The OPTIMAL-BP trial randomised patients with large-vessel-occlusion stroke who achieved successful endovascular thrombectomy and had a systolic pressure of at least 140 mmHg to intensive control below 140 mmHg or conventional control at 140 to 180 mmHg for 24 hours. This secondary analysis asked what that did to their kidneys — a question nobody had examined, in 287 patients with a mean age of 73.2 years.
Acute kidney injury by KDIGO criteria within seven days occurred in 20 of 147 (13.6%) on intensive management against 9 of 140 (6.4%) on conventional, adjusted odds ratio 2.54 (95% CI 1.10 to 6.35). Early injury within two days followed the same pattern. Most events were mild: 20 of 29 were stage 1.
The outcome data attached to those events are what make this matter rather than being an incidental biochemical finding. Patients who developed acute kidney injury achieved functional independence at three months in 4 of 29 cases (13.8%) against 126 of 257 (49.0%), adjusted odds ratio 0.19 (0.05 to 0.55), and stroke-related mortality was 37.9% against 3.1%, adjusted odds ratio 13.8 (4.14 to 49.64). Even mild kidney injury here marks a patient whose systemic perfusion was not tolerating the target.
One caveat has to be stated because it is substantial. In a sensitivity analysis restricted to patients with equal creatinine ascertainment, the association with 48-hour injury did not reach significance (9.2% against 3.0%, adjusted odds ratio 4.20, 95% CI 0.83 to 32.6). More creatinine measurements in one arm can manufacture more diagnoses of acute kidney injury, and that possibility has not been excluded.
What to do with it: this supports the conventional 140 to 180 mmHg target that OPTIMAL-BP's primary result already favoured, and gives a mechanism for why the intensive strategy did harm. Practically, if a colleague is driving pressure below 140 after successful thrombectomy, check the creatinine — and read a rise, however small, as evidence that the target is too aggressive for this patient rather than as a laboratory nuisance. In Indian stroke units, where thrombectomy volumes are rising quickly and post-procedural protocols are still being written, this is the moment to write the conventional target in.
- Keep the post-thrombectomy systolic target at 140 to 180 mmHg after successful reperfusion.
- Check creatinine at 48 hours and at day 7 in patients whose pressure is being driven down.
- Read even stage 1 acute kidney injury as a marker of poor systemic tolerance, not a lab nuisance.
- Note the sensitivity analysis: unequal creatinine testing may partly explain the association.
- Patients who develop acute kidney injury did far worse neurologically — flag them for closer follow-up.
The statistics, in plain English
The headline odds ratio of 2.54 has an interval of 1.10 to 6.35 — it only just clears 1.0, and it rests on 29 events in total. The sensitivity analysis is the honest test of it, and there the association weakened to non-significance. Ascertainment bias is the specific worry: if patients on the intensive arm had creatinine checked more often, they would appear to have more kidney injury even if nothing differed. The association between acute kidney injury and poor neurological outcome is much stronger statistically but is not causal — kidney injury here is most likely a marker of a patient whose circulation was already vulnerable, not the reason their stroke outcome was poor.
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