Almost one-third of people have stopped taking a prescription drug at some time without telling their health care provider, according to the latest NPR-Truven Health Analytics Health Poll.

And while cost certainly influences whether and how people take their drugs, only 10 percent of people in this poll cited it as the reason for their behavior. A separate question asked people who filled a prescription recently whether they missed at least one dose. A full quarter said they had.

The related problems of quitting a drug without consultation with a doctor, missing doses and even not filling the prescription in the first place fall under the umbrella of medication non-adherence. About half of medications for chronic disease aren't taken as directed, according to a review published in 2012 in Annals of Internal Medicine.The problem has been estimated to result in increased hospitalizations, more premature deaths and a tab of between $100 billion and $289 billion a year.

"The implications are big, not just for the well-being of that patient but for the health care system overall," says Bruce Bender, codirector of the Center for Health Promotion at National Jewish Health in Denver.

As the results of the poll indicate, there's no single reason why people don't take their prescription drugs as directed, which means there's no single solution.

"What motivates human behavior? The economic angle is only one part," says Anil Jain, vice president and chief health informatics officer for IBM Watson Health, which owns Truven Health. The poll suggests that people earning at least $100,000 a year were more likely to report that they stopped taking a medication or missed a dose than those earning less.

When people were asked why they stopped taking a drug without consulting with a doctor, they cited side effects (29 percent); a belief they didn't need the drug (17 percent); that they were feeling better (16 percent); and that they felt the drug wasn't working (15 percent).

Bender thinks that people subconsciously do a cost-benefit analysis when faced with a decision whether to take a drug. "Into their head goes all the factors, including the benefits or what they perceive as the benefits, and the costs, including side effects and financial cost," he says.

And the benefits can be hard to gauge. People on medications for chronic diseases may not feel like their blood pressure medication or statin is working because they don't feel different. "Many people like to have a sense of immediate relief," he says.

When asked why they missed a dose of a prescribed drug, 52 percent of poll respondents said they forgot. There are a host of ways, from low-tech pillboxes to high-tech apps, to alert people that their dose is due. But that won't address the other issues. People under 35, for example, were more likely than older people to report having missed a dose, and those who did were more likely to also cite reasons like a perception that the drug wasn't working or that they felt better.

Getting people to take their medications as prescribed hasn't been easy. In August, a study of people with heart disease found a combination of electronic reminders, financial incentives and social support made no difference in adherence or clinical outcomes.

Bender says two areas have shown some promise. One is training health care providers to engage with and talk with patients about their medications. "It's moving away from the paternalistic approach of 'You go take this,' to 'Let's work together and decide whether you'll start a new drug,'" he says. This model has been shown to help in asthma, for example. Using texts and other feedback beyond reminders to help encourage patients to take their medications also seems to help.

The respondents in this poll, at least, reported actually filling prescriptions for medications that they were given in the previous 90 days, with 97 percent saying they did so. (Studies relying on prescription data instead of self-reports have found a higher proportion of prescriptions go unfilled.) Of the small minority that didn't fill the prescription or pick it up, cost was cited as the main reason.

Younger respondents were more likely to shop around and try to save money. Almost a third of people said they looked for the cost of the medication before filling the prescription, including 64 percent of people under age 35. Among that same age group, more than 20 percent responded they had purchased a drug from outside the U.S. to save money, and 34 percent said they'd used drug company coupons or rebates to help cover copays. Younger workers are more likely to use high-deductible health plans that leave them responsible for costs, according to Benefitfocus, a benefits management software company.

Bender says it's really important for people to talk with their health-care provider before stopping a drug that's been prescribed. If side effects or cost are a problem, there may be alternatives, he says.

The Truven Health Analytics-NPR Health Poll is powered by the Truven Health Analytics PULSE® Healthcare Survey, an independently funded multimodal (landline, cellphone, Internet) survey that collects information from approximately 80,000 U.S. households annually. The results depicted here represent responses from 3,003 survey participants interviewed from June 1-15, 2017. The margin of error is plus or minus 1.8 percentage points.

Katherine Hobson is a freelance health and science writer based in Brooklyn, N.Y. She's on Twitter:@katherinehobson.

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