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By Claudine Matthews, Sickle Cell and Thalassaemia Liaison Worker, Homerton University NHS Foundation Trust.
Sickle Cell Disease (SCD) is the most common and fastest growing genetic blood disorder in England and the UK.1 (See references below) However, the disease is not fully recognised as a long term condition (LTC) among dietitians and also in the wider healthcare landscape.
SCD refers to a group of haemoglobinopathies characterized by having at least one sickle (S) beta-gene which is inherited together with another type of abnormal haemoglobin. Among the haemoglobinopathies, sickle cell (HbSS), haemoglobin SC disease (HbSC) and haemoglobin Sβ thalassemia (HbSβ thal) minor and major is most common.2 The most severely affected of this group of patients with sickle cell (HbSS) are primarily of African descent.3,4 Due to the slave trade and migration, HbSS has assumed worldwide geographic distribution.5
100 years after its discovery as a genetically inherited disease, finding a cure for sickle cell anaemia (HbSS) remains a challenge.5 Since its discovery in 1910, efforts have been made to develop clinical care for HbSS patients to lessen the severe problems which are mainly frequent hospital admissions for recurrent painful episodes. Recent years have seen the emergence of a body of literature aimed at seeking nutritional alternatives to improve the quality of life of HbSS patients.
Patients with SCD are hugely affected by the wider determinants of health such as poor housing, poverty, unemployment, and interrupted education. Cumulatively, this places patients at a high risk of malnutrition which in turn has its own negative impact on patient outcomes.
Clinical presentation and pathophysiology
SCD is detectable from birth. As soon as the foetal haemoglobin (HbF) levels fall and the HbS level rises, pathology related to SCD may start to occur therefore initial clinical presentation usually occurs in childhood.6 The most common clinical manifestation of SCD is painful crises, caused by the blockage of small vessels (vaso – occlusion) resulting in tissue infarction. Repeated crises can ultimately result in end organ damage. Stroke, splenic sequestration, overwhelming sepsis, acute chest syndrome, priapism, lung disease, recurrent chronic leg ulceration and proliferative retinopathy leading to progressive visual loss are other common clinical complications.
There are two essential pathological processes: haemolysis and vaso-occlusion. Haemolysis results in anaemia related to the pathological features of SCD due to the shortened lifespan of blood cells.6
Large vessel damage, responsible for complications such as pulmonary hypertension and stroke is caused by repeated endothelial damage by adherent sickle cells, complicated by vasoconstriction and nitric oxide deficiency. Small vessel occlusion is caused directly by sickled cells and vaso-occlusion resulting in painful crisis with acute episodes resulting in chronic damage such as avascular necrosis and renal failure.
Without a doubt SCD fulfils all the requirements provided by the World Health Organisation (WHO) definition which states that a condition is deemed to be a LTC if it requires ongoing treatment and has no cure.7 Being an inherited blood disorder, patients with SCD require lifelong pharmaceutical, medical and dietetic interventions. There is no cure for the disease.
Epidemiology and prevalence
The epidemiology and prevalence of SCD may provide some insights as to why the condition has a low profile. SCD mainly affects people from African, Afro-Caribbean, Asian, Middle Eastern and Mediterranean descent. To date there is an estimated 12,500-15,000 people living with SCD in the UK8 but the number is increasing and around 350 babies are born in England each year.9 In comparison in 2011 there were just under 10,000 people registered with a diagnosis of cystic fibrosis, a condition that well-supported and recognised.
London accounts for the highest distribution of SCD patients; the increase in prevalence of the disease is attributed to immigration into the UK and new births.9
In 2012, a 50% increase in admissions was noted and most likely attributed to increased prevalence of SCD in England.10 In contrast, a reported 15 million people in England and an overall reported 17 million people in the UK, live with a LTC.11 With an obvious disparity in numbers, SCD has a long way to go in enjoying the same recognition as other counterpart LTCs.
Nutritional intervention
SCD affects the nutritional status of people with HbSS which is manifested as slowed growth, delayed sexual maturity and poor immunologic function.5 Only since the late 1980s has under-nutrition been considered as a serious complication of HbSS disease12-14 and identified as a critical feature of SCD which should be treated as part of the required clinical care.15-20 Early research13 has provided evidence demonstrating clinical improvement in HbSS patients following dietary intervention which was caused by insufficient macronutrient availability.
Proposed mechanisms for under-nutrition include protein hyper metabolism, decreased dietary intake possibly due to interleukin-6-related appetite suppression, increased cardiac energy demand/expenditure and increased red cell turnover.5 The above mechanisms manifest as increased resting energy expenditure (REE). In 2013, nutritional intervention utilizing single or multiple nutrient supplementation has led to improved clinical outcome, growth and sexual maturation. Studies are underway to determine the best possible approach to applying nutritional intervention in the management of SCD.5
During 2012/13, Hospital Episodes Statistics show that there were about 13,300 different recorded hospital admissions for sickle cell anaemia with crisis as the primary diagnosis8 compared to 11,109 admissions in 2010/11 with an approximate total cost of around £16.2 million.21 This proves that despite the small number of patients the cost of admissions has a huge impact on the overall cost to the NHS.
Conclusions
SCD is a LTC and deserves a fresh review among dietitians. The recognition of under-nutrition as a critical feature of SCD, calls for the support and expertise of a qualified dietitian.
There is clear evidence in support of dietetic interventions and more research is needed to establish the most effective strategies to ensure positive patient outcomes. Dietitians are well-placed to make valuable contributions to research and patient outcomes. The approach will need to be patient-centred and involve the wider MDT due to the complex nature of the condition. According to the NHS Outcomes Frameworks, Domain 2, much emphasis is placed on improving the Quality of Life (QOL) of people with LTCs. Dietitians in both acute and community settings are hereby challenged to take a fresh look at SCD as a LTC.
References
1.NHS Sickle Cell and thalassaemia screening programme. London: NHS 2006.
2.Mehta AB, Hoffbrand AV. Hematology at a glance. 1st Edition. Masssachusetts: Blackwell publishing; 2000. Hemolytic anemias V Inherited defects of hemoglobin – sickle cell disease; p.50.chapt.17
3.Feldenzer J, Mears JG, burns AL, Natta C, Bank A. Heterogeneity of DNA fragment associated with sickle globin gene. J Clin Invest. 1979;64: 751-5.
4.Kan WY, Dozy AM. Evolution of the haemoglobin S and C genes in world populations. Science. 1980;209: 388-91.
5.Hyacinth HI, Gee BE, Hibbert JM. The role of Nutrition in Sickle Cell Disease. Nutr Metab Insights. 2010;3: 57-67.
6.Sickle Cell Society. Standards for the Clinical Care of Adults with Sickle Cell Disease in the UK. 2008
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8.National Institute for Health and Care Excellence. NICE support for commissioning for sickle cell acute painful episode. NICE: 2014.
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17.Barden EM, Zemel BS, Kawchak DA, et al. Total and resting energy expenditure in children with sickle cell disease. The J Pediatr. 2000; 136 (1):73-9.
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20.Soliman AT, El-Zalabany M, Amer M, et al. Growth and pubertal development in transfusion-dependent children and adolescents with thalassemia major and sickle cell disease: A comparative study. J Trop Pediatr. 1999;45(1):23-30.
21.NICE clinical guideline 138. Patient experience in adult NHS services: improving the experience of care for people using adult NHS services. NICE: 2012.