Cluster randomised controlled trial comparing the effectiveness and cost-effectiveness of two primary care interventions aimed at improving attendance for breast screening

Objectives-To examine the effectiveness and cost-effectiveness of two inter ventions based in primary care aimed at increasing uptake of breast screeni ng. Setting-24 General practices with low uptake in the second round of screeni ng (below 60%) in north west London and the West Midlands, UK. Participants were all women registered with these practices and eligible for screening in the third round. Methods-Pragmatic factorial cluster randomised controlled trial, with pract ices randomised to a systematic intervention (general practitioner letter), an opportunistic intervention (flag in women's notes prompting discussion by health professionals), neither intervention, or both. Outcome measures w ere attendance for screening 6 months after the practices had been screened and cost-effectiveness of the interventions. Results-6133 Women were included: 1721 control; 1818 letter; 1232 flag; 136 2 both interventions. Attendance data were obtained for 5732 (93%) women. T he two interventions independently increased breast screening uptake in a l ogistic regression model adjusted for clustering, with the flag (odds ratio (OR) 1.43, 95% confidence interval (95% CI) 1.14 to 1.79; p=0.0019) margin ally more effective than the letter (OR 1.31, 95% CI 1.05 to 1.64; p=0.015) . Health service costs per additional attendance were pound 26 (letter) and pound 41 (flag). Conclusions-Although both interventions increased attendance for breast scr eening, the letter was the more cost-effective. Any decision to implement b oth interventions rather than just the letter will depend on whether the ad ditional (pound 41) costs are judged worthwhile in terms of the gains in br east screening uptake.