Systemic Fluoroquinolone Use and Risk of Uveitis or Retinal Detachment

Importance

Fluoroquinolone use has been associated with increased risk of uveitis and retinal detachment in noninterventional studies, but the findings have been conflicting and causality is unclear.

Objective

To estimate the association of systemic fluoroquinolone use with acute uveitis or retinal detachment, using multiple analyses and multiple databases to increase the robustness of results.

Design, Setting, and Participants

This cohort study used data from the Clinical Practice Research Datalink Aurum and GOLD UK primary care records databases, which were linked to hospital admissions data. Adults prescribed a fluoroquinolone or a comparator antibiotic, cephalosporin, between April 1997 and December 2019 were included. Adults with uveitis or retinal detachment were analyzed in a separate self-controlled case series. Data analysis was performed from May 2022 to May 2023.

Exposures

Systemic fluoroquinolone or comparator antibiotic.

Main Outcomes and Measures

The primary outcome was a diagnosis of acute uveitis or retinal detachment. Hazard ratios (HRs) were estimated in the cohort study for the association of fluoroquinolone prescription with either uveitis or retinal detachment, using stabilized inverse probability of treatment weighted Cox regression. Rate ratios (RRs) were estimated in the self-controlled case series, using conditional Poisson regression. Estimates were pooled across databases using fixed-effects meta-analysis.

Results

In total, 3 001 256 individuals in Aurum (1 893 561 women [63.1%]; median [IQR] age, 51 [35-68] years) and 434 754 in GOLD (276 259 women [63.5%]; median [IQR] age, 53 [37-70] years) were included in the cohort study. For uveitis, the pooled adjusted HRs (aHRs) for use of fluoroquinolone vs cephalosporin were 0.91 (95% CI, 0.72-1.14) at first treatment episode and 1.07 (95% CI, 0.92-1.25) over all treatment episodes. For retinal detachment, the pooled aHRs were 1.37 (95% CI, 0.80-2.36) at first treatment episode and 1.18 (95% CI, 0.84-1.65) over all treatment episodes. In the self-controlled case series, for uveitis, the pooled adjusted RRs (aRRs) for fluoroquinolone use vs nonuse were 1.13 (95% CI, 0.97-1.31) for 1 to 29 days of exposure, 1.16 (95% CI, 1.00-1.34) for 30 to 59 days, and 0.98 (95% CI, 0.74-1.31) for 60 days for longer. For retinal detachment, pooled aRRs for fluoroquinolone use vs nonuse were 1.15 (95% CI, 0.86-1.54) for 1 to 29 days of exposure, 0.94 (95% CI, 0.69-1.30) for 30 to 59 days, and 1.03 (95% CI, 0.59-1.78) for 60 days or longer.

Conclusions and Relevance

These findings do not support an association of systemic fluoroquinolone use with substantively increased risk of uveitis or retinal detachment. Although an association cannot be completely ruled out, these findings indicate that any absolute increase in risk would be small and, hence, of limited clinical importance.

Use of National Database of Health Insurance Claims and Specific Health Checkups for examining practical utilization and safety signal of a drug to support regulatory assessment on postmarketing drug safety in Japan

The Pharmaceuticals and Medical Devices Agency (PMDA) has conducted many pharmacoepidemiological studies for postmarketing drug safety assessments based on real-world data from medical information databases. One of these databases is the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB), containing health insurance claims of almost all Japanese individuals (over 100 million) since April 2009. This article describes the PMDA's regulatory experiences in utilizing the NDB for postmarketing drug safety assessment, especially focusing on the recent cases of use of the NDB to examine the practical utilization and safety signal of a drug. The studies helped support regulatory decision-making for postmarketing drug safety, such as considering a revision of prescribing information of a drug, confirming the appropriateness of safety measures, and checking safety signals in real-world situations. Different characteristics between the NDB and the MID-NET^® (another database in Japan) were also discussed for appropriate selection of data source for drug safety assessment. Accumulated experiences of pharmacoepidemiological studies based on real-world data for postmarketing drug safety assessment will contribute to evolving regulatory decision-making based on real-world data in Japan.

Treatment with Methylphenidate for Attention Deficit Hyperactivity Disorder (ADHD) and the Risk of All-Cause Poisoning in Children and Adolescents: A Self-Controlled Case Series Study

BACKGROUND

Children and adolescents with attention deficit hyperactivity disorder (ADHD) are at higher risk of all-cause poisoning by drugs and chemicals (intentional or accidental). Currently, there is limited data on whether medication treatment for ADHD can reduce the risk of all-cause poisoning.

METHODS

Patients aged 5-18 years with a methylphenidate (MPH) prescription and an incident poisoning diagnosis between January 2001 and June 2020 were identified from the Hong Kong Clinical Data Analysis and Reporting System. A self-controlled case series study design was used to compare the incidence rate ratios (IRRs) of all-cause poisoning during different risk windows (30 days before the first MPH prescription, exposure periods within 30 days of the first prescription, and periods of subsequent exposure) compared with the reference window (other non-exposure periods).

