Hydroxyurea (hydroxycarbamide) for sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is one of the most common inherited diseases worldwide. It is associated with lifelong morbidity and a reduced life expectancy. Hydroxyurea (hydroxycarbamide), an oral chemotherapeutic drug, ameliorates some of the clinical problems of SCD, in particular that of pain, by raising fetal haemoglobin. This is an update of a previously published Cochrane Review.

OBJECTIVES

To assess the effects of hydroxyurea therapy in people with SCD (all genotypes), of any age, regardless of setting.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Register, comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched online trial registries.Date of the most recent search: 16 January 2017.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials, of one month or longer, comparing hydroxyurea with placebo, standard therapy or other interventions for people with SCD.

DATA COLLECTION AND ANALYSIS

Authors independently assessed studies for inclusion, carried out data extraction and assessed the risk of bias.

MAIN RESULTS

Seventeen studies were identified in the searches; eight randomised controlled trials were included, recruiting 899 adults and children with SCD (haemoglobin SS (HbSS), haemoglobin SC (HbSC) or haemoglobin Sβºthalassaemia (HbSβºthal) genotypes). Studies lasted from six to 30 months.Four studies (577 adults and children with HbSS or HbSβºthal) compared hydroxyurea to placebo; three recruited individuals with only severe disease and one recruited individuals with all disease severities. There were statistically significant improvements in terms of pain alteration (using measures such as pain crisis frequency, duration, intensity, hospital admissions and opoid use), measures of fetal haemoglobin and neutrophil counts and fewer occurrences of acute chest syndrome and blood transfusions in the hydroxyurea groups. There were no consistent statistically significant differences in terms of quality of life and adverse events (including serious or life-threatening events). Seven deaths occurred during the studies, but the rates by treatment group were not statistically significantly different.Two studies (254 children with HbSS or HbSβºthal also with risk of primary or secondary stroke) compared hydroxyurea and phlebotomy to transfusion and chelation; there were statistically significant improvements in terms of measures of fetal haemoglobin and neutrophil counts, but more occurrences of acute chest syndrome and infections in the hydroxyurea and phlebotomy group. There were no consistent statistically significant differences in terms of pain alteration and adverse events (including serious or life-threatening events). Two deaths occurred during the studies (one in a the hydroxyurea treatment arm and one in the control arm), but the rates by treatment group were not statistically significantly different. In the primary prevention study, no strokes occurred in either treatment group but in the secondary prevention study, seven strokes occurred in the hydroxyurea and phlebotomy group (none in the transfusion and chelation group) and the study was terminated early.The quality of the evidence for the above two comparisons was judged as moderate to low as the studies contributing to these comparisons were mostly large and well designed (and at low risk of bias); however evidence was limited and imprecise for some outcomes such as quality of life, deaths during the studies and adverse events and results are applicable only to individuals with HbSS and HbSβºthal genotypes.Of the remaining two studies, one (22 children with HbSS or HbSβºthal also at risk of stoke) compared hydroxyurea to observation; there were statistically significant improvements in terms of measures of fetal haemoglobin and neutrophil counts but no statistically significant differences in terms of adverse events (including serious or life-threatening events).The final study (44 adults and children with HbSC) compared treatment regimens with and without hydroxyurea - there was statistically significant improvement in terms of measures of fetal haemoglobin, but no statistically significant differences in terms of adverse events (including serious or life-threatening events). No participants died in either of these studies and other outcomes relevant to the review were not reported.The quality of the evidence for the above two comparisons was judged to be very low due to the limited number of participants, the lack of statistical power (as both studies were terminated early with approximately only 20% of their target sample size recruited) and the lack of applicability to all age groups and genotypes.

