Antimalarial use before biopsy was not linked to milder lupus nephritis histology

Design

Single-centre retrospective cohort

Population

165 patients with biopsy-proven lupus nephritis in Toronto

Primary outcome

Proliferative class, NIH activity and chronicity indices, IFTA score

Effect

No detectable association with antimalarial exposure on any histological outcome

This Toronto Lupus Clinic cohort study included 165 patients with biopsy-proven lupus nephritis who had been followed in clinic for at least three months before the biopsy. Half were taking an antimalarial at the time.

After adjustment for demographic, clinical and treatment factors, antimalarial exposure was not associated with differences in the proportion with proliferative nephritis, the NIH activity or chronicity indices, or interstitial fibrosis and tubular atrophy. Requiring at least six months or a year of continuous use gave similar results.

Hydroxychloroquine is recommended for nearly all patients with lupus, partly on evidence that it lowers flare risk and protects the kidney over time. This study does not contradict that: it looked at what the biopsy showed once nephritis had developed, in a modest sample, and absence of a detectable difference is not evidence of no benefit. It should not change the advice to continue antimalarials through and after nephritis.

• Continue hydroxychloroquine in patients with lupus nephritis unless there is a specific contraindication.
• Do not expect prior antimalarial use to predict a milder biopsy class.
• Base induction therapy on biopsy findings, not on antimalarial history.
• Check adherence to hydroxychloroquine at every review, since benefit depends on regular use.

Why it matters

It tempers any assumption that antimalarials shift the histological class of nephritis once it develops.

Don't overread it

This does not show antimalarials lack kidney benefit in lupus; current guidance to use them is unchanged.

The statistics, in plain English

With 165 patients split roughly in half, the study could only detect fairly large differences. A null result here means no difference was seen, not that none exists. Exposure was defined from clinic visits, which may not reflect how consistently tablets were taken.

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