Prevalence and prognostic value of electrocardiographic abnormalities in hypokalemia: A multicenter cohort study

BACKGROUND

Hypokalemia is common in hospitalized patients and associated with ECG abnormalities. The prevalence and prognostic value of ECG abnormalities in hypokalemic patients are, however, not well established.

METHODS

The study was a multicentered cohort study, including all ault patients with an ECG and potassium level <4.4 mmol/L recorded at arrival to four emergency departments in Denmark and Sweden. Using computerized measurements from ECGs, we investigated the relationship between potassium levels and heart rate, QRS duration, corrected QT (QTc) interval, ST-segment depressions, T-wave flattening, and T-wave inversion using cubic splines. Within strata of potassium levels, we further estimated the hazard ratio (HR) for 7-day mortality, admission to the intensive care unit (ICU), and diagnosis of ventricular arrhythmia or cardiac arrest, comparing patients with and without specific ECG abnormalities matched 1:2 on propensity scores.

RESULTS

Among 79,599 included patients, decreasing potassium levels were associated with a concentration-dependent increase in all investigated ECG variables. ECG abnormalities were present in 40% of hypokalemic patients ([K+ ] <3.5 mmol/L), with T-wave flattening, ST-segment depression, and QTc prolongation occurring in 27%, 16%, and 14%. In patients with mild hypokalemia ([K+ ] 3.0-3.4 mmol/L), a heart rate >100 bpm, ST-depressions, and T-wave inversion were associated with increased HRs for 7-day mortality and ICU admission, whereas only a heart rate >100 bpm predicted both mortality and ICU admission among patients with [K+ ] <3.0 mmol/L. HR estimates were, however, similar to those in eukalemic patients. The low number of events with ventricular arrhythmia limited evaluation for this outcome.

CONCLUSIONS

ECG abnormalities were common in hypokalemic patients, but they are poor prognostic markers for short-term adverse events under the current standard of care.

Is the sequence ratio an unbiased estimate of the incidence rate ratio? A simulation study

PURPOSE

We aimed to evaluate the conditions under which the sequence ratio (SR) obtained from a sequence symmetry analysis is an unbiased estimate of the true incidence rate ratio (IRR).

METHODS

We simulated cohorts of 1 million individuals who could initiate an exposure drug and experience a very rare, rare, common, or frequent outcome of interest. The outcome rate among exposed individuals was modified by a true incidence rate ratio of 0.2, 0.5, 1.0, 2.0, and 5.0. We further evaluated scenarios where the outcome was fatal and led to immediate censoring or the outcome reduced the rate of initiation of the exposure drug.

RESULTS

We found the SR to be close to unbiased for rare, common, and frequent events, except when the true IRR was 5.0 (mean SR 4.94 and 3.74 for common and frequent events). The SR was slightly biased when the outcome was very rare. When the outcome was potentially fatal, the SR was increasingly biased with an increasing probability of death. Likewise, when the outcome reduced the probability of future exposure, the SR was upwards biased.

CONCLUSION

The SR is a biased estimate of the incidence rate ratio, when the true IRR is high, the outcome has a high mortality, or when the outcome reduces the probability of future exposure.

Effectiveness of the quadrivalent live attenuated influenza vaccine against influenza-related hospitalisations and morbidity among children aged 2 to 6 years in Denmark: a nationwide cohort study emulating a target trial

BACKGROUND

Scant evidence exists on the real-world effectiveness of quadrivalent live attenuated influenza vaccines (LAIV-4) in younger children. We aimed to assess the real-world effectiveness of LAIV-4 against influenza-related hospital contacts and admission and morbidity.

METHODS

Using nationwide Danish health-care registries, we designed a cohort study that emulates a target trial, comparing LAIV-4 to no vaccination in children aged 2-6 years. Eligible children vaccinated from Oct 1, 2021, to Jan 15, 2022, were matched to unvaccinated controls in a 1:1 ratio according to demographic characteristics and risk groups for influenza, and followed-up until May 31, 2022. Primary study outcomes any hospital contact for influenza and influenza-related hospital admissions more than 12 h in duration, while hospital admission for respiratory tract infections, or for wheezing or asthma, and antibiotic prescriptions were evaluated as secondary outcomes. We estimated incidence rate ratios (IRRs) and 95% CIs using Poisson regression for each outcome. Vaccine effectiveness was calculated as 1 - IRR.