AUTHORS' CONCLUSIONS

There is evidence to suggest that hydroxyurea is effective in decreasing the frequency of pain episodes and other acute complications in adults and children with sickle cell anaemia of HbSS or HbSβºthal genotypes and in preventing life-threatening neurological events in those with sickle cell anaemia at risk of primary stroke by maintaining transcranial doppler velocities. However, there is still insufficient evidence on the long-term benefits of hydroxyurea, particularly in preventing chronic complications of SCD, recommending a standard dose or dose escalation to maximum tolerated dose. There is also insufficient evidence about the long-term risks of hydroxyurea, including its effects on fertility and reproduction. Evidence is also limited on the effects of hydroxyurea on individuals with HbSC genotype. Future studies should be designed to address such uncertainties.

Hydroxyurea therapy in adult Nigerian sickle cell disease: a monocentric survey on pattern of use, clinical effects and patient's compliance

BACKGROUND

The clinical prospects of hydroxyurea therapy in the management of sickle cell disease (SCD) require evaluation in the Nigerian setting to develop indigenous guidelines. This survey examines the pattern of hydroxyurea therapy, its clinico-haematologic benefits and safety profile in Nigerian SCD subjects.

METHODS

A cross sectional pilot survey was carried out among 60 adult SCD subjects over 3 months. Data on clinical phenotypes, relevant haematological parameters and details of hydroxyurea therapy were obtained using a structured questionnaire through an interview process and case file review.

RESULTS

The median age was 30 years. Thirty-four (56.7%) of the subjects are aware of hydroxyurea therapy in SCD. Twenty-four (40%) SCD patients had previously used hydroxyurea. Only 4 subjects were fully compliant. Reasons for non-compliance included poor knowledge and lack of funds. In particular, hydroxyurea reduced leucocyte count and increased mean red cell volume (MCV) in compliant subjects.

CONCLUSION

Hydroxyurea use is low among Nigerian SCD subjects despite its proven efficacy/clinical prospects in the developed nations. Large scale multicenter studies and clinical trials are needed to form a basis for developing standard local treatment protocol for its use.

Blood transfusion for preventing primary and secondary stroke in people with sickle cell disease

BACKROUND

Sickle cell disease is one of the commonest severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. Sickle cell disease can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Stroke affects around 10% of children with sickle cell anaemia (HbSS). Chronic blood transfusions may reduce the risk of vaso-occlusion and stroke by diluting the proportion of sickled cells in the circulation.This is an update of a Cochrane Review first published in 2002, and last updated in 2013.

OBJECTIVES

To assess risks and benefits of chronic blood transfusion regimens in people with sickle cell disease for primary and secondary stroke prevention (excluding silent cerebral infarcts).

SEARCH METHODS

We searched for relevant trials in the Cochrane Library, MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1980), and ongoing trial databases; all searches current to 04 April 2016.We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register: 25 April 2016.

SELECTION CRITERIA

Randomised controlled trials comparing red blood cell transfusions as prophylaxis for stroke in people with sickle cell disease to alternative or standard treatment. There were no restrictions by outcomes examined, language or publication status.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility and the risk of bias and extracted data.