RESULTS

42,203 patients were prescribed ADHD medication in Hong Kong during the study period. Of these, 417 patients who had both an MPH prescription and poisoning incident recorded were included in the main analysis. Compared with other non-exposed periods, a higher risk of poisoning was found in the 30 days before the first prescription (IRR 2.64, 95% confidence interval [CI] 1.33-5.22) and exposure periods within 30 days of the first prescription (IRR 2.18, 95% CI 1.06-4.48), but not during prolonged exposure. However, compared with 30 days before the first prescription as well as exposure periods within 30 days of the first prescription, there was a lower risk during the subsequent exposure (IRRs 0.49 and 0.60, respectively). Similar results to the main analysis were also found in the subgroup analysis of intentional poisoning and females, but not in that of accidental poisoning and males.

CONCLUSIONS

The risk of all-cause poisoning was higher shortly before and after the first MPH prescription and became lower during the subsequent prescription period. Our results do not support an association between the use of MPH and an increased risk of all-cause poisoning in children and adolescents and, in fact, suggest that longer-term use of MPH may be associated with a lower risk of all-cause poisoning, although this latter finding requires further study.

Understanding the Association Between Antidepressants and the Risk of Being Diagnosed with Dementia in Older People: A Self-Controlled Case Series Study

BACKGROUND

Given concerns about adverse outcomes for older people taking antidepressants in the literature, we investigated whether taking antidepressants elevates the risk of dementia.

OBJECTIVE

This study aims to investigate the putative association of antidepressants with the risk of dementia.

METHODS

We conducted a population-based self-controlled case series analysis of older people with dementia and taking antidepressants, using territory-wide medical records of 194,507 older patients collected by the Hospital Authority of Hong Kong, to investigate the association between antidepressant treatment and the risk of developing dementia in older people.

RESULTS

There was a significantly higher risk of being diagnosed with dementia during the pre-drug-exposed period (incidence rate ratio (IRR) 20.42 (95% CI: 18.66-22.34)) compared to the non-drug-exposed baseline period. The IRR remained high during the drug-exposed period (IRR 8.86 (7.80-10.06)) before returning to a baseline level after washout (IRR 1.12 (0.77-1.36)).

CONCLUSION

The higher risk of dementia before antidepressant treatment may be related to emerging psychiatric symptoms co-occurring with dementia, which trigger medical consultations that result in a decision to begin antidepressants. Our findings do not support a causal relationship between antidepressant treatment and the risk of dementia.

Application of a Common Data Model (CDM) to rank the paediatric user and prescription prevalence of 15 different drug classes in South Korea, Hong Kong, Taiwan, Japan and Australia: an observational, descriptive study

OBJECTIVE

To measure the paediatric user and prescription prevalence in inpatient and ambulatory settings in South Korea, Hong Kong, Taiwan, Japan and Australia by age and gender. A further objective was to list the most commonly used drugs per drug class, per country.

DESIGN AND SETTING

Hospital inpatient and insurance paediatric healthcare data from the following databases were used to conduct this descriptive drug utilisation study: (i) the South Korean Ajou University School of Medicine database; (ii) the Hong Kong Clinical Data Analysis and Reporting System; (iii) the Japan Medical Data Center; (iv) Taiwan's National Health Insurance Research Database and (v) the Australian Pharmaceutical Benefits Scheme. Country-specific data were transformed into the Observational Medical Outcomes Partnership Common Data Model.

PATIENTS

Children (≤18 years) with at least 1 day of observation in any of the respective databases from January 2009 until December 2013 were included.

MAIN OUTCOME MEASURES

For each drug class, we assessed the per-protocol overall user and prescription prevalence rates (per 1000 persons) per country and setting.

RESULTS

Our study population comprised 1 574 524 children (52.9% male). The highest proportion of dispensings was recorded in the youngest age category (<2 years) for inpatients (45.1%) with a relatively high user prevalence of analgesics and antibiotics. Adrenergics, antihistamines, mucolytics and corticosteroids were used in 10%-15% of patients. For ambulatory patients, the highest proportion of dispensings was recorded in the middle age category (2-11 years, 67.1%) with antibiotics the most dispensed drug overall.

CONCLUSIONS

Country-specific paediatric drug utilisation patterns were described, ranked and compared between four East Asian countries and Australia. The widespread use of mucolytics in East Asia warrants further investigation.

Fluoroquinolones and Aortic Diseases: Is There a Connection

Fluoroquinolones (FQs) are one of the most commonly prescribed classes of antibiotics. Their high tissue distribution and broad-spectrum antibacterial coverage make their use very attractive in numerous infectious diseases. Although generally well tolerated, FQs have been associated with different adverse effects including dysglycemia and arrhythmias. FQs have been also associated with a series of adverse effects related to collagen degradation, such as Achilles tendon rupture and retinal detachment. Recently, an association between consumption of FQs and increased risk of aortic aneurysm and dissection has been proposed. This article reviews the pathogenesis of thoracic aortic diseases, the molecular mechanism of FQ-associated collagen toxicity, and the possible contribution of FQs to aortic diseases.

