This study shows that out of 774 patients tested, the house dust mite (Dermatophagoides pteronyssinus) provoked the maximum response (51.81%) the house dust was second (42.81%), and shrimp was third (23.92%). The moderate allergenic extracts were cat fur (12.79%), dog fur (10.72%), cockroach (8.47%) egg white (7.56%) and orris powder (6.30%). Among the low allergenic extracts were Aspergillus fumigatus (5.38%), Staphyloccus aureaus (3.53%) and chicken feathers (3.18%). The authors are of the opinion that the skin sensitivity test is an important diagnostic tool in allergic rhinitis and since this is a preliminary study any short listing of allergens to be used is not recommended yet. Skin sensitivity tests is a useful tool for differentiating allergic rhinitis from vasomotor rhinitis. Estimation of allergen specific IgE concentration in the serum will not offer any major advantages over the intradermal skin test in determining the clinical significance of house dust mite allergy. 21 The development of local materials for skin testing may enhance the usefulness of these investigations.
We conducted a population-based study involving a stratified cluster disproportionate random sample of 2868 adults aged 20 to 74 years selected from five housing estates (Yishun, Toa Payoh, Jurong East, Geylang/Eunos and Bukit Merah). Chronic rhinitis was defined as the usual presence of symptoms of blocked or running nose, apart from colds or the flu, lasting for more than a year. Allergic rhinitis was considered to be present if these symptoms were associated with conjunctivitis or recognisable provocation by commonly known allergens, namely house dust, dogs, cats, birds, pollen, or medicines. The estimated general population prevalence of chronic rhinitis was 10.8% (95% confidence interval (CI) 8.8-12.7). Higher prevalences were noted in males, in younger adults, in Indians and Chinese, in those with higher socio-economic status, and in Toa Payoh, Jurong East and Geylang/Eunos. The prevalence of allergic rhinitis was 5.5% (95% CI 4.5-6.5). The most common 'allergenic' factor in allergic rhinitis was house dust (73%); provocation by birds, cats or dogs (5%), grass or tree pollens (5%), and medicine (5%) was less common but likely to have been under-recognised. Provocation by change in temperature (54%) and early in the morning (64%) was equally frequent in both 'allergic' and 'non-allergic' rhinitis; cigarette smoke, petrol and diesel fumes, food and work environment were less common (4-12%). Allergic rhinitis was highly significantly associated with asthma (13.9% in allergic rhinitis, 4.4% in non-allergic rhinitis, and 2.2% in non-rhinitic subjects).