Specific IgE antibodies in the diagnosis of atopic disease. Clinical evaluation of a new in vitro test system, UniCAP, in six European allergy clinics.

A new immunoassay system utilizing new automatic instrumentation, new software for evaluation of data, and reagents updated for increased speed and accuracy was evaluated. Six clinical studies included 894 consecutive patients. Major symptoms were rhinoconjunctivitis, asthma, atopic dermatitis, and urticaria. The prevalence of inhalant allergy was 54-69%. Phadiatop, detecting atopic sensitization to common inhalant allergens, agreed with clinical diagnosis in 764/836 cases (91.4%). The clinical sensitivity and specificity were 93% and 89%, respectively. The clinical sensitivity and specificity of UniCAP specific IgE derived from 5170 comparisons with clinical diagnosis were 89% and 91%, respectively. Specific IgE measurements in UniCAP and in the Pharmacia CAP System agreed in 266/274 cases (97%). A comparison of the sensitivity and specificity of Pharmacia CAP System RAST in 1987 and with UniCAP specific IgE in 1995 showed equivalent performance without change of efficacy or degradation of IgE antibodies after 8 years. The systems were equivalent also in terms of measured values (r=0.96, slope=1.12), confirming the standardization of allergens and of assay calibration. UniCAP is an efficient laboratory system for routine diagnostic testing of allergy and a valuable tool for basic studies on allergens and antibodies.

Predictors of self-assessed work ability among subjects with recent-onset asthma.

The objective of the study was to find predictors for work disability among adults with recent-onset asthma. The study was performed in a group of 332 subjects with recent-onset asthma. The predictors were ascertained by structured interviews, pulmonary function measurements, methacholine challenge tests and skin prick tests. Asthma severity was classified into mild, moderate or severe, based on the minimum medication required to maintain asthma control. Work ability was based on self-assessment by inquiring about the subjects' present work ability, expressed in percent. The self-reported work ability decreased significantly with increasing number of days off work, indicating that self-reported work ability reflects the actual work ability. The majority (56%) of the subjects reported 100% working ability. Among women, but not among men, working ability was negatively correlated (rs = -0.33) with age. Among subjects with PC20 < 16 mg ml-1 work ability increased with increasing PC20. There was no relation between FEV1, FVC and working ability. Asthma severity and current respiratory symptoms at the work place showed a significant negative relation with work ability. In a logistic regression model, when controlling for age, gender, smoking and weekly working hours, decreased work ability was associated with asthma severity, respiratory symptoms at the workplace and PC20 < or = 4 mg ml-1. In conclusion, the work ability was assessed as normal in most asthmatic subjects. Significant predictors for decreased work ability were asthma severity, workplace-associated respiratory symptoms and bronchial hyperresponsiveness. The results indicate that work ability among asthmatics could be improved by reducing the workplace-associated symptoms, either by reducing the exposure to triggers or by improving the asthma therapy.

Do patients with severe asthma run an increased risk from ischaemic heart disease?

BACKGROUND: Knowledge of the mortality outcome of asthma is limited to hospital case series follow-up. METHODS: To provide estimates of the mortality and cause of death in patients with asthma comparison of observed and expected number of deaths in patients with asthma for the observation period 1962-1986 was made. The study group was 262 patients aged 19-81 years with severe asthma. The group was a total sample of patients with a daily treatment of oral steroids more than one year, 1962-1963, from the city of Göteborg. RESULTS: Mortality from all causes was significantly raised among the asthmatics (179 deaths versus 83.5 expected, relative risk (RR) - 2.1, 95% confidence interval (CI) : 1.8-2.5). There was an excess mortality from ischaemic heart disease 58 versus 29.9 deaths (RR = 1.9, 95% CI : 1.4-2.4), especially among women (RR = 2.4, 95% CI : 1.7-2.2). However, there was also an increased mortality from asthma (39 versus 0.4 deaths) and chronic obstructive pulmonary disease (11 versus 0.5 deaths). CONCLUSIONS: These findings suggest that subjects with severe asthma, especially women, have an increased mortality from ischaemic heart disease. The results may reflect confounding, mainly smoking and physical inactivity. Other explanations may be side effects of the antiasthmatic drugs or an effect of longstanding airway obstruction.

Short-term and long-term variation in bronchial response to histamine in asthmatic patients.

Standardized histamine provocations were repeated during remission on 10 atopic bronchial asthmatics, at 14 days (short-term) and after more than 12 months (long-term). During the survey, anti-asthmatic medication was not regularly used. For constructing dose-response curves, four doses of histamine (concentration range 0.015-8 mg/ml) were given at each provocation. Two-fold increasing concentrations of histamine solutions were nebulized and inhaled by tidal volume breathing for 2 min at 5 min intervals. When repeated within 14 days, the coefficient of variation, calculated from maximum fall in FEV1, was 23%. The individual range for similar fall in FEV1 was estimated to 0-1 dose-step. When repeated after more than one year, the corresponding coefficient of variation was 26%, the individual range for similar fall in FEV1 being 0-2 dose-steps. It is concluded that the individual variation in bronchial response to standardized histamine challenge in patients with atopic asthma during remission is small during a period of one to two years.

Standardized allergen provocation test. Variation in bronchial response.

Standardized bronchial allergen provocation with the same individual allergen dose was performed 3-9 times in 20 symptomless adult asthmatic patients at intervals of 1 week or more during 1/2-22 months in order to study variations in bronchial response. The immediate type reaction was recorded by monitoring FEV1, FVC, PEFR and MEF50% for 30-40 min after provocation. FEV1 was highly significantly correlated to the other variables. The coefficient of variation corresponding to maximum decrease in FEV1 was 23%. All provocations were followed by a bronchial reaction within clinically acceptable limits. There was no indication of hypo- or hypersensitization. It is concluded that although many different factors influence the bronchial response, careful standardization of the provocation procedure leads to a moderate variation in bronchial response, making the allergen provocation test suitable for pathophysiological studies and clinical evaluation of anti-asthmatic drugs.