Clinical characteristics of patients with drug hypersensitivity in Norway: a single-centre study.

Background: Drug hypersensitivity reactions (DHRs) represent an important public health problem. Knowledge of their clinical characteristics will provide improved diagnostic approaches to this topic.

Objectives: The aim of the present study was to describe the clinical characteristics of patients with suspected DHRs.

Methods: The medical records of 206 outpatients with suspected DHRs, who consulted a Norwegian allergy centre from January 2005 to December 2009, were investigated in a retrospective study.

Results: Mean age (range) was 44.3 (11-84) years, and 72% of the patients were women. The most common underlying diseases justifying the use of drugs were infections (49%) and pain-related diseases (23%). Antibiotics (53%), non-steroidal anti-inflammatory drugs (NSAIDs) (32%), paracetamol (15%) and other drugs (46%), used as monotherapy or combinations, were the most often suspected drugs. Cutaneous symptoms were the most frequently reported symptoms (83%). Hospitalisation or prolonged hospitalisation was needed in 38% of the cases, and anaphylaxis was reported in 28% of all the patients. Skin prick tests were performed in 185 patients, of which 14 patients had positive test results. Drug provocation tests (DPTs) were performed in only 86 patients, six of which had positive reactions. DHRs were confirmed in 24 and rejected in 81 patients. Unsettled cases (39%) were mainly due to not performing DPTs.

Conclusions: Suspected DHRs occur predominantly in women. The most common manifestations are cutaneous symptoms, but life-threatening reactions justifying hospitalisation may occur. Antibiotics and NSAIDs are the two drug families most frequently suspected. DPTs need to be included in diagnostic protocols in order to evaluate suspected DHRs.