Table 2 summarizes the percent of patients relapsing on placebo or drug in several meta-analyses and from one individual NIMH supported 5-year study.

Maintenance Studies

Drug

Placebo

Difference

Ratio/drug

Reference

Early 1953-1976

27%

53%

-26%

2.0

[29]

Three Year Treatment imipramine

30%

72%

-47%

3.4

[22, 23, 33]

Imipramine group from 3 year study randomized to drug or placebo yr. 4-5.

10%

67%

-57%

6.7

[22, 23, 33]

Later 1953-2003

18%

41%

-23%

2.3

[30]

Later 1998-2006

23%

50%

-27%

2.2

[32]