Determining the negative predictive value of provocation tests with beta-lactams.
BACKGROUND
The beta-lactam allergic work-up is mostly standardized. However, the negative predictive value of drug provocation tests is not yet well established.


METHODS
A historical-prospective multicentre cohort study was conducted in four centres (one in France, one in Portugal, two in Italy) to assess the negative predictive value of provocation tests with beta-lactams in patients initially tested for a suspicion of drug allergy/hypersensitivity. Patients were contacted at least 6 months after the work-up, between 2003 and 2007. A new allergic work-up was proposed to reacting patients.


RESULTS
Among the 457 patients included, 365 (79.9%) were followed up (159 [79.1%] from France, 153 [82.7%] from Italy and 53 [74.6%] from Portugal). Only 118 (25.8%) were re-exposed to the negatively tested beta-lactam. Nine (7.6%) reported a non-immediate (occurring more than 1 h after drug administration) reaction: five urticaria, three exanthema and one undefined cutaneous reaction. None were severe. Only four accepted a re-challenge, negative in two cases and positive in the two others. The negative predictive value was 94.1% (89.8-98.3) (111 out of 118 patients).


CONCLUSIONS
Although the negative predictive value of drug provocation tests may not be 100%, none of the false negative patients experienced a life-threatening reaction. This should reassure doctors who might hesitate to prescribe beta-lactams, even in patients with negative allergic work-ups.
Exploration des Allergies, Service des Maladies Respiratoires and Inserm U657, Hôpital A de Villeneuve, University Hospital of Montpellier, avenue du Doyen Gaston Giraud, Montpellier Cedex, France.
P
P
Demoly
A
A
Romano
C
C
Botelho
L
L
Bousquet-Rouanet
F
F
Gaeta
R
R
Silva
G
G
Rumi
J
J
Rodrigues Cernadas
P J
PJ
Bousquet
D001985:Bronchial Provocation Tests; D015331:Cohort Studies; D004342:Drug Hypersensitivity / Q000175:diagnosis*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D047090:beta-Lactams / Q000009:adverse effects* / Q000276:immunology
D047090:beta-Lactams