Cushing’s Syndrome Epidemiology

By Yolanda Smith, BPharm

Cushing’s syndrome is considered to be a rare disorder that results from prolonged exposure to glucocorticoids. However, there are few epidemiological studies to provide adequate data to describe the incidence and prevalence of the condition accurately. Most cases are diagnosed between the ages of 20 and 50, although any individual may be affected at any age.

The presentation of the symptoms of Cushing’s syndrome can vary greatly. In addition, many of the symptoms overlap with those caused by other health conditions, such as metabolic syndrome and polycystic ovary syndrome. This can make the diagnosis of the condition difficult. It is also difficult to establish epidemiological trends in Cushing’s syndrome, because not all cases of the disease are diagnosed. However, it is important that diagnosis is made as soon as possible, because early diagnosis and treatment of the condition are associated with improved morbidity and mortality rates.

Population-based Studies

There are several population-based studies that have reported the incidence and mortality rates of Cushing’s syndrome in certain populations over a discrete period of time.

A study in Denmark followed 166 patients with Cushing’s syndrome for 11 years, finding an incidence of 2 cases per million population per year. Of the 166 patients, 139 had benign disease. There was a mortality rate of 16.5% in the follow-up period of 8 years, with most deaths occurring in the year after the initial diagnosis, often before the initiation of treatment. The causes of death of patients with Cushing’s syndrome in the study included severe infections, cardiac rupture, stroke and suicide.

A study in Spain found 49 cases of Cushing’s syndrome over a period of 18 years, with an incidence of 2.4 cases per million inhabitants per year and a prevalence of 39.1 cases per million. The standard mortality ratio in this study was 3.8, in addition to an increase in morbidity rates.

Incidence

A low incidence of endogenous Cushing’s syndrome was established by the population-based studies outlined above, corresponding to approximately 2 cases per million. Some studies have an estimated incidence as low as 0.7 people per million.

However, the incidence of subclinical Cushing’s syndrome may be underestimated in certain population groups, such as those with osteoporosis, uncontrolled diabetes mellitus or hypertension. For example, of 90 obese patients with uncontrolled diabetes mellitus in one study, three had Cushing’s syndrome. This yielded a prevalence of 3.3%, which is considerably higher than the incidence reported in the population-based studies. However, these findings should be supported by larger studies.

Females are more likely to be affected by Cushing’s syndrome than males, with a risk ratio of approximately 3:1. There does not appear to be a genetic link that involves an ethnic susceptibility to the condition.

Treatment Outcomes

Surgery is the first-line treatment option for most cases of overt disease and remission is achieved in the majority of patients, approximately 65-85%. However, for up to 1 in 5 patients the condition recurs, and the risk does not appear to level off, even after 20 years of follow-up.

The risk of mortality for individuals with Cushing’s syndrome is estimated to be 2-3 times higher than that of the general population, based on epidemiological studies.

Reviewed by Dr Liji Thomas, MD.

From http://www.news-medical.net/health/Cushings-Syndrome-Epidemiology.aspx

Day 29, Cushing’s Awareness Challenge 2016

People sometimes ask me how I found out I had Cushing’s Disease.  Theoretically, it was easy.  In practice, it was very difficult.

Ladies Home Journal, 1983In 1983 I came across a little article in the Ladies Home Journal which said “If you have these symptoms…”

I found the row with my symptoms and the answer read “…ask your doctor about Cushing’s”.

After that article, I started reading everything I could on Cushing’s, I bought books that mentioned Cushing’s. I asked and asked my doctors for many years and all of them said that I couldn’t have it.  It was too rare.  I was rejected each time.

Due to all my reading at the library, I was sure I had Cushing’s but no one would believe me. My doctors would say that Cushing’s Disease is too rare, that I was making this up and that I couldn’t have it.

In med school, student doctors are told “When you hear hoofbeats, think horses, not zebras“.

According to Wikipedia: “Zebra is a medical slang term for a surprising diagnosis. Although rare diseases are, in general, surprising when they are encountered, other diseases can be surprising in a particular person and time, and so “zebra” is the broader concept.

The term derives from the aphorism “When you hear hoofbeats behind you, don’t expect to see a zebra”, which was coined in a slightly modified form in the late 1940s by Dr. Theodore Woodward, a former professor at the University of Maryland School of Medicine in Baltimore.  Since horses are the most commonly encountered hoofed animal and zebras are very rare, logically you could confidently guess that the animal making the hoofbeats is probably a horse. By 1960, the aphorism was widely known in medical circles.”

So, doctors typically go for the easily diagnosed, common diseases.  Just because something is rare doesn’t mean that no one gets it.  We shouldn’t be dismissed because we’re too hard to diagnose.

When I was finally diagnosed in 1987, 4 years later, it was only because I started bleeding under the skin. My husband made circles around the outside perimeter each hour with a marker so my leg looked like a cut log with rings.

When I went to my Internist the next day he was shocked at the size of the rings. He now thought I had a blood disorder so he sent me to a Hematologist/Oncologist.

