Accuracy of childhood asthma control test among Thai childhood asthma patients

BACKGROUND

The Childhood Asthma Control Test (C-ACT) was developed to assess asthma control in children worldwide. A self-administered questionnaire for children translated into Thai language was used.

OBJECTIVE

To validate the C-ACT cut-points for evaluating the level of asthma control among Thai children, using the Global Initiative for Asthma (GINA) guideline as a gold standard.

METHODS

C-ACT score, FEV1 and assessment of level of asthma control were recorded at baseline, 3-month, 6-month, and 1-year visits among children with asthma. Receiver operating characteristic (ROC) curves was used to determine the area under the curve (AUC) of C-ACT score for determining the level of asthma control. Validity indicators were calculated at different C-ACT cut-points to determine those most appropriate for predicting controlled and uncontrolled asthma.

RESULTS

We enrolled 279 children, 64% males, with mean age 6.87±2.4 years. C-ACT score was significantly correlated with FEV1 at 3-month, 6-month, and 1-year visits (p<0.001). The AUC of C-ACT score compared with GINA score were above 80% at all visits. The suggested C-ACT score cut-point of controlled asthma was ≥ 23 (sensitivity 69.5%, specificity 73.3%, positive predictive value (PPV) 81.2%, negative predictive value (NPV) 63.8%); that of uncontrolled asthma was ≤ 18 (sensitivity 54.2%, specificity 96.9%, PPV 61.9%, NPV 95.7%).

CONCLUSIONS

The Thai version of the C-ACT is an accurate, simple, and useful tool for assessing asthma control among Thai children. The high AUC suggests that the Thai C-ACT is as good as the GINA guideline in predicting asthma control level.

Solenopsis geminata (tropical fire ant) anaphylaxis among Thai patients: its allergens and specific IgE-reactivity

BACKGROUND

Specific IgE against Solenopsis invicta (imported fire ant) remains the current diagnostic tool for allergy to ants worldwide. However, S. invicta may not be the only cause of ant anaphylaxis in Thai patients.

OBJECTIVE

To characterize ant species causing anaphylaxis in Thai patients and to test allergenic reactivity to whole body extracts (WBE) of S. geminata (tropical fire ants) in patients with evidence of IgE-mediated ant anaphylaxis.

METHODS

Thirty-two patients with ant anaphylaxis were identified. The causative ants collected by the patients were subjected to species identification. Twelve patients with ant anaphylaxis and showed positive skin test or serum specific IgE to S. invicta and 14 control subjects were recruited. Whole body extraction from S. geminata was performed for protein characterization using SDS-PAGE and protein staining. IgE-immunoblotting and ELISA-specific IgE binding assays were performed on patients' sera and compared with controls.

RESULTS

Of 32 patients with ant anaphylaxis, the most common causative ant identified was S. geminata (37.5%). Western blot analysis of crude S. geminata revealed 13 refined protein components that bound to patients' serum IgE. Three major allergens with molecular masses of 26, 55 and 75 kDa were identified. All 12 patients gave positive results for specific IgE to S. geminata with statistically significant higher absorbance units of 0.390 ± 0.044, compared to healthy control group (0.121 ± 0.010), P < 0.01.

CONCLUSIONS

S. geminata is identified as the most common causative ant anaphylaxis in Thai patients. Its WBE comprises of 13 IgE-binding components and 3 major allergens (26, 55 and 75 kDa), which supported possible IgE-mediated mechanism.

