Social inequalities in HIV-TB and non-HIV-TB patients in two urban areas in southern Spain: multilevel analysis

Abstract

Two towns in Campo de Gibraltar, southern Spain, with a small foreign population and higher tuberculosis (TB) incidence and human immunodeficiency virus (HIV) prevalence than the national average. To determine the relationship between HIV-TB and non-HIV-TB incidence and social deprivation and other potential individual and contextual determinants. In a cross-sectional longitudinal study, individual TB case variables were identified from three sources--routine surveillance, laboratory and hospital discharge records--from 1997 to 2007. Community variables were obtained at the census tract level. A deprivation index was calculated based on percentages of unemployment, low educational level and unskilled labour. Multilevel Poisson models were estimated for TB incidence rates for patients with and without HIV. A total of 490 TB cases were included. Sex and age at individual level and deprivation and residence in the port area at census tract level were associated both with HIV-related TB and with non-HIV-TB. Household crowding contextual variables were also associated with HIV-related TB incidence. Full models account for 78.9% and 51.7% reductions in second-level variance. Socio-economic deprivation is associated with higher rates of HIV-TB and non-HIV-TB. Diverse individual and contextual potential risk factors suggest different pathways of transmission. It is necessary to extend the framework for intervention beyond individual-based strategies to the socio-economic contexts in which people live.