MAIN RESULTS

We included five trials (660 participants) published between 1998 and 2016. Four of these trials were terminated early. The vast majority of participants had the haemoglobin (Hb)SS form of sickle cell disease.Three trials compared regular red cell transfusions to standard care in primary prevention of stroke: two in children with no previous long-term transfusions; and one in children and adolescents on long-term transfusion.Two trials compared the drug hydroxyurea (hydroxycarbamide) and phlebotomy to long-term transfusions and iron chelation therapy: one in primary prevention (children); and one in secondary prevention (children and adolescents).The quality of the evidence was very low to moderate across different outcomes according to GRADE methodology. This was due to the trials being at a high risk of bias due to lack of blinding, indirectness and imprecise outcome estimates. Red cell transfusions versus standard care Children with no previous long-term transfusionsLong-term transfusions probably reduce the incidence of clinical stroke in children with a higher risk of stroke (abnormal transcranial doppler velocities or previous history of silent cerebral infarct), risk ratio 0.12 (95% confidence interval 0.03 to 0.49) (two trials, 326 participants), moderate quality evidence.Long-term transfusions may: reduce the incidence of other sickle cell disease-related complications (acute chest syndrome, risk ratio 0.24 (95% confidence interval 0.12 to 0.48)) (two trials, 326 participants); increase quality of life (difference estimate -0.54, 95% confidence interval -0.92 to -0.17) (one trial, 166 participants); but make little or no difference to IQ scores (least square mean: 1.7, standard error 95% confidence interval -1.1 to 4.4) (one trial, 166 participants), low quality evidence.We are very uncertain whether long-term transfusions: reduce the risk of transient ischaemic attacks, Peto odds ratio 0.13 (95% confidence interval 0.01 to 2.11) (two trials, 323 participants); have any effect on all-cause mortality, no deaths reported (two trials, 326 participants); or increase the risk of alloimmunisation, risk ratio 3.16 (95% confidence interval 0.18 to 57.17) (one trial, 121 participants), very low quality evidence. Children and adolescents with previous long-term transfusions (one trial, 79 participants)We are very uncertain whether continuing long-term transfusions reduces the incidence of: stroke, risk ratio 0.22 (95% confidence interval 0.01 to 4.35); or all-cause mortality, Peto odds ratio 8.00 (95% confidence interval 0.16 to 404.12), very low quality evidence.Several review outcomes were only reported in one trial arm (sickle cell disease-related complications, alloimmunisation, transient ischaemic attacks).The trial did not report neurological impairment, or quality of life. Hydroxyurea and phlebotomy versus red cell transfusions and chelationNeither trial reported on neurological impairment, alloimmunisation, or quality of life. Primary prevention, children (one trial, 121 participants)Switching to hydroxyurea and phlebotomy may have little or no effect on liver iron concentrations, mean difference -1.80 mg Fe/g dry-weight liver (95% confidence interval -5.16 to 1.56), low quality evidence.We are very uncertain whether switching to hydroxyurea and phlebotomy has any effect on: risk of stroke (no strokes); all-cause mortality (no deaths); transient ischaemic attacks, risk ratio 1.02 (95% confidence interval 0.21 to 4.84); or other sickle cell disease-related complications (acute chest syndrome, risk ratio 2.03 (95% confidence interval 0.39 to 10.69)), very low quality evidence. Secondary prevention, children and adolescents (one trial, 133 participants)Switching to hydroxyurea and phlebotomy may: increase the risk of sickle cell disease-related serious adverse events, risk ratio 3.10 (95% confidence interval 1.42 to 6.75); but have little or no effect on median liver iron concentrations (hydroxyurea, 17.3 mg Fe/g dry-weight liver (interquartile range 10.0 to 30.6)); transfusion 17.3 mg Fe/g dry-weight liver (interquartile range 8.8 to 30.7), low quality evidence.We are very uncertain whether switching to hydroxyurea and phlebotomy: increases the risk of stroke, risk ratio 14.78 (95% confidence interval 0.86 to 253.66); or has any effect on all-cause mortality, Peto odds ratio 0.98 (95% confidence interval 0.06 to 15.92); or transient ischaemic attacks, risk ratio 0.66 (95% confidence interval 0.25 to 1.74), very low quality evidence.

AUTHORS' CONCLUSIONS

There is no evidence for managing adults, or children who do not have HbSS sickle cell disease.In children who are at higher risk of stroke and have not had previous long-term transfusions, there is moderate quality evidence that long-term red cell transfusions reduce the risk of stroke, and low quality evidence they also reduce the risk of other sickle cell disease-related complications.In primary and secondary prevention of stroke there is low quality evidence that switching to hydroxyurea with phlebotomy has little or no effect on the liver iron concentration.In secondary prevention of stroke there is low-quality evidence that switching to hydroxyurea with phlebotomy increases the risk of sickle cell disease-related events.All other evidence in this review is of very low quality.

Developmental function in toddlers with sickle cell anemia

BACKGROUND

Neurocognitive impairment occurs in children and adults with sickle cell anemia, but little is known about neurodevelopment in very young children. We examined the neurodevelopmental status of infants participating in the Pediatric Hydroxyurea Phase III Clinical Trial (Baby Hug) to determine relationships with age, cerebral blood flow velocity, and hemoglobin concentration.