The risk profile of rhegmatogenous retinal detachment before and after using a fluoroquinolone: a 12 year nationwide self-controlled case series study

Objectives

To determine whether or not fluoroquinolone use increases the incidence of retinal detachment.

Design

Self-controlled case series analysis.

Participants

Participants were identified using the South Korean National Health Insurance Database between 1 January 2004 and 31 December 2015. A total of 15 134 patients who experienced rhegmatogenous retinal detachment (RRD) with at least one prescription of a fluoroquinolone were included.

Methods

Incidence rate ratios (IRRs) and their 95% CIs were calculated using conditional Poisson regression. The main outcome measure was a recorded diagnosis of RRD (ICD-10: H33.0) with a claim for the surgical code for RRD.

Results

We found an increased risk of retinal detachment in the first 1-30 days following the initiation of fluoroquinolone therapy (IRR 1.85; 95% CI 1.71-1.95), which rose for the 31-60 days period (IRR 2.05; 95% CI 1.43-2.95) but remained constant after more than 60 days (IRR 1.25; 95% CI 0.75-2.10). However, the elevated risk was also found in the 1-30 day period prior to the initiation of fluoroquinolone therapy (IRR 1.58; 95% CI 1.49-1.68) and also 31-60 days before medication use (IRR 1.11; 95% CI 1.03-1.19).

Conclusions

Our case-based study indicated that the risk after fluoroquinolone exposure doubled; however, the risk profile before and after fluoroquinolone use means that the association between fluoroquinolone use and retinal detachment might not be a causal relationship.

Signal Detection Between Fluoroquinolone Use and the Risk of Rhegmatogenous Retinal Detachment: Sequence Symmetry Analysis Using Nationwide South Korean Healthcare Database Between 2004 and 2015

BACKGROUND AND OBJECTIVES

The association between fluoroquinolone and rhegmatogenous retinal detachment (RRD) has been controversial as a result of inconsistent findings. We set out to detect a possible association of fluoroquinolone use and risk of RRD, using sequence symmetry analysis (SSA).

METHODS

We conducted an SSA, case-only design, using a Korean nationwide healthcare database between 2004 and 2015. Exposure was defined as new fluoroquinolone use and outcome as an incident RRD, defined by a diagnosis of RRD (ICD-10: "H33.0") or surgery for RRD. Pairs of exposure and RRD within a 1-year time-window were included. The sequence ratio (SR) was calculated by the ratio of the number of patients prescribed with exposure first and diagnosed with RRD second divided by the number of patients diagnosed with RRD first and prescribed with exposure second. SR was adjusted (aSR) for underlying trends and 95% confidence intervals (CIs) were calculated. In order to observe whether the estimated ratio stabilized over time, we did repeated time-sequential analyses with the cumulative data starting from the 3-year period 2004-2006 to 2015.

RESULTS

Fluoroquinolone use had a greater association with RRD as compared with other antibiotics [fluoroquinolone: 5234 pairs; aSR = 1.70 (95% CI 1.61-1.80), first-generation cephalosporin: 4139 pairs; aSR = 1.39 (95% CI 1.31-1.80), second-generation cephalosporin: 5914 pairs; aSR = 1.31 (95% CI 1.24-1.38), third-generation cephalosporin: 3650 pairs; aSR = 0.88 (95% CI 0.83-0.95), extended-spectrum penicillin: 4823 pairs; aSR = 1.29 (95% CI 1.31-1.47), macrolides: 4115 pairs; aSR = 1.31 (95% CI 1.24-1.39)]. Time-sequential analyses supported the association between fluoroquinolone and RRD.

CONCLUSIONS

Our detection suggests a possible association between fluoroquinolone use and RRD. However, possible overestimation and reverse causality bias may have influenced our findings due to the limitation of an SSA design.

Administration of oral fluoroquinolone and the risk of rhegmatogenous retinal detachment: A nationwide population-based study in Korea

PURPOSE

To investigate the association between oral fluoroquinolones (FQ) and the risk of rhegmatogenous retinal detachment (RRD) using a nationwide population-based study in Korea, designed to control for time-related bias.

METHODS

As a nested case-control study within a cohort, the KNHIS-NSC 2002-2013 (Korean National Health Insurance Service National Sample Cohort) data used for the investigation. The subjects who visited an ophthalmologist were included in a cohort. Subjects with infectious ocular diseases, severe ocular trauma, and congenital diseases were excluded. Within the cohort, subjects who underwent surgery for RRD were defined as cases, and controls were matched by age group, sex, and cohort entry date using an incidence density sampling method. After investigating the exposure to oral FQ, the odds ratio was calculated by the FQ exposure rate of both groups and adjusted by the confounding factors of demography, health service utilization, and comorbidities.

RESULTS

A total of 1,151 subjects in the case group and 11,470 subjects in the control group were included. There were intergroup differences in household income, numbers of ophthalmologic visits and drug prescriptions, events of intraocular surgeries, and prevalence of diabetes and degenerative myopia (all P's<0.05). The crude odds ratio of the total group was 1.06 (P = 0.53, 95% CI 0.88-1.28), and the odds ratio adjusted for all pre-defined confounders was 1.00 (P = 0.99, 95% CI 0.81-1.24). The crude and adjusted odds ratios were not showed statistical significance (all P's>0.05).

