Optimizing colorectal cancer screening through quality circles of primary care physicians: a cluster randomized controlled trial.

Of 120 invited quality circles, nine participated (5 intervention, 4 control).

A total of 63 PCPs (32 intervention, 31 control) collected data on 2,112 patients (1,130 intervention, 982 control; mean age 61.5, 53% women).

Screening rates in the intervention group increased from 55% to 57.9% (absolute increase: 2.9%; 95% CI:1.1%-6.9%; OR1.29; 95% CI:1.08-1.55, p < 0.01).