Table 2.

Main risk or protective factors for overt ischemic stroke in sickle cell disease.

Risk or protective factor	Effect on risk of stroke	References
Validated predictive factor
Doppler TAMMV ≥200 cm/s in MCA/ICA	Increases risk	12, 13
Laboratory factors
High steady state reticulocyte count	Increases risk	7, 13, 79, 82, 83, 109, 110, 111, 138, 148
Low total hemoglobin	Increases risk	8, 21, 72, 76, 79, 80, 99, 109, 110, 148
High LDH	Increases risk	7, 77, 79, 99, 108
High WBC	Increases risk	13, 44, 82, 135
G6PD deficiency	Very controversial	7, 77, 101, 109, 112, 120, 122, 147, 151
Genetic factors
Coinheritance of alpha-thalassemia	Protective	7, 8, 51, 75, 76, 77, 79, 80, 81, 98, 101, 102, 138, 151
Other genetic factors	Controversial or preliminary	78, 82, 89, 90, 91, 96, 97 and others (see references)
Clinical factors
Silent infarcts	Increases risk	122, 127
Prior transient ischemic attack	Increases risk	8, 127
Doppler TAMMV ≥170 cm/s in ACA	Increases risk	146
Low nocturnal or daytime SpO2	Increases risk	21, 126, 129, 130, 131
Relative high systolic blood pressure	Increases risk	8, 137, 140
Recurrent acute chest syndrome	Increases risk	8, 82

TAMMV: time averaged maximum mean velocity; MCA: middle cerebral artery; ICA: internal carotid artery; LDH: lactate dehydrogenase; WBC: white blood cell; G6PD: glucose-6-phosphate dehydrogenase; ACA: anterior cerebral artery; SpO₂: peripheral capillary oxygen saturation.