Difference in symptom severity between early and late grass pollen season in patients with seasonal allergic rhinitis

Phenological Analysis of Grasses (Poaceae) in Comparison with Aerobiological Data in Moscow (Russia)

Grasses (Poaceae) produce large amounts of pollen and are among the main causes of pollinosis worldwide. Despite their morphological similarity, pollen grains of different grass species may have different allergenicities. Therefore, quantification of the roles of individual species in airborne pollen is an important task. There are very few studies on this topic, and none of them have been conducted in a temperate continental climate. Our study was carried out for three years (2020-2022) in the urban territory of Moscow (Russia) and aimed to understand what grass species contribute the most to the total pollen load of the atmosphere. The comparison of aerobiological and phenological data was based on calculating the phenological index, which is a combination of phenological parameters, pollen productivity of individual species, and their abundance. Our data showed that the decomposition of pollination curves based on the phenological index was sometimes very efficient but not always possible in temperate continental climates. The main reasons for disagreement between aerobiological and phenological data were weather conditions and lawn mowing. Not all grasses were equally important as sources of allergenic pollen. The greatest contribution to the pollen load at the beginning of the season in Moscow was made by Dactylis glomerata, and to a lesser extent by Phleum pratense and Festuca pratensis. These are the most common species, which are widespread throughout Europe. The contribution of minor components is insignificant.

Ambient pollen exposure and pollen allergy symptom severity in the EPOCHAL study

BACKGROUND

Ambient pollen exposure causes nasal, ocular, and pulmonary symptoms in allergic individuals, but the shape of the exposure-response association is not well characterized. We evaluated this association and determined (1) whether symptom severity differs between subpopulations; (2) how the association changes over the course of the pollen season; and (3) which pollen exposure time lags affect symptoms.

METHODS

Adult study participants (n = 396) repeatedly scored severity of nasal, ocular, and pulmonary allergic symptoms, resulting in three composite symptom scores. We calculated hourly individually relevant pollen exposure to seven allergenic plants (alder, ash, birch, hazel, grasses, mugwort, and ragweed) considering personal sensitization and exposure time lags of up to 96 h. We fitted generalized additive mixed models, with a random personal intercept, adjusting for weather and air pollution as potential time-varying confounders.

RESULTS

We identified a clear nonlinear positive association between pollen exposure and ocular and nasal symptom severity in the pollen allergy group: Symptom severity increased steeply with increasing exposure initially, but attenuated beyond approximately 80 pollen/m3. We found no evidence of an exposure threshold, below which no symptoms occur. While recent pollen exposure in the last approximately 5 h affected symptoms most, associations lingered for up to 60 h. Grass pollen exposure (compared to tree pollen) and younger age (18-30 years, as opposed to 30-65 years) were both associated with higher nasal and ocular symptom severity.

CONCLUSIONS

The lack of a threshold and attenuated dose-response curve may have implications for pollen warning systems, which may be revised to include multiday pollen concentrations in the future.

Aerobiological Monitoring and Metabarcoding of Grass Pollen

Grass pollen is one of the leading causes of pollinosis, affecting 10-30% of the world's population. The allergenicity of pollen from different Poaceae species is not the same and is estimated from moderate to high. Aerobiological monitoring is a standard method that allows one to track and predict the dynamics of allergen concentration in the air. Poaceae is a stenopalynous family, and thus grass pollen can usually be identified only at the family level with optical microscopy. Molecular methods, in particular the DNA barcoding technique, can be used to conduct a more accurate analysis of aerobiological samples containing the DNA of various plant species. This study aimed to test the possibility of using the ITS1 and ITS2 nuclear loci for determining the presence of grass pollen from air samples via metabarcoding and to compare the analysis results with the results of phenological observations. Based on the high-throughput sequencing data, we analyzed the changes in the composition of aerobiological samples taken in the Moscow and Ryazan regions for three years during the period of active flowering of grasses. Ten genera of the Poaceae family were detected in airborne pollen samples. The representation for most of them for ITS1 and ITS2 barcodes was similar. At the same time, in some samples, the presence of specific genera was characterized by only one sequence: either ITS1 or ITS2. Based on the analysis of the abundance of both barcode reads in the samples, the following order could describe the change with time in the dominant species in the air: Poa, Alopecurus, and Arrhenatherum in early mid-June, Lolium, Bromus, Dactylis, and Briza in mid-late June, Phleum, Elymus in late June to early July, and Calamagrostis in early mid-July. In most samples, the number of taxa found via metabarcoding analysis was higher compared to that in the phenological observations. The semi-quantitative analysis of high-throughput sequencing data well reflects the abundance of only major grass species at the flowering stage.

