[Late diagnostics and inadequate follow-up of asthma exacerbation]

Late diagnostics and inadequate follow-up of an asthma patient could have been avoided by use of accessible initiatives. Several differential diagnoses to dyspnoea and oppression of the chest exist and in this case a spirometry would have established the asthma diagnosis. Increasing specialization causes necessity to focus on differential diagnosis from nearby specialities. After hospitalization with asthma, the patient should be followed closely until asthma control is achieved and the necessary education is given so that inhalation technique and adherence is optimized.

House dust mites and their allergens at selected locations in the homes of house dust mite-allergic patients

BACKGROUND

Knowledge of the occurrence of house dust mites (HDM) and their allergens in domestic locations is important when planning intervention.

OBJECTIVE

The aim of this study was to describe the distribution of HDMs and their allergens before intervention in multiple locations in the homes of newly diagnosed HDM-allergic patients with a known high Der 1 concentration in their mattress dust.

METHODS

Dust was collected from ten locations in the homes of eight HDM-allergic patients. Dust was analysed for allergen content with ELISAs for Der f 1, Der p 1 and Der m 1; and HDM were counted. Total allergen concentrations ( micro g Der 1/g dust) were expressed as the sum of Der f 1, Der p 1 and Der m 1.

RESULTS

On mattresses the median concentration was 86 micro g Der 1/g dust (range 30-288) and 188 mites/g dust (range 12-1910). Der 1 exceeded 10 micro g/g dust in mattresses (8/8), duvets/pillows (3/8), a bedroom carpet (1/1), a living room carpet (1/6), upholstered furniture (2/8) and a curtain (1/5). Uncarpeted floors, upholstered furniture, bookshelves and walls had significantly lower Der 1 concentration than the mattresses. The relative contribution of Der p 1, Der f 1 or Der m 1 to Der 1 was related to homes, rather than to the location. Der m 1 only occurred in minute amounts.

CONCLUSION

For HDM intervention, our results indicate that priority should be given to the removal of allergens from mattresses, and in addition from carpets, duvets/pillows and upholstered furniture. Dust from walls, uncarpeted floors, bookshelves and curtains appear to contribute insignificantly to the domestic HDM allergen load.

Decay of house-dust mite allergen Der f 1 at indoor climatic conditions

BACKGROUND

The decay of house-dust mite allergens is important for the outcome of avoidance measures for house-dust mite-allergic patients.

OBJECTIVE

To quantify the stability of Der f 1 from mattress dust when exposed to domestic conditions.

METHODS

Three samples of mattress dust were individually homogenized and divided into 64 subsamples. Mites were killed by freezing for 48 hours at -30 degrees C. The subsamples were exposed in eight homes, three storerooms, and one greenhouse, where temperature and relative humidity were recorded. Der f 1 was determined in extracts of subsamples (enzyme-linked immunoadsorbent assay) at 0, 3, 12, and 24 months.

RESULTS

In the three samples of mattress dust, the initial concentrations of Der f 1 (mean +/- standard deviation; STD) were: 169 (12), 3.9 (0.4), and 31 (2.6) microg/g, respectively. Median half-life of Der f 1 in the mattress dust samples was 10 years in the exposure homes, 18 years in the store rooms, and 1.0 year in the greenhouse. No correlations among preserved Der f 1 and temperature, relative humidity, and absolute humidity in homes were found (Spearman rank correlation test).

CONCLUSION

Natural decay of Der f 1, with an estimated half-life of 10 years at housing conditions, has no practical consequence in reducing allergen exposure. Therefore, avoidance measures should include an active removal of the allergens.

