Prevalence of asthma, rhinitis, and eczema in Northern Thai children from Chiang Mai (International Study of Asthma and Allergies in Childhood, ISAAC).

The Phase One International Study of Asthma and Allergies in Childhood (ISAAC) was developed for geographical and temporal comparisons of the prevalence and severity of asthma and allergic diseases in childhood within and between countries. In Thailand, a study was carried out in Bangkok and this is a further study undertaken in Chiang Mai. Using the ISAAC questionnaire, schoolchildren of two age groups were studied: 6-7 years old (n = 3,828) and 13-14 years old (n = 3,927). The data were entered and analyzed using the Epi-info computer program. The prevalence over the past 12 months, in 6-7 and 13-14 years olds, respectively, are as follows; wheezing, 5.5% and 12.6%; rhinitis, 18.5% and 38.3%; rash at flexural areas, 12.9% and 10.7%. The prevalence of these three conditions was found to be close to, but slightly lower than, that from Bangkok, except for eczema in older children.

Comparative study of the pharmacokinetic characteristics of slow release theophylline oral preparations in Thai children with persistent asthma.

Significant differences in the rate and extent of absorption exist between slow release theophylline (SRT) preparations. The pharmacokinetic characteristics of Xanthium were compared with those of Theo-Dur in twelve Thai children with stable persistent asthma by randomized, double blind, crossover study. Serum theophylline concentrations (STCs) were determined by fluorescence polarization immunoassay. The pharmacokinetic parameters were estimated by using a computer program (Topfit 2.0). The STCs, at steady state after different doses, were predicted by using the modified Wagner-Nelson Equation. The mean resident time (MRT) and apparent T1/2 were significantly larger for Xanthium, but the Cmax and AUC0-infinity of Xanthium were significantly lower than those of Theo-Dur. The Frel of Xanthium was 80.1% relative to Theo-Dur. The appropriate dosing interval of both preparations for Thai children was twice a day.

Skin prick reaction and nasal provocation response in diagnosis of nasal allergy to the house dust mite.

BACKGROUND: The allergen skin test is commonly used to ensure the diagnosis of allergic rhinitis even though positive results do not necessarily indicate that rhinitis is of allergic origin. OBJECTIVE: To determine the association between skin prick reactions and nasal provocation responses to Dermatophagoides pteronyssinus (Der p) allergen extract. METHODS: Twenty-six patients with perennial rhinitis and 25 controls underwent skin prick and nasal provocation tests to standardized Der p allergen extract. With the use of allergen extract titration delivered by a metered dose pump, nasal stuffiness, itching, and sneezing were noted, the amount of secretions measured, and nasal airway resistance was recorded by active anterior rhinomanometry. RESULTS: The majority of the patients with rhinitis (20/26), but none of the controls, exhibited strong skin test positivity (4+) to Der p allergen extract. In addition, the majority of the patients with 4+ skin reactions (16/20) had moderate to severe rhinitis. Significantly increased nasal reactivity to the allergen was also observed among those with 4+ skin test positivity. The controls exhibited nasal provocation responses only with significantly higher end-point doses of the allergen extract regardless of the skin test results. CONCLUSION: Only 4+ skin test positivity was closely associated with increased nasal reactivity to Der p allergen among the patients with perennial rhinitis. The nasal provocation technique would be a useful adjunct testing to ensure the diagnosis of nasal allergy to the Der p mite, particularly among those patients with rhinitis with only mild to moderate skin test positivity.

Evaluation of threshold criteria for the nasal histamine challenge test in perennial allergic rhinitis.

Nasal reactivity to histamine was determined in patients with perennial allergic rhinitis and in control subjects. A histamine titration method delivered by a metered dose pump was used. Stuffiness, itching, and the number of sneezes were recorded, nasal secretions measured, and nasal airway resistance was recorded by active anterior rhinomanometry. Increased nasal reactivity to histamine was observed among rhinitic patients and inversely correlated with the severity of nasal symptoms. A 3-fold increase of post-saline nasal airway resistance (NAR) best differentiated the nasal responses to histamine in rhinitic patients from those in control subjects. A histamine dose of < or = 2.5 microg provoked a 3-fold increase in NAR, strongly suggesting moderate or severe symptomatic rhinitis in most cases. Nasal provocation techniques might be a useful tool for objectively assessing disease severity and response to treatment in perennial allergic rhinitis.