A meta-analysis of baseline characteristics in trials on mite allergen avoidance in asthmatics: room for improvement

Abstract

Background: Evidence regarding the clinical effectiveness of mite allergen avoidance for the treatment of asthma is lacking. In previous meta-analyses on mite allergen control, the baseline data were not discussed in detail. This study updates and extends the existing Cochrane review by Gøtzsche and Johansen (Cochrane Database of Systematic Reviews, 2008, Art. No: CD001187), with a focus on baseline asthma outcomes and allergen exposures. Methods: We used the existing trials in the original Cochrane review and included newly published studies. The baseline data for the mite allergen load from the mattress, the standardized asthma symptom score (ASS), the forced expiratory volume in 1 s percentage of predicted (FEV 1 %pred.), and the histamine provocative concentration causing a 20% drop in FEV 1 (PC 20) were extracted. First, the mean values of the outcomes were calculated. The influence of the mite allergen load was examined with a random-effect meta-regression using the Metafor package in R. Results: Forty-five trials were included; 39 trials reported strategies for concurrent bedroom interventions, and 6 trails reported strategies for air purification. The mite allergen load ranged from 0.44 to 24.83 μg/g dust, with a mean of 9.86 μg/g dust (95% CI 5.66 to 14.05 μg/g dust, I 2 = 99.8%). All health outcomes showed considerable heterogeneity (standardized ASS mean: 0.13, 95% CI 0.08 to 0.18, I 2 = 99.9%; FEV 1 %pred. mean: 85.3%, 95% CI 80.5 to 90.1%, I 2 = 95.8%; PC 20 mean: 1.69 mg/mL, 95% CI 0.86 to 2.52 mg/mL, I 2 = 95.6%). The covariate mite allergen load did not significantly influence health outcomes. Discussion: This meta-analysis shows that mite avoidance studies are characterized by the inclusion of patients with rather mild to moderate asthma and with varying and sometimes negligible levels of allergen exposure. Future studies should focus on patients with severe asthma and increased levels of allergen exposure.

Detection and assessment of dust mite allergens in an indoor environment in Anhui, China

“…The mite species in dust samples were preliminarily observed using an optical microscope. Most of them were identified as Dermatophagoides and Acarus (K. Sharma et al 2019 ; van Boven et al, 2020a , b ). Some living mites were obtained (Fig.…”

“…Exposure to microbes and allergens in people with an allergic constitution and at different exposure levels can exacerbate allergic conditions in the course of diseases (Wilson & Platts-Mills, 2018 ). The home is a key microenvironment for exposure to allergens, yet children and adults are estimated to spend an average of 60 to 80% of their time indoors, since continuous exposure, even to low levels of allergens, in individuals with mild asthma may exacerbate symptoms and bronchial hyperresponsiveness (Van Boven et al 2020a ) . Therefore, it is critical to evaluate the allergen level of dust mites in the indoor environment for the prevention and treatment of allergic diseases.…”

Population adjusted‐indirect comparisons in health technology assessment: A methodological systematic review

“…This is practically challenging as recent evidence continues to show that the collection and reporting of patient characteristics data among clinical studies in the same field remain very inconsistent. [17][18][19] In recent years, significant efforts have been made to improve this concern. Across many therapeutic areas, a so-called core patient characteristic set (CPCS) is specifically developed to identify all key prognostic factors that should be commonly collected and reported (among studies and databases evaluating a similar target condition), while keeping the additional burden on the implementation acceptable.…”

“…However, in many cases, variable selection was affected by the availability of covariates data in individual studies. This is practically challenging as recent evidence continues to show that the collection and reporting of patient characteristics data among clinical studies in the same field remain very inconsistent 17–19 . In recent years, significant efforts have been made to improve this concern.…”

Development of minimum reporting sets of patient characteristics in epidemiological research: A methodological systematic review

“…13 Similar issues are also prevalent in many other medical fields, including asthma, diabetes, hypertension, or colorectal cancer. [14][15][16][17][18] In these recent years, significant efforts have been made to standardize the collection and reporting of patient characteristics in epidemiological research. Across many therapeutic areas, a so-called core patient characteristic set (CPCS) is specifically developed to identify all key prognostic factors that should be commonly collected and reported (among studies and databases evaluating a target medical condition), while keeping the additional burden on the implementation acceptable (Figure 1).…”