METHODS

Standardized measures of infant neurodevelopment were administered to 193 infants with hemoglobin SS or hemoglobin S-β(0) thalassemia between 7 and 18 months of age at the time of their baseline evaluation. Associations between neurodevelopmental scores and age, family income, parent education, hemoglobin concentration, and transcranial Doppler velocity were examined.

RESULTS

Mean functioning on the baseline neurodevelopment scales was in the average range. There were no mental development scores <70 (impaired); 22 children had scores in the clinically significant range, 11 with impaired psychomotor scores and 11 with problematic behavior rating scores. Significantly poorer performance was observed with older age at baseline. Behavior rating scores were an average of 2.82 percentile points lower per month of age, with similar patterns observed with parent report using adaptive behavior scales. Parent-reported functional abilities and hemoglobin were negatively associated with higher transcranial Doppler velocities.

CONCLUSIONS

Whereas overall functioning was in the normal range, behavioral and adaptive function was poorer with older age, even in this very young group of children. Explanatory mechanisms for this association between poorer developmental function and older age need to be identified.

Biochemical features of hepatic dysfunction in Nigerians with sickle cell anaemia

AIMS AND OBJECTIVES

This study seeks to document the biochemical manifestations of liver dysfunction in Nigerians with sickle cell anaemia with the aim of alerting physicians on the need to consider these changes in the overall management of the disease condition.

PATIENTS AND METHODS

Serum total proteins, albumin, bilirubin, alkaline phosphatase (ALP), alanine aminotransferase(ALT) and aspartate aminotransferase(AST) levels were estimated in 150 patients with sickle cell anaemia (HbSS) and 100 control (HbAA) subjects.

RESULTS

The serum total proteins and albumin levels were found to fall within the reference intervals in both the HbSSpatients and the controls. However, the mean bilirubin (total and conjugated) levels and the activities of alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase were significantly higher (P<0.05) in the HbSSpatients than the control subjects.

CONCLUSION

This study demonstrated elevated levels of serum bilirubin, ALP, ALT and AST in patients with sickle cell anaemia.

Impact of hydroxyurea on clinical events in the BABY HUG trial

The Pediatric Hydroxyurea Phase 3 Clinical Trial (BABY HUG) was a phase 3 multicenter, randomized, double-blind, placebo-controlled clinical trial of hydroxyurea in infants (beginning at 9-18 months of age) with sickle cell anemia. An important secondary objective of this study was to compare clinical events between the hydroxyurea and placebo groups. One hundred and ninety-three subjects were randomized to hydroxyurea (20 mg/kg/d) or placebo; there were 374 patient-years of on-study observation. Hydroxyurea was associated with statistically significantly lower rates of initial and recurrent episodes of pain, dactylitis, acute chest syndrome, and hospitalization; even infants who were asymptomatic at enrollment had less dactylitis as well as fewer hospitalizations and transfusions if treated with hydroxyurea. Despite expected mild myelosuppression, hydroxyurea was not associated with an increased risk of bacteremia or serious infection. These data provide important safety and efficacy information for clinicians considering hydroxyurea therapy for very young children with sickle cell anemia. This clinical trial is registered with the National Institutes of Health (NCT00006400, www.clinicaltrials.gov).

Massive accidental overdose of hydroxyurea in a young child with sickle cell anemia

The Pediatric Hydroxyurea Phase III Clinical Trial (BABY HUG) confirmed safety and efficacy of hydroxyurea therapy for infants with sickle cell anemia. Treatment was associated with reduction in rates of pain, acute chest syndrome, hospitalizations, and blood transfusions; improved hematologic values; and, perhaps, preservation of organ function. During the study, a 2-year-old ingested at one time an entire 35-day supply of hydroxyurea (612 mg/kg body weight). Despite a serum level of 7,756 µM 4 hours post-ingestion, the only toxicity was transient mild myelosuppression. With wider usage of hydroxyurea anticipated, conservative management of future overdoses seems reasonable (ClinicalTrials.gov NCT00006400).

