- Design
- Retrospective single-centre diagnostic study
- Population
- 100 consecutive sera with suspected bullous pemphigoid
- Primary outcome
- Sensitivity of LABD97, BP180 NC16A and BP230 IgG ELISAs
- Effect
- 87% vs 66% vs 52%; 83% of double-negative sera LABD97 positive
A US immunodermatology laboratory tested 100 consecutive sera from patients with suspected bullous pemphigoid who had epidermal-pattern IgG on salt-split skin immunofluorescence.
An IgG ELISA against LABD97, a larger fragment of BP180, was positive in 87%, compared with 66% for the commercial BP180 NC16A ELISA and 52% for BP230. Of sera negative on both commercial tests, 83% were LABD97 positive.
The standard tests miss about one in four patients, which can delay treatment in older adults with itch or a pre-bullous phase. The study is single-centre with limited clinical follow-up, and the LABD97 assay is not widely available, so for now biopsy with direct immunofluorescence remains central.
- Do not exclude bullous pemphigoid on a negative BP180 and BP230 ELISA alone
- Take a perilesional biopsy for direct immunofluorescence when clinical suspicion is high
- Consider pemphigoid in older adults with persistent itch even without blisters
- Ask your immunology laboratory whether extended antigen testing is available
Why it matters
One in four pemphigoid cases can test negative on standard serology, delaying treatment in frail older adults.
Don't overread it
A single-laboratory study in pre-selected sera; specificity and real-world performance are not yet established.
The statistics, in plain English
Sensitivity is the share of true cases the test detects. 87% versus 66% means about 21 more cases in every 100 were picked up. All samples came from one laboratory and were already positive on immunofluorescence, which may flatter the results.
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