Although statins may be the most prescribed medicines in the world, researchers suggest that more patients with risks for developing heart disease should be taking the cholesterol-lowering drugs. Heart disease is the number-1 killer in the United States and is often caused by high cholesterol. A study at Stanford University in California looked into 2 national databases that included outpatient visits to hospitals and doctor's offices between 1992 and 2002, taking note of the types of drugs either continued or prescribed. The study showed that statin use grew from 47% to 87% during that time. It also showed that, among high-risk patients, use rose from 14% to 50%; for those at moderate risk, use of statins went up from 9% to 44%. While these numbers appear to be promising, researchers pointed out that "the predominant problem appears to be underuse in higher-risk patients," while stating that "we did observe some inappropriate use of statins in low-risk patients." They emphasized that statins "have to be prescribed for the right reasons and for the right groups of patients."