CONCLUSIONS

By the nested case-control design, this study showed that oral administration of FQ was not associated with the increased risk of development of RRD.

ADHD Drug Prescribing Trend Is Increasing Among Children and Adolescents in Hong Kong

OBJECTIVE

To investigate the prevalence of ADHD medication prescribing of school-aged children in Hong Kong (HK) from 2001 to 2013 and to compare with other countries.

METHOD

Using the Hong Kong Hospital Authority Clinical Data Analysis and Reporting System, we investigated the epidemiology and prevalence of ADHD medication prescribing.

RESULTS

The prevalence of children on ADHD medication increased 14 times throughout the study period-0.072% in 2001 (95% confidence interval [CI] = [0.068%, 0.077%]) to 1.027% (95% CI = [1.008%, 1.047%]) in 2013. Prevalence in females increased at a faster rate than in males. The prescribing trend in kindergarten children (3- to 5-year-old) was relatively steady from 2001 to 2008-0.025% (95% CI = [0.019%, 0.033%]) in 2001-until a marked increase from 2009 to 2013-0.121% (95% CI = [0.105%, 0.139%]) in 2013.

CONCLUSION

The prevalence of ADHD medication prescribing in Hong Kong is increasing but remains lower than most Western countries. However, the prevalence of ADHD medication prescribing for kindergarten children should be monitored to ensure appropriate use.

Bleeding-related hospital admissions and 30-day readmissions in patients with non-valvular atrial fibrillation treated with dabigatran versus warfarin

Essentials Bleeding is a common cause of hospital admission and readmission in oral anticoagulant users. Patients with dabigatran and warfarin were included to assess hospital admission risk. Dabigatran users had a higher risk of 30-day readmission with bleeding than warfarin users. Close monitoring following hospital discharge for dabigatran-related bleeding is warranted.

SUMMARY

Background Reducing 30-day hospital readmission is a policy priority worldwide. Warfarin-related bleeding is among the most common cause of hospital admissions as a result of adverse drug events. Compared with warfarin, dabigatran achieves a full anticoagulation effect more quickly following its initiation; hence it may lead to early-onset bleeds. Objectives To compare the incidence of bleeding-related hospital admissions and 30-day readmissions with dabigatran vs. warfarin in patients with non-valvular atrial fibrillation (NVAF). Methods This was a retrospective cohort study using a population-wide database managed by the Hong Kong Hospital Authority. Patients newly diagnosed with NVAF from 2010 through to 2014 and prescribed dabigatran or warfarin were 1:1 matched by propensity score. The incidence rate of hospital admission with bleeding (a composite of gastrointestinal bleeding, intracranial hemorrhage and bleeding at other sites) was assessed. Results Among the 51 946 patients with NVAF, 8309 users of dabigatran or warfarin were identified, with 5160 patients matched by propensity score. The incidence of first hospitalized bleeding did not differ significantly between groups (incidence rate ratio, 0.92; 95% confidence interval [CI], 0.66-1.28). Among patients who were continuously prescribed their initial anticoagulants upon discharge, dabigatran use was associated with a higher risk of 30-day readmission with bleeding over warfarin (adjusted hazard ratio, 2.87; 95%CI, 1.10-7.43). Conclusion When compared with warfarin, dabigatran was associated with a comparable incidence of first hospital admission but a higher risk of 30-day redmission with respect to bleeding. Close early monitoring of patients initiated on dabigatran following hospital discharge for bleeding is warranted.

Association of Risk of Suicide Attempts With Methylphenidate Treatment

IMPORTANCE

Patients with attention-deficit/hyperactivity disorder (ADHD) are at an increased risk of attempting suicide. Stimulants, such as methylphenidate hydrochloride, are the most common treatment for ADHD, but the association between their therapeutic use and suicide is unclear.

OBJECTIVE

To investigate the association between methylphenidate and the risk of suicide attempts.

DESIGN, SETTING, AND PARTICIPANTS

A population-based, electronic medical records database from the Hong Kong Clinical Data Analysis & Reporting System was used to identify 25 629 individuals aged 6 to 25 years who were treated with methylphenidate between January 1, 2001, and December 31, 2015. Those who had attempted suicide were included in the analysis. A self-controlled case series design was used to control for time-invariant characteristics of the patients.

MAIN OUTCOMES AND MEASURES

Relative incidence of suicide attempt during periods when patients were exposed to methylphenidate compared with nonexposed periods.

RESULTS

Among 25 629 patients with methylphenidate prescriptions, 154 had their first recorded suicide attempt within the study period; of these individuals, 111 (72.1%) were male; mean (SD) age at baseline was 7.15 (2.19) years. The overall incidence of suicide attempts during methylphenidate treatment was 9.27 per 10 000 patient-years. An increased risk of suicide attempts was detected during the 90-day period before methylphenidate was initiated, with an incidence rate ratio (IRR) of 6.55 (95% CI, 3.37-12.72). The IRR remained elevated during the first 90 days of treatment (IRR, 3.91; 95% CI, 1.62-9.42) before returning to baseline levels during ongoing treatment (IRR, 1.35; 95% CI, 0.77-2.38). When the risk during the first 90 days of treatment was compared with the 90 days preceding first treatment, the incidence of suicide attempts was not elevated (IRR, 0.78; 95% CI, 0.26-2.35).

