“…Enrolment growth has been much slower than hoped, and some of the On Lok features, such as intensive use of day health centres, are impractical and cumbersome when geographical catchment areas are much larger. The original On Lok site was only 2.5 square miles, and the expanded On Lok sites is 10 miles; however, the Columbia PACE site covers 1,400 square miles, which imposes a substantial burden of change on some of the On Lok features (Branch et al, 1998). We will return to the issue of generalisability of this model in the second portion of the paper.…”