Hydroxycarbamide in very young children with sickle-cell anaemia: a multicentre, randomised, controlled trial (BABY HUG)

BACKGROUND

Sickle-cell anaemia is associated with substantial morbidity from acute complications and organ dysfunction beginning in the first year of life. Hydroxycarbamide substantially reduces episodes of pain and acute chest syndrome, admissions to hospital, and transfusions in adults with sickle-cell anaemia. We assessed the effect of hydroxycarbamide therapy on organ dysfunction and clinical complications, and examined laboratory findings and toxic effects.

METHODS

This randomised trial was undertaken in 13 centres in the USA between October, 2003, and September, 2009. Eligible participants had haemoglobin SS (HbSS) or haemoglobin Sβ(0)thalassaemia, were aged 9-18 months at randomisation, and were not selected for clinical severity. Participants received liquid hydroxycarbamide, 20 mg/kg per day, or placebo for 2 years. Randomisation assignments were generated by the medical coordinating centre by a pre-decided schedule. Identical appearing and tasting formulations were used for hydroxycarbamide and placebo. Patients, caregivers, and coordinating centre staff were masked to treatment allocation. Primary study endpoints were splenic function (qualitative uptake on (99)Tc spleen scan) and renal function (glomerular filtration rate by (99m)Tc-DTPA clearance). Additional assessments included blood counts, fetal haemoglobin concentration, chemistry profiles, spleen function biomarkers, urine osmolality, neurodevelopment, transcranial Doppler ultrasonography, growth, and mutagenicity. Study visits occurred every 2-4 weeks. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00006400.

FINDINGS

96 patients received hydroxycarbamide and 97 placebo, of whom 83 patients in the hydroxycarbamide group and 84 in the placebo group completed the study. Significant differences were not seen between groups for the primary endpoints (19 of 70 patients with decreased spleen function at exit in the hydroxycarbamide group vs 28 of 74 patients in the placebo group, p=0·21; and a difference in the mean increase in DTPA glomerular filtration rate in the hydroxycarbamide group versus the placebo group of 2 mL/min per 1·73 m(2), p=0·84). Hydroxycarbamide significantly decreased pain (177 events in 62 patients vs 375 events in 75 patients in the placebo group, p=0·002) and dactylitis (24 events in 14 patients vs 123 events in 42 patients in the placebo group, p<0·0001), with some evidence for decreased acute chest syndrome, hospitalisation rates, and transfusion. Hydroxyurea increased haemoglobin and fetal haemoglobin, and decreased white blood-cell count. Toxicity was limited to mild-to-moderate neutropenia.

INTERPRETATION

On the basis of the safety and efficacy data from this trial, hydroxycarbamide can now be considered for all very young children with sickle-cell anaemia.

FUNDING

The US National Heart, Lung, and Blood Institute; and the National Institute of Child Health and Human Development.

Examining the characteristics and beliefs of hydroxyurea users and nonusers among adults with sickle cell disease

The attitudes of patients with sickle cell disease (SCD) toward the use of hydroxyurea (HU) therapy may contribute to the underutilization of HU in the United States, yet our understanding of these attitudes is limited. We examined the attitudes and beliefs of 94 adult SCD patients, comparing those who never used HU (n 5 37), formerly used HU (n 5 23), and were currently using HU (n 5 34). Seventy percent of current HU users reported some level of improvement from the drug ("average" or "very much") and 80% reported little or no trouble from side effects. Fifty-seven percent of former users reported taking HU for less than 6 months, with "doctor"s recommendation," or "not liking the way it made me feel" given as the most commonly reported reasons for stopping HU. Fifty percent of the never users reported receiving no information about HU from any source, and 85% of the never users thought that they would receive no improvement if they were to take HU. A deeper understanding of patient perspectives toward HU utilization is required as part of multipronged efforts to combat its underutilization in the treatment of SCD.