IgE+ plasmablasts predict the onset of clinical allergy

Introduction

IgE+ plasmablasts develop following allergen exposure and B cell activation. They secrete IgE and therefore are directly linked to maintain the mechanisms of IgE-mediated allergies. Here, we show that the presence of IgE+ plasmablasts in peripheral blood not only coincides with clinical allergy, but also predicts the upcoming development of clinical disease.

Methods

Using an equine model of naturally occurring allergy, we compared the timing of allergen exposure, arrival of IgE+ plasmablasts in peripheral blood, and onset of clinical disease.

Results

We found that IgE+ plasmablasts predict the development of clinical allergy by at least 3 weeks and can be measured directly by flow cytometry or by IgE secretion following in vitro culture. We also compared the IgE secretion by IgE+ plasmablasts with total plasma IgE concentrations and found that while IgE secretion consistently correlates with clinical allergy, total plasma IgE does not.

Discussion

Together, we describe IgE+ plasmablasts as a reliable and sensitive predictive biomarker of allergic disease development.

The association between outdoor allergens - pollen, fungal spore season and high asthma admission days in children and adolescents

Periods when asthma admissions peaks have serious implications for asthma sufferers and hospitals. We assessed the association between aeroallergen exposure and childhood asthma peak periods during two grass pollen seasons using the Melbourne Air Pollen Children and Adolescent Health (MAPCAH) study conducted in Melbourne, Australia. Two peak periods were identified. Effect modifications by atopy and sex were considered. All pollen 2 days prior was associated with increased odds of these peak periods. Same day fungal spores, but not pollen, were important. Grass at lag 2 was associated with increased odds 1.03 (95%CI 1.01, 1.05) as was the same day Alternaria 1.02 (1.00, 1.04) per spore/m³ for boys. In addition to pollen, fungal spores particularly Alternaria may result in days of high exacerbations during pollen seasons. Further guidance is needed to better prepare families/carers with information about the increased risk of asthma attacks in children prior to pollen seasons.

Importance of allergen–environment interactions in epidemic thunderstorm asthma

Australia is home to one of the highest rates of allergic rhinitis worldwide. Commonly known as ‘hay fever’, this chronic condition affects up to 30% of the population and is characterised by sensitisation to pollen and fungal spores. Exposure to these aeroallergens has been strongly associated with causing allergic reactions and worsening asthma symptoms. Over the last few decades, incidences of respiratory admissions have risen due to the increased atmospheric concentration of airborne allergens. The fragmentation and dispersion of these allergens is aided by environmental factors like rainfall, temperature and interactions with atmospheric aerosols. Extreme weather parameters, which continue to become more frequent due to the impacts of climate change, have greatly fluctuated allergen concentrations and led to epidemic thunderstorm asthma (ETSA) events that have left hundreds, if not thousands, struggling to breathe. While a link exists between airborne allergens, weather and respiratory admissions, the underlying factors that influence these epidemics remain unknown. It is important we understand the potential threat these events pose on our susceptible populations and ensure our health infrastructure is prepared for the next epidemic.

Impact of Local Grasslands on Wild Grass Pollen Emission in Bavaria, Germany

Meteorological conditions and the distribution of pollen sources are the two most decisive factors influencing the concentration of airborne grass pollen. However, knowledge about land-use types, their potential pollen emission, and the importance of local sources remains limited. In this study, wild grass pollen concentrations from 27 stations in Bavaria, Germany, were linked to potential pollen within a 30 km radius. Agricultural grass pollen sources were derived from the InVeKos database, which contains detailed information on agricultural land-use types and their spatial distribution. Non-agricultural grassland was identified by OpenStreetMap. Further source classification was conducted using a cultivation intensity indicator and wind direction. We show that the grassland percentage and pollen concentrations, specified as annual pollen integral and pollen peak vary strongly between pollen stations. Correlation analyses indicated that the impact of the grassland on pollen concentration was greater within 10 km of the pollen traps. At greater distances, the correlation coefficient between the grassland percentage and pollen indicators steadily declined.

