Anemia, Sickle Cell
Conditions
Keywords
Sickle Cell Disease, Sickle Cell Anemia, Hemoglobin SS, Hemoglobin SB0
Brief summary
Sickle cell disease (SCD), also known as sickle cell anemia, is an inherited blood disease that can cause intense pain episodes and may lead to organ failure. Preliminary studies have shown that adults with SCD may have brain abnormalities that contribute to problems with cognitive functioning, including attention and memory difficulties. This study will use brain magnetic resonance imaging (MRI) and neuropsychological testing to examine the differences in cognitive functioning in adults with SCD and adults without SCD. 212 subjects participated in this cross-sectional study consisting of screening questionnaires, a neuropsychological testing battery, and MRI testing. Enrollment into this study ended in May 2008.
Detailed description
SCD is an inherited blood disorder. Symptoms include anemia, infections, organ damage, and intense episodes of pain, which are called sickle cell crises. In the past, SCD was considered a fatal disease, and many people with SCD died at a young age. Due to advances in medical care, people with SCD are now living longer lives; however, they often experience a deterioration in quality of life due to progressive organ failure. Past research has suggested that children with SCD commonly have frontal lobe dysfunction syndrome, which is a brain disorder that can affect cognitive functioning in areas such as attention, concentration, information processing, and decision making. Often times, however, neurocognitive and brain disorders are not diagnosed or treated in people with SCD. In preliminary brain imaging studies, at least half of adult participants with SCD had cognitive dysfunction that could be seen in images of the brain, while participants without SCD rarely had visible changes in the brain. Brain dysfunction may be one of the most important and least-studied problems affecting adults with SCD. The purpose of this study is to evaluate the extent of cognitive functioning problems in adults with SCD. The study will also determine if there is a connection between cognitive functioning problems and abnormalities seen on MRI brain images of adults with SCD. This study is an observational case/control study that will enroll adults with SCD and a control group of healthy adults who do not have SCD. At a study visit on Day 1, participants will undergo blood collection and will complete psychosocial questionnaires. Female participants will provide a urine sample for pregnancy testing. Study researchers will conduct a medical record review, a physical exam, and a neurological exam. They will also interview participants to collect medical history information. On Day 2, participants will undergo either a brain MRI or neuropsychological testing; on Day 3, the other procedure will be completed. On Day 4, study researchers will explain the study procedure results to participants. Participants will be asked if they are willing to take part in a second phase of the study in the future. Enrollment into this study ended in May 2008. A pilot interventional study follows this study, and is reported separately in ClinicalTrials.gov under NCT 00850018.
Interventions
BEHAVIORALNP Battery
Neuropsych Battery with 7 different tests that evaluate the patients neurological functioning.
PROCEDUREMRI
The MRI is a standard procedure involving 30 minutes under the machine in order to obtain various images of the patients brain.
Sponsors
National Heart, Lung, and Blood Institute (NHLBI)
UCSF Benioff Children's Hospital Oakland
Study design
Observational model
CASE_CONTROL
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Age
21 Years to 55 Years
Healthy volunteers
Yes
Inclusion criteria
Individuals who meet all of the following criteria are eligible for enrollment as cases into the study: 1. Adult between the ages of 21 and 55 2. African descent 3. Proficient/fluent in English 4. Hemoglobin electrophoresis confirming hemoglobin SS or SB0 (%A \<= 15) 5. Hemoglobin \<= 10 g/dL 6. Capable of giving informed consent for the protocol Individuals who meet all of the following criteria are eligible for enrollment as community controls into the study: 1. Adult between the ages of 21 and 55 2. African descent 3. Proficient/fluent in English 4. Capable of giving informed consent for the protocol
Exclusion criteria
Individuals who meet any of the following criteria are disqualified from enrollment in the case group of the study: 1. Overt stroke 2. Previous evidence of an abnormal MRI or CT other than small peri-ventricular or watershed lesions 3. History of head injury that resulted in neurological symptoms or medical visit 4. Abnormal neurologic exam with focal findings 5. Mini-Mental Status Examination (MMSE) score of \< 20 6. Profile of Mood States (POMS) score on the Depression-Dejection Subscale suggestive of a clinical depression (score \> 40) 7. Alcohol consumption exceeding 14 drinks/week if female, 21 drinks/week if male 8. Drug abuse, defined as using non-prescribed medication 9. History of claustrophobia and/or presence of metallic implants such as pacemakers, surgical aneurysm clips, or known metal fragments embedded in the body 10. Pregnancy 11. Baseline blood pressure \> 140/90 on two