Drug allergy labels were associated with more complications after surgery

Design

Prospective multicentre cohort

Population

13,646 adults having common elective and obstetric surgery, 21 UK hospitals

Primary outcome

30-day postoperative complications (composite)

Effect

25% vs 20%; OR 1.21 (95% CI 1.10 to 1.34)

A prospective cohort in 21 NHS hospitals followed 13,646 adults having common operations — joint replacement, fracture fixation, colorectal resection, transurethral resection, caesarean delivery and hysterectomy.

Twenty-nine per cent carried at least one drug allergy label. They had more 30-day complications (25% vs 20%; OR 1.21, 95% CI 1.10 to 1.34), more surgical site infections (OR 1.19) and more infections overall (OR 1.24). Allergic reactions were more common but rare in both groups. Mortality did not differ.

Most labels — up to 90% — are thought to be wrong, and a penicillin label usually means a second-line antibiotic. This study does not prove the label causes the complications, but it gives a reason to question labels before surgery rather than after.

• Take a proper allergy history at pre-assessment: what drug, what reaction, when.
• Distinguish intolerance from allergy and record it accurately.
• Refer low-risk penicillin labels for delabelling or direct oral challenge where a pathway exists.
• Where a low-risk label remains, consider cefazolin for prophylaxis rather than a second-line agent, per local policy.

Why it matters

A line in the notes that is usually wrong may be shaping antibiotic choice and outcome.

Don't overread it

Observational: it shows labelled patients do worse, not that removing labels would change outcomes.

The statistics, in plain English

An odds ratio of 1.21 means about a fifth higher odds of any complication. In an observational study, labelled patients may differ in other ways — age, comorbidity — that the label merely marks.

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