Regarding CVI and gender:
I looked into this a while back and found conflicting info - a few older sources claimed more women than men get CVI, but more recent studies said:
"in contrast with the findings in most previous studies, mainly conducted in the 1960s and 1970s, chronic venous insufficiency and mild varicose veins were more common in men than women,"
"Prevalence of CVI correlated closely with age and sex, being 21.2% in men >50 years and 12.0% in women >50 years," and
"Many of the previously suggested associations found with CVI are in reality due to this population's greater age. Patients with CVI are older, male, obese, have a history of phlebitis, and have a history of serious leg injury. These results suggest that a prior deep vein thrombosis, either clinical or subclinical, may be a predisposing factor for CVI."