If the future can be extrapolated from the recent past, the HMO market will be dominated increasingly by plans of the independent practice association model, according to data from a leading HMO directory. Such plans tend to be of more recent vintage, while staff- and group-model HMOs are older. Here is the national distribution of HMOs by plan type and year of origin.

SOURCE: CALCULATIONS BY MANAGED CARE BASED ON HMO DIRECTORY FROM INTERSTUDY PUBLICATIONS, ST. PAUL, MINN.