House dust mites and their allergens in Danish mattresses -- results from a population based study

The purpose of this study was to identify the level of house dust mites (HDMs) and their allergens in mattresses, not selected on their owners atopic status, and to find associated factors. Dust was collected from 68 mattresses. The recruitment was population-based and conducted during the screening phase of a HDM intervention study. The visited persons declared to have had a "cold" bedroom the previous winter. HDMs were counted and dust was analysed by ELISA for Der 1 (= Der f 1+ Der p 1+ Der m 1). Multiple regression analysis was carried out to find housing conditions associated with high HDM levels. Type of housing, mattress age and self-assessed winter bedroom-temperature explained 47% of Der 1. Median concentrations were 3.77 microg Der 1/g and 1 HDM/0.1 g dust. Both immunochemically and microscopically Dermatophagoides farinae was dominant; D. pteronyssinus less frequent but important; and D. microceras insignificant. In 62% of these suburban homes the mattress dust exceeded 2 microg Der 1/g; and measurement of both Der f 1 and Der p 1 was necessary and sufficient to evaluate HDM allergen exposure. The association with a high HDM level was highest and most consistent for one-family houses.

A controlled intervention study concerning the effect of intended temperature rise on house dust mite load

In epidemiological studies, increased indoor temperature--producing a lower relative humidity--is associated with low house dust mite (HDM) load. Twenty-eight dwellings were allocated for either intervention (12/15 completed) or control (11/13 completed). In the intervention group, participants were asked to increase the bedroom temperature by at least 3 degrees C compared to the self-assessed temperature of the previous winter. Dust samples were repeatedly collected from mattress and floor, and bedroom temperature and relative humidity were recorded hourly throughout one year. Dust was analysed for allergen (Der f 1 + Der p 1 + Der m 1 = Der 1) by ELISA and HDMs were counted. Changes in mite and in mite allergen concentration were the same in the control and intervention groups, and measured temperatures did not differ during intervention period in the groups (18 degrees C and 19 degrees C). Groups turned out not to be comparable with respect to initial (self-assessed) bedroom temperature (lowest in the intervention group). There was a significant seasonal variation, with doubled Der 1 concentrations in dust collected in July-November compared to January-May samples. No effect was obtained on mites or mite allergens, but this may be due either to a general lack of effect of increase in bedroom temperature, or to an insufficient increase in temperature in our intervention group. Seasonal variations in HDM and HDM allergens must be accounted for when data on exposure are interpreted.

[Reliability of recorded deaths from asthma in Denmark during a 1-year period 1994-1995]

INTRODUCTION

The aim of this study was to evaluate the accuracy of death certificates over a one-year period, where asthma was given as the cause of death.

METHODS

All medical information available was collected on 218 patients by reviewing hospital records, records from general practitioners, and sometimes by interviewing close relatives. A panel of four pulmonologists each examined the information and independently assessed the cause of death.

RESULTS

Thirty-nine were excluded, as the cause of death could not be validated. In 16 (9%) of the subjects, asthma was judged to be the definite cause of death and in 12 (7%) a possible cause. Of 151 non-asthma deaths, but registered as asthma, 109 were judged to have suffered or died from COPD and 14 from heart disease.

DISCUSSION

The accuracy of Danish death certification in asthma deaths is poor, especially in the elderly, where COPD is often classified as asthma. We conclude that the true mortality from asthma in Denmark is substantially lower than that officially recorded.

Accuracy of recorded asthma deaths in Denmark in a 12-months period in 1994/95

Many studies of asthma mortality rely on official registration. The aim of this study was to evaluate the accuracy of death certificates, where asthma was coded as cause of death. In a 12-month period, medical information on all subjects with asthma officially coded as the underlying cause of death in Denmark, was obtained by reviewing hospital records, contacting general practitioners and sometimes close relatives. A panel of four pulmonologists each examined the obtained information and independently assessed the cause of death. Of a total of 218 death certificates, 39 were excluded as the cause of death could not be validated. In 16 (9%) of the subjects death from asthma was judged to be the definite cause of death and in 12 (7%) death from asthma was possible. Of 151 non-asthma deaths coded as due to asthma, 109 were judged to have suffered or died from COPD and 14 from heart disease. The accuracy of Danish death certification in asthma deaths is poor, especially in the elderly, where COPD is often classified as asthma. We conclude that the true asthma mortality in Denmark is substantially lower than officially recorded.