Age would certainly play a part in women ,as studies have shown premenopausal women have a better response to therapy that postmenopausal.
It has been my understanding from articles that I have read in the past that, yes, both age and race play a part. Here's one article I found:
http://hepatitis-c.healthytreatment.com/do-african-americans-react-worse-to-hepatitis-c-treatment/
The longest part of the article is the section which reports fess and support paid to the doctors and researchers. Go figure.
Probably the most significant factor is genotype.
This was just released today in the NEJM..as it pertains to ethnicity in a Boce trial.
http://www.nejm.org/doi/full/10.1056/NEJMoa1010494?query=featured_home