Early eGFR and albuminuria changes in one patient reflect disease course as much as drug effect

Design

Individual patient meta-analysis of 49 randomised trials

Population

66,449 participants in CKD progression trials

Primary outcome

Association of early GFR change with early albuminuria change

Effect

Trial-level slope 0.00 (−0.08 to 0.09); ACR fell 8.0% (treatment) and 6.6% (control) per SD GFR decline

This individual patient meta-analysis pooled 49 randomised CKD progression trials with 66,449 participants. It related early change in GFR (to three months) to early change in albuminuria (to six months), both across trials and within individual patients.

At trial level, a treatment's acute effect on GFR showed no association with its effect on albuminuria (slope 0.00, 95% credible interval −0.08 to 0.09). Within individuals, a larger early GFR decline was associated with a slightly larger fall in albuminuria — 8.0% per standard deviation on treatment and 6.6% on control — and the relationship was almost the same in both arms. It held across drug classes except immunosuppression.

Because the pattern was nearly identical with or without active treatment, an individual patient's early dip in eGFR or fall in albuminuria mostly reflects natural fluctuation and disease course, not proof the drug is working. This does not weaken albuminuria as a trial-level surrogate or the case for kidney-protective drugs. It cautions against reading single early measurements in one patient as response or failure.

• Do not judge an individual's drug response from a single early eGFR or albuminuria change.
• Repeat albuminuria measurements before concluding a treatment has or has not worked.
• Continue proven kidney-protective therapy regardless of early individual changes, if tolerated.
• Interpret early changes alongside blood pressure, volume status and intercurrent illness.
• Keep using albuminuria for risk staging and long-term monitoring.

Why it matters

It challenges the common practice of judging kidney-protective drugs by the first follow-up result.

Don't overread it

This does not undermine albuminuria as a trial surrogate or the benefit of RAS blockers and SGLT2 inhibitors.

The statistics, in plain English

A slope of 0.00 with an interval of −0.08 to 0.09 means trials that lowered GFR acutely did not also lower albuminuria more. The similar 8.0% and 6.6% values in treated and control patients show the within-person link is not specific to the drug.

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