Characterising non-linear associations between airborne pollen counts and respiratory symptoms from the AirRater smartphone app in Tasmania, Australia: A case time series approach

Pollen is a well-established trigger of asthma and allergic rhinitis, yet concentration-response relationships, lagged effects, and interactions with other environmental factors remain poorly understood. Smartphone technology offers an opportunity to address these challenges using large, multi-year datasets that capture individual symptoms and exposures in real time. We aimed to characterise associations between six pollen types and respiratory symptoms logged by users of the AirRater smartphone app in Tasmania, Australia. We analyzed 44,820 symptom reports logged by 2272 AirRater app users in Tasmania over four years (2015-2019). With these data we evaluated associations between daily respiratory symptoms and atmospheric pollen concentrations. We implemented Poisson regression models, using the case time series approach designed for app-sourced data. We assessed potentially non-linear and lagged associations with (a) total pollen and (b) six individual pollen taxa. We adjusted for seasonality and meteorology and tested for interactions with particulate air pollution (PM_2.5). We found evidence of non-linear associations between total pollen and respiratory symptoms for up to three days following exposure. For total pollen, the same-day relative risk (RR) increased to 1.31 (95% CI: 1.26-1.37) at a concentration of 50 grains/m³ before plateauing. Associations with individual pollen taxa were also non-linear with some diversity in shapes. For all pollen taxa the same-day RR was highest. The interaction between total pollen and PM_2.5 was positive, with risks associated with pollen significantly higher in the presence of high concentrations of PM_2.5. Our results support a non-linear response between airborne pollen and respiratory symptoms. The association was strongest on the day of exposure and synergistic with particulate air pollution. The associations found with Dodonaea and Myrtaceae highlight the need to further investigate the role of Australian native pollen types in allergic respiratory disease.

Variability of grass pollen allergy symptoms throughout the season: Comparing symptom data profiles from the Patient's Hayfever Diary from 2014 to 2016 in Vienna (Austria)

Background

Grass pollen allergy is the most widespread pollen allergy in the world. It still remains unknown in which aspects and in which extent symptoms from grass pollen allergy differ throughout the grass pollen season, although individual sensitization profiles of persons concerned are known for a long time.

Methods

The crowd-sourced symptom data of users of the Patient's Hayfever Diary were filtered for significant positive correlated users to grass pollen from Vienna (Austria) during the respective grass pollen seasons from 2014, 2015, and 2016. These symptom data were the foundation for 3 statistical approaches in order to examine different sections of the grass pollen season defined either by grass pollen data, phenology (grass species determination in the field), or symptom data itself.

Results

Results from all 3 approaches are similar and come to the same major conclusion. The symptom peak of most users is observed in the second section of the grass pollen season (70%), followed by the first section (20%), and with the least user numbers (10%) the third section. The profiles from single users entering data for all 3 years under study are robust and show a comparable behavior from year to year.

Conclusion

Grass taxa such as Arrhenatherum, Festuca, and Lolium seem to induce the highest symptom severity in most users during the second section of the grass pollen season. Poa and Dactylis are the main triggers for the first section of the grass pollen season. The flower of Phleum und Cynodon is documented for the last section of the grass pollen season. Crowd-sourced symptom data is the prerequisite for personal pollen information to consider the individuality of grass pollen allergy sufferers. Phenological monitoring is needed to provide information on specific grass taxa of importance to allergic persons.

