Effect on smoking quit rate of telling patients their lung age: the Step2quit randomised controlled trial.
OBJECTIVE
To evaluate the impact of telling patients their estimated spirometric lung age as an incentive to quit smoking.


METHODS
Randomised controlled trial.


METHODS
Five general practices in Hertfordshire, England.


METHODS
561 current smokers aged over 35.


METHODS
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.


METHODS
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.


RESULTS
Follow-up was 89%. Independently verified quit rates at 12 months in the intervention and control groups, respectively, were 13.6% and 6.4% (difference 7.2%, P=0.005, 95% confidence interval 2.2% to 12.1%; number needed to treat 14). People with worse spirometric lung age were no more likely to have quit than those with normal lung age in either group. Cost per successful quitter was estimated at 280 pounds sterling (366 euros, $556). A new diagnosis of obstructive lung disease was made in 17% in the intervention group and 14% in the control group; a total of 16% (89/561) of participants.


CONCLUSIONS
Telling smokers their lung age significantly improves the likelihood of them quitting smoking, but the mechanism by which this intervention achieves its effect is unclear.


BACKGROUND
National Research Register N0096173751.
Parkes
Gary
G
The Limes Surgery, Hoddesdon, Hertfordshire EN11 8EP. Parkesko@hotmail.co.uk
Greenhalgh
Trisha
T
Griffin
Mark
M
Dent
Richard
R
D000328:Adult; D000367:Age Factors; D000368:Aged; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008171:Lung Diseases / Q000503:physiopathology*; D008875:Middle Aged; D011379:Prognosis; D012907:Smoking / Q000503:physiopathology* / Q000523:psychology; D016540:Smoking Cessation / Q000523:psychology / Q000706:statistics & numerical data*; D013147:Spirometry; D014797:Vital Capacity / Q000502:physiology