Society and culture
Economics
In 2015 it cost about US$14,100 per year. One article calculated this to be about $400,000 to $500,000 per quality-adjusted life year (QALY), which did not meet "generally accepted" cost-benefit thresholds. The authors calculated that an annual cost of $4,500 would meet an acceptable $100,000 per QALY standard. On October 26, 2018 the maker of the drug, Amgen, announced a 60% cut in price and the drug now costs $5,850 per year. References
External links
"Evolocumab". Drug Information Portal. U.S. National Library of Medicine.
In botany, the term is most common in its adjectival forms, where it is used in binomial names to refer to species that are distinguished by hollow or tubular structures. Monarda fistulosa, for example, has tubular flowers. The term was first used in the 14th century. Definition
A fistula is an abnormal connection between vessels or organs that do not usually connect. It can be due to a disease or trauma, or purposely surgically created. Classification
Various types of fistulas include:

Blind: Only one open end; may also be called sinus tracts. Complete: Both internal and external openings. Incomplete: An external skin opening that does not connect to any internal organ.Although most fistulas are in forms of a tube, some can also have multiple branches. Location
Types of fistula can be described by their location. Anal fistulas connect between the epithelialized surface of the anal canal and the perianal skin. Anovaginal or rectovaginal fistulas occur when a hole develops between the anus or rectum and the vagina. Colovaginal fistulas occur between the colon and the vagina. Urinary tract fistulas are abnormal openings within the urinary tract or an abnormal connection between the urinary tract and another organ such as between the bladder and the uterus in a vesicouterine fistula, between the bladder and the vagina in a vesicovaginal fistula, and between the urethra and the vagina in urethrovaginal fistula.