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CAL (CHRONIC AIRFLOW LIMITATION) BENEFITS FROM SMOKING CESSATION

Clinical Bottom Lines:

The evidence is limited, but does suggest increased long-term survival and decreased decline of FEV₁ if COPD patients quit smoking.

Benefit can be seen even in severe COPD (FEV₁ < 1.0 litre).

Appraised by: HN Lee, December 6th 1992

The Evidence:

The Inception Cohort: Outpatient COPD patients without severe hypoxemia.

The Outcomes: Annual decline of FEV₁ and all-cause mortality.

Study and Length of Follow-up

Cohort (n)

FEV₁ decline

Survival

Postma et al [1]

Follow-up: 2-21 years

59 smokers

22 smokers who quit

87 ± 5 ml/yr

47 ± 7 ml/yr

not reported

Hughes et al [2]

Follow-up: ave. 3 years

37 smokers

19 smokers who quit

54 ± 5 ml/yr

16 ± 9 ml/yr

p < .001

8/37 = .22

3/19 = .16

p = .60

Kanner et al [3]

Follow-up: 12 years

21 non-smokers

24 smokers who quit

55 smokers

Not analyzed

12 year F/U:

86% survival

79% survival

64% survival

Postma et al [4]

Follow-up: 18 years

SEVERE COPD (FEV₁ < 1.0)

83 smokers

46 smokers who quit

Not analyzed

18 year F/U:

Mortality Risk

Ratio approx 1.4

p < .01

NIH IPPBT, Anthonisen [5]

Follow-up: 2.5 years

985 COPD patients

133 lost to follow-up

Reported as "negative", but no data given.

Not analyzed

Comments:

1. Some studies show an increased short-term mortality in the smoking cessation cohort but this is thought to reflect the acute event at the time of inception cohort.

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REFERENCES:

[1] Postma DS et al. Long-term COPD course of lung function. Am Rev Resp Dis 1986;134(2):276-280.

[2] Hughes JA et al. The influence of cigarette smoking and lung function. Q J Med 1982;51(202):115-124.

[3] Kanner RE et al. Predictors of COPD survival. Am J Med 1983;74:249-255.

[4] Postma DS et al. Survival and CAL. Eur J Resp Dis 1985 67(5):360-368.

[5] Anthonisen et al. Prognosis in COPD. Am Rev Resp Dis 1986;133:14-20.

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