Ambient pollen concentrations and asthma hospitalization in children and adolescents: a systematic review and meta-analysis

ObjectiveWe aimed to conduct a systematic review examining the association between outdoor pollen and childhood asthma hospitalizations.Data SourceA systematic search of articles in MEDLINE, EMBASE, CINAHL, ProQuest Central, Web of Science and Google Scholar published to 18 July 2019.Study selection: Studies that presented data on pollen exposure and childhood asthma hospitalization were included and evaluated for potential risk of bias by two independent authors. Random effects meta-analysis was performed where possible.ResultsA total of 1048 records were identified, and twelve studies included in the review. The synthesis suggested possible associations between outdoor pollen, especially for grass and birch and childhood asthma hospitalization. However, the results varied widely across geographical areas and settings for other pollen taxa. The meta-analysis of the case-crossover studies showed a positive association between grass and childhood asthma hospitalization, an increase in 10 grass pollen grains/m³ was associated with a 3% increase in childhood asthma admission (OR = 1.03; 95%CI:1.01, 1.04), but the pooled estimate was not significant for timeseries studies. The meta-analysis of the timeseries studies for birch pollen showed an increase in 10 pollen grains/m³ being significantly associated with a Mean Percentage Change (MPC) in childhood asthma admissions (MPC= 0.85; 95%CI:0.40, 1.30).Conclusion: Globally, grass and birch pollen are important triggers of childhood asthma hospitalization, but the association could not be ascertained for other pollen taxa. Pollen is a major environmental trigger of asthma exacerbations and more focus on early interventions to reduce this burden needs to be considered.

Asthma admission among children in Hong Kong during the first year of the COVID-19 pandemic

BACKGROUND

Multiple nonpharmaceutical interventions (NPIs) had been introduced in Hong Kong during coronavirus disease 2019 (COVID-19) pandemic. The impact on asthma admission, which was closely related to viral infection, was of concern.

OBJECTIVE

The study aimed to identify the impact of NPIs on pediatric asthma admissions and their association with respiratory viruses.

METHODS

We conducted a retrospective observational study to compare the difference in pediatric asthma hospital admission rates between pre-COVID-19 and COVID-19 periods. Information on demographics, nasopharyngeal specimen results, ventilatory support, intensive care admission, hospital stay duration, asthma control therapy, and previous admission episodes was collected. Weather parameters including temperature, rainfall, humidity, and air quality data that was reflected by the air quality health index were recorded.

RESULTS

A total of 1808 pediatric asthma admissions were recorded during the pre-COVID-19 period while there were 62 admissions during COVID-19 period, among which 54 admissions from the pre-COVID-19 period and 4 admissions from COVID-19 period were excluded. Weekly pediatric asthma admissions per total pediatric admissions during COVID-19 was one-third of that during the pre-COVID-19 period (0.3% vs. 0.9%, p < 0.001). During COVID-19 period, a significantly lower percentage of respiratory virus isolates was noted (58.6% vs. 72.6%, p = 0.019). Poisson regression analysis showed that the COVID-19 period (odds ratio [OR] = 0.202, 95% confidence interval  [CI, 0.16-0.26]; p ≤ 0.001), summer vacation period (OR = 0.512, 95% CI [0.43-0.62]; p ≤ 0.001), and humidity (OR = 0.99, 95% CI [0.98-1.00]; p = 0.004) were independent protective factors for asthma admission.

CONCLUSIONS

There was a significant reduction in pediatric asthma hospitalizations and respiratory virus isolates in the first year of COVID-19 pandemic in Hong Kong with the implementation of NPIs. Rhinovirus remained the key respiratory virus isolate. Incorporation of appropriate NPIs in long run could reduce virus infection-related pediatric asthma admission.

Health Effects of the Asthma Care Program under the Universal Coverage Scheme in Children and Young Adults in Thailand

This study aimed to evaluate the effect of the asthma care program available under the Universal Coverage Scheme (UCS) in Thailand on hospital admissions per 100,000 population, its regional and seasonal variation, readmission within 28 days, and the asthma-specific fatality rate of patients aged 0–29 years in 2009–2016 compared with those in 2007–2008. A retrospective study was conducted using data sources from the UCS register and in-patient databases from the National Health Security Office (NHSO), Thailand. Hospital admissions per 100,000 population was the highest among those aged 0–4 years, but the trends decreased from 470.8 to 288.1 per 100,000 population in 2010–2014. The hospital admission rates were high in Southern Thailand and common in rainy seasons. The readmission rates within 28 days slightly decreased in all age groups in 2016 compared to those in 2007. The case fatality rate of patients aged 20–29 years decreased from 0.40% in 2007 to 0.34% in 2016. The readmission rate within 28 days and case fatality rate were the highest in patients aged 20–29 years. In conclusion, the asthma hospital admission, readmission, and case fatality rates declined over time along with the investment in the asthma care program under the UCS in Thailand. The highest hospital admission rates in patients aged 0–4 years and the readmission and case fatality rates in patients aged 20–29 years should be given more attention. Recordings of individual service utilization data in asthma patients, including quality of care provided, should be monitored to improve the asthma care system.