Effectiveness of house dust mite allergen reduction in infants beds: a randomised controlled trial

Introduction: Exposure and sensitisation to house dust mite (HDM) allergens in early childhood are thought to be important risk factors for the development of asthma. The largest reservoir of HDM allergen in the home is in beds, and this is an important source of exposure for infants because of the large proportion of their of time spent sleeping. We are conducting a randomised controlled trial to test the effectiveness of a strategy intended to reduce infants' exposure to HDM allergen. Methods: Families of infants at high risk of developing asthma were recruited antenatally and randomised into control and intervention groups. The intervention group was asked to wash the infants' bedding in an acaricidal detergent (Acarif, Allergopharma) at 3-month intervals and to use impermeable cot mattress covers. Dust samples were collected at regular intervals and assayed for Der p 1. Results: The table shows the geometric means concentrations of Der p l (ng/g dust) in infants' beds. Der p l concentrations in the intervention group beds were significantly lower than the control group at all time points. Age Control group Intervention group Rvalue n Mean(95%CiT n Mean (95% Cl) 1 month 296 5.2 (4.3-6.2) ~289 3.3 (2.8-3.8) <0.0001 3 month 284 9.4(7.9-11.1) 284 4.0(3.4-4.7) 0.0001 6 month 276 15.5(13.2-18.3) 278 4.0(3.4-4.7) 0.0001 12 month 209 21.2(17.5-25.7) 210 4.9(4.0-6.1) <0.0001 18 month 153 26.8(22.1-32.3) 145 5.5 (4.4-6.9) 0.0001 Conclusion: An intervention based on washing bedding in acaricide and using impermeable mattress covers was effective in reducing concentrations of Der p l in infants' beds. The study is continuing to determine whether these reductions are effective in preventing the onset of asthma and allergy.