| Number (%)with symptoms | Change in symptoms* | |||||
| Baseline | Follow-up | Number reduced | Number increased | Number no change | p Value† | |
| (A) Smokers (n = 65) | ||||||
| Respiratory symptoms | ||||||
| Median number of symptoms (IQR) | 2 (1–3) | 1 (0–3) | 28§ | 14§ | 23 | 0.03‡ |
| Any symptom | 55 (85) | 46 (71) | 11 | 2 | 52 | 0.059 |
| Wheezing/whistling | 31 (48) | 20 (31) | 14 | 3 | 48 | 0.006 |
| Shortness of breath | 27 (42) | 19 (29) | 12 | 4 | 49 | 0.038 |
| Cough, morning | 24 (37) | 17 (26) | 13 | 6 | 46 | 0.084 |
| Cough, rest of day or night | 37 (57) | 33 (51) | 14 | 10 | 41 | 0.271 |
| Phlegm production | 26 (40) | 20 (31) | 9 | 3 | 53 | 0.073 |
| Sensory symptoms | ||||||
| Median number of symptoms | 1 (0.75–2) | 1 (0–2) | 23§ | 9§ | 33 | 0.234‡ |
| Any symptom | 49 (75) | 40 (62) | 14 | 5 | 46 | 0.091 |
| Eyes, red or irritated | 23 (35) | 16 (25) | 8 | 1 | 56 | 0.02 |
| Nose, runny or sneezing | 35 (54) | 36 (55) | 10 | 11 | 44 | 0.5 |
| Throat, sore or scratchy | 32 (49) | 24 (37) | 15 | 7 | 43 | 0.067 |
| (B) Smokers who did not report a cold at either baseline or follow-up (n = 48) | ||||||
| Respiratory symptoms | ||||||
| Median number of symptoms | 2 (1–3) | 1.5 (0–3) | 21§ | 10§ | 17 | 0.056‡ |
| Any symptom | 40 (83) | 35 (73) | 7 | 2 | 39 | 0.203 |
| Wheezing/whistling | 23 (48) | 16 (33) | 9 | 2 | 37 | 0.033 |
| Shortness of breath | 22 (46) | 13 (27) | 12 | 3 | 33 | 0.018 |
| Cough, morning | 18 (38) | 14 (29) | 9 | 5 | 34 | 0.212 |
| Cough, rest of day or night | 27 (56) | 24 (50) | 10 | 7 | 31 | 0.315 |
| Phlegm production | 19 (40) | 14 (29) | 6 | 1 | 41 | 0.062 |
| Sensory symptoms | ||||||
| Median number of symptoms | 1 (0–2) | 1 (0–2) | 16§ | 8§ | 24 | 0.377§ |
| Any symptom | 34 (71) | 27 (56) | 11 | 4 | 33 | 0.324 |
| Eyes, red or irritated | 17 (35) | 12 (25) | 6 | 1 | 41 | 0.062 |
| Nose, runny or sneezing | 23 (48) | 24 (50) | 7 | 8 | 33 | 0.5 |
| Throat, sore or scratchy | 21 (44) | 17 (35) | 10 | 6 | 32 | 0.227 |
*Reduction: symptoms at baseline, none at follow-up; increase: no symptoms at baseline, symptoms at follow-up; †the p value relates to the McNemar test for matched pairs, with exact probabilities based on a binomial assumption with the exception of ‡which relates to the Wilcoxon–Mann–Whitney test; §reduction: fewer symptoms at follow-up; increase: more symptoms at follow-up. IQR, interquartile range.