Using all Medigap plans that had usable data in each of the four years from 2007 and 2010, we estimated a model to predict annual changes in premiums within plans. Important findings are:
- Medicare per capita spending trend within states was a significant and positive predictor of increases in Medigap premiums.
- Both the level and change in Medicare Advantage penetration within a state were associated with lower rates of growth of Medigap premiums during the 2007‐2010 period.
- Older and individual policies experienced larger increases in Medigap premiums than newer and group policies, respectively.
- In general, plans with the largest number of covered lives had smaller premium increases
- Plans in states with issue‐age rating requirements had smaller rates of premium increase than plans states with attained‐age rating.