Longitudinal changes in skin-prick test reactivity over 2 years in a population of schoolchildren with respiratory symptoms

New Allergen Sensitization Might be Associated with Increased Body Mass Index in Children

Background

Results of previous studies have shown a relationship between obesity and allergic diseases. However, concrete evidence about the association between obesity and allergies has been lacking.

Objective

The present study aimed to evaluate the potential association between body mass index (BMI) and the change in sensitization on skin-prick tests in children over a 2-year follow-up period.

Methods

Children in first and second grade from six elementary schools were recruited in 2010. The same participants, now in third and fourth grade, were recruited again in 2012. The enrolled children underwent skin-prick tests and physical examinations in 2010 and again in 2012.

Results

Four hundred fourteen children (boys to girls, 208 to 206) were included. Among 414 participants, 73 children showed new sensitization and 24 children showed negative conversion of allergic sensitization after 2 years. One hundred sixty-one children showed positive results on both tests, and 156 children showed negative results on both tests. The mean (standard deviation) change in BMI (1.09 ± 1.81 kg/m2) over a 2-year follow-up in newly sensitized children was significantly greater than that of other groups (p = 0.008).

Conclusion

Children who became newly sensitized to allergens tended to exhibit significant increases in BMI. Therefore, further evaluation of the relationship between obesity and allergy is needed.

Allergen skin prick testing in early childhood: reproducibility and prediction of allergic symptoms into early adulthood

OBJECTIVE

To assess the predictive value of skin prick testing in early childhood on subsequent allergic symptoms up to adult age.

STUDY DESIGN

A cohort of 200 unselected healthy newborns was prospectively followed from birth to 20 years of age. Of them, 163 (82%) were reassessed at age 5 years, 150 (76%) at age 11 years, and 164 (83%) at age 20 years with a skin prick test that included 11 common allergens. On the basis of clinical examination and structured interview, the occurrence of atopic dermatitis, allergic rhinoconjunctivitis, recurrent wheezing, and symptoms of food hypersensitivity were recorded at each of the follow-up visits.

RESULTS

The reproducibility of skin prick test positivity at age 5 years was 100% at ages 11 and 20 years, ie, none of the skin prick-positive subjects turned negative during the follow-up. Gaining of new sensitizations to aeroallergens was common. Skin prick test positivity at age 5 years predicted allergic symptoms at ages 11 (sensitivity 28%, specificity 94%) and 20 years (sensitivity 23%, specificity 91%) but not atopic dermatitis.

CONCLUSIONS

Skin prick test positivity at age 5 years strongly predicts later skin prick test positivity and is associated with respiratory symptoms, ie, allergic rhinoconjunctivitis and recurrent wheezing, at ages 11 and 20 years. However, skin prick test negativity at age 5 years does not exclude sensitization and allergic symptoms at a later age.

Is there a need for repetition of skin test in childhood allergic diseases? Repetition of skin test and allergic diseases

BACKGROUND

Skin prick tests are widely used to determine sensitivity in allergic diseases. There is limited information about the natural history of skin sensitization tests and factors that affect them. It was aimed to determine the changes in skin test results and the factors affecting the reactivity of skin tests after a period of approximately four years in children with allergic disease.

METHODS

SPT of 170 patients among 2485 children with asthma and/or allergic rhinitis and/or atopic dermatitis, who underwent SPT between 2005 and 2007, were repeated after an interval of at least 3 years.

RESULTS

The mean age was 10.7 ± 3.1 (5-18) years and 70% of the patients were male. In total 66 (39.0% of the study population) had a different skin tests result in follow-up. Alterations: loss of sensitivity in 18 (11%) patients, the formation of a new sensitivity in 37 (22%) patients, and 11 (6%) both gained and lost sensitization. The presence of atopy in the family, the presence of allergic rhinitis and IgE elevation significantly predicted the incidence of new sensitization. The presence of sensitization to multiple allergens significantly predicted the incidence of loss of sensitization.

CONCLUSIONS

It is found that there was an alteration of sensitization in 4/10 children at the end of the average 4-year period. The presence of family atopy, the presence of allergic rhinitis and serum total IgE elevation were risk factors for the development of new sensitization. On the other hand sensitization to multiple allergens was risk factors for the loss of sensitization.

