Table 1 Adult studies assessing the association between anemia and the development of perioperative stroke or cognitive dysfunction among patients undergoing cardiac surgery

Karkouti and colleagues [97]

10,179

Retrospective(prospective database)

Single-center

Logistic regression

Maximum decrease intraoperative Hb compared with baseline

Composite of in-hospital death, stroke (new persistent postoperative neurologic deficit), or dialysis-dependent renal failure

>50% decrement in Hb independently associated with composite outcome

Bell and colleagues [98]

36,658 (CABG)

Retrospective (prospective database)

Multi-center

Logistic regression

Preoperative Hb

Postoperative stroke (not further defined)

No significant association between Hb and stroke

Karkouti and colleagues [99]

3286

(CABG)

Retrospective

Multi-center

Logistic regression and propensity scores

Preoperative anemia (Hb <12.5 g/dl)

Postoperative stroke (new neurologic deficit)

- Risk of stroke 1.1% in non-anemic pts vs. 2.8% in anemic patients

- Trend towards more stroke among anemic patients in propensity-matched analysis

Chang and colleagues [100]

288

Retrospective

Single-center

Logistic regression

Postoperative Hct <30%

Delirium (DSM-IV criteria)

Postoperative hct <30% associated with development of delirium (OR = 2.2, P = 0.02)

Kulier and colleagues [101]

4804

Retrospective (prospective database)

Multi-center

Logistic regression

Preoperative Hb

'Cerebral outcomes' = stroke or encephalopathy (not further defined)

- Each 10 g/L Hb reduction associated with 15% increase in risk of non-cardiac (renal or CNS) complications

- Association stronger for renal complications

Matthew and colleagues [102]

121 (CABG; age >65)

Prospective RCT

Single-center

Logistic regression

Comparison of hemodilution to hct of ≥27% vs. 15 to 18%

Six-week postoperative neurocognitive function (battery of 5 tests)

- Trial stopped early because of unusually high rate of complications in both groups

- Significant interaction between age and hct; more neurocognitive deficits among older patients with low hct

Cladellas and colleagues [103]

201 (VR)

Retrospective (prospective database)

Single-center

None

Preoperative anemia (Hb <12 g/dl)

New permanent stroke or transient ischemic attack (not further defined)

- Risk of TIA or stroke 9.5% in anemic patients vs. 4.4% in non-anemic

Giltay and colleagues [104]

8139 (CABG)

Retrospective

Single-center

Logistic regression

Lowest hematocrit first 24 hours ICU

Psychotic symptoms (hallucinations and/or delusions)

Hct <25% associated with psychosis (OR = 2.5 vs. hct >30%, CI 1.2 to 5.3)

Karkouti and colleagues [105]

10,949

Retrospective (prospective database)

Single-center

Logistic regression

Nadir intraoperative hct

Postoperative stroke (new persistent postoperative neurologic deficit) that was present on emergence from anesthesia

Each 1% hct reduction associated with OR = 1.1 for stroke (P = 0.002)

Habib and colleagues [106]

5000

Retrospective (prospective database)

Single-center

None

Nadir intraoperative hct

Transient or permanent postoperative stroke (not further defined)

Risk of TIA or stroke 5.4% in quintile with lowest hct vs. 1.3% in quintile with highest hct (P < 0.001)

DeFoe and colleagues [107]

6980 (CABG)

Retrospective (prospective database)

Multi-center

Logistic regression

Nadir intraoperative hct

Intra- or postoperative stroke (new focal neurologic deficit which appears and is still at least partially evident more than 24 hours after onset; occurs during or following CABG)

No statistically significant association between hct and stroke

Van Wermeskerken and colleagues [108]

2804 (CABG)

Retrospective

Single-center

Logistic regression

Nadir intraoperative hct

Adverse neurologic outcomes: stroke, coma, or TIA; verified retrospectively by neurologist

No significant association between hct and outcome