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Research

# Effect on smoking quit rate of telling patients their lung age: the Step2quit randomised controlled trial

BMJ 2008; 336 (Published 13 March 2008) Cite this as: BMJ 2008;336:598
1. Gary Parkes, general practitioner1,
2. Trisha Greenhalgh, professor 2,
3. Mark Griffin, lecturer in medical statistics2,
4. Richard Dent, consultant chest physician department of chest medicine3
1. 1The Limes Surgery, Hoddesdon, Hertfordshire EN11 8EP
2. 2Department of Primary Care and Population Sciences, University College London, London N19 5LW
3. 3Queen Elizabeth II Hospital, Welwyn Garden City, Hertfordshire AL7 4HQ
1. Correspondence to: G Parkes Parkesko{at}hotmail.co.uk
• Accepted 30 January 2008

## Abstract

Objective To evaluate the impact of telling patients their estimated spirometric lung age as an incentive to quit smoking.

Design Randomised controlled trial.

Setting Five general practices in Hertfordshire, England.

Participants 561 current smokers aged over 35.

Intervention All participants were offered spirometric assessment of lung function. Participants in intervention group received their results in terms of “lung age” (the age of the average healthy individual who would perform similar to them on spirometry). Those in the control group received a raw figure for forced expiratory volume at one second (FEV1). Both groups were advised to quit and offered referral to local NHS smoking cessation services.

Main outcome measures The primary outcome measure was verified cessation of smoking by salivary cotinine testing 12 months after recruitment. Secondary outcomes were reported changes in daily consumption of cigarettes and identification of new diagnoses of chronic obstructive lung disease.

## Discussion

This large randomised controlled trial with adequate follow-up and independent proof of cessation has shown that individualised feedback of “lung age” is effective in promoting smoking cessation. This study strongly supports the policy of giving patients their spirometry results expressed as “lung age” along with advice about the dangers of continuing to smoke and methods of quitting.

### Comparison with other research

In 2001 a non-systematic overview analysed 12 studies that provided feedback on personal biomarkers as part of strategies to change behaviour in smokers.12 The authors concluded that success was likely to depend on how the information was conveyed and understood and how it related to behaviour. They also suggested that success might depend on graphic displays or written individualised information as well as the prospect of gain rather than negative messages about costs or disadvantage.

A Cochrane review of the evidence for the effectiveness of biomarkers in smoking cessation was published in October 2005.6 Observational studies were included in the background discussion but only randomised controlled trials were included in the analysis, which concluded that because of limited evidence no definitive statements could be made about the effectiveness of assessment of biomarkers as an aid for smoking cessation.6 None of the primary studies included in the Cochrane review had used “lung age” in the intervention. The negative conclusions of that review should be updated in the light of this new study.

The debate about the usefulness of screening with spirometry was recently rekindled by a large non-randomised observational study of 4494 smokers from Poland.7 Their results indicated that spirometry promoted cessation. Those with airways obstruction were more likely to quit, but even the group with normal lungs on spirometry had a higher quit rate (12%) than would normally be expected after simple advice from a physician (4-6%).13 They did not use “lung age” to explain results to participants but did use a visual display of Fletcher and Peto’s diagram11 to compare the participant’s result with the average for age and project the likely deterioration with continued smoking. These authors did not have a control group but attributed the high quit rates in those with normal lung function to a “healthy volunteer” effect (those who had opted for the programme were seen as more motivated to quit).

The results of our study are broadly consistent with the findings of the Polish observational study, with one important difference. Contrary to the conclusions of the latter (and to clinical speculation), we found no evidence that successful quitting depends on the severity of lung damage as demonstrated by spirometry. Our study, however, was not powered to detect this difference, and we found, for example, that a 45 year old smoker who is told that their “lung age” is normal is as likely to quit as one who is told that his or her “lung age” is 65. Presentation of information in an understandable and visual way, whether the news is positive or negative, seems to encourage higher levels of successful smoking cessation than when patients are given feedback that is not easily understandable.

