Late onset asthma clinical and immunological data: importance of allergy.
In people over 65 years of age (mean age 72) late onset asthma (LOA) is often mistaken for chronic obstructive pulmonary disease (COPD). Furthermore, it is generally believed that true allergic asthma starts very seldom in old age and that, in this case, it is actually intrinsic asthma i.e., without any sensitization to aeroallergens. The aim of this study was to show that LOA is not an uncommon entity and is often allergic. Among a population of 1,888 subjects (over 65 years of age) in a general medicine ward we found 21 patients (1.1%) corresponding to this entity. The diagnosis of asthma was assessed according to clinical data, pulmonary function and nasal provocation tests, and blood eosinophilia. The diagnosis of atopy was assessed on total IgE, prick tests and RAST for the commonest allergens of our area. This group of 21 patients was compared to three groups of age-matched subjects including: 68 patients afflicted with chronic bronchitis, a group of 14 patients who had asthma before the age of 65 (presenile asthma), and 20 normal controls. A group of 15 asthmatics under age 65 was also included (young asthma mean age 37). We found a rather high incidence of allergy (72%), mostly to Dermatophagoides pteronyssinus, but also to the pollens Parietaria judaica, grasses and Olea europea. Although the average age (except in the young asthma group) and the severity of symptoms were the same in the four groups, unexpectedly mean RAST and skin test values were higher in LOA than in the two groups of young asthmatics and presenile asthmatics. It was concluded that LOA is not uncommon among elderly patients over 65, which is in contrast with most previous studies; 72% of our cases were allergic, the main allergens being mite, and Parietaria judaica pollen.