Daily pain from sickle cell disease may be far more common - and severe - than previously thought, research suggests.
The sickle cell has a distinctive shape
Virginia Commonwealth University researchers asked 232 sickle cell patients to keep diaries.
The Annals of Internal Medicine study found many experienced daily pain - but many tried to cope with it at home, rather than seeking medical help.
Previous research has assumed that, if patients did not seek help, then they were not in pain.
Sickle cell disease is caused by a mutation in a red blood cell gene that changes smooth, round blood cells into a sickle-shaped or C-shaped cells that are stiff and sticky and tend to clot in blood vessels.
When they get stuck in small blood vessels, the sickle cells block blood flow to the limbs and organs and can cause pain, serious infections, and organ damage, especially in the lungs, kidneys, spleen and brain.
Pain can be both acute - in which case it is known as a crisis - and long-lasting.
In the current study, over half of the sickle cell disease patients completing up to six months of pain diaries reported having pain on a majority of days. Almost one-third had pain nearly every day.
Researcher Dr Wally Smith said: "The major finding of our study was that pain in sickle cell disease is a daily phenomenon and that patients are at home mostly struggling with their pain rather than coming into the hospital or emergency department.
"I believe that this study could change the way people view the pain of the disease.
"We need more drugs to prevent the underlying processes that cause pain in this disease.
"And we need better treatments to reduce the chronic pain and suffering that these patients go through."
Dr Alison Streetly, a medical advisor to the Sickle Cell Society and director of the NHS Sickle Cell and Thalassaemia Screening Programme, welcomed the study, and hoped it would help to raise awareness.
She said: "There is a tendency to underestimate the serious impact sickle cell can have on people's lives.
"Many people with the condition are living with pain on a regular basis, but managing it on their own.
"It is important that the NHS takes it seriously."
Dr Phil Darbyshire, a consultant paediatric haematologist at Birmingham's Children's Hospital, said the findings echoed anecdotal evidence from patients.
However, he said there were big differences between the US and UK health systems, and so extrapolating from the American experience was not necessarily appropriate.
"In general terms this study adds weight to efforts we are all making to improve health provision for people with sickle cell disease and suggests that much of these efforts should go to supporting people in their own homes trying to control symptoms better to allow people to work and as far as possible lead normal lives."