Objective To determine if area of residence is an independent factor influencing uptake of breast screening.

Design Record linkage study combining anonymised data from the National Breast Screening System and the Northern Ireland Longitudinal Study with cohort attributes as per their 2001 census return. Five mutually exclusive areas were defined; the Belfast metropolitan area (BMA) (comprising 21% population) and the remaining parts the four Health Boards responsible for the organisation and promotion of screening but not part of the BMA.

Setting All women enumerated at the 2001 Census of Northern Ireland.

Participants 37 059 women aged 48–64 at the time of the census who had been invited for routine breast screening during the 3 years following the census.

Main outcome measure Attendance for routine breast screening in the 3 years following the census.

Results Overall uptake was 75% during the study period. In the fully adjusted model uptake was lower among women aged 60 and over, not currently married and among women whose general health was “not good” in the year before the census. Uptake was related to car ownership and housing tenure but not to educational status or NS-SEC. Even after adjustment for all other demographic and SES factors there was significant variation in uptake among Health Boards; uptake was lowest in the Eastern Board (OR 0.61, 95% CI 0.56 to 0.66, compared to the Northern Board) and lower again in the BMA (OR 0.49, 95% CI 0.45 to 0.53). The reduction in Belfast was evident across most social strata and was confirmed with maps and use of different definitions of “city”.

Conclusions Linkage of screening data to census-based longitudinal studies is an efficient and powerful way to increase the evidence base on sources of variation in uptake within the UK. This study shows that the lower breast screening uptake rate in and around the city is of concern as it affects a large number of women. It requires further investigation. The lower attendance rates are not due to socio-economic factors and appear to be independent of factors related to organisation of the service. Possible reasons and solutions for this problem will be discussed at presentation.