Natural history of reactive airways dysfunction syndrome: outcome of symptoms, airway obstruction, and nonspecific bronchial hyperresponsiveness in cohort studies
| Type of exposure | No. studied/target population | Interval of time since exposure | Persistence of outcome variables | 1st author [ref no.] yr of study | ||
| Symptoms# | FEV1 <80% pred# | NSBH# | ||||
| Single, acute exposure to chlorine | 13/20 exposed workers | 12 yr | NA | NA | 5/13 (25%) | Schwartz 42 1990 |
| Acetic acid spill (hospital workers) | 51/56 exposed workers | 8 months | 8/51 | NA | 9/24 (16%) (4/7 with Sx >3 months) | Kern 46 1991 |
| Inhalation accidents reported to | 10/45 Sx>12–24 h (no pre-existing | 8±4 days+ | 9/10 | 0/10 | 8/10 (18%) | Blanc 47 1993 |
| poison-control centre | lung disease) | 3 months§ | 4/9 | 0/9 | 7/9 | |
| Single exposure to methyl-isocyanate (pesticide spill) | 197/700 exposed public (includes pre-existing lung disease) | 3–14 months | 48/197 | 2/187 (1%)¶ | 20/187 (10%)¶ | Cone 43 1994 |
| Repeated exposures to chlorine over a 3‐month period (pulp-mill workers) | 64/71 symptomatic workers (“at risk of RADS”) | 18–24 months | 58/64 | 16/51 (23%) | 29/51 (41%) | Bherer 48 1994 |
| Repeated exposures to chlorine over a 3‐month period (pulp-mill workers) | 20/29 subjects with NSBH | 30–36 months | 18/20 | 8/20 (29%) | 14/19 (48%) (6 improved) | Malo 49 1994 |
| Acute exposure to SO2 (pyrite dust explosion) | 6/7 exposed workers | 13 yrs | 6/6 | 5/6 (71%) | 4/5 (57%) | Piirila 44 1996 |
| Acute exposure to chlorine | 13 presented to first aid visit | 5–25 days+ | 13 | 1/13 | 2/13 (15%) | Leroyer 50 1998 |
| (metal production plant) | over a 4‐yr period | 3 months§ | NA | 2/13 | 0/13 | |
NSBH: nonspecific bronchial hyperresponsiveness
NA: data not available
Sx: respiratory symptoms
FEV1: forced expiratory volume in one second
pred: predicted
RADS: reactive airways dysfunction syndrome
SO2: sulphur dioxide
#: number of subjects with outcome variable/number of subjects studied (% of the target population)
¶: excluding 10 subjects with aggravation of pre-existing asthma
+: initial assessment
§: follow-up assessment