Ant allergens and hypersensitivity reactions in response to ant stings

Hypersensitivity reactions caused by ant stings are increasingly recognized as an important cause of death by anaphylaxis. Only some species of ants ( e.g. Solenopsis spp., Myrmecia spp., and Pachycondyla spp.) cause allergic reactions. Ant species are identified by evaluating the morphologic structures of worker ants or by molecular techniques. Ant venom contains substances, including acids and alkaloids, that cause toxic reactions, and those from Solenopsis invicta or the imported fire ant have been widely studied. Piperidine alkaloids and low protein contents can cause local reactions (sterile pustules) and systemic reactions (anaphylaxis). Imported fire ant venoms are cross-reactive; for example, the Sol i 1 allergen from S. invicta has cross-reactivity with yellow jacket phospholipase. The Sol i 3 allergen is a member of the antigen 5 family that has amino acid sequence identity with vespid antigen 5. The clinical presentations of ant hypersensitivity are categorized into immediate and delayed reactions: immediate reactions, such as small local reactions, large local reactions, and systemic reactions, occur within 1-4 hours after the ant stings, whereas delayed reactions, such as serum sickness and vasculitis, usually occur more than 4 hours after the stings. Tools for the diagnosis of ant hypersensitivity are skin testing, serum specific IgE, and sting challenge tests. Management of ant hypersensitivity can be divided into immediate (epinephrine, corticosteroids), symptomatic (antihistamines, bronchodilators), supportive (fluid resuscitation, oxygen therapy), and preventive (re-sting avoidance and immunotherapy) treatments.

ADVERSE EVENTS POST-DTAP AND DTwP VACCINATION IN THAI CHILDREN

We conducted a prospective study to compare the development of fever (axillary T ≥ 37.9 °C) within 4 hours of vaccination, determine the proportion of children who develop high fever (T ≥ 39°C) and evaluate parental days missed from work due to their children's vaccination with either the diphtheria-tetanus-whole cell pertussis (DTwP) or diphtheria-tetanus-acellular pertussis (DTaP) vaccine. The results of this study can help physicians and parents decide whether to have their child vaccinated with the DTwP or more expensive DTaP vaccine. We studied 140 healthy Thai children aged 2 months to 6 years from December 2011 to March 2012 who presented for vaccination. Parents recorded their child's temperature, local and systemic adverse reactions and missed days from work due to these adverse events on a diary card. Of the 140 participants, 72 received the DTwP vaccine and 68 received the DTaP vaccine. The median (IQR) age was 4 (2-6) months and the median weight was 7.1 (5.6-8.7) kg. Twenty children developed fever (axillary T ≥ 37.9°C) within 4 hours following vaccination, 17 (23.6%) had received the DTwP vaccine and 3 (4.4%) had received the DTaP vaccine (p = 0.040). One child (1.4%) who had received the DTwP vaccine and none who received the DTaP vaccine developed high fever (T ≥ 39°C) within 4 hours of vaccination (p = 0.329). Parents of two children who received the DTwP vaccine and one child who received the DTaP vaccine missed work following vaccination (p = 0.059). In conclusion, children who received the DTwP vaccines were more likely to have early post-vaccination fever and higher fever but there was no significant difference between the two groups in parental days lost from work.

Immunoglobulin values in healthy Thai children aged ≤ 24 months determined by nephelometry

BACKGROUND

Variation of normal immunoglobulin (Ig) levels between different genetic and environment factors has been studied. Although antibody deficiency diseases can start from infancy, data of Ig reference levels in children aged ≤24 months are still limited, especially in Asian children.

PURPOSE

The aim of this study was to determine serum IgG, IgA, IgM, and IgG subclasses in healthy Thai children from the newborn period to age 24 months.

METHODS

Serum samples were collected from healthy Thai children age <1-24 months to measured serum IgG, IgA, IgM, and IgG subclasses by nephelometry.

RESULTS

Of the 100 infants, 44% were female with a median (range) age of 13 (0.3-24) months. The geometric mean IgG was 803 mg/dL, IgA 36 mg/dL, and IgM 102 mg/dL. The mean IgG1 was 646 mg/dL, IgG2 127 mg/dL, IgG3 45 mg/dL, and IgG4 17 mg/dL. The average ratios of IgG subclass 1:2:3:4 were 77:15:6:2%. No significant differences in each immunoglobulin isotype between genders were found. Our mean IgG level was slightly lower than that in healthy Thai children, measured by radial diffusion method but not significant except 1-3 months (p = 0.016). However, the mean IgG level in our study was higher than that reported by radial diffusion in healthy US children (p <0.001).

