Effect of environmental interventions to reduce exposure to asthma triggers in homes of low-income children in Seattle

Journal of Exposure Analysis and Environmental Epidemiology (2004) 14, S133–S143 r 2004 Nature Publishing Group All rights reserved 1053-4245/04/$25.00 www.nature.com/jea Effect of environmental interventions to reduce exposure to asthma triggers in homes of low-income children in Seattle TIM K. TAKARO,a,b JAMES W. KRIEGERa,b,c,d AND LIN SONGc a University of Washington School of Public Health and Community Medicine, USA University of Washington School of Medicine, USA c Public Health – Seattle and King County, USA d Seattle Partners for Healthy Communities, USA b The effectiveness of community health workers (CHWs) assisting families in reducing exposure to indoor asthma triggers has not been studied. In all, 274 low-income asthmatic children were randomly assigned to high- or low-intensity groups. CHWs visited all homes to assess exposures, develop action plans and provide bedding encasements. The higher-intensity group also received cleaning equipment and five to nine visits over a year focusing on asthma trigger reduction. The asthma trigger composite score decreased from 1.56 to 1.19 (D ¼ 0.37, 95% CI 0.13, 0.61) in the higher-intensity group and from 1.63 to 1.43 in the low-intensity group (D ¼ 0.20, 95% CI 0.004, 0.4). The difference in this measure due to the intervention was significant at the P ¼ 0.096 level. The higher-intensity group also showed improvement during the intervention year in measurements of condensation, roaches, moisture, cleaning behavior, dust weight, dust mite antigen, and total antigens above a cut point, effects not demonstrated in the low-intensity group. CHWs are effective in reducing asthma trigger exposure in low-income children. Further research is needed to determine the effectiveness of specific interventions and structural improvements on asthma trigger exposure and health. Journal of Exposure Analysis and Environmental Epidemiology (2004) 14, S133–S143. doi:10.1038/sj.jea.7500367 Keywords: asthma, indoor environment, antigen exposure, interventions, community health workers, Healthy Homes, inner city. Introduction Asthma affects 15 million Americans (7% of the population), a third of them under the age of 18 years (Mannino et al., 2002). It is the most common chronic disease in children, the leading noninjury cause of hospitalization for children aged 0–15 years and the most common medical cause of missed school days (Graves and Kozak, 1998; Akinbami and Schoendorf, 2002; Mannino et al., 2002). Asthma prevalence, health service utilization, and mortality have increased among children and young adults in the US since 1980. The self-reported prevalence of childhood asthma increased by 75% between 1980 and 1994. From 1975 to 1993–1995, the estimated annual number of pediatric office visits for asthma more than doubled, from 4.6 million to 10.4 million, and the hospitalization rate also increased by 1.4% per year on average. The mortality of childhood asthma increased by 118% between 1978 and 1995 (Gergen, 1992; Mannino et al., 1998; Akinbami and Schoendorf, 2002). 1. Address all correspondence to: Dr. Tim K. Takaro, Occupational and Environmental Medicine, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105, USA. Tel.: þ 1-206-616-7458. Fax: þ 1-206-616-4875. E-mail: Asthma is an immunologic disease triggered by specific allergens as well as respiratory irritants. These triggers induce airway inflammation and accompanying bronchial hyperresponsiveness. Exposure to indoor asthma triggers plays an important role in the development and exacerbation of childhood asthma (On allergens and asthma, 2001). Sensitized or atopic individuals are at greater risk of developing disease and are more likely to have severe disease (Sears et al., 1993; Nelson et al., 1999; Dharmage et al., 2001). Although we cannot yet quantify the precise role of the indoor environment in the increase in asthma, a variety of exposures concentrated in the indoor environment have been associated with asthma. The most reported exposures that trigger asthma are house dust mites (De Blay et al., 1992; Van der Heide et al., 1994; Carswell et al., 1996; Arlian and PlattsMills, 2001), environmental tobacco smoke (Burchfield et al., 1986; Weitzman et al., 1990; Young et al., 1991; Chilmonczyk et al., 1993), dampness and mold (Brunekreef et al., 1989; Verhoeff et al., 1995; Andriessen et al., 1998; Dharmage et al., 1999, 2001; Bush and Portnoy, 2001), household pets (Dales, 1991; De Blay et al., 1991; InfanteRivard, 1993; Bierman, 1996; Institute of Medicine, 2000), and cockroaches (Rosenstreich et al., 1997; Institute of Medicine, 2000; Eggleston and Arruda, 2001). Viral infections, endotoxins, and residues from combustion also play a role in childhood asthma (Johnston et al., 1995; Environmental interventions for asthma triggers Takaro et al. Institute of Medicine, 2000; Wooton and Ashley, 2000). While rodents appear to be a significant asthma trigger in laboratory workers (Hollander et al., 1996; Nieuwenhuijsen et al., 2003), and the US National Cooperative Inner City Asthma Study found 19% of children allergic to rats (Kattan et al., 1997), the role of these pests in asthma is not well defined (Institute of Medicine, 2000). Reported exposure assessments vary widely, with many studies using both questionnaire data and quantitative environmental measures to characterize exposures. Dharmage et al. (1999) suggest that interview and visual inspection can provide valid measures of home environmental conditions when compared with the researcher’s assessment for cat antigen, relative humidity, and ergosterol (a surrogate for mold). Antigen assessment in house dust has been correlated with increases in asthma activity (Rosenstreich et al., 1997; Shapiro et al., 1999; Institute of Medicine, 2000; Platts-Mills et al., 2000; Carter et al., 2001). A few studies have demonstrated that home environmental interventions can reduce symptoms of asthma and bronchial hyper-responsiveness, through reduction of exposure to single triggers such as dust mite antigen (Shapiro et al., 1999; Platts-Mills et al., 2000; Carter et al., 2001; Maestrelli et al., 2001) and tobacco smoke (Greenberg et al., 1994), but none have assessed the benefit of a global reduction in indoor asthma triggers (Institute of Medicine, 2000). Most patients with asthma are sensitive and exposed to multiple allergens. Therefore, a global approach to reducing asthma triggers in the home environment is likely to be the most effective and efficient approach. Despite the lack of adequate evidence supporting such a comprehensive approach and the need for additional randomized controlled trials to test its efficacy, the American Academy of Asthma, Allergy and Immunology has taken a precautionary approach and recommended that physicians include indoor allergen avoidance measures in their therapeutic plan for patients with chronic allergic asthma (Eggleston and Bush, 2001). Their recommendations along wi (...truncated)