repeated measurements. A second measurement is needed only if the first is \> 140/90 12. History of uncontrolled hypertension 13. Any chronic disorder that may result in neurocognitive or brain dysfunction that is not secondary to SCD including: 1. Inflammatory arterial disorders (lupus, polyarteritis) 2. History of cancer requiring chemotherapy and/or radiation 3. Untreated hyperlipidemia 4. Diabetes 5. Ongoing active infection such as HIV, tuberculosis, sarcoidosis 6. History of chronic transfusion 7. Chronic renal failure/Dialysis 8. Chronic lung disease characterized by need for oxygen 9. Morbid obesity (weight \>115 kg) 10. Heart disease: history of congestive heart failure, history of severe coronary artery disease characterized by angioplasty or surgery, or history of angina 11. Active hepatitis or liver failure 12. Acquired or congenital immune deficiency 13. History of psychoses (delusions, hallucinations) and/or schizophrenia 14. Neurodegenerative disorders 15. Genetic disorder associated with neurocognitive dysfunction such as Down Syndrome 16. Other chronic illness or disorder other than SCD that will adversely affect the subject's performance in the study 14. Currently on Procrit or related drug that stimulates red blood cell production Individuals who meet any of the following criteria are disqualified from enrollment as community controls in to the study: 1. Hb electrophoresis other than AA 2. Abnormal Hb (females: \< 12 g/dL; males: \< 13.5 g/dL) 3. Overt stroke 4. Previous abnormal MRI or CT 5. History of head injury that resulted in neurological symptoms or medical visit 6. Abnormal neurologic exam with focal findings 7. Mini-Mental Status Examination (MMSE) score of \< 20 8. Profile of Mood States (POMS) score on the Depression-Dejection Subscale suggestive of a clinical depression (score \> 40) 9. Alcohol consumption exceeding 14 drinks/week if female, 21 drinks/week if male 10. Drug abuse, defined as using non-prescribed medication 11. History of claustrophobia and/or presence of metallic implants such as pacemakers, surgical aneurysm clips, or known metal fragments embedded in the body 12. Pregnancy 13. Baseline blood pressure \> 140/90 on two repeated measurements. A second measurement is needed only if the first is \> 140/90 14. History of uncontrolled hypertension 15. Any chronic disorder that may result in neurocognitive or brain dysfunction including: 1. Inflammatory arterial disorders (lupus, polyarteritis) 2. History of cancer requiring chemotherapy and/or radiation 3. Untreated hyperlipidemia 4. Diabetes 5. Ongoing active infection such as HIV, tuberculosis, sarcoidosis 6. History of chronic transfusion 7. Chronic renal failure/Dialysis 8. Chronic lung disease characterized by need for oxygen 9. Morbid obesity (weight \> 115 kg) 10. Heart disease: history of congestive heart failure, history of severe coronary artery disease characterized by angioplasty or surgery, or history of angina 11. Active hepatitis or liver failure 12. Acquired or congenital immune deficiency 13. History of psychoses (delusions, hallucinations) and/or schizophrenia 14. Neurodegenerative disorders 15. Genetic disorder associated with neurocognitive dysfunction such as Down Syndrome 16. Other chronic illness or disorder that will adversely affect the subject's performance in the study 16. Currently on Procrit or related drug that stimulates red blood cell production
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Wechsler Adult Intelligence Scale (WAIS)-III Performance IQ | Within 2 months of signing informed consent. | Extent of neurocognitive dysfunction in neurologically asymptomatic adult patients with sickle cell disease as measured by WAIS-III performance IQ. This quotient is based on an average of 100, with a standard deviation of 15. The Wechsler intelligence scales are not considered adequate measures of extremely high and low intelligence (IQ scores above 160 and below 40, respectively). The performance IQ is derived from scores on seven subtests: picture completion, picture arrangement, block design, object assembly, digit symbol, matrix reasoning, and symbol search. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Participants With Brain Lacunae as Measured by Clinical MRI | Within 2 months of informed consent | Particpants with imaging abnormalities as measured by MRI (Magnetic Resonance Imaging) specifically brain lacunae. Lacunar infarcts are 3-15 mm in diameter located at the basal ganglia, capsular and thalamic regions. Lesions located at the level of the anterior commisure are considered perivascular spaces unless \>5 mm in diameter. |
| Volume of Total Cortical Gray Matter as Measured by Volumetric MRI. | Within 2 months of informed consent | The cortical gray matter is the gray matter of the cerebral cortex only and does not include subcortical gray matter such as hippocampus or basal ganglia. |
Countries
United States
Participant flow
Recruitment details
Patients with HB SS/SB0 were recruited from 12 sickle cell centers from Dec 2004 through May 2008. To eliminate selection bias, all eligible patients at these centers were approached. Matched peer controls of African descent were recruited from patients' community-based churches or neighborhoods, and matched for gender, age and education.