FINDINGS

Among 308 520 Danish children aged 2-6 years, 95 434 vaccinated children were matched with 95 434 unvaccinated children who acted as controls. Receipt of LAIV-4 compared with no vaccination was associated with a reduced IRR of 0·36 (95% CI 0·27 to 0·46) and estimated vaccine effectiveness of 64·3% (53·6 to 72·6) against influenza-related hospital contacts (76 vs 210 events). The corresponding IRR and vaccine effectiveness against influenza-related hospital admissions were 0·63 (0·38 to 1·05) and 36·9% (-5·2 to 62·1; 24 vs 38 events), respectively. LAIV-4 was not associated with reductions in admission rates for respiratory tract infections (IRR 1·14, 95% CI 0·94 to 1·38), wheezing or asthma (1·04, 0·83 to 1·31), or antibiotic prescriptions for respiratory tract infections (0·97, 0·93 to 1·00). Vaccine effectiveness assessed across risk groups for influenza showed similar effectiveness in children with and without coexisting risk factors for severe influenza.

INTERPRETATION

LAIV-4 offered moderate protection in younger children against influenza-related hospital contacts during a season dominated by influenza A(H3N2); however vaccination was not associated with reductions in secondary outcomes. This real-world study thereby supports trial evidence of moderate vaccine effectiveness of LAIV-4 against influenza-related outcomes when implementing broad vaccination schedules in younger children.

FUNDING

Beckett-Fonden.

Melatonin use among children, adolescents, and young adults: a Danish nationwide drug utilization study

We aimed to provide a detailed description of the use of melatonin in Danish children, adolescents, and young adults during 2012-2019. We identified melatonin users 0-24 years of age (n = 43,652; median age 16 years) via the Danish nationwide health registers. Melatonin is a prescription drug in Denmark. The incidence of melatonin use increased from 2.4 to 3.9/1000 person-years during 2012 to 2019. Among 6,557 incident users in 2019, 53% filled only a single prescription within the first 6 months. Long-term use was most common among the younger age groups, with 17% of 5-9-year-olds and 14% of 10-13-year-olds being in continued treatment (no treatment breaks) 12 months after their first melatonin prescription. Disregarding treatment breaks, 3 in 10 were using melatonin 12 months after their first melatonin prescription and this proportion was also highest among 5-9-year-olds (63%) and 10-13-year-olds (51%). Psychopathology was common among melatonin users with 75% registered with either a psychiatric disorder diagnosis (54%), a filled prescription for another psychotropic (58%), or a contact to a private practice psychiatrist (15%) within ± 12 months of treatment initiation. General practitioners authorized melatonin prescriptions to almost half of all new users (48%), while psychiatric specialists authorized 37% of first prescriptions. In conclusion, the incidence of melatonin use increased in Denmark from 2012 to 2019. A substantial proportion of users had concurrent psychopathology most likely explaining their use of melatonin. Long-term melatonin use was more common among the youngest age groups, which should be a focus of interest due to limited safety data.

In utero exposure to ADHD medication and long-term offspring outcomes

Attention Deficit Hyperactivity Disorder (ADHD) medication is increasingly being used during pregnancy. Concerns have been raised as to whether ADHD medication has long-term adverse effects on the offspring. The authors investigated whether in utero exposure to ADHD medication was associated with adverse long-term neurodevelopmental and growth outcomes in offspring. The population-based cohort study in the Danish national registers included 1,068,073 liveborn singletons from 1998 to 2015 followed until any developmental diagnosis, death, emigration, or December 31, 2018. Children of mothers who continued ADHD medication (methylphenidate, amphetamine, dexamphetamine, lisdexamphetamine, modafinil, atomoxetine, clonidine) during pregnancy and children of mothers who discontinued ADHD medication before pregnancy were compared using Cox regression. Main outcomes were neurodevelopmental psychiatric disorders, impairments in vision or hearing, epilepsy, seizures, or growth impairment during childhood or adolescence. In total, 898 children were exposed to ADHD medication during pregnancy compared to 1270 children whose mothers discontinued ADHD medication before pregnancy. After adjustment for demographic and psychiatric characteristics of the mother, no increased risk of any offspring developmental disorders was found combined (aHR 0.97, 95% CI 0.81 to 1.17) or for separate subcategories. Similarly, no increased risk was found for any sub-categories of outcomes in the negative control or sibling controlled analyses. Neurodevelopment and growth in offspring do not differ based on antenatal exposure to ADHD medication. These findings provide reassurance for women with ADHD who depend on ADHD medication for daily functioning and who consider continuing medication in pregnancy.