Can sensitization to aeroallergens disappear over time in children with allergic disease?

BACKGROUND

Remittance of aeroallergen sensitization has been shown in population-based studies, but there is a common perception that sensitization to aeroallergens rarely if ever disappears in children with allergic disease.

METHODS

We retrospectively reviewed all specific IgE tests carried out in children aged 0-18 years at our hospital laboratory over a 14-year period. Of 3115 children sensitized to one or more aeroallergens, 244 (7.8%) were retested after a mean (SD) period of 45 (28) months at their physician's discretion.

RESULTS

Disappearance of sensitization to individual aeroallergens did occur, with remittance rates ranging from 3.1% for house dust mite to 17.5% for cat. However, complete remittance of aeroallergen sensitization was found in only one subject. In up to 35% of cases, remittance of sensitization was offset by the appearance of one or more new aeroallergen sensitizations. Remittance was only observed in children sensitized to multiple allergens (with a median of 3 aeroallergen sensitizations), and their median degree of sensitization was low (median 2.1 kU/L).

CONCLUSION

Aeroallergen sensitization can disappear in children with allergic disease, but only in polysensitized individuals. Complete remittance of sensitization to aeroallergens is rare in symptomatic children.

Patterns of sensitization to food and aeroallergens in the first 3 years of life

BACKGROUND

There is a paucity of longitudinal studies of allergen sensitization in childhood.

OBJECTIVE

To investigate the pattern of sensitization in early childhood.

METHODS

A nested cohort of children (n = 543) were followed up from birth and given a skin prick test (SPT) at 1, 2, and 3 years of age. A detailed clinical history was obtained.

RESULTS

The prevalences of sensitization to aeroallergens were 1.3%, 6.4%, and 10.7% at 1, 2, and 3 years of age. The figures for food allergens were 2.8%, 3.9%, and 3.7%. There was a statistically significant increase in the prevalence of sensitization to >or=1 allergen between years 1 and 2 (P < .001) and years 2 and 3 (P = .032). Among those with a positive SPT at 1 year, 29% tested positive to additional allergens at 2 years (P = .0054). Sensitization to milk or egg at 1 year was a predictor for increased sensitization to peanut at 3 years (odds ratio, 34.8; P < .0001). Sensitization to egg at 1 year was associated with increased sensitization to aeroallergens at 3 years (odds ratios, house dust mite, 27.1, P < .001; cat, 8.9, P < .01; grass, 11.8, P = .005). For peanut and cat allergens, wheal size increases with the age of the child (P = .009 and P = .017, respectively).

CONCLUSION

Sensitization to allergens as demonstrated by positive SPT tends to increase with age, and this change can be detected in the first 3 years of life.

CLINICAL IMPLICATIONS

The high predictive value for early sensitization and a linear increase in SPT reactivity provide an opportunity for early intervention.

The natural course of atopy determined by skin prick tests in patients with bronchial asthma and/or rhinitis

BACKGROUND

The skin prick test (SPT) is the cheapest, most widely used and practical method for the diagnosis of allergic diseases. The results of repeat test might show variations due to aging.

OBJECTIVE

To perform repeat SPTs to determine possible changes in the atopy rate in general as well as changes in the allergen spectrum of atopic patients occurring over time and to identify the factors that could affect this change.

METHODS

A total of 222 patients who received a diagnosis of bronchial asthma and/or persistent rhinitis in our Adult Allergy Unit and who attended follow-up visits in the outpatient unit over a 2-year period were enrolled. SPT with 10 visit common aeroallergens were performed at the first and the second test was performed after an interval of at least 2 years.

RESULTS

The mean age was 36.4 +/- 11.4 years and 77.5 % of the patients were women. The mean interval between the two tests was 43.4 +/- 20.0 (minimum = 24-maximum = 105) months. Repeat tests showed that the atopy rate decreased from 58.6 % to 47.7 %; sensitivity rates to 10 allergens also decreased. These differences were statistically significant (p <0.05).

CONCLUSION

The atopy rate determined by SPTs tends to decrease over time. The most important factor affecting this decrease is time itself.

Do asthma patients in general practice profit from a structured allergy evaluation and skin testing? A pilot study

BACKGROUND

Although allergy is central to the pathophysiology of asthma, little is known about the benefits of a structured approach to allergen diagnosis and management in primary care asthma patients.