Pre-assignment details
The NP Battery and the MRI could be scheduled in either order. A 4 week visit window was set between screening and the first of the two procedures. An additional 4 week window was set between the first procedure and the second.
Participants by arm
| Arm | Count |
|---|---|
| Phase I: Cases These are patients diagnosed with sickle cell disease (confirmed by hemoglobin electrophoresis). | 160 |
| Phase I: Controls These are patients that do not have sickle cell disease (confirmed by hemoglobin electrophoresis); matched to cases by age, gender, and education level | 52 |
| Total | 212 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Administrative Reasons | 0 | 1 |
| Overall Study | Lost to Follow-up | 15 | 4 |
| Overall Study | Protocol Violation | 11 | 5 |
| Overall Study | Withdrawal by Subject | 1 | 1 |
Baseline characteristics
| Characteristic | Phase I: Controls | Phase I: Cases | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 52 Participants | 160 Participants | 212 Participants |
| Age, Continuous | 33.10 years STANDARD_DEVIATION 10.06 | 31.57 years STANDARD_DEVIATION 8.95 | 31.94 years STANDARD_DEVIATION 9.24 |
| Region of Enrollment United States | 52 participants | 160 participants | 212 participants |
| Sex: Female, Male Female | 27 Participants | 100 Participants | 127 Participants |
| Sex: Female, Male Male | 25 Participants | 60 Participants | 85 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 0 | 0 / 0 |
| serious Total, serious adverse events | 0 / 0 | 0 / 0 |
Outcome results
Primary
Wechsler Adult Intelligence Scale (WAIS)-III Performance IQ
Extent of neurocognitive dysfunction in neurologically asymptomatic adult patients with sickle cell disease as measured by WAIS-III performance IQ. This quotient is based on an average of 100, with a standard deviation of 15. The Wechsler intelligence scales are not considered adequate measures of extremely high and low intelligence (IQ scores above 160 and below 40, respectively). The performance IQ is derived from scores on seven subtests: picture completion, picture arrangement, block design, object assembly, digit symbol, matrix reasoning, and symbol search.
Time frame: Within 2 months of signing informed consent.
Population: Per protocol, no imputation used.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Phase I: Cases | Wechsler Adult Intelligence Scale (WAIS)-III Performance IQ | 90.6 Points on a scale | Standard Deviation 12.7 |
| Phase I: Controls | Wechsler Adult Intelligence Scale (WAIS)-III Performance IQ | 95.9 Points on a scale | Standard Deviation 12.13 |
Comparison: Null hypothesis is no difference between cases and controls in the WAIS-III Perormance IQ (PIQ) Index. A linear model controlling for gender, age, and education was used to compare controls versus cases using an F statistic. Based on sample-size calculations, 120 patients and 36 controls were needed to have 80% power to detect an 8-point difference on the WAIS-III PIQ Index.p-value: 0.008Mixed Models Analysis
Secondary
Participants With Brain Lacunae as Measured by Clinical MRI
Particpants with imaging abnormalities as measured by MRI (Magnetic Resonance Imaging) specifically brain lacunae. Lacunar infarcts are 3-15 mm in diameter located at the basal ganglia, capsular and thalamic regions. Lesions located at the level of the anterior commisure are considered perivascular spaces unless \>5 mm in diameter.
Time frame: Within 2 months of informed consent
Population: Per protocol, no imputation.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Phase I: Cases | Participants With Brain Lacunae as Measured by Clinical MRI | 19 Participants |
| Phase I: Controls | Participants With Brain Lacunae as Measured by Clinical MRI | 1 Participants |
Comparison: Null hypothesis is no difference between cases and controls in the proportion of subjects with lacunae. This was tested using a Fisher's Exact Test.p-value: 0.04895% CI: [0.026, 0.199]Fisher Exact
Secondary
Volume of Total Cortical Gray Matter as Measured by Volumetric MRI.
The cortical gray matter is the gray matter of the cerebral cortex only and does not include subcortical gray matter such as hippocampus or basal ganglia.
Time frame: Within 2 months of informed consent
Population: Per protocol, no imputations.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Phase I: Cases | Volume of Total Cortical Gray Matter as Measured by Volumetric MRI. | 543.5 mL | Standard Deviation 52.71 |
| Phase I: Controls | Volume of Total Cortical Gray Matter as Measured by Volumetric MRI. | 569.7 mL | Standard Deviation 63.04 |