My claim was not that it was the only factor, but that it was a major factor - I list three other major factors, the first being the most important. Comparison to the EU misses the point; both the EU and the US have intellectual property laws creating monopolies over drug production. The comparison should be to the state of the world if intellectual property law was not in force. There is little evidence that this would lead to a major reduction in production, although drug companies would really like you to believe this.