1987 – Aventis blood thinner Lovenox becomes available in Europe to fight clots in hospital patients.

1988 – Two British researchers coin the term "economy class syndrome" to describe venous thromboembolism during or after prolonged travel.

1990s – Blood thinners become the fastest growing part of the cardiovascular market with $9.1 billion sales.

October 2000 – Emma Christoffersen, 28, collapses at London's Heathrow airport after flying 12,000 miles in coach class from Australia. She later dies, and an autopsy shows a fatal blood clot from her leg, provoking wide-spread media attention in England and Australia.

February 2001 – Dr. Ross Baker, president of Australian Society of Thrombosis, says the risk of fatal blood clots from long flights "has been overstated, vastly overstated."

March 12-13, 2001 – WHO hosts a conference on links between air travel and DVT. WHO's coordinator of cardiovascular disease acknowledges conflicting opinions. Group unanimously votes for urgent study under WHO auspices.

May 3, 2001 – Aventis pledges $25 million to WHO to combat deadly sleeping sickness in sub-Saharan Africa.

Aug. 17, 2001 – WHO announces it will conduct large-scale research on air travel and DVT.

February 2002 – Aventis sets up the Council for Leadership on Thrombosis (CLOT) to target doctors and the public with information and to establish free screening.

May 14, 2002 – WHO launches its study of venous thrombosis and air travel, promising results within a year. WHO calls the link between air travel and DVT "an important public health problem."

September 2002 – Aventis hires public relations firm Burson-Marsteller for a DVT campaign. The company sets up the Coalition to Prevent Deep-Vein Thrombosis and a DVT awareness month.

November 2002 – WHO stops its study of 200,000 frequent flyers.

Feb 26, 2003 – Aventis sponsors Public Health Leadership Conference on DVT in the U.S., with the prestigious American Public Health Association and Centers for Disease Control. Aventis press release calls long distance travel one of the risk factors, and quotes APHA's executive director saying DVT is "an under-estimated, under-diagnosed and under-treated public health threat."

May 21, 2003 – Aviation Health Institute study, based on 67 people who died, says DVT could be a health hazard on short-haul flights as well. Aviation medical specialists accuse the group of "scare mongering."

Sept. 26, 2004 – Britain's Aviation Health Institute blames Aventis for spreading unnecessary alarm to sell more drugs, The Observer reports.

October 2004 – U.S. government group that writes the International Classification of Disease (ICD) adds a specific disease code for DVT.

Sources: Aventis Pharmaceuticals;
Pharma Marketletter