Impermeable dust mite covers in the primary and tertiary prevention of allergic disease: a meta-analysis

Background Up to 40% of the world's population has been diagnosed with an allergic disease. The most prevalent allergy is to house dust mites. Impermeable mattress covers are often the first treatment in the prevention and decrease of symptoms of allergic disease. Objective To perform a meta-analysis evaluating the effectiveness of impermeable mattress covers in the primary prevention of allergic disease and as a single intervention in the tertiary prevention of allergic disease symptoms. Methods MEDLINE, Embase, Web of Science, and CINAHL were systematically searched for relevant publications. Seven primary prevention trials (n = 3,461) and 17 tertiary prevention trials (n = 1,671) met the inclusion criteria and were included in the review. All article reviews and abstractions were performed in duplicate. Results No significant pooled relative risks were found for the prevention of allergic disease. The pooled relative risks were 0.97 (95% confidence interval [CI] 0.62–1.51) for house dust mite sensitization, 0.92 (95% CI 0.81–1.05) for wheeze, 0.85 (95% CI 0.70–1.02) for asthma, 1.03 (95% CI 0.90–1.19) for allergic rhinitis, and 1.05 (95% CI 0.84–1.32) for allergic dermatitis. Likewise, no significant pooled standardized mean differences were found in the tertiary prevention of symptoms. The pooled standardized mean differences were −0.03 (95% CI −0.15 to 0.09) for peak flow, −0.06 (95% CI –0.32 to 0.20) for asthma symptom score, and −0.39 (95% CI −0.88 to 0.11) for nasal symptom score. A significant effect was seen in the decrease of house mite dust level in the mattress (−0.79, 95% CI −0.98 to −0.60). Conclusion No evidence was found to support the use of impermeable mattress covers in the primary prevention of allergic disease or in the tertiary prevention of allergic disease symptoms.