| First author [ref.] | Agent | Assessment of NSBHR# | Reduction of exposure | Cessation of exposure | ||||
| NSBHR recovered¶ | NSBHR improved+ | NSBHR worse | NSBHR recovered | NSBHR improved+ | NSBHR worse | |||
| Burge [11] | Colophony | H PC20 <32 mg·mL−1; >1 doubling concentration§ | 1/8 | 2/8 | 1/8 | 9/20 | 11/20 | 0/20 |
| Rosenberg [12] | Isocyanates | A PC15 <0.1 mg·mL−1; >1 doubling concentration§ | 0/6 | 0/6 | 2/6 | 0/14 | 5/14 | 1/14 |
| Paggiaro [15] | Isocyanates | M PD20 <1 mg; >1 doubling dose | 3/7 | 4/7 | 0/7 | 3/9 | 5/9 | 0/9 |
| Vandenplas [18] | Latex | H PC20 <16 mg·mL−1; >3-fold increase in PC20 | 1/20 | 15/20 | NA | 0/16 | 8/16 | NA |
| Munoz [20] | Persulfate salts | M PC20 <8 mg·mL−1; >3.2-fold increase in PC20 | 0/3 | 0/3 | 1/3 | 5/7 | 6/7 | 0/7 |
| Pooled estimate | 5/44 | 21/44 | 4/24 | 17/66 | 35/66 | 1/50 | ||
| 15.5% (5.7–35.5%) | 39.1% (14.7–70.5%) | 21.4% (8.5–44.2%) | 28.8% (10.1–59.3%) | 51.9% (39.3–64.2%) | 5.2% (1.5–16.4%) | |||
H: histamine; PC/PD15/20: concentration or dose of the pharmacological agent inducing a 15 or 20% fall in forced expiratory volume in 1 s; A: acetylcholine; M: methacholine; NA: not available. #: cut-off values for asthma and significant improvement; ¶: recovery from NSBHR was considered when the concentration or dose of the pharmacological agent inducing the specified functional change exceeded the cut-off value for asthma at the follow-up assessment; +: subjects with improved NSBHR, including those who recovered; §: threshold value for a significant change assigned by the authors.