### What makes people quit

What triggers the decision to quit and which methods result in successful and sustained quitting? Clinical experience suggests that deterioration in health does not necessarily lead to altered behaviour, whether that is related to smoking, drugs, or diet. The high rate of comorbidity (20%) in our participants confirms that many people who are likely to exacerbate a chronic health problem by smoking continue to smoke. Anecdotally, some participants in our trial were relieved when the results were found to be normal and therefore thought it was “not too late” to be trying to quit.

This apparent win-win situation might explain the apparently paradoxical finding that knowing one’s lung age helps a smoker to quit whatever the result. If lung age is normal there is an incentive to stop before it is too late. If lung age is abnormal then this is a clear message that the lungs are undergoing accelerated deterioration that would be slowed if the smoker stopped. Further research is needed to elucidate the psychological forces that are active in successful quitting in different circumstances.

In this study, we measured stage of change (using Prochaska and DiClemente’s transtheoretical model14) to ensure that the groups were comparable for this variable at baseline, but the study was underpowered to test the hypothesis that a smoker in the “active” phase of quitting would find feedback on lung age more useful than someone in the “pre-contemplative” phase. Some addiction experts have proposed that the transtheoretical model should be rejected in favour of a new integrated model.15 16 Any new psychological theory of smoking cessation will need to explain the unexpected finding that normal results within personal biomarkers are as likely to promote cessation as abnormal ones.

Current National Institute for Health and Clinical Excellence guidelines include one on brief interventions and referral for smoking cessation17 18 (which do not mention spirometry testing at all) and another on the management of chronic obstructive pulmonary disease.4 The implication is that spirometry testing is useful only when the patient has (or is suspected of having) established lung damage. Our results suggest that both these guidelines should be reviewed and that lung age testing (which is a quick, office based test that can be undertaken by a healthcare assistant) should be considered as part of a brief intervention package—either in all smokers over 35 (the lower age limit for this study) or all smokers. Currently the new contract for general practitioners in the UK includes incentives to confirm the diagnosis of chronic obstructive pulmonary disease with spirometry and to record smoking status in those with a record of relevant comorbidity (coronary heart disease, hypertension, diabetes, stroke, and asthma) and to give cessation advice. There is no incentive, however, to actively find cases of chronic obstructive pulmonary disease among smokers (or ex-smokers) in these high risk groups or in the general population. We recommend that the new UK NHS general practitioner contract should include incentives for spirometric assessment accompanied by individualised communication of lung age in smokers.

Our cost estimates, which assume that spirometry is carried out in UK general practice, suggest that estimation and communication of lung age is of comparable effectiveness to, and potentially cheaper than, other currently available treatments on the NHS, including nicotine replacement therapy,19 bupropion,20 face to face counselling,21 and telephone counselling.22 Given the heavy health and economic burden of smoking, we believe that formal economic evaluation of this new and simple intervention should be a research priority.

#### What is already known on this topic

• There is insufficient evidence to make a definitive statement about the evidence for the effectiveness of biomarkers (including spirometry) in smoking cessation

• Smoking cessation rates can be improved by reporting estimation of lung age with spirometry in primary care

• Screening smokers over the age of 35 could reduce smoking and improve early diagnosis of chronic obstructive pulmonary disease

## Footnotes

• We thank Liane Andrews (healthcare assistant) and members of the practice based steering group of nurses, manager, and lay members. We also thank the doctors and staff of the five local general practice surgeries for their help and cooperation. We thank P W Jones for permission to use the St George’s respiratory questionnaire and for supplying copies of the questionnaire and the electronic scoring tool.

• Contributors: All authors made a substantial contribution to: conception and design, or analysis and interpretation of data, drafting the article or revising it critically for important intellectual content, and final approval of the version to be published. GP conceived, designed, and piloted the original study. The work formed part of a research PhD thesis at University College London, with TG and RD as supervisors. MG supplied statistical advice and analysis and wrote the statistical section. GP is guarantor.

• Funding: Leading practice through research award from the Health Foundation.

• Competing interests: None declared.

• Ethical approval: Hertfordshire local research ethics committee (application number EC03718) and West Essex local research ethics committee (1608-0104).

• Provenance and peer review: Not commissioned; externally peer reviewed.