Cancer morbidity among methyl isocyanate exposed long- term survivors and their offspring: a hospital-based five year descriptive study (2006 - 2011) and future directions to predict cancer risk in the affected population

The purpose of this study was to update both researchers and clinicians about the cancer incidence in methyl isocyanate (MIC) exposed long-term survivors and in their offspring, focusing on the etiological plausibility. In the time period 2006-2011, cancer morbidity was evaluated in the population surviving after exposure to (MIC) on December 3rd, 1984, in Bhopal. This descriptive study is based on hospital registration of 1261 cancer patients those are MIC gas victims and their subsequently born offspring. Morbidity status was studied on the basis of gender, age, organ and site with relative percentages. Cancers on specific sites, with special reference to breast (n=231) (18.31%), lung (n=103) (8.16%), tongue (n=103) (8.16%), buccal mucosa (n=94) (7.45%), cervix (n=72) (5.70%), and esophagus (n=68) (5.39%) were found in high proportions. Ovary (n=43) (3.40%), brain (n=42) (3.33%), larynx (n=40) (3.17%), non-Hodgkin's (n=31) (2.45%), gallbladder (n=29) (2.29%), stomach (n=28) (2.22%), head and neck (n=28) (2.22%), liver (n=27) (2.14%), acute lymphoid leukemia (n=24) (1.90%), rectum (n=20) (1.58%), colon (n=20) (1.58%), chronic myeloid leukemia (n=17) (1.34%), alveolus (n=17) (1.34%), Hodgkin's (n=14) (1.11%), uterus (n=14) (1.11%), multiple myeloma (n=14) (1.11%), and prostate (n=11) (0.87%) lesions were observed less frequently. Remarkably, gradual increase of cancers on different organs and sites were observed in the long- term survivors and their offspring. The present study observed some cancers which were not previously reported in this population. In addition, we also present the future research directions with systematic approaches to predict cancer risk in long-term survivors and their future generations. On the basis of this morbidity report, we suggest the need of biological surveillance through immune system biomonitoring and cytogenetic screening to predict the cancer risk in the MIC exposed population and their offspring.

The pediatric hydroxyurea phase III clinical trial (BABY HUG): challenges of study design

Evidence of the laboratory benefits of hydroxyurea and its clinical efficacy in reducing acute vaso-occlusive events in adults and children with sickle cell anemia has accumulated for more than 15 years. A definitive clinical trial showing that hydroxyurea can also prevent organ damage might support widespread use of the drug at an early age. BABY HUG is a randomized, double-blind placebo-controlled trial to test whether treating young children ages 9-17 months at entry with a liquid preparation of hydroxyurea (20 mg/kg/day for 2 years) can decrease organ damage in the kidneys and spleen by at least 50%. Creation of BABY HUG entailed unique challenges and opportunities. Although protection of brain function might be considered a more compelling endpoint, preservation of spleen and renal function has clinical relevance, and significant treatment effects might be discernable within the mandated sample size of 200. Concerns about unanticipated severe toxicity and burdensome testing and monitoring requirements were addressed in part by an internal Feasibility and Safety Pilot Study, the successful completion of which was required prior to enrolling a larger number of children on the protocol. Concerns over recruitment of potentially vulnerable subjects were allayed by inclusion of a research subject advocate, or ombudsman. Finally, maintenance of blinding of research personnel was aided by inclusion of an unblinded primary endpoint person, charged with transmitting endpoint data and monitoring blood work locally for toxicity (ClinicalTrials.gov number, NCT00006400).

Systematic review: Hydroxyurea for the treatment of adults with sickle cell disease

BACKGROUND

Hydroxyurea is the only approved drug for treatment of sickle cell disease.

OBJECTIVE

To synthesize the published literature on the efficacy, effectiveness, and toxicity of hydroxyurea when used in adults with sickle cell disease.

DATA SOURCES

MEDLINE, EMBASE, TOXLine, and CINAHL were searched through 30 June 2007.

STUDY SELECTION

Randomized trials, observational studies, and case reports evaluating efficacy and toxicity of hydroxyurea in adults with sickle cell disease, and toxicity studies of hydroxyurea in other conditions that were published in English.

DATA EXTRACTION

Paired reviewers abstracted data on study design, patient characteristics, and outcomes sequentially and did quality assessments independently.

