BACKGROUND:

The prevalence of asthma has increased in developed countries in the past 2 decades. The effectiveness of intervention measures on the primary prevention of asthma has not been well studied.

OBJECTIVE:

To assess the effectiveness of a multifaceted intervention program in the primary prevention of asthma in high-risk infants (in this study, infants are defined as persons from birth to the age of 1 year).

DESIGN:

Prospective, prenatally randomized, controlled study with follow-up through the age of 1 year.

SETTING:

University hospital-based settings at 2 Canadian centers: Vancouver, British Columbia, and Winnipeg, Manitoba.

PARTICIPANTS:

A total of 545 high-risk infants (at least 1 first-degree relative with asthma or 2 first-degree relatives with other IgE-mediated allergic diseases) identified before birth.

INTERVENTIONS:

Avoidance of house dust mite and pet allergens and environmental tobacco smoke, encouragement of breastfeeding, and supplementation with a partially hydrolyzed formula.

MAIN OUTCOME MEASURES:

Probable or possible asthma, rhinitis without apparent colds, and a prick skin test result positive for common inhalant allergens.

RESULTS:

Thirty-eight (15.1%) of the 251 infants available for assessment in the intervention group and 49 (20.2%) of the 242 infants available for assessment in the control group fulfilled the criteria for possible or probable asthma (adjusted relative risk, 0.66; 90% confidence interval, 0.44-0.98). Also, 16.7% of the infants in the intervention group and 27.3% of the infants in the control group developed rhinitis without colds (adjusted relative risk, 0.51; 90% confidence interval, 0.35-0.74). The incidence of positive skin test results to 1 or more inhalant allergens was similar in both groups (4.4% in the intervention group and 4.6% in the control group).

CONCLUSIONS:

Our multifaceted intervention program resulted in a modest but significant (P= .04) reduction in the risk of possible or probable asthma and rhinitis without apparent colds at the age of 12 months in high-risk infants. In the absence of a validated definition of asthma at the age of 12 months, follow-up studies are needed to determine the effectiveness of the intervention program in the primary prevention of asthma in high-risk infants.