Social factors associated with increases in tuberculosis notifications.

This study assessed the contribution of immigration and deprivation to the changes in tuberculosis notifications in Liverpool over the last 20 yrs. Ethnic origin was retrospectively assigned to all named cases from 1974 to 1995. Average tuberculosis rates were calculated for the 33 council wards in Liverpool for 1981-1985 and 1991-1995. Multiple regression was used to determine the independent effects of socioeconomic and population measures from the 1981 and 1991 censuses in explaining these ward-based rates. Since 1974, there has been a steady increase in the percentage of non-Caucasian cases of tuberculosis, from 8.7% in 1975-1977, 15.1% in 1981-1983, 17.5% in 1987-1989 to 28.0% in 1993-1995. Multiple regression analysis showed that in 1981 only unemployment had a significant independent relationship with tuberculosis rates, but in 1991 two indices of deprivation and ethnicity had a significant influence. The increasing proportion of non-Caucasian tuberculosis cases, both while the number of notifications was declining before 1987 and increasing afterwards, is not necessarily consistent with the concept that immigration has influenced the recent increase. However, the fact that ethnicity now independently explains some of the council ward variations but did not in the early 1980s suggests that immigration does influence the distribution of disease within the city.