OBJECTIVES

We studied effects of a structured allergen evaluation and allergen avoidance advice combined with or without additional allergy skin testing on health status, illness perception, and lung function of asthma patients treated in general practice.

METHOD

Fifty-four asthma patients were randomly assigned to three groups: (i) Standard asthma care with information on the stepwise treatment approach, a written action plan, and inhaler technique training; (ii) Additional structured allergen evaluation and avoidance advice; (iii) Additional structured allergen evaluation and avoidance advice based on skin prick test results. Patients were seen for one initial appointment at a primary care asthma clinic and a follow-up examination 3 months later. On both occasions, questionnaire measures of symptoms, illness perception, and the perceived control of asthma were administered. Lung function was measured by spirometry (PEF, FEV1). Perceived allergic asthma triggers, the trigger impact, and the trigger control were assessed in both intervention groups.

RESULTS

Following intervention, a decrease in beta-adrenergic inhaler use, an increase in the perceived control of asthma, and a decrease in the bothering from asthma symptoms were observed for all three groups. Intervention groups showed a higher awareness of animal-allergic triggers, and the perceived control of asthma triggers was increased in the group receiving no skin tests. FEV1 showed an improvement in both intervention groups.

CONCLUSION

Structured allergy evaluation and avoidance advice can improve lung function and the control of asthma in primary care. Further research is needed on the additional benefits of allergy skin testing.

Long-term repeatability of the skin prick test is high when supported by history or allergen-sensitivity tests: a prospective clinical study

BACKGROUND

Long-term reproducibility of the skin-prick test (SPT) has been questioned. The aim of the study was to investigate the clinical relevance of SPT changes.

METHODS

SPT to 10 common inhalation allergens was performed annually from 1999 to 2001 in 25 nonsensitized and 21 sensitized subjects. An SPT was positive when > or =3 mm, and repeatable if either persistently positive or negative. Clinical sensitivity to birch pollen was used as model for inhalation allergy, and was investigated at inclusion and at study termination by challenge tests, intradermal test, titrated SPT and IgE measurements. Birch pollen symptoms were confirmed in diaries.

RESULTS

The repeatability of a positive SPT was 67%, increasing significantly to 100% when supported by the history. When not supported by history, the presence of specific IgE was significantly associated with a repeatable SPT. Allergen sensitivity was significantly lower in subjects loosing SPT positivity. The repeatability of a negative test was 95%, decreasing significantly to 87% by the presence of other sensitization. Development of a positive SPT was clinically relevant. Elevation of SPT cut-off point did not enhance repeatability.

CONCLUSION

SPT changes are clinically relevant. Further studies using other allergens are needed. Long-term repeatability of SPT is high in the presence of a supportive history.

Time course of onset of sensitization to common and occupational inhalants in apprentices

BACKGROUND

Incident sensitization to common allergens in the setting of sensitization to an occupational allergen has not been described.

OBJECTIVE

Our aim was to determine the risk and timing of development of sensitization to common allergens in subjects with incident sensitization to a work-related allergen.

METHODS

Data from a cohort of 769 apprentices in animal-health technology, pastry making, and dental hygiene were used. Skin prick tests to work-related allergens (laboratory animal, flour, and latex) and common allergens (mites, molds, pets, and pollen) were administered at baseline and at up to 3 subsequent annual visits. Risk ratios (RRs) and 95% CIs were calculated.

RESULTS

Eighty-three subjects had sensitization to a work-related allergen. Four (4.8%) subjects became sensitized to common and then occupational allergens. Nine (10.8%) subjects had sensitization to a common allergen after sensitization to a work-related allergen. In 20 (24.1%) subjects new sensitizations to specific and common allergens were detected simultaneously. Fifty subjects remained free from new sensitization to occupational allergen during development of sensitization to common allergens. An increased risk of development of sensitization to molds (RR = 3.49) and pets (RR = 2.51) was found in subjects with incident sensitization to occupational allergens relative to the risk in subjects without sensitization.

CONCLUSION

New sensitization to common aeroallergens is frequent in subjects not previously exposed to work-related allergens; it often occurs around the same time as sensitization to work-related agents. Subjects with new occupational sensitization are at a greater risk of development of sensitization to common aeroallergens than subjects without sensitization.