Fortunately, that new doctor ran a twenty-four hour urine test and really looked at me and listened to me.  Both he and his partner recognized that I had Cushing’s but, of course, couldn’t do anything further with me.  They packed me off to an endo where the process started again.

My final diagnosis was in October, 1987.  Quite a long time to simply  “…ask your doctor about Cushing’s”.

Looking back, I can see Cushing’s symptoms much earlier than 1983.  But, that ‘s for a different post.

 

Straight Talk Cushing’s

awareness

 

On April 8th, people from around the world unite in support of Cushing’s Disease Awareness Day.

In this animated video, learn more about Cushing’s disease, including the mechanism of disease, clinical manifestations, symptoms and diagnosis challenges.

https://youtu.be/Z2vS7sVvx0o

Cushing’s: Update on signs, symptoms and biochemical screening

10.1530/EJE-15-0464

  1. Lynnette Nieman

+Author Affiliations


  1. L Nieman, RBMB, NIH, Bethesda, 20817-1109, United States
  1. Correspondence: Lynnette Nieman, Email: niemanl@mail.nih.gov

Abstract

Endogenous pathologic hypercortisolism, or Cushing’s syndrome, is associated with poor quality of life, morbidity and increased mortality. Early diagnosis may mitigate against this natural history of the disorder.

The clinical presentation of Cushing’s syndrome varies, in part related to the extent and duration of cortisol excess. When hypercortisolism is severe, its signs and symptoms are unmistakable. However, most of the signs and symptoms of Cushing’s syndrome are common in the general population (e.g. hypertension and weight gain) and not all are present in every patient.

In addition to classical features of glucocorticoid excess, such as proximal muscle weakness and wide purple striae, patients may present with the associated co-morbidities that are caused by hypercortisolism. These include cardiovascular disease, thromboembolic disease, psychiatric and cognitive deficits, and infections. As a result, internists and generalists must consider Cushing’s syndrome as a cause, and endocrinologists should search for and treat these co-morbidities.

Recommended tests to screen for Cushing’s syndrome include 1 mg dexamethasone suppression, urine free cortisol and late night salivary cortisol. These may be slightly elevated in patients with physiologic hypercortisolism, which should be excluded, along with exogenous glucocorticoid use. Each screening test has caveats and the choice of tests should be individualized based on each patient’s characteristics and lifestyle.

The objective of this review was to update the readership on the clinical and biochemical features of Cushing’s syndrome that are useful when evaluating patients for this diagnosis.

Read the entire manuscript at http://www.eje-online.org/content/early/2015/07/08/EJE-15-0464.full.pdf+html

Day 6: Cushing’s Awareness Challenge 2015

People sometimes ask me how I found out I had Cushing’s Disease.  Theoretically, it was easy.  In practice, it was very difficult.

Ladies Home Journal, 1983In 1983 I came across a little article in the Ladies Home Journal which said “If you have these symptoms…”

I found the row with my symptoms and the answer read “…ask your doctor about Cushing’s”.

After that article, I started reading everything I could on Cushing’s, I bought books that mentioned Cushing’s. I asked and asked my doctors for many years and all of them said that I couldn’t have it.  It was too rare.  I was rejected each time.

 

 

Due to all my reading at the library, I was sure I had Cushing’s but no one would believe me. My doctors would say that Cushing’s Disease is too rare, that I was making this up and that I couldn’t have it.

In med school, student doctors are told “When you hear hoofbeats, think horses, not zebras“.

According to Wikipedia: “Zebra is a medical slang term for a surprising diagnosis. Although rare diseases are, in general, surprising when they are encountered, other diseases can be surprising in a particular person and time, and so “zebra” is the broader concept.

The term derives from the aphorism “When you hear hoofbeats behind you, don’t expect to see a zebra”, which was coined in a slightly modified form in the late 1940s by Dr. Theodore Woodward, a former professor at the University of Maryland School of Medicine in Baltimore.  Since horses are the most commonly encountered hoofed animal and zebras are very rare, logically you could confidently guess that the animal making the hoofbeats is probably a horse. By 1960, the aphorism was widely known in medical circles.”

So doctors typically go for the easily diagnosed, common diseases.  Just because something is rare doesn’t mean that no one gets it.  We shouldn’t be dismissed because we’re too hard to diagnose.

When I was finally diagnosed in 1987, 4 years later, it was only because I started bleeding under the skin. My husband made circles around the outside perimeter each hour with a marker so my leg looked like a cut log with rings.

When I went to my Internist the next day he was shocked at the size of the rings. He now thought I had a blood disorder so he sent me to a Hematologist/Oncologist.

Fortunately, he ran a twenty-four hour urine test and really looked at me and listened to me.  Both he and his partner recognized that I had Cushing’s but, of course, couldn’t do anything further with me.  They packed me off to an endo where the process started again.

My final diagnosis was in October, 1987.  Quite a long time to simply  “…ask your doctor about Cushing’s”.

Looking back, I can see Cushing’s symptoms much earlier than 1983.  But, that ‘s for a different post.