(Christoph Schmidt/European Pressphoto Agency)

Patients can be bullheaded, forgetful and lazy. That is why even the greatest medical breakthroughs can sometimes not have any real impact. If a patient was uncooperative, there was little a doctor could do beyond trying to coax or scare him into helping himself.

That’s changing as a growing number of researchers, insurers and health-care providers are experimenting with a new approach: offering cash.

The idea of giving people financial rewards for seeing a doctor, taking drugs or exercising has become a popular subject of study in recent years and it’s unclear whether it will become the new norm or is just a passing trend, as research findings have been mixed.

The most recent large study on the subject, published in the New England Journal of Medicine on Wednesday and involving 2,538 participants, was promising. When researchers offered rewards worth $800 to employees of CVS to get them to quit smoking, nearly everyone accepted the challenge.

In a randomized trial, patients divided into four groups with a different type of financial incentive and were all given typical care for smoking cessation, such as free nicotine replacement therapy. At six months, the rate of smoking abstinence ranged from 9.4 percent to 16 percent among those who had cash incentives while those who were not offered any money had a 6 percent improvement.

Interestingly, the biggest improvement was in the group that had the most to lose and was asked to give researchers a deposit of $150 that would be refunded if they reached the six-month mark without smoking. This group received $200 at 14 days, $200 at 30 days and $400 at six months.

Some other studies have been less successful. In February, researchers announced that two major studies, in Brooklyn and Washington, had essentially been  failure. One offered HIV patients up to $280 a year to take their pills daily; the other offered people $25 to take an HIV test and $100 to come back to get the results.

The researchers expressed disappointment but said they were trying to figure out whether more money would help – some models showed that $5,000 a year could be the magic number -- or whether it could work for patients with certain demographics.