Published in Arthritis and Rheumatism, Volume 54, Issue 8
What problem was studied?
Systemic lupus erythematosus (SLE, also known as lupus) is a multisystem, autoimmune disorder that can be severe and life threatening. It has long been suspected that people with SLE have an increased mortality rate compared with people who do not have SLE. This suspicion has been shown to be true in several small studies. Recently, a large team of researchers, including Arthritis Foundation-funded researcher Rosalind Ramsey-Goldman, MD, DrPH, of Northwestern University in Chicago, have assembled data from the largest group of people with SLE ever studied and analyzed mortality rates.
What was done in the study?
Researchers from 23 lupus centers in 7 countries compiled information regarding 9,547 people with SLE. Data were collected on each patient’s date of birth, sex, date of SLE diagnosis, date of entry into the study, date of death, if applicable, and cause of death. The number of observed deaths was then compared with the number of expected deaths according to general population mortality rates. The ratio of observed to expected deaths is called the standardized mortality ratio (SMR).
What were the study results?
Of the total study group, 1,255 deaths occurred during the observation period. The overall SMR for people with SLE was 2.4, meaning that a person with lupus was 2.4 times more likely to die of any cause than a demographically matched person without lupus. Demographically matched means that the comparator group was of the same geography, age, sex and time in history as the person being studied.
Lupus was the official cause of death in 291 cases; however, the most common cause of death was circulatory disease (with an SMR of 1.7), including all types of heart disease, arterial disease and strokes. People with lupus were less likely to die of cancer than the general population except for two circumstances: non-Hodgkin’s lymphoma had an SMR of 2.8 and lung cancer had an SMR of 2.3. Although the total number of people who died of nephritis (kidney disease) and infections other than pneumonia were small, these conditions as causes of death in SLE were higher than the comparator groups, with SMRs of 7.9 and 5.0, respectively.
Patients who were female, younger than 25 years or had a disease duration of less than one year all had particularly high SMRs. Thus, early in the disease course, the risk of death is particularly high and is usually related to the disease itself or treatment for the disease. It also was found that in the United States (the only participating country with ethnic/race data available), African-Americans had a higher SMR than Caucasians (2.6 versus 1.4).
What is the relevance to people with lupus?
Although the death rate among people with lupus has drastically declined in the past decade because of better and early treatment, this study demonstrates a high incidence of death in young women early in their disease course and a high incidence of death due to circulatory disease. People with SLE should use this information to work closely with their doctors to mitigate these risks through close monitoring for worsening disease activity and treatment complications.
In addition, people with SLE should be careful to avoid unnecessary dangers that can lead to circulatory disease, such as smoking, high-fat or high-calorie diets, lack of exercise or being obese.