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Why Antibiotic Allergy De-labelling Is Important

Small retrospective studies initially suggested that being labeled as antibiotic-allergic results in frequent subsequent sub-optimal antibiotic therapy and clinical outcomes.

These effects were now more recently examined in a large national prospective surveillance study in Australia;

Australian hospitals gathered by the National Antimicrobial Prescribing Survey to assess the effect of recording a patient as being antibiotic allergic on subsequent antibiotic prescribing.

-21, 031 patients

-33, 421 antimicrobial prescriptions:

-18% had received an antimicrobial allergy label (AAL)

-no description of the allergic manifestation was available so some may not, in fact, have been immune mediated.

Compared to those with no antimicrobial allergy label (NAAL), those with an AAL were

-older (65 vs 71 years, respectively)

-59% were female. Patient Mix:

-25% solid organ transplant

-25% respiratory units

Among those with an antimicrobial allergy label (AAL): drugs IMPLICATED included

  1. β-lactams (13.1%)* Most frequently implicated

  2. Sulfonamides (2.1%)

  3. Macrolides (1.3%);

  4. Tetracyclines (<1%)

  5. Fluoroquinolones (<1%)

  6. Glycopeptides (<1%).

Of those labeled with a β-lactam allergy, 5.1%, 2%, and 1.1% were recorded as also having concomitant sulfonamide, fluoroquinolone, or glycopeptide allergy, respectively.

Examination of the inverse relationship found that β-lactam allergy was recorded in 31% with a putative sulfonamide allergy, as well as 43% and 28% with a fluoroquinolone or glycopeptide allergy, respectively.

An assessment of appropriateness of antimicrobial therapy was based on

(1) compliance with the national or locally endorsed guidelines

(2) antimicrobial coverage of causative pathogens

(3) use of narrow-spectrum antimicrobials when possible

(4) dosage and/or route

(5) duration

(6) allergy mismatch or drug interaction

(7) surgical prophylaxis duration <24 hours.

Based on this analysis, inappropriate antimicrobial use was significantly more frequent in the AAL group than in the NAAL group (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.05–1.22; P < .002).

The median number of antibiotics prescribed per patient was modestly higher in AAL than in NAAL patients (1.47 vs 1.44; P = .024) and they were less frequently concordant with the Australian Antibiotic Guidelines (2713/6309 [43.0%] vs 12 291/27 240 [45.1%]; P = .009).

Patients with an AAL were more likely to be prescribed restricted antibiotics (third- or fourth-generation cephalosporin, fluoroquinolone, glycopeptide, or carbapenem) (OR, 1.95; 95% CI, 1.78–2.15; P < .0001).

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