New research published in the British Medical Journal has found New Zealanders who participated in the First World War lost around eight years off their lives.

Researchers compared the life-spans of soldiers who embarked on troopships in 1914, with those who departed once the war had ended, and didn't get to the frontline.

They found a quarter of the soldiers who were in combat died, mostly from injury.

Yet those who survived still died 1.7 years earlier than those who didn't go to combat.

Researchers say many committed suicide, and a number received life-threatening surgical operations for injuries received when fighting.