 autoimmune diseases, with an adjusted hazard ratio (aHR) of 1.88 (95% confidence interval [CI], 1.49-2.37, p < 0.001). Compared with the control group, the dengue group had higher risks of Reiter's syndrome (aHR 14.03, 95 % CI 1.63-120.58), multiple sclerosis (aHR 11.57, 95 % CI 1.8-74.4), myasthenia gravis (aHR 5.35, 95 % CI 1.43-20.02), autoimmune encephalomyelitis (aHR 3.8, 95% CI 1.85-7.8), systemic vasculitis (aHR 3.7, 95 % CI 1.11-12.28), systemic lupus erythematosus (aHR 3.5, 95% CI 1.85-6.63), and primary adrenocortical insufficiency (aHR 2.05, 95% CI 1.25-3.35). CONCLUSION: Dengue patients were associated with an increased risk of autoimmune diseases.

Risk of stroke in patients with dengue fever: a population-based cohort study.

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

The effect of antibiotic prophylaxis for acute pelvic inflammatory disease after hysterosalpingography: a retrospective cohort study.

AIMS: Concerns about acute pelvic inflammatory disease (PID) after hysterosalpingography (HSG) have been raised since 1980. However, the effectiveness of prophylactic antibiotics remains unclear. This study investigated the effect of antibiotic prophylaxis in women undergoing HSG. METHODS: Women undergoing HSG between 2000 and 2012 were screened from the Taiwan National Health Insurance Research Database for eligibility. The prophylactic cohort included patients using any antibiotics of 1st-generation cephalosporins, doxycycline, clindamycin, and metronidazole, within 7 days before HSG (n = 3257). Patients not using any antibiotics were registered as the non-prophylactic cohort (n = 4662). An unconditional logistic regression model was applied to calculate the odds ratio (OR) and 95% confidence interval (CI) of acute PID after HSG associated with prophylactic antibiotics. RESULTS: The cumulative incidences of acute PID after HSG were 0.46% and 1.42% in the prophylactic and non-prophylactic cohorts, respectively. Prophylactic patients had a significantly reduced estimated relative risk of acute PID compared with non-prophylactic patients (adjusted OR = 0.33, 95% CI = 0.19-0.58; p = .001). Doxycycline users had the lowest adjusted OR of 0.20 (95% CI = 0.04-0.81; p = .02), followed by users of 1st-generation cephalosporins (adjusted OR = 0.35, 95% CI = 0.18-0.68; p = .002). Multivariate sub-group analysis verified this protective effect for almost all sub-groups of prophylactic patients. CONCLUSIONS: Antibiotic prophylaxis is associated with a decreased estimated relative risk of acute PID in HSG patients. Doxycycline and 1st-generation cephalosporins may be effective prophylactic regimens for HSG.

The Association Between Barium Examination and Subsequent Appendicitis: A Nationwide Population-Based Study.

OBJECTIVE: The incidence and association between appendicitis and barium examination (BE) remain unclear. Such potential risk may be omitted. We conducted a longitudinal, nationwide, population-based cohort study to investigate the association between BE and appendicitis risk. METHODS: From the Taiwan National Health Insurance Research Database, a total of 24,885 patients who underwent BE between January 1, 2000 and December 31, 2010 were enrolled in a BE cohort; an additional 98,384 subjects without BE exposure were selected as a non-BE cohort, matched by age, sex, and index date. The cumulative incidences of subsequent appendicitis in the BE and non-BE cohorts were assessed using the Kaplan-Meier curves and log-rank test. Cox proportional hazards regression analyses were employed to calculate the appendicitis risk between the groups. RESULTS: The cumulative incidence of appendicitis was higher in the BE cohort than in the non-BE cohort (P = .001). The overall incidence rates of appendicitis for the BE and non-BE cohorts were 1.19 and 0.80 per 1000 person-years, respectively. After adjustment for sex, age, and comorbidities, the risk of appendicitis was higher in the BE cohort (adjusted hazard ratio = 1.46, 95% confidence interval = 1.23-1.73) compared with the non-BE cohort, especially in the first 2 months (adjusted hazard ratio = 9.72, 95% confidence interval = 4.65-20.3). CONCLUSIONS: BE was associated with an increased, time-dependent appendicitis risk. Clinicians should be aware of this potential risk to avoid delayed diagnoses.