In December of 2002, a large study showed that generic pills for high blood pressure, which had been in use since the 1950’s and cost only pennies a day, worked better than newer drugs that were up to 20 times as expensive.
Six years later, the use of the inexpensive pills is far smaller than some of the trial’s organizers had hoped. Although the used of the cheaper pills, called diuretics, rose to around 40 percent in the year after the study’s results were announced, they have since stayed at that plateau. Over all, use of newer hypertension drugs has grown faster than the use of diuretics since 2002.
The aftereffects of the study show how hard it is to change medical practice, even after a government-sanctioned trial costing $130 million produced what appeared to be solid evidence. Several factors blunted the study’s impact. One was the simple difficulty of persuading doctors to change their habits. But another issue was that pharmaceutical companies responded by heavily marketing their own expensive hypertension drugs and, in some cases, paying speakers to interpret the study’s results in ways that made their products look better.