Tracking seasonal changes in diversity of pollen allergen exposure: Targeted metabarcoding of a subtropical aerobiome

The importance of grass pollen to the global burden of allergic respiratory disease is well established but exposure to subtropical and temperate pollens is difficult to discern. Current monitoring of airborne pollen relies on light microscopy, limiting identification of taxa to family level. This informs seasonal fluctuations in pollen aerobiology but restricts analysis of aerobiological composition. We aimed to test the utility of DNA metabarcoding to identify specific taxa contributing to the aerobiome of environmental air samples, using routine pollen and spore monitoring equipment, as well as assess temporal variation of Poaceae pollen across an entire season. Airborne pollen concentrations were determined by light microscopy over two pollen seasons in the subtropical city of Brisbane (27°32'S, 153°00E), Australia. Thirty daily pollen samples were subjected to high throughput sequencing of the plastid rbcL amplicon. Amplicons corresponded to plants observed in the local biogeographical region with up to 3238 different operational taxonomic units (OTU) detected. The aerobiome sequencing data frequently identified pollen to genus levels with significant quantitative differences in aerobiome diversity between the months and seasons detected. Moreover, multiple peaks of Chloridoideae and Panicoideae pollen were evident over the collection period confirming these grasses as the dominant Poaceae pollen source across the season. Targeted high throughput sequencing of routinely collected airborne pollen samples appears to offer utility to track temporal changes in the aerobiome and shifts in pollen exposure. Precise identification of the composition and temporal distributions of airborne pollen is important for tracking biodiversity and for management of allergic respiratory disease.

Cross-reactivity between the Betulaceae family and fallout in the real atmospheric aeroallergen load

Betulaceae family is a dominant tree pollen type in the atmosphere at Northwest Spain, being a major cause of allergenic rhinitis or asthma symptoms. Alnus pollen cause symptoms in the 9-20% of the total hay fever sufferers mean while the 41.89% of patients present a positive skin-prick-test for Betula allergens. Aln g1 and Bet v1 aeroallergens belong to PR-10 protein family and are associated to cross-reactivity processes. Airborne pollen and aeroallergens from Alnus and Betula were sampled during their Main Pollen Season from 2016 to 2019. Pollen sampling was conducted by means of a Hirst volumetric trap and aeroallergens were sampled using a Multi Vial Cyclone Sampler. Alnus flowering took place from January to February, with an average duration of 44 days. Betula bloom occurred from April to May with an average pollen season of 33 days. The major innovation of our study was the first detection of Aln g1 allergens in the atmosphere by using Bet v1 antibodies. This fact verified the cross-reactivity between the main allergens of Betula and Alnus pollen. Along the study period, an average of 18 days/year and 14 days/year with high potential risk of allergy due to Alnus pollen and allergen respectively, was registered. For Betula an average of 16 days/year with high potential risk of allergy due to pollen and 22 days for allergen was registered. The main consequence of the successive bloom of both trees would be the so-called "priming effect". Urban population sensitized to Betula pollen could suffer allergic symptoms during winter (as a consequence of Alnus), and in spring with the manifestation of higher symptoms under low birch pollen grain levels in the atmosphere. The traditional information to prevent allergies, such as the airborne pollen concentrations, should be combined with the data of aeroallergen to identify the real allergenic load in the atmosphere.

New European Academy of Allergy and Clinical Immunology definition on pollen season mirrors symptom load for grass and birch pollen-induced allergic rhinitis

BACKGROUND

The use of allergen immunotherapy (AIT) for allergic rhinitis and its clinical efficacy in clinical trials depends on the effective determination of pollen allergen exposure time periods. We evaluate pollen data from Germany to examine the new definitions on pollen season and peak pollen period start and end as proposed by the European Academy of Allergy and Clinical Immunology (EAACI) in a recently published Position Paper. The aim was to demonstrate the ability of these definitions to mirror symptom loads for grass and birch pollen-induced allergic rhinitis based on real-life data.

METHODS

Data coming from four pollen monitoring stations in the Berlin and Brandenburg area in Germany and for 3 years (2014-2016) were used to investigate the correlation of season definitions, birch and grass pollen counts and total nasal symptom and mediation scores as reported by patients in "Patients Hay fever Diaries" (PHDs). After the identification of pollen periods on the basis of the EACCI criteria, a statistical analysis was employed, followed by a detailed graphical investigation.

RESULTS

The analysis revealed that the definitions of pollen season as well as peak pollen period start and end as proposed by the EAACI are correlated to symptom loads for grass and birch pollen-induced allergic rhinitis reported by patients in PHDs.

CONCLUSION

Based on our analysis, the validity of the EAACI definitions on pollen season is confirmed. Their use is recommended in future clinical trials on AIT as well as in daily routine for optimal patient care.

