Ex-smokers who had quit <31 days before baseline# | Ex-smokers who had quit >365 days before baseline¶ | Chi-squared | p-value+ | |||
Baseline % | 30 days % | Baseline % | 30 days % | |||
Do you often cough even without a cold? | 26.0 | 10.5*** | 14.2 | 12.4§ | 17.0 | <.001 |
Expectoration when you cough in the morning? | 33.6 | 15.2*** | 19.5 | 16.0§ | 12.9 | 0.002 |
Are you out of breath after an effort like climbing the stairs or a quick walk? | 67.5 | 48.0*** | 56.2 | 58.0§ | 33.4 | <.001 |
Do you have a wheezing respiration? | 19.9 | 5.1*** | 17.8 | 16.6§ | 15.9 | <.001 |
None of the above four symptoms | 19.5 | 42.3*** | 38.5 | 34.9§ | 62.8 | <.001 |
#: n = 220; ¶: n = 162; +: p-values for difference between groups in change over time, from Chi-squared tests. p-values for change over time within groups: ***: p<0.001; §: not statistically significant, from McNemar tests.