Acute kidney injury predicts anaemia

Patients with acute kidney injury (AKI) appear to be prone to developing subsequent anaemia, which somehow slightly lowers AKI-related mortality, according to a study.

The analysis included a retrospective cohort of 6,692 adults who underwent noncardiac surgery, of whom 445 (6.6 percent) developed AKI (stage 1, n=258; stage 2, n=149; stage 3, n=38). AKI lasted ≤1 day for 211 patients and ≥2 days for 234 patients.

Patients with versus without AKI were older, had lower estimated glomerular filtration rate (eGFR) and albumin, higher C-reactive protein (CRP) at baseline, and were more likely to have diabetes mellitus, hypertension, and history of cancer. Haematocrit levels were significantly and consistently lower prior to and after surgery in the AKI group (p<0.001).

Multivariable linear regression analyses revealed an independent association between AKI and lower haematocrit at 3, 6, and 12 months postoperatively, with coefficients of −0.79 (95 percent confidence interval [CI], −1.47 to −0.11; n=1,750), −1.35 (95 percent CI, −2.11 to −0.60; n=1,558), and −0.91 (−1.59 to −0.22; n=2,463), respectively.

Of note, higher stages of or prolonged AKI correlated with more severe anaemia. AKI conferred an increased risk of death at month 3 following surgery (hazard ratio, 1.54, 95 percent CI, 1.12–2.12).

However, haematocrit attenuated the association, with the mediation effect proving to be significant (p=0.02).

More studies are needed to establish whether correction of anaemia following AKI improves mortality.