DATA SYNTHESIS

In the single randomized trial, the hemoglobin level was higher in hydroxyurea recipients than placebo recipients after 2 years (difference, 6 g/L), as was fetal hemoglobin (absolute difference, 3.2%). The median number of painful crises was 44% lower than in the placebo group. The 12 observational studies that enrolled adults reported a relative increase in fetal hemoglobin of 4% to 20% and a relative reduction in crisis rates by 68% to 84%. Hospital admissions declined by 18% to 32%. The evidence suggests that hydroxyurea may impair spermatogenesis. Limited evidence indicates that hydroxyurea treatment in adults with sickle cell disease is not associated with leukemia. Likewise, limited evidence suggests that hydroxyurea and leg ulcers are not associated in patients with sickle cell disease, and evidence is insufficient to estimate the risk for skin neoplasms, although these outcomes can be attributed to hydroxyurea in other conditions.

LIMITATION

Only English-language articles were included, and some studies were of lower quality.

CONCLUSION

Hydroxyurea has demonstrated efficacy in adults with sickle cell disease. The paucity of long-term studies limits conclusions about toxicity.

Hydroxyurea for the treatment of sickle cell disease

OBJECTIVES

To synthesize the published literature on the efficacy, effectiveness, and toxicity of hydroxyurea (HU) when used for treatment of sickle cell disease (SCD); and to review the evidence regarding barriers to its use.

DATA SOURCES

Articles cited in MEDLlNE, EMBASE, TOXLine, and CINAHL through June 30, 2007.

REVIEW METHODS

Paired reviewers reviewed each title, abstract, and article to assess eligibility. They abstracted data sequentially and then independently graded the evidence.

RESULTS

In one small, randomized trial of HU in children with SCD; the yearly hospitalization rate was lower with HU than placebo (1.1 versus 2.8, p=0.002). The absolute increase in fetal hemoglobin (Hb F%) was 10.7 percent. Twenty observational studies of HU in children reported similar increases in Hb F%, while hemoglobin concentration increased by roughly 1 g/dl. One large randomized trial tested the efficacy of HU in adults with SCD and found that after 2 years of treatment, Hb F% increased by 3.2 percent and hemoglobin increased by 0.6 g/dl, The median number of painful crises was 44 percent (p<0.001) lower among patients treated with HU. The 12 observational studies of HU enrolling adults with SCD supported these findings. Panelists from the Center for the Evaluation of Risks to Human Reproduction reviewed the literature for potential toxicities of HU. They concluded that HU does not cause a growth delay in children 5-15 years old. There were no data on the effects on subsequent generations following exposure of developing germ cells to HU in utero. Some evidence supported impaired spermatogenesis with use of HU. Although we identified six patients taking HU who developed leukemia, the evidence did not support causality. Similarly, the evidence suggested no association between HU and leg ulcers in patients with SCD, although there was in patients with other illnesses. The literature supported neutropenia, skin rashes and nail changes associated with use of HU, but was sparse regarding skin neoplasms or other secondary malignancies in SCD. Only two studies investigated barriers to use of HU. Perceived efficacy and perceived safety of HU had the largest influence on patients' (or parents' ) choice to use HU. Providers reported barriers to be patient concerns about side effects; and their own concerns about HU in older patients, patient compliance, lack of contraception, side effects and carcinogenic potential, doubts about effectiveness, and concern about costs.

CONCLUSIONS

HU is efficacious in children and adults with SCD; with an increase in Hb F%, and reduction in hospitalizations and pain crises. However, few studies have measured the effectiveness of HU for SCD in usual practice. The paucity of long-term studies limits conclusions about toxicities and about mortality. Future studies of interventions to overcome the barriers to use of HU in patients with SCD are necessary.

