Complete mattress encasing is not superior to partial encasing in the reduction of mite allergen

Background: Partial mattress encasing was found to be effective in reducing exposure to mite allergen in our previous investigation. We aimed to compa re the short-term efficacy of partial and complete mattress encasing and to study miteallergen levels within these mattresses. Methods: Thirty-one mattresses with high mite-allergen content were selecte d and were randomized into one of three study groups (10 for the control gr oup [CG], 11 for the partial encasing group [PE], and 10 for the complete e ncasing group [CE]). A special mite-impermeable membrane was used. In the P E group, mattresses were encased on tops and sides only, whereas complete m attress encasement was undertaken in the CE group. Regular bedsheets were a pplied to all groups. Dust samples were collected over bedsheets at baselin e and at months 3 and 6, and over mattresses at baseline and at the end of the study. Group I mite allergens in these samples were measured and compar ed. Results: At baseline, mattress mite allergens were similar in all groups (P =0.84). Mite allergen at the surfaces of bedsheets lover membranes) from bo th encasing groups were significantly reduced as compared to the CG group ( P=0.003). Such reduction was maintained throughout the 6-month study. At th e end of the study, mite antigens within mattresses in the CG and CE groups were increased as compared to baselines, whereas a decrease was observed i n the PE group. Significant difference was observed only between the CG and PE groups (P=0.006). Conclusions: Mattress encasing with a special membrane in this study was hi ghly efficacious in the reduction of mite allergen (>90%). However, with co mplete encasing, mite allergens within mattresses were increased at the end of the study. Complete mattress encasing in a tropical environment does no t offer any advantage over partial encasing.