CONCLUSIONS AND RELEVANCE

The incidence of suicide attempts was higher in the period immediately before the start of methylphenidate treatment. The risk remained elevated immediately after the start of methylphenidate treatment and returned to baseline levels during continuation of methylphenidate treatment. The observed higher risk of suicide attempts before treatment may reflect emerging psychiatric symptoms that trigger medical consultations that result in a decision to begin ADHD treatment. Therefore, this study's results do not support a causal association between methylphenidate treatment and suicide attempts.

Prenatal antidepressant use and risk of attention-deficit/hyperactivity disorder in offspring: population based cohort study

Objective To assess the potential association between prenatal use of antidepressants and the risk of attention-deficit/hyperactivity disorder (ADHD) in offspring.Design Population based cohort study.Setting Data from the Hong Kong population based electronic medical records on the Clinical Data Analysis and Reporting System.Participants 190 618 children born in Hong Kong public hospitals between January 2001 and December 2009 and followed-up to December 2015.Main outcome measure Hazard ratio of maternal antidepressant use during pregnancy and ADHD in children aged 6 to 14 years, with an average follow-up time of 9.3 years (range 7.4-11.0 years).Results Among 190 618 children, 1252 had a mother who used prenatal antidepressants. 5659 children (3.0%) were given a diagnosis of ADHD or received treatment for ADHD. The crude hazard ratio of maternal antidepressant use during pregnancy was 2.26 (P<0.01) compared with non-use. After adjustment for potential confounding factors, including maternal psychiatric disorders and use of other psychiatric drugs, the adjusted hazard ratio was reduced to 1.39 (95% confidence interval 1.07 to 1.82, P=0.01). Likewise, similar results were observed when comparing children of mothers who had used antidepressants before pregnancy with those who were never users (1.76, 1.36 to 2.30, P<0.01). The risk of ADHD in the children of mothers with psychiatric disorders was higher compared with the children of mothers without psychiatric disorders even if the mothers had never used antidepressants (1.84, 1.54 to 2.18, P<0.01). All sensitivity analyses yielded similar results. Sibling matched analysis identified no significant difference in risk of ADHD in siblings exposed to antidepressants during gestation and those not exposed during gestation (0.54, 0.17 to 1.74, P=0.30).Conclusions The findings suggest that the association between prenatal use of antidepressants and risk of ADHD in offspring can be partially explained by confounding by indication of antidepressants. If there is a causal association, the size of the effect is probably smaller than that reported previously.

Methylphenidate and the risk of psychotic disorders and hallucinations in children and adolescents in a large health system

Previous studies have suggested that risk of psychotic events may be increased in children exposed to methylphenidate (MPH). However, this risk has not been fully examined, and the possibility of confounding factors has not been excluded. Patients aged 6-19 years who received at least one MPH prescription were identified using Hong Kong population-based electronic medical records on the Clinical Data Analysis and Reporting System (2001-2014). Using the self-controlled case series design, relative incidence of psychotic events was calculated comparing periods when patients were exposed to MPH with non-exposed periods. Of 20,586 patients prescribed MPH, 103 had an incident psychotic event; 72 (69.9%) were male and 31 (30.1%) female. The mean age at commencement of observation was 6.95 years and the mean follow-up per participant was 10.16 years. On average, each participant was exposed to MPH for 2.17 years. The overall incidence of psychotic events during the MPH exposure period was 6.14 per 10,000 patient-years. No increased risk was found during MPH-exposed compared with non-exposed periods (incidence rate ratio (IRR) 1.02 (0.53-1.97)). However, an increased risk was found during the pre-exposure period (IRR 4.64 (2.17-9.92)). Results were consistent across all sensitivity analyses. This study does not support the hypothesis that MPH increases risk of incident psychotic events. It does indicate an increased risk of psychotic events before the first prescription of MPH, which may be because of an association between psychotic events and the behavioural and attentional symptoms that led to psychiatric assessment and initiation of MPH treatment.

A systematic review and meta-analysis of the association between systemic fluoroquinolones and retinal detachment

PURPOSE

Several pharmacoepidemiologic studies have been carried out evaluating the risk of retinal detachment associated with systemic fluoroquinolones. This meta-analysis aims to investigate such association, in the light of the best scientific evidence available.

METHODS

A literature search was conducted to identify relevant studies evaluating the risk for retinal detachment associated with systemic fluoroquinolones. A meta-analysis was performed to pool rate ratios (RRs). Meta-regressions were conducted aiming to evaluate the influence of time interval between fluoroquinolones use and retinal detachment diagnosis or treatment risk estimates.

