A watchful eye: Population-based study refutes anecdotes that cutaneous lupus is on the rise

August 4, 2009

The results of a recent population-based study confirms that the incidence of Cutaneous lupus erythematosus is not two to three times higher than the incidence of the more severe systemic lupus erythematosus form of the autoimmune disease, as anecdotally once thought.

Rochester, Minn. - A watchful eye kept on the frequency of incidence of autoimmune diseases, such as systemic lupus erythematosus (SLE) and cutaneous lupus erythematosus (CLE), is important because of the severe pathology that these two diseases can cause in patients. A recent study showed that the incidence of CLE was comparable to the published incidence of SLE.

"Cutaneous lupus erythematosus is a variant of systemic lupus erythematosus, but fortunately, CLE has a much lighter course and a much better prognosis for patients. As the cutaneous form can develop and progress into the systemic form of lupus, we thought that it might be important to find out the incidence of cutaneous lupus compared to systemic lupus in the general population and negate the anecdotes that cutaneous lupus is on the rise," says Olayemi Durosaro, B.S., a fourth-year medical student at the Mayo Clinic College of Medicine, Rochester, Minn.

Ms. Durosaro and her colleague Mark D. Davis, M.D., professor and vice chairman of the division of dermatology, department of dermatology, Mayo Clinic, Rochester, Minn., conducted a retrospective, population-based study in which the incidence of cutaneous lupus was evaluated in the general population of Olmsted County, Minn., with the help of the Rochester epidemiologic project (REP).


Study parameters

Using the community-based tool’s database, a comprehensive and thorough review of all medical records of the patients in the county was undertaken and those patients with the medical diagnosis of any subtype of CLE who resided in Olmsted County between 1965 and 2005 were identified.

Subtypes included classic discoid lupus erythematosus (CDLE), lupus panniculitis, bullous lupus erythematosus and subcutaneous lupus erythematosus (SCLE).

This data was then compared to the data of a previous similar study conducted by Uramoto et al, where the incidence of SLE (also using the REP) was evaluated in patients between 1950 and 1992, providing a direct comparison of the incidences of CLE and SLE in the same population.

Ms. Durosaro reviewed both data sets and adjusted them to analyze only the data between 1965 and 1992, where the two projects overlapped according to time.


Results

Study results showed that the incidence of SLE between 1965 and 1992 was 2.78 per 100,000 in the population. Ms. Durosaro found that in the same time frame, CLE occurred in 3.08 per 100,000 in the same study group population. Overall between 1965 and 2005, the incidence of CLE including SCLE, CDLE, bullous lupus erythematosus and lupus panniculitis was 4.3 per 100,000 in the population.


Limitations

"One of the limitations of the study is that Rochester, Minn., is not very racially diverse. This influences the study results, because it is well known that lupus erythematosus in general and particularly cutaneous lupus erythematosus is predominantly seen in minority populations, such as African-Americans.

"Therefore, if we had a more diverse population and patient base, the incidence statistic could possibly be higher that what we recorded," Ms. Durosaro says.


Future study


Ms. Durosaro says that the next follow-up study, which is already underway, aims to analyze the features of the CLE patients who transitioned to full-blown SLE and just how many actually did so. According to the researchers, the incidences of CLE and SLE and those patients who progress from one disease to the other is important for dermatologists to know.

"Cutaneous lupus erythematosus is defined as isolated cutaneous lupus lesions occurring in the absence of significant evidence of SLE. Many dermatologists who closely follow their CLE patients perform extensive work up on these patients and closely watch and control whether the patient will progress to SLE. “This work-up can have economic implications that can significantly impact dermatologic practices," Ms. Durosaro says. DT

Disclosures: Ms. Durosaro