New biomolecular tools for aerobiological monitoring: Identification of major allergenic Poaceae species through fast real-time PCR

Grasses (Poaceae) are very common plants, which are widespread in all environments and urban areas. Despite their economical importance, they can represent a problem to humans due to their abundant production of allergenic pollen. Detailed information about the pollen season for these species is needed in order to plan adequate therapies and to warn allergic people about the risks they take in certain areas at certain moments. Moreover, precise identification of the causative species and their allergens is necessary when the patient is treated with allergen‐specific immunotherapy. The intrafamily morphological similarity of grass pollen grains makes it impossible to distinguish which particular species is present in the atmosphere at a given moment. This study aimed at developing new biomolecular tools to analyze aerobiological samples and identifying major allergenic Poaceae taxa at subfamily or species level, exploiting fast real‐time PCR. Protocols were tested for DNA extraction from pollen sampled with volumetric and gravimetric methods. A fragment of the matK plastidial gene was amplified and sequenced in Poaceae species known to have high allergological impact. Species‐ and subfamily‐specific primer–probe systems were designed and tested in fast real‐time PCRs to evaluate the presence of these taxa in aerobiological pollen samples. Species‐specific systems were obtained for four of five studied species. A primer–probe set was also proposed for the detection of Pooideae (a grass subfamily that includes also major cereal grains) in aerobiological samples, as this subfamily includes species carrying both grass allergens from groups 1 and 5. These, among the 11 groups in which grass pollen allergens are classified, are considered responsible for the most frequent and severe symptoms.

Defining pollen exposure times for clinical trials of allergen immunotherapy for pollen-induced rhinoconjunctivitis - an EAACI position paper

BACKGROUND

Clinical efficacy of pollen allergen immunotherapy (AIT) has been broadly documented in randomized controlled trials. The underlying clinical endpoints are analysed in seasonal time periods predefined based on the background pollen concentration. However, any validated or generally accepted definition from academia or regulatory authorities for this relevant pollen exposure intensity or period of time (season) is currently not available. Therefore, this Task Force initiative of the European Academy of Allergy and Clinical Immunology (EAACI) aimed to propose definitions based on expert consensus.

METHODS

A Task Force of the Immunotherapy and Aerobiology and Pollution Interest Groups of the EAACI reviewed the literature on pollen exposure in the context of defining relevant time intervals for evaluation of efficacy in AIT trials. Underlying principles in measuring pollen exposure and associated methodological problems and limitations were considered to achieve a consensus.

RESULTS

The Task Force achieved a comprehensive position in defining pollen exposure times for different pollen types. Definitions are presented for 'pollen season', 'high pollen season' (or 'peak pollen period') and 'high pollen days'.

CONCLUSION

This EAACI position paper provides definitions of pollen exposures for different pollen types for use in AIT trials. Their validity as standards remains to be tested in future studies.

Probiotics (Lactobacillus gasseri KS-13, Bifidobacterium bifidum G9-1, and Bifidobacterium longum MM-2) improve rhinoconjunctivitis-specific quality of life in individuals with seasonal allergies: a double-blind, placebo-controlled, randomized trial

Background: Rhinoconjunctivitis-specific quality of life is often reduced during seasonal allergies. The Mini Rhinoconjunctivitis Quality of Life Questionnaire (MRQLQ) is a validated tool used to measure quality of life in people experiencing allergies (0 = not troubled to 6 = extremely troubled). Probiotics may improve quality of life during allergy season by increasing the percentage of regulatory T cells (Tregs) and inducing tolerance.Objective: The objective of this study was to determine whether consuming Lactobacillus gasseri KS-13, Bifidobacterium bifidum G9-1, and B. longum MM-2 compared with placebo would result in beneficial effects on MRQLQ scores throughout allergy season in individuals who typically experience seasonal allergies. Secondary outcomes included changes in immune markers as part of a potential mechanism for changes in MRQLQ scores.Design: In this double-blind, placebo-controlled, parallel, randomized clinical trial, 173 participants (mean ± SEM: age 27 ± 1 y) who self-identified as having seasonal allergies received either a probiotic (2 capsules/d, 1.5 billion colony-forming units/capsule) or placebo during spring allergy season for 8 wk. MRQLQ scores were collected weekly throughout the study. Fasting blood samples were taken from a subgroup (placebo, n = 37; probiotic, n = 35) at baseline and week 6 (predicted peak of pollen) to determine serum immunoglobulin (Ig) E concentrations and Treg percentages.Results: The probiotic group reported an improvement in the MRQLQ global score from baseline to pollen peak (-0.68 ± 0.13) when compared with the placebo group (-0.19 ± 0.14; P = 0.0092). Both serum total IgE and the percentage of Tregs increased from baseline to week 6, but changes were not different between groups.Conclusions: This combination probiotic improved rhinoconjunctivitis-specific quality of life during allergy season for healthy individuals with self-reported seasonal allergies; however, the associated mechanism is still unclear. This trial was registered at clinicaltrials.gov as NCT02349711.