RESULTS

Ten observational studies from seven publications were included. Overall, fluoroquinolones were not associated with an increased risk for retinal detachment [RR 1.47 (95% CI 0.95-2.27): p = 0.09; I(2)  = 92.8%]. When the analysis was stratified according to different study designs, the result was statistically significant for retrospective cohort studies [RR 1.87 (95% CI 1.36-2.58); p < 0.001; I(2)  = 0.0%] and for past users of fluoroquinolones, based on data from case-control studies [RR 1.07 (95% CI 1.01-1.12); p = 0.01; I(2)  = 0.0%]. According to meta-regressions, the risk for retinal detachment did not vary due to different time intervals between fluoroquinolones prescription and retinal detachment occurrence. No statistically significant results were identified among studies evaluating only rhegmatogenous retinal detachments, as well as among studies that evaluated patients not requiring a prior ophthalmologist visit to be included.

CONCLUSIONS

In light of the current available evidence, systemic fluoroquinolones do not seem to be associated with retinal detachment.

Association between oral fluoroquinolones and seizures: A self-controlled case series study

OBJECTIVES

The aim of this study was to investigate the association and to estimate the crude absolute risk of seizure among patients exposed to fluoroquinolones (FQs) in Hong Kong and the United Kingdom.

METHODS

A self-controlled case series study was conducted. Data were collected from the Hong Kong Clinical Data Analysis and Reporting System database and the Clinical Practice Research Datalink. Patients who were prescribed any oral FQ and had an incident seizure diagnosis from 2001 to 2013 were included. The risk windows were defined as pre-FQ start, FQ-exposed, and post-FQ completion. Incidence rate ratios were estimated in all risk windows and compared with baseline periods. A post hoc subgroup analysis was conducted to examine the effect of patients with a history of seizure.

RESULTS

An increased incidence rate ratio was found in the pre-FQ start periods and no association was found in the post-FQ completion periods in both databases. The crude absolute risk of an incident seizure in 10,000 oral FQ prescriptions was 0.72 (95% confidence interval 0.47-1.10) in the Clinical Data Analysis and Reporting System and 0.40 (95% confidence interval 0.30-0.54) in the Clinical Practice Research Datalink. The rate ratio during treatment was not higher than pre-FQ start periods among patients with a history of seizure, therefore the results did not raise serious concerns.

CONCLUSIONS

This study does not support a causal association between the use of oral FQs and the subsequent occurrence of seizure. An increased risk before the FQ exposure period suggests that the clinical indication for which FQ was prescribed may have contributed to the development of seizure rather than the drug itself.

Effect of suboptimal anticoagulation treatment with antiplatelet therapy and warfarin on clinical outcomes in patients with nonvalvular atrial fibrillation: A population-wide cohort study

BACKGROUND

The actual consequence of suboptimal anticoagulation management in patients with nonvalvular atrial fibrillation (NVAF) is unclear in the real-life practice.

OBJECTIVE

The purpose of this study was to identify the prevalence of suboptimally anticoagulated patients with NVAF and compare the effectiveness and safety of antiplatelet drugs with warfarin.

METHODS

We performed a retrospective cohort study using a population-wide database managed by the Hong Kong Hospital Authority. Patients newly diagnosed with NVAF during 2010-2013 were included in the analysis. A Cox proportional hazards regression model with 1:1 propensity score matching was used to compare the risk of ischemic stroke, intracranial hemorrhage, gastrointestinal bleeding, and all-cause mortality between patients receiving antiplatelet drugs and those receiving warfarin stratified by level of international normalized ratio (INR) control.

RESULTS

Of the 35,551 patients with NVAF, 30,294 (85.2%) had a CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years [doubled], diabetes mellitus, age 65-74 years, prior stroke/transient ischemic attack [doubled], vascular disease, and sex category [female]) score of ≥2 (target group for anticoagulation). Of these, 7029 (23.2%) received oral anticoagulants and 18,508 (61.1%) received antiplatelet drugs alone. There were 1541 (67.7%) of warfarin users who had poor INR control (time in therapeutic range [2.0-3.0] <60%). Patients receiving warfarin had comparable risks of intracranial hemorrhage (hazard ratio [HR] 1.24; 95% confidence interval [CI] 0.65-2.34) and gastrointestinal bleeding (HR 1.23; 95% CI 0.84-1.81) and lower risk of ischemic stroke (HR 0.40; 95% CI 0.28-0.57) and all-cause mortality (HR 0.45; 95% CI 0.36-0.57) than did patients receiving antiplatelet drugs alone. Good INR control was associated with a reduced risk of ischemic stroke (HR 0.48; 95% CI 0.27-0.86) as compared with poor INR control. Modeling analyses suggested that ~40,000 stroke cases could be potentially prevented per year in the Chinese population if patients were optimally treated.

CONCLUSION

More than three-quarters of high-risk patients among this Chinese population with NVAF were not anticoagulated or had poor INR control. There is an urgent need to improve the optimization of anticoagulation for stroke prevention in patients with atrial fibrillation.

