Prevalence of Lupus Across Patient Populations

Anne E. Winkler, MD, PhD, MACP: Welcome to this rheumatology network presentation entitled “Clinical decision-making evaluating biologics in lupus management.” I am Anne Winkler, a rheumatologist in Southwest Missouri. And joining me today is Dr Kristi Mizelle who is a rheumatologist at TPMG in Newport News, [Tidewater Physicians Multispecialty Group] Virginia. Our discussion today will focus on the practical considerations and the role of biologics in the management of patients with lupus. We will also discuss a case scenario to explore real-world within this arena. Kristi, what kind of population of patients are we thinking about when we talk about lupus? Which are the ones most affected? And what do we worry most about with some of these different populations?

Kristi V. Mizelle, MD, MPH, FACR: The most common populations that have systemic lupus erythematosus is women. That's the most common group. And particularly women of reproductive age within a subgroup of women also African Americans are most affected by systemic lupus or SLE [systemic lupus erythematosus]. Also, that's followed by an amount or number of incidents is Latinx, Asian, and Caucasians in the United States. Lupus in men is unusual or uncommon but it can happen and in my clinical experience men with lupus tend to have more severe disease. And often have family history of lupus as well. The predisposition of lupus occurs in women thought partly or possibly related to estrogen and because of its immune functions in the body. That's the group that we're most likely to see lupus occur in.

Anne E. Winkler, MD, PhD, MACP: And when we think about lupus, we still have some difficulty understanding the triggers for lupus. And of course, we think about sunlight. One of my very first patients as a rheumatology was a young woman a redhead who was out all day in a canoe in the middle of July with the super heavy sun out. Any other triggers or anything else we at least understand about the development of lupus in our patients?

Kristi V. Mizelle, MD, MPH, FACR: There's probably a couple of things that impact the likelihood of a woman or person developing lupus. One is a genetic predisposition and the other are triggers which you mentioned earlier with the redhead who had been out in the sun all day. Genetically we know that lupus is higher, a higher occurrence in first-degree relatives of patients who do have lupus. When we look at twin studies the concordance of lupus in identical twins is approximately 25 to 50%. It doesn't mean it's automatic even if you have the same genetic information that you are going to develop lupus. And then also the concordance of lupus in dizygotic twins is about 5%. This suggests there is some genetic role but that the genetics don't completely tell the whole story. There's also there in the question of triggers that might potentially set off lupus in a genetically predisposed person. The hypothesis is that there are multiple environmental or even unknown factors that may be responsible for triggering or setting off the lupus. And some people have even estimated that patients may even need as far as their genetic makeup for susceptibility genes needed for the development of lupus. There's not necessarily one specific gene that is going to definitely say this person is going to have lupus. Interestingly enough there's been a lot of news about TLR7 which is a genetic mutation on the X chromosome that is basically named a toll-like receptor 7 that may be implicated as a genetic driver in lupus. But there are also some other potential predisposing genetic makeups that can potentially impact the development of lupus. As far as environmental things that can then set off lupus any number of things. Like Anne mentioned, there can be chemical or physical factors like sunlight exposure, other things like hair dyes, tobacco smoke, exposure to aromatic amines. That's a possibility and those have been proposed. Also, infectious agents have also been proposed as well as potentially dietary factors even. And then of course hormones which makes sense and takes us back to that thought about estrogen as well. People who are on contraceptives potentially or even hormone replacement therapy, potentially increased amounts of estrogen may be a trigger for the development of SLE in patients who are pre-genetic, predisposed genetically.

Anne E. Winkler, MD, PhD, MACP: I find that interesting because I have identical twins. One that has very severe lupus, the other one pretty mild. And it's interesting because genetics obviously play a role but there's obviously other environmental factors that have played some sort of role with those as well.

Transcript Edited for Clarity