Molecular approaches for the analysis of airborne pollen: A case study of Juniperus pollen

BACKGROUND

Pollen monitoring is a common and vital tool in the field of allergy, creating awareness in pollen sensitive individuals. Traditionally, pollen monitoring has been based on conventional microscopic counting techniques that are labor intensive and limited in the identification to the genus or family level. Molecular techniques provide an alternative approach that is less labor intensive and enable identification of any species by its genetic fingerprint.

OBJECTIVE

To use quantitative polymerase chain reaction (qPCR) to evaluate pollen concentrations in air samples.

METHODS

Juniperus pollen was selected as our model because of the importance of this pollen in the southcentral United States. We analyzed 105 air samples collected with a Burkard spore trap from 2013 to 2015 using species-specific primers and probes. To evaluate the feasibility of a molecular approach, we used duplicate air samples that allowed us to compare results from classical identification based on light microscopy with our qPCR results.

RESULTS

Pollen concentrations from the qPCR data were significantly correlated with concentrations determined through light microscopy (R = 0.902, P < .001). We also confirmed an overlap in the pollination seasons between Juniperus ashei and Juniperus pinchotii and between J ashei and Juniperus virginiana.

CONCLUSION

We found that this method correctly identified different Juniperus species present in mixed air samples in the southcentral United States, an accomplishment that cannot be achieved using microscopic identification. We conclude that the qPCR method is more accurate and sensitive than current pollen monitoring techniques and, therefore, has the potential to be used in various pollen monitoring stations.

Regional and seasonal variation in airborne grass pollen levels between cities of Australia and New Zealand

Although grass pollen is widely regarded as the major outdoor aeroallergen source in Australia and New Zealand (NZ), no assemblage of airborne pollen data for the region has been previously compiled. Grass pollen count data collected at 14 urban sites in Australia and NZ over periods ranging from 1 to 17 years were acquired, assembled and compared, revealing considerable spatiotemporal variability. Although direct comparison between these data is problematic due to methodological differences between monitoring sites, the following patterns are apparent. Grass pollen seasons tended to have more than one peak from tropics to latitudes of 37°S and single peaks at sites south of this latitude. A longer grass pollen season was therefore found at sites below 37°S, driven by later seasonal end dates for grass growth and flowering. Daily pollen counts increased with latitude; subtropical regions had seasons of both high intensity and long duration. At higher latitude sites, the single springtime grass pollen peak is potentially due to a cooler growing season and a predominance of pollen from C₃ grasses. The multiple peaks at lower latitude sites may be due to a warmer season and the predominance of pollen from C₄ grasses. Prevalence and duration of seasonal allergies may reflect the differing pollen seasons across Australia and NZ. It must be emphasized that these findings are tentative due to limitations in the available data, reinforcing the need to implement standardized pollen-monitoring methods across Australasia. Furthermore, spatiotemporal differences in grass pollen counts indicate that local, current, standardized pollen monitoring would assist with the management of pollen allergen exposure for patients at risk of allergic rhinitis and asthma.