Citrus red mite (Panonychus citri) may be an important allergen in the development of asthma among exposed children

BACKGROUND

Recent investigations have demonstrated that spider mites are important allergens in the development of asthma in fruit-cultivating farmers.

OBJECTIVE

The aim of this study was to evaluate the sensitization rate to the citrus red mite (Panonychus citri) in children living in rural areas, and to determine the allergenic cross-reactivity with other mites.

METHODS

A total of 7254 children (ages 7-15 years) living in rural areas were enrolled, and each subject was evaluated by a questionnaire and a skin prick test. Allergenic cross-reactivity was evaluated by ELISA inhibition tests.

RESULTS

The most common sensitizing allergens were house dust mites, followed by citrus red mite and cockroach. High serum-specific IgE bindings to the citrus red mite were detected in 21 of 100 randomly selected subjects. The prevalence of asthma was higher among those with positive skin responses to the citrus red mite than with negative skin responses to this mite. ELISA inhibition tests showed that IgE bindings to this mite were minimally inhibited with additions of domestic mites.

CONCLUSION

Spider mites such as the citrus red mite may be important outdoor allergens among children living in rural areas, and spider mite-derived allergens have unique allergenic determinants compared with domestic mites.

Outdoor air pollutants derived from industrial processes may be causally related to the development of asthma in children

BACKGROUND

There is no consistent evidence that outdoor air pollutants are involved in the development of asthma.

OBJECTIVE

The aim of this study was to determine whether outdoor air pollutants derived from industrial processes were related to the prevalence of asthma, bronchial hyperresponsiveness, and atopy in exposed children.

METHODS

A total of 7,511 children from 7 to 12 years of age were recruited in the study. Eight hundred eighty-eight of 1,009 (88%) of the subjects living around industrial factories and 5,998 of 6,502 (92%) living in a less polluted neighboring area responded to the ISAAC questionnaire. A total of 1,492 subjects 8 to 9 years old underwent skin prick tests for 11 common aeroallergens. A total of 732 of the subjects from 8 to 9 years of age underwent bronchial provocation tests with hypertonic saline (BPT-HS).

RESULTS

The prevalence of ever experiencing wheezing and wheeze during the last 12 months was 25.6%, and 18.8% among the children living in the more polluted area. This was significantly higher than for those living in the less polluted area (14.2% and 9.0%, respectively). The positive rate of BPT-HS (the provocative dose of hypertonic saline causing 20% fall of FEV, < or = 23 mL) was higher among those in the more polluted area than in children living in the less polluted area (12.2% vs 7.5%). However, the rate of atopy based on the skin tests was the same in the two groups (28.3% vs 30.6%).

CONCLUSIONS

The prevalence of asthma and bronchial hyperresponsiveness was higher among children living around the heavily industrial area compared with those living in the less polluted area, despite similar atopic sensitization.

Changes in IgE-mediated allergy to ubiquitous inhalants after removal from or diminution of exposure to the agent causing occupational asthma

BACKGROUND

One possibility, among others, for explaining the persistence of asthma symptoms in occupational asthma (OA) after the cessation of exposure to the causal agents may be that subjects become sensitized to ubiquitous inhalants.

OBJECTIVE

The aim of this study was to evaluate the development or increase of IgE-mediated sensitization to ubiquitous allergens, both to high- and low-molecular-weight agents, in 100 subjects with OA after cessation of exposure.

METHODS

Subjects were evaluated on a first visit, at the time of diagnosis of OA, coinciding with the cessation or diminution of exposure to the causal agent, and on a second visit, 5.8+/-3.3 years afterwards. At each visit, a history of ocular, nasal and asthmatic symptoms related to exposure to common allergens was obtained together with spirometry and assessment of bronchial responsiveness to methacholine. We analysed total IgE and specific IgE to Dermatophagoides farinae, D. pteronyssinus, birch, ragweed and timothy grass pollens, cat and dog danders, and Alternaria, using enzyme allergosorbent test (EAST) from blood samples taken on each visit.