CONCLUSIONS

This study illustrated the importance of having normal Ig values from age- and ethnically-matched controls by high precision nephelometric assay in order to appropriately diagnose immunologic disorders in Asian infants.

Allergic diseases and helminth infections

The relationships between allergic diseases and helminth infections are inconsistent. Some studies have suggested that helminth infections induce or increase the severity of atopic diseases. Other studies report that children infected with some helminths have lower prevalence and milder atopic symptoms. Expanding our knowledge on the mechanism of immunological modification as a result of helminth infection, and understanding the interaction between helminth infections and allergic diseases will be useful for developing potentially new treatments using some helminths, and for evaluating the risks and benefits of eradicating helminth infections in endemic areas. This article reviews current knowledge on the mechanisms of allergic disease, the immunological modifications that result from helminth infections, and clinical evidence of the effects of these infections on allergic diseases.

Differences in clinical features between children and adults with dengue hemorrhagic fever/dengue shock syndrome

This retrospective study was conducted to assess the differences in clinical features between children and adults with dengue hemorrhagic fever/ dengue shock syndrome (DHF/DSS) admitted to Ratchaburi Hospital, Ratchaburi Province, Thailand. A total of 273 patients with DHF/DSS admitted to Ratchaburi Hospital during January 2007 to May 2008 were included in the study. The median age (range) of studied subjects was 16 years (6 months to 62 years) and the ratio of adults to children was 1.6:1. Forty-eight percent of subjects were 16-30 years old. The common signs, symptoms and clinical features were: nausea/vomiting (74.0%), a positive tourniquet test (73.0%), anorexia (67.0%), hemoconcentration (58.0%), headache (54.0%), abdominal tenderness (43.0%), myalgia (39.0%) and pleural effusion (20.0%). Children had anorexia, a positive tourniquet test, abdominal tenderness and a convalescent rash more frequently than adults. Children also had significantly more prominent plasma leakage as shown by lower serum albumin and sodium and a higher prevalence of pleural effusion, ascites and shock. Although not statistically significant, the prevalence of bleeding in children was higher than in adults but more adults needed blood transfusion. This study provides additional insight into the clinical picture of DHF/DSS in adults and children and may be beneficial for clinicians caring for these adults and children.

Nephelometry determined serum immunoglobulin isotypes in healthy Thai children aged 2-15 years

Knowledge of what constitute normal serum immunoglobulin (Ig) concentrations are important for the diagnosis of immunologic disorders. Data on normal Ig evaluated by nephelometry are limited in healthy Asian children, none being available for Thai children. One hundred and forty-eight healthy Thai children aged 2-15 years were tested for serum immunoglobulins G, A, M, G1, G2, G3, and G4 (Ig G, A, M, G1, G2, G3, and G4) by nephelometry. Sixty-three percent were girls of median interquartile range age 6.9 (4.8-9.7) years. The geometric means for each Ig were summarized and categorized by age. Statistical analyses were used to compare Igs between sexes and age groups, and to compare IgG in this study with data from other published studies. The average ratios of IgG subclasses/IgG for Ig G1:2:3:4 were 66:22:5:7%. IgG, IgA, IgG2, and IgG3 concentrations showed a gradual increase with increasing age. There were no significant sex differences for any immunoglobulin isotype (P= 0.971). Our mean IgG concentration was lower than that measured by the radial diffusion method in healthy Thai children (P < 0.05). In all age groups, the mean IgG concentration in our study was significantly higher than that reported in Turkish and USA children, evaluated by the nephelometric and radial diffusion techniques, respectively (both P < 0.001). This study provides information about normal Ig concentrations measured by nephelometry in healthy Asian children and illustrates the importance of ascertaining normal Ig values for age- and ethnic-matched controls using the same assay to diagnose immunologic disorders correctly.