Table 5—

Change in respiratory symptoms between baseline and 30-day follow-up in smokers who did not change their cigarette consumption at follow-up, and in baseline smokers who quit at follow-up

	Smokers^#		Recent quitters^¶		Chi-squared	p-value⁺
	Baseline %	30 days %	Baseline %	30 days %
Do you often cough even without a cold?	46.6	49.2^§	51.6	15.5***	70.5	<0.001
Do you expectorate when you cough in the morning?	47.7	46.6^§	47.6	19.4***	38.4	<0.001
Are you out of breath after an effort like climbing stairs or a quick walk?	77.1	72.9^§	75.0	48.4***	28.6	<0.001
Do you have a wheezing respiration?	41.0	31.2***	33.7	10.3***	11.9	0.003
None of the above four symptoms	9.4	10.9*	9.1	40.1***	89.7	<0.001

^#: smokers who did not change the number of cigarettes smoked per day at follow-up, n = 266; ^¶: smoked at baseline and quit at follow-up, n = 252; ⁺: p-values for difference between groups in change over time, from Chi-squared tests. p-values for change over time within groups: *: p≤0.05; ***: p<0.001; ^§: not statistically significant, from McNemar tests.