Comparison of asthma severity after cessation or reduction of exposure to the causative agent
| Causative agent | Persistence of symptoms | Persistence of NSBH | Improvement of asthma# | Worsening of asthma# | 1st author [ref no.] | Year of study |
| Cessation of exposure | ||||||
| Colophony | 16/20 | 3/7 | 5/7 | 0/7 | Burge 7 | 1982 |
| Isocyanates | 10/20 | 9/12 | 10/20 | 6/20 | Rosenberg 9 | 1987 |
| Isocyanates | 31/43 | 31/43 | 22/43 | 5/43 | Pisati 11 | 1993 |
| Isocyanates | NA | 6/9 | 3/9 | 0/9 | Paggiaro 12 | 1993 |
| Red cedar | 37/75 | 25/33 | 20/33 | 4/33 | Chan-Yeung 14 | 1982 |
| Latex | 13/16 | 16/16 | 8/16 | 1/16 | Vandenplas 15 | 2002 |
| Total | 107/174 (61) | 90/120 (75) | 68/128 (53) | 16/128 (12) | ||
| Reduction of exposure | ||||||
| Colophony | 5/8 | 4/4 | 1/4 | 0/4 | Burge 7 | 1982 |
| Isocyanates | 7/7 | 7/7 | 4/7 | 0/7 | Rosenberg 9 | 1987 |
| Isocyanates | 17/17 | 17/17 | 0/17 | 13/17 | Pisati 11 | 1993 |
| Isocyanates | NA | 4/7 | 3/7 | 0/7 | Paggiaro 12 | 1993 |
| Red cedar | 50/50 | 22/22 | 0/22 | 9/22 | Chan-Yeung 14 | 1982 |
| Latex | 16/20 | 19/20 | 15/20 | 0/20 | Vandenplas 15 | 2002 |
| Total | 95/102 (93) | 73/77 (95) | 23/77 (30) | 22/77 (28) |
Data are presented as number of subjects with outcome variable/number of subjects studied, data in the totals rows are presented as number of subjects with outcome variable/number of subjects studied (% with outcome variable)
NA: data not available
NSBH: nonspecific bronchial hyperresponsiveness
#: improvement and worsening of asthma assessed on changes in symptoms and/or medication 9, NSBH 7, 12, 14, 15, or a combination of symptoms, spirometry, and NSBH 11