Concentration, Health and Reflexes are dependent attributes that are influenced by your character’s attributes. Concentration is determined by Discipline, Health by Constitution, and Reflexes by Dexterity and Perception, Armor and Strength.
The corresponding formulas are as follows:
Health: 10 + 2* Constitution
Concentration: 10 + 2* Discipline
Reflexes: Perception + Dexterity – (Armor hindrance – Strength (not less than 0)).