Psychotropic Medication Use and Psychiatric Disorders During the COVID-19 Pandemic Among Danish Children, Adolescents, and Young Adults

Importance

The direct and indirect implications of the COVID-19 pandemic have been associated with the mental health of children and adolescents, but it is uncertain whether these implications have been associated with changes in prescribing and diagnosis patterns.

Objective

To examine psychotropic medication use and rates of psychiatric disorders in Danish children, adolescents, and young adults during the COVID-19 pandemic.

Design, Setting, and Participants

This population-based, descriptive register-based cohort study included all Danish individuals aged 5 to 24 years from January 1, 2017, until June 30, 2022.

Main Outcomes and Measures

Rates of filled prescriptions of psychotropic medications, including antipsychotics, anxiolytics, hypnotics, sedatives, antidepressants, and psychostimulants, and all inpatient and outpatient contacts with mental and behavioral disorders. Rates of new (incident) and total (prevalent) psychotropic medication use and psychiatric diagnoses were estimated. Rate ratios (RRs) were assessed between observed and expected numbers of incident psychotropic medication use or psychiatric diagnoses from March 2020 to June 30, 2022, comparing observed numbers with expected numbers predicted from the modeled prepandemic trend.

Results

The study identified 108 840 (58 856 female individuals [54%]; median [IQR] age, 18 [14-22] years) incident psychotropic medication users. From March 2020 (first national lockdown) to June 2022, the rate of incident users of any psychotropic medication showed a relative increase of 18% (RR, 1.18; CI, 1.17-1.20) compared with expected numbers, which was primarily associated with an increase among those aged 12 to 17 years of 37% (RR, 1.37; 95% CI, 1.34-1.41). Similarly, there was an overall relative increase of incident psychiatric disorders of 5% (incidence rate, 1.05; CI, 1.04-1.07) (incident cases, 114 048 [58 708 female individuals (51%)]), which was associated with an increase in hyperkinetic disorders (RR, 1.13; CI, 1.09-1.18) and anxiety disorders (RR, 1.04; CI, 1.02-1.06). Prevalence patterns showed similar trends of an overall increase in psychotropic medication use and psychiatric disorders. One of 3 new users of an individual drug group had filled a prescription for a drug from another psychotropic medication group within the prior 6 months.

Conclusions and Relevance

The results of this cohort study suggest that Danish youths experienced an increase in rates of psychotropic treatment and psychiatric disorder diagnoses during the COVID-19 pandemic, which was most pronounced among those aged 12 to 17 years. The increase was observed for children and adolescents with and without a psychiatric history within the last 5 years.

Changing characteristics over time of individuals receiving COVID-19 vaccines in Denmark: A population-based descriptive study of vaccine uptake

AIMS

The Danish authorities implemented a differential rollout of the COVID-19 vaccines where individuals at high risk of COVID-19 were prioritized. We describe the temporal uptake and characteristics of COVID-19 vaccine recipients in Denmark.

METHODS

Using nationwide healthcare registries, we identified all Danish residents ⩾5 years of age who received at least one dose of a COVID-19 vaccine from 27 December 2020-29 January 2022. We charted the daily number of newly vaccinated individuals and the cumulative vaccine coverage over time, stratified by vaccine type, age groups and vaccination priority groups, and described characteristics of vaccine recipients during two-month-intervals and in vaccination priority groups.

RESULTS

By 29 January 2022, 88%, 86% and 64% of Danish residents ⩾5 years (n=5,562,008) had received a first, second and third dose, respectively, of a COVID-19 vaccine, most commonly the BNT162b2 vaccine (84%). Uptake ranged from 48% in 5-11-year-olds to 98% in 65-74-year-olds. Individuals vaccinated before June 2021 were older (median age 61-70 years vs 10-35 years in later periods) and had more comorbidities such as hypertension (22-28% vs 0.77-2.8% in later periods), chronic lung disease (9.4-15% vs 3.7-4.6% in later periods) and diabetes (9.3-12% vs 0.91-2.4% in later periods).

CONCLUSIONS

We document substantial changes over time in, for example, age, sex and medical history of COVID-19 vaccine recipients. Though these results are related to the differential vaccine rollout in Denmark, similar findings are probable in other countries and should be considered when designing and interpreting studies on the effectiveness and safety of COVID-19 vaccines.

Risk of Appendicitis After mRNA COVID-19 Vaccination in a Danish Population

This cohort study used data from Danish registers to assess whether recipients of mRNA COVID-19 vaccines had a higher risk of appendicitis after receiving the shot compared with individuals who did not receive the vaccine.