Medication safety research by observational study design

Observational studies have been recognised to be essential for investigating the safety profile of medications. Numerous observational studies have been conducted on the platform of large population databases, which provide adequate sample size and follow-up length to detect infrequent and/or delayed clinical outcomes. Cohort and case-control are well-accepted traditional methodologies for hypothesis testing, while within-individual study designs are developing and evolving, addressing previous known methodological limitations to reduce confounding and bias. Respective examples of observational studies of different study designs using medical databases are shown. Methodology characteristics, study assumptions, strengths and weaknesses of each method are discussed in this review.

Prevention of Dabigatran-Related Gastrointestinal Bleeding With Gastroprotective Agents: A Population-Based Study

BACKGROUND & AIMS

Use of dabigatran, an inhibitor of thrombin, increases the risk of gastrointestinal bleeding (GIB). However, it is not clear whether gastroprotective agents (GPAs) prevent GIB in dabigatran users. We investigated the risk of GIB and the role of gastroprotective agents (including proton pump inhibitors and histamine type-2-receptor antagonists) in patients using dabigatran.

METHODS

We performed a retrospective cohort study using a population-wide database managed by the Hong Kong Hospital Authority. Patients newly prescribed dabigatran from 2010 through 2013 were included in the analysis. Poisson regression was used to assess the risk of GIB in dabigatran users by incidence rate ratio (IRR), adjusted for patient characteristics, comorbidities, and concurrent medications.

RESULTS

Among the 5041 patients newly prescribed dabigatran, 124 (2.5%) developed GIB during follow-up evaluation (4.2/100 patient-years). The risk of GIB in this population increased among patients 75 years and older (IRR, 2.47; 95% confidence interval [CI], 1.66-3.68), patients with a history of peptic ulcers or GIB (IRR, 2.31; 95% CI, 1.54-3.46), and patients who used aspirin (IRR, 1.52; 95% CI, 1.03-2.24). Concomitant use of gastroprotective agents was associated with a reduced risk of GIB (IRR, 0.52; 95% CI, 0.35-0.77). Subcategory analysis showed that use of proton pump inhibitors (IRR, 0.53; 95% CI, 0.31-0.91) or histamine type-2-receptor antagonists (IRR, 0.61; 95% CI, 0.40-0.94) were associated with a lower risk of GIB. Further analysis showed that the risk reduction by gastroprotective agents was significant for only upper GIB (IRR, 0.29; 95% CI, 0.15-0.54), and only for patients with a prior history of peptic ulcers or GIB (IRR, 0.14; 95% CI, 0.06-0.30).

CONCLUSIONS

In the Hong Kong population, use of gastroprotective agents was associated with a reduced risk of GIB in patients taking dabigatran. The association was stronger for upper GIB than lower GIB, and in patients with a prior history of peptic ulcers or GIB.

Risk and Risk Periods for Stroke and Acute Myocardial Infarction in Patients with Central Retinal Artery Occlusion

PURPOSE

To investigate the risk of stroke and acute myocardial infarction (AMI) in patients with incident central retinal artery occlusion (CRAO).

DESIGN

A self-controlled case series (SCCS) study.

PARTICIPANTS

Patients with incident CRAO from the entire Korean population of 48 million individuals.

METHODS

We used the Korean national claim database (2007-2011) for analyses. After identifying patients with incident CRAO, the relative incidence rate ratios (IRRs) for stroke and AMI in risk periods were measured in these patients using a SCCS method.

MAIN OUTCOME MEASURES

The IRRs of stroke and AMI by risk periods.

RESULTS

Of 1655 patients with incident CRAO in 2009-2010, 165 had stroke/AMI (ischemic stroke in 139, hemorrhagic stroke in 13, and AMI in 15) in the observation period spanning 365 days before and after the occurrence of CRAO. The IRR of stroke/AMI 1 to 30 days after CRAO occurrence significantly increased (14.0; 95% confidence interval [CI], 8.90-22.00); the IRR peaked during the 1 to 7 days after CRAO occurrence (44.51; 95% CI, 27.07-73.20), and the increased risk was present for the first 30 days. The IRR of stroke/AMI also significantly increased 1 to 30 days (6.82; 95% CI, 4.01-11.60) and 31 to 90 days (2.86; 95% CI, 1.66-4.93) before CRAO occurrence. Subanalysis for only ischemic stroke showed similar, magnified IRRs in the risk periods compared with all events. The IRRs were not significantly different between sexes or age groups (<65 vs. ≥65 years).

CONCLUSIONS

Patients with incident CRAO are at increased risk of ischemic stroke just after CRAO occurrence, and the risk is particularly increased during the first week immediately after the CRAO occurrence. The results suggest that patients with incident CRAO require immediate neurologic evaluation and preventive treatment to reduce mortality and morbidity.

Adverse drug reactions - examples of detection of rare events using databases

It is recognised that randomised controlled trials are not feasible for capturing rare adverse events. There is an increasing trend towards observational research methodologies using large population-based health databases. These databases offer more scope for adequate sample sizes, allowing for comprehensive patient characterisation and assessment of the associated factors. While direct causality cannot be established and confounders cannot be ignored, databases present an opportunity to explore and quantify rare events. The use of databases for the detection of rare adverse events in the following conditions, sudden death associated with attention deficit hyperactivity disorder (ADHD) treatment, retinal detachment associated with the use of fluoroquinolones and toxic epidermal necrolysis associated with drug exposure, are discussed as examples. In general, rare adverse events tend to have immediate and important clinical implications and may be life-threatening. An understanding of the causative factors is therefore important, in addition to the research methodologies and database platforms that enable the undertaking of the research.

