Background: Chronic Lower Respiratory Diseases (CLRD), such as asthma, chronic obstructive pulmonary disease (COPD), chronic bronchitis and emphysema are preventable diseases that constitute a serious public health concern. Estimates indicate that there is an increased prevalence of mortality from these diseases worldwide. Low socio-economic positions (SEP) and poor indoor environmental conditions have been identified as risk factors for CLRD among adults. Given the public health burden of CLRD, there is increasing interest among researchers to identify all relevant factors associated with CLRD. However, many studies identified in the literature only controlled for individual or specific risk factors and most of these studies vary in their definition of risk factors. As a result, the evidence was contradictory. Some studies reported statistical associations while other studies reported no statistical association between specific risk factors and CLRD. Furthermore, questions remain on which risk factors mediate the relationships between socio-demographic factors and respiratory health outcomes. Given this, the study will examine if one or more indoor environmental factors and access to healthcare mediates the relationships between socio-demographic factors and CLRD among adult ACBS respondents in the United States (U.S). The study will further examine if the effects of socio-demographic factors on CLRD depend on indoor environmental factors and access to healthcare.
Methods: This study examined three different years of secondary cross-sectional data collected from adults 18 years or older by the Behavioral Risk Factor Surveillance Survey (BRFSS) and Asthma Call-Back Survey (ACBS). 15,403 participants from 2009, 17,753 from 2010 and 16,693 from 2011 were included in the study. Bivariate analyses were used to identify significant predictors, and logistic regression models were used to examine mediation and predictor-mediator interaction effects. CLRD was
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the outcome of interest, socio-demographic factors were used as predictors, and indoor environmental factors and healthcare access were used as potential mediators.
Results: The bivariate analyses revealed that gender, age, marital status, education, employment status, income, mold, pest infestation, smoking indoors, being a current or former smoker, occupational exposure and medical cost were significant predictors of CLRD. The mediation tests revealed that mold, mice presence, being a current smoker, smoke indoors and occupational exposure fully or partially mediated the relationship between age, education, employment, income and current asthma. Being a current or former smoker, smoking indoors, and occupational exposure fully or partially mediated the effects of age, marital status, education, employment, income on COPD, bronchitis and emphysema. Mold and medical cost were also identified as mediators for bronchitis and mold for emphysema. These findings indicate that indoor environmental factors and medical cost, fully or partially explain the effects of socio-demographic factors on the reporting of CLRD. The statistical significant predictor-mediator interaction effects that were identified revealed that the effects of gender, age, education, employment and income on the reporting of CLRD depends on mold, mice presence, being a current or former smoker, smoking indoors, occupational exposure and medical cost.
Conclusion: This is the first study to use rich cross-sectional secondary data from three different years to demonstrate that poor indoor environmental conditions and inadequate access to healthcare play a significant role in explaining the reporting of CLRD among ACBS respondents in different social, economic and demographic groups. These findings have clear implications for related public health policies. These policies should focus on creating more resources in deprived neighborhoods, improving inadequate housing conditions through housing refurbishment and ensuring adequate access to healthcare for all groups regardless of their SEP.