Best test to use?

[amanco]

Hi Everyone,

I am trying to design a medical study and having difficult for teh best to use, in summary:

Stage 1: Patients are classified into 4 categories based on their enzyme level (X) (A Quantitative variable).

Question 1: Since each patient has many encounters with different enzyme levels of (X), What is the best test to represent the different enzyme levels at many encounters? average/mode/median/variance?

Stage 2: Each patient can present with a complication (Z) (Categorical Variable).

Question 2: Since each patient has many encounters with different complications, say complication Z (Yes/No answer), so sometimes they present with complication (Z) as Yes and sometimes as NO. What is the best test to represent the most accurate presenting complication?

Stage 3: Enzyme (X) VS Complication (Z)

Question 3: Each enzyme X will be studied against a complication with Yes/No, what is the best test to find the relationship between X and the complication (Z) (Yes/No)?

I really appreciate your help.
Thanks alot,
Amanco