Experiences of adolescents and young adults with ADHD in Hong Kong: treatment services and clinical management

BACKGROUND

Specialist services for the treatment of attention deficit hyperactivity disorder (ADHD) in adulthood in Hong Kong are yet to be developed. This study aims to explore the experiences of adolescents and young adults with ADHD in accessing treatment and services, coping with ADHD-related impairment, and their expectations of future treatment in Hong Kong.

METHOD

Qualitative interviews were conducted with a semi-structured guide. Forty young adult patients aged between 16 and 23 were included in the study. The interview recordings were transcribed verbatim and anonymised. Data were analysed with a thematic approach based on key principles of Grounded Theory.

RESULTS

Four meta-themes were developed: Accessing ADHD diagnosis and treatment services; ADHD-related impairment; Experience of ADHD treatments; and Attitudes and expectations of future ADHD treatment. The role of parents and schools were highly significant in accessing services for patients diagnosed with ADHD in childhood. In general, ADHD affected every aspect of patients' lives including academic outcome, employment, family and social relationships. Medications were the principal treatment for ADHD amongst the interviewees and were reported to be generally effective. Half of the patients received non-pharmacological treatments in childhood but these effects were reported to be temporary. There was general consensus that the needs of patients with ADHD could not be met by the current service. In particular, there is a lack of specialist service for adults with ADHD, follow-up by different clinicians, and insufficient provision of non-pharmacological treatments.

CONCLUSION

The findings suggest that further development of specialist ADHD services and non-pharmacological options for young adults are essential to meet their diverse needs with a holistic approach.

Methylphenidate and the risk of trauma

BACKGROUND AND OBJECTIVE

Children and adolescents with attention-deficit/hyperactivity disorder (ADHD) are prone to sustaining trauma that requires emergency department (ED) admission. Methylphenidate (MPH) can reduce ADHD symptoms and may thus theoretically reduce the risk of trauma-related ED admission, but previous studies do not make this association clear. This study examines this association.

METHODS

A total of 17 381 patients aged 6 to 19 years who received MPH prescriptions were identified by using the Clinical Data Analysis & Reporting System (2001-2013). Using a self-controlled case series study design, the relative incidence of trauma-related ED admissions was compared with periods of patient exposure and nonexposure to MPH.

RESULTS

Among 17 381 patients prescribed MPH, 4934 had at least 1 trauma-related ED admission. The rate of trauma-related ED admission was lower during exposed periods compared with nonexposed periods (incidence rate ratio [IRR]: 0.91 [95% confidence interval (CI): 0.86-0.97]). The findings were similar only when the incident trauma episode was assessed (IRR: 0.89 [95% CI: 0.82-0.96]). A similar protective association was found in both genders. In validation analysis using nontrauma-related ED admissions as a negative control outcome, no statistically significant association was found (IRR: 0.99 [95% CI: 0.95-1.02]). All sensitivity analyses demonstrated consistent results.

CONCLUSIONS

This study supports the hypothesis that MPH is associated with a reduced risk of trauma-related ED admission in children and adolescents. A similar protective association was found in both male and female patients. This protective association should be considered in clinical practice.

Association between oral fluoroquinolone use and the development of retinal detachment: a systematic review and meta-analysis of observational studies

OBJECTIVES

Several observational studies have been published investigating the association between oral fluoroquinolone use and the development of retinal detachment; however, the findings are not concordant. This study is a meta-analysis of the existing literature and estimates the overall absolute risk of such an event.

METHODS

Electronic databases were searched for observational studies on the association between oral fluoroquinolone and retinal detachment up to August 2014. Studies that did not meet the criteria for meta-analysis were narratively reviewed. Cases of retinal detachment during current fluoroquinolone use were also extracted for absolute risk calculation.

RESULTS

Seven observational studies were included. Three (case-control and self-controlled case series studies) were eligible for meta-analysis and four (cohort studies) were narratively reviewed. The rate ratio of the case-control studies was 1.82 (95% CI 0.67-4.93), I(2) =96% and the incidence rate ratio of the self-controlled case series was 1.03 (95% CI 0.84-1.27), I(2) =36%. Three of the four cohort studies found no significant association between oral fluoroquinolone use and the development of retinal detachment. The pooled absolute risk of retinal detachment whilst on current oral fluoroquinolone treatment is estimated to be 4.85 per 1000000 prescriptions (95% CI 0.78-8.91).

CONCLUSIONS

The findings of this systematic review and meta-analysis do not support an association between oral fluoroquinolone use and the development of retinal detachment. Given the low absolute risk, such an event would be rare if there were an association. The current prescribing practice for fluoroquinolones should not be altered because of a previously suggested potential risk of retinal detachment.