Is Some Physician Advice on Smoking
Cessation Better Than No Advice?
An Instrumental Variable Analysis of the 2001 National
Health Interview Survey
Yuhua Bao, Ph.D.
Naihua Duan, Ph.D.
Sarah Fox, Ed.D.
UCLA
Academy Health Annual Research Meeting
June 6, 2004
One-third smoking patients do not receive
any medical advice to quit smoking
 Nearly 1/4 of American adults remain smokers in
2001
 Of all the adult smokers, 65% had some contact with
health care providers annually. However,
 About 1/3 of these smoking patients were not
advised to quit by their providers.
2
Providers lack confidence in the
effectiveness of their advice
 Various barriers exist in providers’ intervention for
smoking cessation
 One barrier is providers’ lack of confidence
 Disbelief that their advice would deter patients
 Belief that successful intervention requires excessive time
commitment
 Few have studied the effectiveness of provider
advice performed in routine practice.
3
Why is evidence from RCTs not enough?
RCTs tell the effectiveness of …
Practitioners need to …
 Advice compared to “routine
care”
 Choose between advice and
no advice
 Well-defined intervention
modalities, certain length of
discussion by certain type of
providers
 Develop strategies suitable
for their own practice
 Advice only
 Provide advice and
additional help as needed
4
Data: NHIS 2001 Sample Adult File
Adults
1) Who were either current smokers or quit smoking
during the last 12 months, and
2) Who had contact with their regular health providers
in the past 12 months
n
Entire Sample
5,512
% of reference
population
100
Current Smokers
4,975
90
537
10
3,596
66
Patients who reported quitting
in the past 12 months
Patients who received some
advice to quit smoking
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Patients advised vs. not advised
Patient Characteristics
Advised
Not
Advised
0.07
0.16
Years of regular smoking*
# of cigarettes smoked per day**
(current smokers only)
26.2
23.1
16.4
13.1
Serious cardiovascular conditions***
Other heart conditions
Lung-breathing related conditions**
Cancer***
0.12
0.35
0.26
0.10
0.07
0.26
0.18
0.07
n
3,596
1,916
Quit smoking in the last 12
months***
Source: NHIS 2001
* p<0.1; **p<0.05; ***p<0.01
6
Use provider advice for diet and physical
activity as IVs for smoking cessation
advice
Advicei   A  Z i '  X iA ' A   iA
*
Quit i   Q   * Advicei  X iQ ' Q   iQ
*
  0  1
 A 
 Q  ~ BVN   , 
 
 0 
 
  

.
1  
Quit
Quit smoking in the last 12 months (0,1)
Advice
Received advice to quit smoking in the last 12 months (0, 1)
XA
Patient age group, presence of smoking-related conditions
XQ
Variables in XA, age started smoking, gender, education,
living with spouse, working now, social support index
Z (IVs)
1) Provider advised on diet/nutrition (0,1)
2) Provider advised on physical activity (0,1)
7
Results: Effect of some advice on oneyear smoking cessation
IV estimation
(bi-probit)
Entire Sample
Patients with no
smoking-related
conditions
No
advice
Some
Advice
No
advice
Some
Advice
6.9%
14.8%
7.3%
13.8%
8
Results: Effect of some advice on oneyear smoking cessation
Entire Sample
Patients with no
smoking-related
conditions
No
advice
Some
Advice
No
advice
Some
Advice
IV estimation
(bi-probit)
6.9%
14.8%
7.3%
13.8%
Single Probit
15.4%
7.0%
14.0%
6.8%
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Conclusions
 Smoking cessation advice as performed in routine
care doubles the probability of self-reported
abstinence within one year.
 Community practitioners should be
 Informed of the effectiveness of the way they currently
advise, and
 encouraged to provide consistent and universal advice
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