Chronic complications of sickle cell disease: Universal definitions

Chronic complications of sickle cell disease: Universal definitions

If you’ve been following our articles about sickle cell disease, you’ve realized that we’ve looked at all the acute complications of this condition as well as the recommendations about their management as put forward by the expert panel on evidence-based management of sickle cell disease. The story doesn’t, however, stop there; some of the acute complications can persist and span the entire life of an individual: they thus become chronic.

The severity of these chronic complications varies among the different subtypes of sickle cell disease as well as in the same individual over time. The incidence of these complications increases with age. It puts across a notion that understanding the pathophysiology, aggravating factors, and predictors is key to preventing or minimizing morbidity.

There are both direct and indirect complications of sickle cell disease: the indirect ones also termed co-existing complications like rheumatoid arthritis and peptic ulcer disease. They are anaemia and its after-effects, pain syndromes, and organ damage or failure.

However, there are seven groups of chronic complications of sickle cell disease. Let’s look at the universal definitions. Details of each will be discussed in separate articles when we shall be looking at the recommendations of their management.

Related article:

Health Management for People with Sickle Cell Disease

Let’s get this started.

Chronic pain in sickle cell disease is the pain that lasts more than three months. Pain in sickle cell disease is both nociceptive and neuropathic. Nociceptive pain tends to be the hallmark of acute pain, chronic pain is, however, more of neuropathic than nociceptive in nature.

Avascular necrosis is also known as aseptic necrosis, osteonecrosis or ischemic necrosis. We define it as bone death due to compromised blood supply. It occurs when capillaries are occluded by sickled red cells at the distal portions of a bone near the joint where hypoxia is highest – there’s almost no collateral circulation. The most affected joints are the hip joints. Prevalence is about 10% overall. It increases to 50% among people with HbSS by 33 years of age. The highest risk is seen in people with HbSS with concomitant α- thalassemia.

Leg ulcers are quite common in sickle cell disease, but especially in sickle cell anaemia. They are not uncommon from age 10 to 20; more common in males and older people. A high haemoglobin level, high concentrations of fetal haemoglobin, as well as having an α-gene deletion reduces the risk of developing leg ulcers. On the contrary, though, severe anaemia, trauma, and infection increase the risk of developing leg ulcers. We find them mostly on the medial or lateral surfaces of the ankles.

Pulmonary hypertension is defined as an elevation of the resting mean pulmonary arterial pressure (≥25 mm Hg) as determined by right heart catheterization. There are several categories of pulmonary hypertension put into various groups depending on the etiologies. 

Renal complications are other complications of sickle cell disease that can be chronic, for example, chronic kidney disease. We define it as either having a glomerular filtration rate of <60 ml/min/1.73ml for three months or more, with or without kidney damage or evidence of kidney damage for three months or more, with or without decreased glomerular filtration rate. Chronic kidney disease affects about 4% to 18% of people living with sickle cell disease. The inability to concentrate urine (hyposthenuria) is the most common renal complication among these people: it progresses with age.

Stuttering or recurrent priapism is the occurrence of multiple self-limited episodes of unwanted, often painful erections lasting <4 hours. Priapism affects up to 35% of boys and men with sickle cell disease. Stuttering priapism can lead to a severe episode of priapism: if management is not timely, impotence may become inevitable.

Lastly, chronic ophthalmologic complications of sickle cell disease are; proliferative sickle retinopathy and vitreous haemorrhage. These affect up to 50% of the people with sickle cell disease. Recognizing these complications on time will preserve vision which almost always hangs in the balance in such conditions.

In a nutshell, sickle cell disease affects pretty much any part of the body and knowing these complications is key to identification, evaluation, and management of these effects.

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Dr A. M. Ssekandi is a medical officer, researcher, content creator, author, and founder of He does private practice with a public touch. He is a certified digital marketer. He has earned certificates in Understanding Clinical Research and Writing in Sciences from the University of Cape Town and Stanford University respectively. He also has a certificate of Good Clinical Practice from

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