House dust mite allergen avoidance strategies for the treatment of allergic asthma: A hypothesis-generating meta-analysis.

BACKGROUND: This study continues the review by Gøtzsche and Johansen (Cochrane Database of Systematic Reviews, 2008, Art. No: CD001187), aiming to systematically generate hypotheses on the effectiveness of (sub)strategies for house dust mite allergen avoidance in the treatment of allergic asthma.

METHODS: We used the trials previously analysed by Gøtzsche and Johansen and searched recently published studies. Data on asthma symptom scores (ASS), ACQ, number of improved patients, AQLQ-scores, medication use, FEV1 %, PC20 , and FeNO levels were analysed. The effectiveness of strategies was assessed using Metafor in R.

RESULTS: Thirty-five trials involving 2419 patients were included in the final study. The patient-reported outcome number of patients with improved condition following total bedroom control was RR = 3.39 (95% confidence interval: 1.04 to 11.04, P = 0.04). The mean differences in the ASS by nocturnal air purification was -0.7 (95% confidence interval: -1.08 to -0.32, P < 0.001). Other outcomes including partial bedroom control were non-significant or clinically not of importance.

CONCLUSIONS: Total bedroom control and nocturnal air purification of the breathing zone hypothetically provides clinical benefits in patients with house dust mite-induced allergic asthma. The number of patients with improvements in their condition respectively the asthma symptom score differences showed potential in small subgroups, consisting of single studies. Partial bedroom control is not recommended.

SYSTEMATIC REVIEW REGISTRATION: Prospero CRD42022323660.