Partial mattress encasing significantly reduces house dust mite antigen on bed sheet surface: a controlled trial.

BACKGROUND The most effective measure in house dust mite antigen reduction is mattress encasing with an impermeable membrane. A reduction in encasing costs will help increase patients' compliance in mite antigen avoidance. OBJECTIVE To investigate the effectiveness of partial mattress encasing with a nylon sheet produced in Thailand on the reduction of group I mite antigens from beddings. METHODS Sixty regularly-used beds from the house officers' dormitory of the Siriraj Hospital Mahidol University, Thailand, were randomly matched into two groups according to mite antigen levels. The control group (CG) used only regular cotton bed sheets whereas the partial encasing group (PG) used mattresses partially covered with a locally produced nylon sheet underneath the regular cotton bed sheets. Dust collection from the beddings was performed at baseline, 2, 4 and 6 months after application of the nylon sheet. Mite antigen levels were detected by a two step monoclonal antibody ELISA. RESULTS Mite antigen levels in both groups were not different at the beginning of the study. The PG had significantly lower group I antigen levels on regular bed sheet surfaces than the CG (P < .004) at the 2, 4 and 6 month timepoints. However, antigen levels on the mattress surface of the PG was significantly higher than the CG at the end of the study (P < .004). The barrier efficacy of the nylon sheet in preventing migration of group I mite antigens from the mattress to the surface of the regular cotton bed sheet was 94% whereas that of the regular cotton bed sheet was 66% (P = .007). CONCLUSION Partial mattress encasing with a locally made nylon sheet can reduce mite antigens on the regular cotton bed sheet surfaces for up to 6 months.