Short-Term Effect of Pollen and Spore Exposure on Allergy Morbidity in the Brussels-Capital Region

Belgium is among the European countries that are the most affected by allergic rhinitis. Pollen grains and fungal spores represent important triggers of symptoms. However, few studies have investigated their real link with disease morbidity over several years. Based on aeroallergen counts and health insurance datasets, the relationship between daily changes in pollen, fungal spore concentrations and daily changes in reimbursable systemic antihistamine sales has been investigated between 2005 and 2011 in the Brussels-Capital Region. A Generalized Linear Model was used and adjusted for air pollution, meteorological conditions, flu, seasonal component and day of the week. We observed an augmentation in drug sales despite no significant increase in allergen levels in the long term. The relative risk of buying allergy medications associated with an interquartile augmentation in pollen distributions increased significantly for Poaceae, Betula, Carpinus, Fraxinus and Quercus. Poaceae affected the widest age group and led to the highest increase of risk which reached 1.13 (95% CI [1.11-1.14]) among the 19- to 39-year-old men. Betula showed the second most consistent relationship across age groups. Clear identification of the provoking agents may improve disease management by customizing prevention programmes. This work also opens several research perspectives related to impact of climate modification or subpopulation sensitivity.

The minimal clinically important difference of the Control of Allergic Rhinitis and Asthma Test (CARAT): cross-cultural validation and relation with pollen counts

BACKGROUND

The Control of Allergic Rhinitis and Asthma Test (CARAT) monitors control of asthma and allergic rhinitis.

AIMS

To determine the CARAT's minimal clinically important difference (MCID) and to evaluate the psychometric properties of the Dutch CARAT.

METHODS

CARAT was applied in three measurements at 1-month intervals. Patients diagnosed with asthma and/or rhinitis were approached. MCID was evaluated using Global Rating of Change (GRC) and standard error of measurement (s.e.m.). Cronbach's alpha was used to evaluate internal consistency. Spearman's correlation coefficients were calculated between CARAT, the Asthma Control Questionnaire (ACQ5) and the Visual Analog Scale (VAS) on airway symptoms to determine construct and longitudinal validity. Test-retest reliability was evaluated with intra-class correlation coefficient (ICC). Changes in pollen counts were compared with delta CARAT and ACQ5 scores.

RESULTS

A total of 92 patients were included. The MCID of the CARAT was 3.50 based on GRC scores; the s.e.m. was 2.83. Cronbach's alpha was 0.82. Correlation coefficients between CARAT and ACQ5 and VAS questions ranged from 0.64 to 0.76 (P < 0.01). Longitudinally, correlation coefficients between delta CARAT scores and delta ACQ5 and VAS scores ranged from 0.41 to 0.67 (P < 0.01). Test-retest reliability showed an ICC of 0.81 (P < 0.01) and 0.80 (P < 0.01). Correlations with pollen counts were higher for CARAT than for ACQ5.

CONCLUSIONS

This is the first investigation of the MCID of the CARAT. The CARAT uses a whole-point scale, which suggests that the MCID is 4 points. The CARAT is a valid and reliable tool that is also applicable in the Dutch population.

Spatiotemporal monitoring of allergic rhinitis symptoms in The Netherlands using citizen science

BACKGROUND

Airborne pollen is a major symptom trigger in allergic rhinitis patients, but the impact of pollen differs among patients and regions and is influenced by environmental factors. To study these complex relationships, there is a need for data on the severity of symptoms in space and time. 'Citizen science' is increasingly recognized as an effective tool to monitor changes in our environment. The aim of this study was to investigate the feasibility of a citizen science-based survey to monitor spatiotemporal variation in allergic rhinitis symptoms.

METHODS

Participants were recruited through the Web site Allergieradar.nl. After registering by completing an extensive questionnaire, they entered (preferably daily) their symptoms of eyes, nose, and lungs on a scale from 1 to 10, as well as their geographic location.

RESULTS

The registration questionnaire revealed that the majority of the participants (77%) had physician-diagnosed hay fever and 65% of the participants had been tested positively for their allergy. This study shows that the symptom scores of the participants are related to (i) pollen concentrations in the air, (ii) the self-reported sensitivity profile, and (iii) the sales of prescription antihistamines in The Netherlands.

CONCLUSION

Our data indicate that the collection of allergic rhinitis symptom data by 'citizen science' is feasible and has an added value in studies on the impact of pollen.

