“When we calculated the ratio of decrease in death rate from SLE compared to decrease in death rate in the general population, it comes out that the differential is 35% higher in 2013 than it was in 1968,” says Dr. Singh. “So lupus patients are falling behind relative to people who do not have lupus.”
Year-to-year rate changes also proved interesting. Because of the smaller number of people enrolled in other studies, those researchers usually had to bunch data in five- to 10-year periods. According to Dr. Singh, his study appears to be first in which the size of the study population was large enough to break changes down on a yearly basis.
Similar patterns appeared with both sexes, among African Americans and those residing in the South. However, statistically significant increases in SLE ASMR did not occur among white persons over the entire 46-year period.
“We also noticed significant regional variation in SLE mortality in each racial group,” says Dr. Yen. “Where you live matters. People living in the South and the West experienced the highest mortality risk.”
Females, African Americans and residents of southern states had higher SLE ASMRs and larger cumulative increases in the SLE/non-SLE ASMR ratios (31.4%, 62.5% and 58.6% respectively) than males, other ethnicities/races and other regions.
The researchers next looked at the results of multiple logistic regression analysis. These showed independent associations of race, sex and region with SLE mortality risk, and the researchers noted significant racial/ethnic differences in associations of SLE mortality with sex and region.
“Much of gender difference is [because] women are diagnosed more often with SLE than men,” says Dr. Singh. “African Americans and Hispanics have one-third higher rates than whites. There was also an increase in death rate in those over 65 years of age compared to those who are younger.”
One study limitation was the use of death certificates as the data source. Some studies suggest that perhaps as many as 50% of lupus patients do not have the disease included on their death certificates. This may cause an underestimation of the death rate, leading Dr. Singh to suggest educating primary care physicians and internists to recognize SLE as an important cause of death and to record SLE on death certificates.
Important Conclusions
“One message is that we have done well in the short term, and fewer people are dying in the first few years after diagnosis of lupus and, thus, living longer,” says Dr. Singh and Dr. Yen. “However, death rates in this group haven’t fallen as much as the decrease in the general population. These observations do add to the urgency to the question of why, and show we need to find better ways to manage SLE.”
