Prevalence of reported drug allergy and its impact on Beta lactam use with financial and health implications

Background:While recognition and documentation of true drug allergy is critically important, most physicians acknowledge that its prevalence is likely overestimated, often on the basis of historical, sometimes anecdotal evidence. Correct or not, once applied, drug allergy labels may result in altered, potentially inferior therapy, increased costs and prolonged hospitalisation. Objective:Estimate the point prevalence, accuracy and symptomatology of self-reported drug allergy in a typical, large NHS Acute Trust adult inpatient population. In the subset with penicillin allergy (PA), estimate additional management costs from the use of alternative antibiotics and readmission rates in the previous 5 years. Methods:Data on self-reported drug allergies were extracted from 440 adult inpatient prescription charts over a 4 month period. Where penicillin allergy (PA) was reported, alternative antibiotic regimens were recorded and their additional costs calculated. Hospital electronic records were used to assess readmission rates of PA patients. Results:194/440 inpatients (44.5%) reported at least one drug allergy. Antibiotic allergy was most commonly reported (51%), followed by analgesic (23%) and antiemetic (12%) allergy. PA accounted for 76% of reported antibiotic allergy. The commonest reported symptoms were cutaneous (42%) and gastrointestinal (18%). Where antibiotic therapy was required for patients with PA to manage acute infections, Ciprofloxacin, Clarithromycin, Teicoplanin, Clindamycin and Cefuroxime were the most commonly employed alternatives. Extrapolation of these figures to include the entire Trust inpatient population suggested that the use of alternative antibiotics in PA patients incurred additional annual expenditure of £268,000. Further, 87% of PA patients had been admitted more than once in the preceding 5 years, with 74% requiring further courses of antibiotics during these admissions. Conclusion:Self-reported drug allergy, and in particular PA, is common in hospital inpatient populations and, in addition to the potentially unnecessary hazards to individual patients resulting from the use of alternative antibiotics, results in a considerable additional financial burden to the healthcare system. This problem could be eliminated by the provision of a nationwide and equitable tertiary Allergy service