Wirksamkeit von hausstaubmilben- und allergendichten Encasings bei Patienten mit Hausstaubmilbenallergie

Abstract

The clinical impact of allergen tight mattress encasings has still been debated. Beside encasings, recommended measures include the use of HEPA filter in the vacuum cleaner, reducing the humidity by increased ventilation rate and weekly change of bed linen. Materials and methods: A double-blind, placebo-controlled crossover study was performed to evaluate the clinical efficacy of mattress covers (VarioProtect encasings, Sanders, Germany). We included 30 patients with rhinitis or asthma due to house dust mite allergy of which 26 completed the study. At an initial visit for evaluation of the inclusion criteria, patients received a hygrometer and were seen 4 additional times for blood sampling and delivery of the active cover and later the placebo cover (cotton cover) or vice versa. Both study phases lasted 9 - 11 weeks, the wash-out period in-between lasted 2 - 10 weeks to avoid any interference with pollen allergy. At the patients' homes, a study-independent person collected dust samples which were analyzed for house dust mite allergen using an immunodot assay with monoclonal antibodies against the house dust mite allergen Der p 1, Der f 1 and mite group 2. For the evaluation of allergen content, the sum of the 3 allergens was used. Serum eosinophil cationic protein was measured to define the underlying allergic inflammation. Subjective clinical complaints regarding rhinoconjunctivitis and asthma were asked using a standardized questionnaire by E. Juniper. All patients were informed to wash their bed linen weekly and to increase the level of air exchange. A score for medication intake was calculated and the sleeping comfort with the active or placebo covers was evaluated. Results: A statistically significant reduction of the allergen content from 1.43 μg/m 2 /2 min to 0.65 μg/m 2 /2 min was found after using the active cover, but not after using the placebo cover (1.49 μg/m 2 /2 min). The measurement of the relative humidity in the air revealed no change throughout the study. At the beginning of the study, 49.5% relative humidity was measured, at the end of the study in summer time 64.3% were measured. The clinical complaints did not significantly change comparing both groups (active/placebo or placebo/active). A carry-over effect could be excluded since baseline values were similar. Pooling all data for the subjective rhinitis score revealed a statistically significant decrease in all 26 patients receiving either placebo or active treatment. In 8 patients with an elevated serum ECP level (> 16 μg/l), an amelioration of rhinitis could be seen in the active phase compared to the placebo phase. In addition, 12 patients with asthma reported fewer symptoms using the active cover compared with the placebo cover. After the active cover phase, 6 of the 8 patients with elevated ECP had a lower level of ECP, while 6 patients with the placebo cover had a higher level of ECP (p < 0.025). The medication intake was reduced during the active phase as well as during the placebo phase. The general comfort using the active cover was good with the exception of some rustling. The data confirm the clinical efficacy of allergen impermeable covers: an allergen reduction as well as a clinical relieve can be achieved, whereby the patients with elevated ECP may be particularly susceptible to allergen avoidance measurements.