Oral Provocation Test in Non-Steroidal Anti-Inflammatory Drug Hypersensitive Patients Referred to Singapore General Hospital

Abstract

Introduction: Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently prescribed classes of drugs and are easily accessible as over-the-counter anti-inflammatory drugs in Singapore. NSAIDs hypersensitivity is the second most common referral to allergy clinic in a tertiary referral centre. Methods: Referred patients with history of NSAID intolerance were underwent open challenge with 1) putative NSAID to confirm the diagnosis; 2) Aspirin to determine the cross-reactivity or 3) selective cyclooxygenase-2 (COX-2) inhibitor to identify the suitable alternative. Data were analysed retrospectively. Results: Over a 4-year period (2010-2014), a total of 127 patients (mean age SD 40.7 /- 15.2) underwent a total of 155 open-labelled labelled NSAIDs oral provocation tests (OPT). Overall positive challenge rate is 26.5% (41 out of 155). Despite having a clinical relevant history of causative, only 29.4% (20 out of 68) had positive OPT to putative NSAIDs. Using selective COX-2 inhibitor challenge for assessing the tolerability of suitable alternative, we found only 8.8% (5 out of 57) positive challenge. Conclusions: In our 4-year patients cohort with history of NSAIDs of intolerance, positive OPT rate of 26.5% in confirming diagnosis of NSAIDs hypersensitivity. The intolerance to selective COX-2 inhibitor was found in 8.8% of patients with non-steroidal anti-inflammatory drugs hypersensitivity patients.