**4.5 Survival**

COPD patients have been known to have improved mortality with cessation of smoking. There is some signal that an association exists between completion of PR and survival based on a retrospective analysis involving 1515 patients [42]. But a systematic review conducted of two randomized control trials showed significant survival benefit at 1 year in one trial but no significant benefit with another study at end of 3 years. Neither of the study was powered to really derive the desired outcome [43].
