What are Cochrane Reviews

Cochrane Reviews are systematic reviews of primary research in human health care and health policy, and are internationally recognised as the highest standard in evidence-based health care. They investigate the effects of interventions for prevention, treatment, and rehabilitation. They also assess the accuracy of a diagnostic test for a given condition in a specific patient group and setting.

Each systematic review addresses a clearly formulated question, for example: Can antibiotics help in alleviating the symptoms of a sore throat? All the existing primary research on a topic that meets certain criteria is searched for and collated, and then assessed using stringent guidelines, to establish whether or not there is conclusive evidence about a specific treatment. The reviews are updated as new evidence becomes available, ensuring that treatment decisions can be based on the most up-to-date and reliable evidence.

Cochrane Reviews are widely used to inform healthcare guidelines, best practice guidance in primary care and patient decision aids in shared decision making initiatives.

Source: Systematic reviews explained

What are the results of the review?

“More people probably stop smoking for at least six months using nicotine e‐cigarettes than using nicotine replacement therapy (3 studies; 1498 people), or nicotine‐free e‑cigarettes (3 studies; 802 people).

Nicotine e‐cigarettes may help more people to stop smoking than no support or behavioural support only (4 studies; 2312 people).

For every 100 people using nicotine e‐cigarettes to stop smoking, 10 might successfully stop, compared with only six of 100 people using nicotine‐replacement therapy or nicotine‐free e‐cigarettes, or four of 100 people having no support or behavioural support only.

We are uncertain if there is a difference between how many unwanted effects occur using nicotine e‐cigarettes compared with using nicotine‐free e‐cigarettes, nicotine replacement therapy, no support or behavioural support only. Similar low numbers of unwanted effects, including serious unwanted effects, were reported for all groups.

The unwanted effects reported most often with nicotine e‐cigarettes were throat or mouth irritation, headache, cough and feeling sick. These effects reduced over time as people continued using nicotine e‐cigarettes.”

Why was this Cochrane Review done

“Stopping smoking lowers your risk of getting lung cancer and other diseases. But many people find it difficult to quit. We wanted to find out if using e‐cigarettes could help people to stop smoking, and if people using them for this purpose experienced any unwanted effects.”

What did the Cochrane Review do?

“We searched for studies that looked at the use of e‐cigarettes to help people stop smoking.

We looked for randomized controlled trials, in which the treatments people received were decided at random. This type of study usually gives the most reliable evidence about the effects of a treatment. We also looked for studies in which everyone received an e‐cigarette treatment.

We were interested in finding out:

· how many people stopped smoking for at least six months; and
· how many people had any unwanted effects.

We included studies that reported on smoking habits for at least six months, or reported on unwanted effects for at least one week.

Search date: We included evidence published up to January 2020.”

What did the Cochrane Review find

“We found 50 studies in 12,430 adults who smoked. The studies compared e‑cigarettes with:

· nicotine replacement therapy, such as patches or gum;

· varenicline;
· nicotine‐free e‐cigarettes;
· behavioural support, such as advice or counselling; or
· no support, for stopping smoking.

Some studies also tested using NRT and e‐cigarettes together.

The studies took place in the USA (21 studies), the UK (9), Italy (7), Australia (2), New Zealand (2), Greece (2), and one study each in Belgium, Canada, Poland, South Korea, South Africa, Switzerland and Turkey.”

Key message

“Nicotine e‐cigarettes probably do help people to stop smoking for at least six months. They probably work better than nicotine replacement therapy and nicotine‑free e‐cigarettes.

They may work better than no support, or behavioural support alone, and they may not be associated with serious unwanted effects.

However, we need more, reliable evidence to be confident about the effects of e‐cigarettes, particularly the effects of newer types of e‐cigarettes that have better nicotine delivery.”