Development and validation of a 5-day-ahead hay fever forecast for patients with grass-pollen-induced allergic rhinitis

One-third of the Dutch population suffers from allergic rhinitis, including hay fever. In this study, a 5-day-ahead hay fever forecast was developed and validated for grass pollen allergic patients in the Netherlands. Using multiple regression analysis, a two-step pollen and hay fever symptom prediction model was developed using actual and forecasted weather parameters, grass pollen data and patient symptom diaries. Therefore, 80 patients with a grass pollen allergy rated the severity of their hay fever symptoms during the grass pollen season in 2007 and 2008. First, a grass pollen forecast model was developed using the following predictors: (1) daily means of grass pollen counts of the previous 10 years; (2) grass pollen counts of the previous 2-week period of the current year; and (3) maximum, minimum and mean temperature (R (2)=0.76). The second modeling step concerned the forecasting of hay fever symptom severity and included the following predictors: (1) forecasted grass pollen counts; (2) day number of the year; (3) moving average of the grass pollen counts of the previous 2 week-periods; and (4) maximum and mean temperatures (R (2)=0.81). Since the daily hay fever forecast is reported in three categories (low-, medium- and high symptom risk), we assessed the agreement between the observed and the 1- to 5-day-ahead predicted risk categories by kappa, which ranged from 65 % to 77 %. These results indicate that a model based on forecasted temperature and grass pollen counts performs well in predicting symptoms of hay fever up to 5 days ahead.

Magnitude of efficacy measurements in grass allergy immunotherapy trials is highly dependent on pollen exposure

Background

The objective was to evaluate the association between grass pollen exposure, allergy symptoms and impact on measured treatment effect after grass sublingual immunotherapy (SLIT)-tablet treatment.

Methods

The association between grass pollen counts and total combined rhinoconjunctivitis symptom and medication score (TCS) was based on a post hoc analysis of data collected over six trials and seven grass pollen seasons across North America and Europe, including 2363 subjects treated with grass SLIT-tablet or placebo. Daily pollen counts were obtained from centralized pollen databases. The effect of treatment on the relationship between the TCS and pollen counts was investigated, and the relative difference between grass SLIT-tablet and placebo as a function of average grass pollen counts was modelled by linear regression.

Results

The magnitude of treatment effect based on TCS was greater with higher pollen exposure (P < 0.001). The relative treatment effect in terms of TCS for each trial was correlated with the average grass pollen exposure during the first period of the season, with predicted reduction in TCS = 12% + 0.35% × pollen count (slope significantly different from 0, P = 0.003; R² = 0.66). Corresponding correlations to the entire grass pollen season and to the peak season were equally good, whereas there was a poor correlation between difference in measured efficacy and pollen exposure during the last part of the season.

Conclusions

In seasonal allergy trials with grass SLIT-tablet, the observed treatment effect is highly dependent on pollen exposure with the magnitude being greater with higher pollen exposure. This is an important relationship to consider when interpreting individual clinical trial results.

Grass pollen allergy in children and adolescents-symptoms, health related quality of life and the value of pollen prognosis

INTRODUCTION

An association between pollen count (Poaceae) and symptoms is well known, but to a lesser degree the importance of priming and lag effects. Also, threshold levels for changes in symptom severity need to be validated. The present study aims to investigate the relationship between pollen counts, symptoms and health related quality of life (HRQL), and to validate thresholds levels, useful in public pollen warnings.

MATERIAL AND METHODS

Children aged 7-18 with grass pollen allergy filled out a symptom diary during the pollen season for nose, eyes and lung symptoms, as well as a HRQL questionnaire every week. Pollen counts were monitored using a volumetric spore trap.

RESULTS

89 (91%) of the included 98 children completed the study. There was a clear association between pollen count, symptom severity and HRQL during the whole pollen season, but no difference in this respect between early and late pollen season. There was a lag effect of 1-3 days after pollen exposure except for lung symptoms. We found only two threshold levels, at 30 and 80 pollen grains/m(3) for the total symptom score, not three as is used today. The nose and eyes reacted to low doses, but for the lung symptoms, symptom strength did hardly change until 50 pollen grains/m(3).

CONCLUSION

Grass pollen has an effect on symptoms and HRQL, lasting up to 5 days after exposure. Symptoms from the lungs appear to have higher threshold levels than the eyes and the nose. Overall symptom severity does not appear to change during the course of season. Threshold levels need to be revised. We suggest a traffic light model for public pollen warnings directed to children, where green signifies "no problem", yellow signifies "can be problems, especially if you are highly sensitive" and red signifies "alert - take action".