Abstract

Background: This study systematically reviews literature regarding the diagnosis of occupational asthma (OA) and compares specific inhalation challenge (SIC) testing with alternative tests.

Methods: Electronic databases and trials registries were searched; additional references were identified from bibliographic searches of included studies, hand searches of conferences, and author contacts. Various study designs (clinical trials, cohorts, cross-sectional, or case series) were included involving workers with suspected OA. All diagnostic tests were compared to a "reference standard," and two researchers independently extracted 2 x 2 data. Pooled sensitivities and specificities (95% confidence intervals [CIs]) were derived.

Results: Seventy-seven studies were included. For high molecular weight (HMW) agents, the nonspecific bronchial provocation (NSBP) test, skin-prick test (SPT), and serum-specific IgE had sensitivities > 73% when compared to SIC. Specificity was highest for specific IgE vs SIC (79.0%; 95% CI, 50.5 to 93.3%). The highest sensitivity among low molecular weight asthmagens occurred between combined NSBP and SPT vs SIC (100%; 95% CI, 74.1 to 100%). When compared to SIC, specific IgE and SPT had similar specificities (88.9%; 95% CI, 84.7 to 92.1%; and 86.2%; 95% CI, 77.4 to 91.9%, respectively). For HMW agents, high specificity was demonstrated for positive NSBP tests and SPTs alone (82.5%; 95% CI, 54.0 to 95.0%) or when combined with specific IgE (74.3%; 95% CI, 45.0 to 91.0%) vs SIC. Sensitivity was somewhat lower (60.6% and 65.2%, respectively).

Conclusions: In appropriate clinical situations when SIC is not available, the combination of a NSBP test with a specific SPT or specific IgE may be an appropriate alternative to SIC in diagnosing OA. While positive results of single NSBP test, specific SPT, or serum-specific IgE testing would increase the likelihood of OA, a negative result could not exclude OA.

Full Text

Comments

This systematic review supports the BOHRF evidence based review using inverse variance methods for random effects to calculate pooled estimates of sensitivity and specificity. Comparing results with specific challenge tests the rresults showed (mean and 95% CI) Non-specific hyper-responsibeness sensitivity 79.3% (68-88) High MW 66.7% (58-74) Low MW specificity 51.3% (35-67) High MW 63.9% (56-71) Low MW Skin prick tests sensitivity 80.6% (70-88) High MW 72.9% (60-83) Low MW specificity 59.6% (42-75) High MW 86.2% (77-92) Low MW Specific IgE sensitivity 73.3% (64-81) High MW 31.2% (23-41) Low MW specificity 79.0% (50-93) High MW 88.9% (77-92) Low MW Skin prick test plus NSBR sensitivity 60.6% (21-90) High MW specificity 82.5% (54-95) High MW

4/18/2008

Full report available at http://www.ahrq.gov/downloads/pub/evidence/pdf/asthmawork/asthwork.pdf

5/5/2010