Recent 5-year trends of asthma severity and allergen sensitization among children in southern Thailand.

BACKGROUND: Asthma is a major public health issue that affects morbidity. The greater severity of asthma requires more health care resource utilization. OBJECTIVE: To investigate the possible changes in disease severity and allergen sensitization of children with asthma in an interim period of 5 years. METHODS: We retrospectively reviewed the charts of 200 patients with established asthma in the pediatric allergy clinic. The data were collected in different time periods with 100 consecutive cases in each group starting in January of 2004 and in January of 2009. All patients underwent a skin prick test (SPT) to common allergens, with positive and negative controls. SPTs with a mean wheal diameter 3 mm greater than a negative control were considered test-positive. RESULTS: The mean ages of patients in the 2004 and 2009 groups were 7.54 and 7.73 years. Compared with patients in the 2004 group, the 2009 group had more severe asthma (p = 0.006). The distribution of asthma severity was mild (intermittent and mild persistent) 98.0% in 2004 and 87.9% in 2009, and moderate to severe persistent 2.0% in 2004 and 12.1% in 2009. The prevalence of patients sensitized to both house dust (HD) and house dust mites (HDM) increased from 21.2% in 2004 to 34.3% in 2009 (p =0.007). Sensitization to allergens of HD, HDM and cockroach increased to 14.1% in 2009 from 9.1% in 2004 (p =0.021). CONCLUSIONS: During the years between 2004 and 2009, asthma severity increased with increasing sensitization to HD, HDM and cockroach. Awareness of these changes and further studies are required.

Comparison of skin test reactivity to histamine on back and forearm in young children.

RATIONALE: Skin responses to standardized positive and negative controls are important in the interpretation of a skin prick tests (SPT). However, this information in young children is lacking. We aimed to determine skin reactivity and compare the skin responses to these controls on the upper back and forearm in young children. METHODS: SPTs for histamine hydrochloride 1 mg/ml (positive control) and 50% glycerol-saline (negative control) were performed on the upper back and forearm of children aged 6-25 months who came to the well-child clinic at Songklanagarind Hospital. SPTs to common allergens (cow's milk, soybean, egg white and house dust mite) were also evaluated. RESULTS: A total of 133 children with a mean age of 12.4 months were enrolled in the study. Seventy-five children (56.4%) were male. The results from the upper back and the forearm of the histamine-induced mean wheal diameter + standard deviation (SD) were 4.74+1.37 mm and 3.86+1.82mm (p < 0.0001). The mean flare responses to histamine on the upper back and the forearm were 18.47 +/- 4.28 mm and 16.37 +/- 5.50 mm (p < 0.0001). The SPT results from the negative control on the upper back and forearm also had significant differences among the sizes of the wheal (0.57+1.17 vs. 0.34+0.89 mm, p = 0.007) and flare (4.57 +/- 3.04 mm vs. 3.34 +/- 1.91 mm, p < 0.0001). CONCLUSIONS: Our study showed regional differences in wheal and flare responses to standardized positive and negative controls in young children. The upper back is more reactive than the forearm and is the preferred SPT site in young-aged children.