RESULTS

Total IgE levels showed a tendency to diminish. No changes were found in the number of positive EAST (presence of detectable levels of specific IgE) or in the levels of specific IgE. Although significantly more symptoms of rhinoconjunctivitis and asthma in contact with house dust (P < 0.05) and pets (P < 0.01) were reported on the second visit than on the first, no significant changes in the frequency of symptomatic sensitized subjects were found.

CONCLUSION

Subjects with OA are unlikely to develop IgE-dependent sensitization to common inhalants after removal from exposure to occupational agents.

Asthma, allergy, and atopy in three south-east Asian populations

BACKGROUND

Whilst many recent reports have suggested a rise in the prevalence of asthma and allergic disease in Western countries, little is known about the epidemiology of these common conditions in south-east Asia. This study compared the prevalence of asthma and allergic disease amongst secondary school students in three south-east Asian populations--Hong Kong, Kota Kinabalu in Malaysia, and San Bu in China--and investigated the associations with atopy and family history.

METHODS

Secondary school students were given standard questionnaires on respiratory and allergic symptoms for completion by parents with response rates of 89.2% in Hong Kong (611 male, 451 female; mean (SD) age = 13.9 (1.8 years), 87.6% in Kota Kinabalu (134 male, 275 female; 15.5 (2.1) years), and 98.6% in San Bu (492 male, 245 female; 16.4 (1.8) years). Skin tests were performed in a subsample of students to determine atopic status.

RESULTS

The respective prevalence (and 95% CI) for hayfever, eczema, and wheeze or asthma were 15.7% (13.5, 17.9), 20.1% (17.7, 22.5), 11.6% (9.3, 13.9) in Hong Kong, 11.2% (8.2, 14.3), 7.6% (5.0, 10.1), 8.2% (5.5, 10.9) in Kota Kinabalu, and 2.1% (1.2, 3.1), 7.2% (5.4, 9.1), 1.9% (0.7, 3.1) in San Bu. Atopy was common and was present in 49.0-63.9% of subjects in the three populations. Dust mite and cockroach were the commonest allergens that gave positive reactions in 42.8-60.5% and 25.7-35.9% of students respectively. A higher proportion of students in Hong Kong had severe degree of reactivity on skin test than the other two populations. Family history was associated with asthma and allergic symptoms in the three populations conferring a 3-80-fold increase in risk to family members and was a stronger predictor for asthma and allergy than atopy.

CONCLUSIONS

Prevalence of asthma and allergic disease is low compared with Western countries, but considerable differences exist between the three south-east Asian populations despite similar rates of atopy. Asthma and allergic disease are more strongly associated with family history than atopy, which suggests that genetic and environmental factors common to the family, other than aeroallergen sensitisation, are important in the pathogenesis of asthma and allergy in the region.

Asthma, allergy and atopy in southern Chinese school students

In order to determine the prevalence of asthma, allergy and atopy in southern China and the relative importance of atopy and parental history in predicting asthma and allergic diseases, we carried out a cross-sectional study on 737 secondary school students aged 12-20 (492 boys, 245 girls; mean age = 16.4 years, SD = 1.8 years) in the city of San Bu, Guangdong, China. Standard questionnaires on respiratory and allergic symptoms were distributed for completion by parents with an overall response of 98.6%. Skinprick tests to common aeroallergens were performed on 647 subjects (87.8%) to determine atopic status. The prevalence (and 95% CI) of a history of hay fever, eczema, wheeze or asthma ever and wheeze in past 12 months were 1.6% (0.7-2.5), 10.4% (8.2-12.6), 1.9% (0.9-1.9) and 1.1% (0.3-1.9) respectively. Forty-nine per cent (45.2-52.9) of students had one or more positive skin tests to common aeroallergens. Amongst atopic subjects, 87.3% reacted to house dust mite (Dermatophagoides pteronyssinus) and 73.3% to cockroach. There was a close association between the degree of atopy and the prevalence of a history of wheeze (P < 0.05) but not with hay fever or eczema. After adjusting for age and sex, parental histories of hay fever, eczema and wheeze were strongly associated with the respective symptoms in the subjects (OR = 17.4 (3.2-93.9) for hay fever, 27.4 (12.7-59.0) for eczema, 79.4 (21.9-288.4) for wheeze). It is concluded that respiratory and allergic symptoms were uncommon in Chinese school students despite a high prevalence of atopy, and that parental history is more important in predicting asthma and allergy than atopy.