NIH consensus development statement on hydroxyurea treatment for sickle cell disease

National Institutes of Health consensus and state-of-the-science statements are prepared by independent panels of health professionals and public representatives on the basis of (1) the results of a systematic literature review prepared under contract with the Agency for Healthcare Research and Quality (AHRQ), (2) presentations by investigators working in areas relevant to the conference questions during a 2-day public session, (3) questions and statements from conference attendees during open discussion periods that are part of the public session, and (4) closed deliberations by the panel during the remainder of the second day and morning of the third. This statement is an independent report of the panel and is not a policy statement of the NIH or the U.S. Government.The statement reflects the panel's assessment of medical knowledge available at the time the statement was written. Thus, it provides a "snapshot in time" of the state of knowledge on the conference topic. When reading the statement, keep in mind that new knowledge is inevitably accumulating through medical research.

Effect of hydroxyurea on sperm count, motility and morphology in adult men with sickle cell or myeloproliferative disease

Hydroxyurea (HU) is not infrequently used in patients with sickle cell disease and myeloproliferative disorders. Despite murine data showing adverse effects on sperm counts, motility and morphology, there is little information on the effect of HU on human spermatogenesis. A retrospective review of four adult men who had semen analysis during HU therapy and in three cases after its cessation suggests that HU generally reduces sperm counts and motility and results in abnormal morphology. Cessation of HU in one case with azoospermia resulted in recovery of spermatogenesis; in two of the three cases, however, sperm morphology and mobility remained impaired. Recommendations for fertility management in adult men receiving long-term HU therapy are proposed.

Parents' assessment of risk in sickle cell disease treatment with hydroxyurea

Hydroxyurea is the only medication shown to reduce the severity of sickle cell disease (SCD), but its long-term risks are unknown. Families of 58 children with SCD were interviewed on their perception of the potential risks of hydroxyurea treatment, and whether disease severity was a major factor in their treatment decision. Parents rated the severity of their child's SCD (86% as severe, 26% moderate, and 47% mild) and then the highest levels of risk that they would tolerate for both potential cancer (range 1/1,000 to 1/2) and potential birth defects (range 1/1,000 to 1/3) to benefit their child with hypothetical hydroxyurea treatment. Parents of 29 of the 58 children were unwilling to take any cancer risk whatsoever as a potential side effect of treatment, and 29 of 58 (not all the same parents) were unwilling to take any risk for birth defects, including half the children with severe SCD. For those families who did accept some risk, higher acceptable risk correlated with higher disease severity in the child (P = 0.04). The study's mixed findings highlight the complexities of risk perception and suggest that future studies of risks and benefits from the parental viewpoint are needed as candidate therapies are developed for SCD.

Clinical evaluation of extract of Cajanus cajan (Ciklavit) in sickle cell anaemia

The major pathology in sickle cell anaemia (SCA) is sickling of red cells due to the precipitation of reduced haemoglobin. We report our experience with extract of Cajanus cajan as a possible antisickling agent by determining changes, if any, in clinical and laboratory features of the disease in patients given the extract in a single-blind placebo-controlled study. One hundred patients with steady-state SCA were randomized into treatment and placebo arms. The extract/placebo were administered twice daily to the subjects. Weight, hepatosplenomegaly, blood levels of biliurubin, urea, creatinine, and packed cell volume (PCV) were monitored over a 6-month period. Recall episodes of pain 6 months before enrolment were compared with episodes of pains recorded during the treatment period. Twenty-six cases (55.3 per cent) had hepatomegaly on enrolment. This significantly reduced to 33.3 per cent at 6 months (p = 0.03); but increased in the placebo arm (p > 0.05). The total number of recall painful episodes in cases was 207 (mean 4.4 +/- 10.3 (SD), range 0-60) and fell to 191 (mean 4.2 +/- 4.4 (SD), range 0-16); p = 0.03. Episodes of pain increased from 109 in controls (mean 2.6 +/- 5.0 (SD), range 0-26) to 164 (mean 3.9 +/- 4.3 (SD), range 0-22); p = 0.01. Mean PCV in the cases showed no appreciable changes (p = 0.1) but there was a significant increase in the controls (p = 0.02). In conclusion, the extract may cause a reduction of painful crises and may ameliorate the adverse effects of sickle cell anaemia on the liver. The mechanism of action remains to be determined.