An upcoming study of thousands of Americans aims to measure how effectively U.S. Food and Drug Administration-approved medications, including nicotine patches and prescription pills, help people quit smoking while living their normal lives.
FDA-approved medicines appear to successfully help people quit smoking when used in tightly controlled clinical trials in medical centers, but naturalistic studies of the medications produce mixed results. Many observational studies find they are roughly as effective as going "cold turkey" and quitting without aid, said Adam Leventhal, director of the USC Institute for Addiction Science.
The study is a collaboration between USC and the University of Nebraska and is funded by a grant of $4.7 million over five years from the National Cancer Institute. The new methodology will combine intensive research assessment with real-world conditions in a nationally representative study to definitively determine how effective FDA-approved aids for smoking cessation are for people living their everyday lives. The study will also collect data to discover if various non-FDA-approved products that smokers use actually work and assist quitting, said Leventhal, who is a co-principal investigator on the grant with Hongying "Daisy" Dai of the University of Nebraska Medical Center.
The collaboration is part of a growing number of joint projects for which the USC Institute for Addiction Science has partnered with fellow Big 10 universities, Leventhal said. The institute is also currently collaborating with University of Michigan, Ohio State University, University of Minnesota, UCLA and Rutgers University colleagues.
Many Americans want to quit but face long odds
As of 2025, approximately 9% of American adults smoke cigarettes, according to the Centers for Disease Control and Prevention. The adult smoking rate peaked at 42% in 1965 following a landmark U.S. Surgeon General's report on the health risks of smoking.
Each year, about 75% of all smokers in the United States say they want to kick the habit. About half of them attempt to quit, but only 8% manage to successfully stop smoking, Leventhal said. These statistics have been the same for more than a decade, he added, noting that many of individuals who manage to quit smoking for a period of time still eventually relapse.
"While fewer people in the U.S. smoke each year, the reason is not because more people are quitting smoking; it is because fewer young people are picking up smoking each year due to education regarding tobacco risks and policies that restrict tobacco use, sales and marketing," he said.
To help improve American smokers' low chances of quitting for good, Leventhal and Dai have assembled a robust, interdisciplinary team, Leventhal said. USC Institute for Addiction Science experts have partnered with University of Nebraska Medical Center quantitative scientists to analyze new data that will be obtained by the USC Center for Economic and Social Research's Understanding America Study.
"Our collaboration between USC and UNMC brings together complementary expertise in addiction science and advanced modeling," Dai said. "We will also integrate rich auxiliary data to examine how policy and environmental factors influence cessation aid uptake and smoking outcomes."
The study enables researchers to survey thousands of U.S. adults who smoke and track individuals who make quit-smoking attempts "with more detail and precision than ever before," Leventhal said.
"We will track what happens before the quit attempt, what quit-smoking aids they use and what happens after the quit attempt up to four years later," he said. "This will allow us to determine which FDA-approved medications, as well as non-FDA-approved methods such as e-cigarettes and CBD, help people get motivated to quit and keep them smoke-free for years without relapsing."
Immediate impact for improving lives
The need for better information on how people can quit smoking is huge for public health. Smoking remains the leading cause of preventable death in the United States and accounts for more costs to the healthcare system than nearly every other modifiable health behavior, Leventhal said.
"Due to persistently low smoking cessation rates in the U.S., it is important to provide new evidence that will compel healthcare professionals and insurance plans to encourage their patients to use evidence-based smoking cessation methods," he said.
Leventhal said he hopes the data collected during the new study will help determine which FDA-approved medications are most effective for helping people quit tobacco and increase the rate at which Americans give up smoking. He also is looking forward to learning whether nonmedicinal methods anecdotally used to support quitting, such as e-cigarette vaping or taking cannabis-based products with THC or CBD, actually help people during the quitting process.
"Ideally, our findings will help doctors, nurses, psychologists, social workers and other clinicians have the knowledge of which smoking cessation aids to recommend to their patients," he said. "Also, I hope more policymakers will introduce legislation to mandate coverage of quit-smoking aids that show real-world effectiveness in our study. If more healthcare plans cover smoking cessation aids, they can help their customers and patients stay smoke-free for good."
