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Profile: Cari Free

Cari Free

Cari Free

Sarah Harrop talks to public health researcher Cari Free about Txt2stop, text message-based support for smokers, in the third of a series of scientist profiles taken from our Annual Review 2011/12.

In January 2012 the Department of Health launched an affordable mobile phone support programme for smokers, which has been proven to double quit rates. This programme was developed for UK patients by Dr Cari Free at the London School of Hygiene and Tropical Medicine (LSHTM) with MRC funding. Around 1,000 smokers are now signing up each month.

Cari’s office at the LSHTM is high-ceilinged and airy. The walls are lined with medical textbooks on everything from cancer to condoms. It’s here that she works four days a week as a senior lecturer, leading research studies in public health. On the fifth day of the week she’s a GP in South London which keeps her in touch with some of the patients her research will benefit.

Smoking is a notorious public health problem, causing heart attacks, stroke and lung cancer and it’s fast becoming an epidemic in developing countries like India and China. So affordable and effective ways to help people quit are in higher demand than ever.

A few years ago, Cari heard about a study in New Zealand called Stomp, which used motivational mobile phone text messages to encourage smokers to give up. Results were promising, but it was unclear whether the text messages helped people to stop long term. So the LSHTM researchers decided to do a modified version of the study in the UK to pin down whether text message support really does help people to stay off cigarettes. After a successful pilot study, the MRC agreed to fund a large-scale trial involving 5,800 people, known as Txt2stop.

Five text messages were sent each day to participants for the first six weeks of the study, preparing them to quit by asking them to think about why they wanted to stop smoking. After the quit date they were sent supportive messages, including reassurances about when the cravings would subside.

The results were very exciting, says Cari: “The trial very clearly demonstrated that text message support doubles the number of people who quit smoking after six months compared with those who didn’t receive the texts.”

An important part of the study’s design was independently measuring whether people really had quit. So study members also had to post in samples of their saliva six months after taking part in the trial. These were tested for cotinine, a by-product of nicotine, which is a stable and reliable test of whether someone is smoking or has smoked over the previous few days.

“That was really just to check they were telling the truth,” explains Cari. “That’s important, because about 30 per cent of people who said they’d quit had either relapsed by the time they saw us or just cut down rather than quit.”

So what is Txt2stop’s secret to success? Was there a winning formula for the text messages that really cut to the core of people’s nicotine addiction?

“People said that it was like having somebody at your side reminding you that you were going to quit and why you were doing it – and the tone of the messages was definitely set up to be supportive in that way,” says Cari.

“People particularly liked the messages where they got feedback about what they’d gained and how well they’d done. For example we sent messages saying ‘shortly after you start quitting your carbon monoxide level goes back to normal’ and then they’d receive a message at the point when their levels had returned to normal saying ‘well done’. One person said she was on the way to the shops to buy cigarettes when she got that message and then turned around and went home again.”

The research team thinks the text message support works by helping to sustain people’s motivation at times when their resolve is weaker, and through providing contact and support over a 24-hour period. For example, trial members could text the word CRAVE to receive a supportive message when they were struggling with craving.

“The peak of a cigarette craving only lasts for a minute, so part of the idea behind that message was whilst you’re texting, waiting for the message to arrive and then reading it, you’re not smoking – and by that point, the craving has usually subsided,” explains Cari.

Txt2stop was equally effective for all age groups and across all levels of addiction and its benefits were so immediately clear that the Department of Health launched the programme on the NHS smoking website earlier this year.

“Smoking cessation is one of the most cost-effective interventions you can make from a public health perspective because about half of people who smoke beyond the age of 40 will shorten their life as a result. The intervention represents a major cost saving to the NHS,” says Cari.

Txt2stop could have an even bigger impact beyond our shores. The World Health Organization predicts that by 2030 the annual worldwide smoking death toll will have risen from six million to eight million, with the biggest rise occurring in poorer countries. With mobile phone usage widespread across the world, Txt2stop could offer a low-cost and effective means of helping people in these countries to give up.

Download the MRC Annual Review 2011/12: Advancing medicine, changing lives, available in pdf or ebook formats.

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