Comparison of prevalence of asthma symptoms by written questionnaire among South African adolescents, 2002 (ISAAC III) and 2017 (GAN I)
| 2002 (ISAAC III) n (%) | 2017 (GAN I) n (%) | 2002 to 2017 OR (95% CI) | |
| Subjects n | 5037 | 3979 | |
| Wheeze ever | 1670 (33.1) | 1373 (34.5) | 1.06 (0.97–1.16) |
| Wheezing last 12 months | 1025 (20.3) | 847 (21.3) | 1.06 (0.96–1.17) |
| Four or more attacks of wheezing in last 12 months | 254 (5.0) | 230 (5.8) | 1.15 (0.96–1.39) |
| Woken by wheezing one or more nights per week in last 12 months | 252 (5.0) | 275 (6.9) | 1.41 (1.18–1.68) |
| Severe wheeze limiting speech to one or two words at a time in last 12 months | 395 (7.8) | 468 (11.8) | 1.57 (1.36–1.80) |
| Exercise-induced wheeze in last 12 months | 1641 (32.6) | 1431 (36.0) | 1.16 (1.06–1.27) |
| Night cough in last 12 months | 1846 (36.6) | 1648 (41.4) | 1.22 (1.12–1.33) |
| Diagnosis of asthma ever | 725 (14.4) | 660 (16.6) | 1.18 (1.05–1.33) |