NPC Archive Item: Informing smokers about their lung age may help them to stop smoking

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Parkes G, Greenhalgh T, Griffin M, et al. Effect on smoking quit rate of telling patients their lung age : the Step2quit randomised controlled trial. BMJ Online first doi:10.1136/bmj.39503.582396.25 (published 6 March 2008)

What is the background to this?

NICE guidance makes recommendations on brief interventions and referral for smoking cessation in primary care and other settings. NICE advises that everybody who smokes should be encouraged to quit, opportunistically, at least once a year. The interventions offered will depend on a number of factors, including the individual’s willingness to quit, how acceptable they find the intervention on offer and the previous ways they have tried to quit. However, brief interventions typically take between 5 and 10 minutes and should include one or more of the following: simple opportunistic advice to stop, an assessment of the patient’s commitment to quit, an offer of pharmacotherapy and/or behavioural support, provision of self-help material and referral to more intensive support such as NHS smoking cessation services.

This study suggests that testing a smoker’s lung age with spirometry, and providing information in an understandable and visual way, is potentially an effective, brief intervention that helps more people to stop smoking.

What does this study claim?

This randomised controlled trial (n=561) found that telling smokers their lung age following spirometry significantly improved the likelihood of them stopping smoking compared with simply giving them results in terms of forced expiratory volume at one second (FEV1). Lung age is the age of the average healthy person who has an FEV1 equal to the smoker being tested. It was developed as a way of making spirometry data more understandable and as a potential psychological tool to show smokers the apparent premature aging of their lungs.

All the participants had spirometry to assess their lung function. Participants in the intervention group received their results in terms of lung age and graphs were used as a visual aid to explain how lung function gradually reduces with age, and that smoking can damage the lungs as if they are aging more rapidly than normal. They were also told that smoking cessation would slow the rate of lung deterioration back to normal, but would not repair the damage already done. Participants in the control group received a raw figure for FEV1 with no further explanation. Both groups were advised of the importance of stopping smoking and offered referral to NHS smoking cessation services. It was also explained that the lung function test did not give the risk of serious diseases related to smoking (e.g. lung cancer, heart disease or stroke).

After 12 months, verified quit rates were 6.4% in the control group and 13.6% in the intervention group (absolute difference 7.2%, 95%CI 2.2% to 12.1%; p=0.005). The number needed to treat (NNT) for telling smokers their lung age, and presenting the information in an understandable, visual way, is 14 to achieve one additional sustained quitter.

So what?
The study shows that testing lung age and giving individualised feedback, explaining the results clearly, verbally and in writing, encourages significantly more patients to give up smoking compared with giving them simple test results without explanation. An editorial accompanying the study states that, although the study has some limitations (e.g. lack of information about the comparability of the study sample with the entire recruitment population, longer duration of contact between participants and caregivers in the intervention group than in the control group, and outcome data that are limited to point-prevalence abstinence) providing feedback on lung age with graphic displays seems to be the best option so far for communicating the results of spirometry.

The authors of the article suggest that lung age testing could be considered as part of a brief intervention package in smokers to encourage them to stop, and to actively find cases of chronic obstructive pulmonary disease (COPD). However, this strategy is not advised in current NICE guidance on smoking cessation or COPD.

The full paper gives the table used to calculate lung age, which you can access here (subscription to BMJ may be required).

Action – People who smoke should be advised about the dangers of continuing to do so and given advice about stopping. Healthcare professionals should follow NICE guidance on brief interventions for smoking cessation. Testing a smoker’s lung age with spirometry, and providing information in an understandable and visual way, could be a useful additional option.

Further information on smoking cessation will be available in due course on the respiratory tract floor of NPC.

Study details
The study included 561 smokers aged 35 years and over from five general practices in Hertfordshire. Patients receiving oxygen, and those with a history of lung cancer, tuberculosis, asbestosis, silicosis, bronchiectasis or pneumonectomy were excluded. Participants were randomised to receive results of spirometry as FEV1 or in terms of lung age. There were few significant differences in patient characteristics at baseline. However, there were significantly more people with a history of stroke in the control group. Overall, the incidence of co-morbidity was around 20%. Follow-up at 12 months was available in 89% of participants.

The primary outcome measure was smoking cessation after 12 months, verified by salivary cotinine testing. Despite an average of 33 pack years of smoking, only 23.5% of the control group and 26.8% of the intervention group had an abnormal baseline lung function. Significantly more patients in the intervention group stopped smoking (6.4% compared with 13.6% (absolute difference 7.2%, 95%CI 2.2% to 12.1%; p=0.005); NNT=14. There was no evidence that individuals with poorer lung age deficits were more likely to quit, although the study was not powered to detect this.

The study was funded via a ‘leading practice through research award’ from the Health Foundation

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