Risk of adverse events after covid-19 in Danish children and adolescents and effectiveness of BNT162b2 in adolescents: cohort study

OBJECTIVES

To assess the risk of acute and post-acute adverse events after SARS-CoV-2 infection in children and adolescents in Denmark and to evaluate the real world effectiveness of the BNT162b2 mRNA vaccine (Pfizer-BioNTech) among adolescents.

DESIGN

Cohort study.

SETTING

Nationwide Danish healthcare registers.

PARTICIPANTS

All Danish people younger than 18 years who were either tested for SARS-CoV-2 using reverse transcriptase polymerase chain reaction (RT-PCR) or vaccinated with BNT162b2 to 1 October 2021.

MAIN OUTCOME MEASURES

Risk of hospital admissions (any hospital contact of ≥12 hours); intensive care unit (ICU) admissions; serious complications, including multisystem inflammatory syndrome in children (MIS-C), myocarditis, and neuroimmune disorders; and initiating drug treatment and health service use up to six months after being tested. Vaccine effectiveness in vaccine recipients compared with unvaccinated peers was evaluated as one minus the risk ratio at 20 days after the first dose and 60 days after the second dose.

RESULTS

Of 991 682 children and adolescents tested for SARS-CoV-2 using RT-PCR in Denmark, 74 611 (7.5%) were positive. The risk of hospital admission with any variant for ≥12 hours was 0.49% (95% confidence interval 0.44% to 0.54%; 361/74 350), and 0.01% (0.01% to 0.03%; 10/73 187) of participants were admitted to an ICU within 30 days of testing positive. The risk of MIS-C within two months of SARS-CoV-2 infection was 0.05% (0.03% to 0.06%; 32/70 666), whereas no participants had myocarditis outside of MIS-C or encephalitis and fewer than five had Guillain-Barré syndrome. In the post-acute phase (1-6 months after infection), participants who tested positive for SARS-CoV-2 showed a 1.08-fold (95% confidence interval 1.06-fold to 1.10-fold) increase in rate of contacts with general practitioners compared with a reference cohort sampled among all children tested for SARS-CoV-2 during the study period. Overall, 278 649 adolescents received BNT162b2. Compared with unvaccinated adolescents, the estimated vaccine effectiveness among 229 799 adolescents vaccinated with one dose was 62% (95% confidence interval 59% to 65%) after 20 days, and among 175 176 vaccinated with two doses was 93% (92% to 94%) after 60 days during a period when delta was the dominant variant.

CONCLUSIONS

The absolute risks of adverse events after SARS-CoV-2 infection were generally low in Danish children and adolescents, although MIS-C occurred in 0.05% (32/70 666) of participants with RT-PCR confirmed SARS-CoV-2 infection. In adjusted analyses, rates of general practitioner visits were slightly increased in SARS-CoV-2 positive children and adolescents, which could indicate persisting symptoms. BNT162b2 appeared to be effective in reducing the risk of SARS-CoV-2 infection with the delta variant in adolescents.

PR interval prolongation and 1-year mortality among emergency department patients: a multicentre transnational cohort study

OBJECTIVES

Emerging evidence supports that PR interval prolongation is associated with increased mortality. However, most previous studies have limited confounder control, and clinical impact in a population of acute ill patients is unknown. The aim of this study was to investigate whether 1-year all-cause mortality was increased in patients presenting with PR interval prolongation in the emergency department (ED).

DESIGN AND SETTING

We conducted a register-based cohort study in two Swedish and two Danish EDs. We included all adult patients with an ECG performed at arrival to the Danish EDs during March 2013 to May 2014 and Swedish EDs during January 2010 to January 2011. Using propensity score matching, we analysed HR for 1-year all-cause mortality comparing patients with PR interval prolongation (>200 ms) and normal PR interval (120-200 ms).

PARTICIPANTS AND RESULTS

We included 106 124 patients. PR interval prolongation occurred in 8.9% (95% CI 8.7% to 9.0%); these patients were older and had more comorbidity than those with a normal PR interval. The absolute 1-year risk of death was 13% (95% CI 12.3% to 13.7%) for patients with PR interval prolongation and 7.9% (95% CI 7.7% to 8.0%) for those without. After confounder adjustments by propensity score matching, PR interval prolongation showed no association with 1-year mortality with a HR of 1.00 (95% CI 0.93% to 1.08%).

CONCLUSION

PR interval prolongation does not constitute an independent risk factor for 1-year mortality in ED patients.