Influence of neighbourhood-level crowding on sleep-disordered breathing severity: mediation by body size.

Neighbourhood-level crowding, a measure of the percentage of households with more than one person per room, may impact the severity of sleep-disordered breathing. This study examined the association of neighbourhood-level crowding with apnoea-hypopnoea index in a large clinical sample of diverse adults with sleep-disordered breathing. Sleepdisordered breathing severity was quantified as the apnoea-hypopnoea index calculated from overnight polysomnogram; analyses were restricted to those with apnoea-hypopnoea index >5. Neighbourhoodlevel crowding was defined using 2000 US Census tract data as percentage of households in a census tract with >1 person per room. Multivariable linear mixed models were fit to examine the associations between the percentage of neighbourhood-level crowding and apnoeahypopnoea index, and a causal mediation analysis was conducted to determine if body mass index acted as a mediator between neighbourhood-level crowding and apnoea-hypopnoea index. Among 1789 patients (43% African American; 68% male; 80% obese), the mean apnoea-hypopnoea index was 29.0 25.3. After adjusting for race, age, marital status and gender, neighbourhood-level crowding was associated with apnoea-hypopnoea index; for every one-unit increase in percentage of neighbourhood-level crowding mean, the apnoea-hypopnoea index increased by 0.40 0.20 (P = 0.04). There was a statistically significant indirect effect of neighbourhood-level crowding through body mass index on the apnoea-hypopnoea index (P< 0.001). Neighbourhood-level crowding is associated with severity of sleep-disordered breathing. Body mass index partially mediated the association between neighbourhoodlevel crowding and sleep-disordered breathing. Investigating prevalent neighbourhood conditions impacting breathing in urban settings may be promising.