High protein levels in the urine, poor kidney function, and high blood pressure at the time of systemic sclerosis (SSc) diagnosis are strong predictors for the future development of scleroderma renal crisis (SRC), a study suggests.
These and other laboratory findings can help identify those patients who are at a higher risk of renal crisis, allowing for early identification and timely therapeutic interventions, according to researchers.
The study, “Risk Factors for Future Scleroderma Renal Crisis at Systemic Sclerosis Diagnosis,” was published in The Journal of Rheumatology.
SRC is one of the most serious complications of SSc. It affects 5 to 15 percent of patients, causing the abrupt onset of high blood pressure and acute kidney failure.
A few risk factors are known to predispose SSc patients to renal crisis, including exposure to corticosteroids, the presence of anti-RNA polymerase III antibodies, skin thickness, and significant tendon friction rubs.
Other conditions, such as high blood pressure, protein in the urine, anemia, low platelet counts, and kidney disease, have been associated with renal crisis, but it is unknown if these risk factors are already present when scleroderma is first diagnosed.
To determine whether these clinical and lab parameters are predictors of future renal crisis at SSc diagnosis, researchers retrospectively compared data between SSc patients who later developed renal crisis and those who did not.
Patient data was derived from the military medical registry of the U.S. Department of Defense between 2005 and 2016. In total, researchers included 31 SSc patients who later developed renal crisis and 322 SSc patients without SRC, used as controls.
Results showed that, at the time of SSc diagnosis, patients who eventually developed renal crisis were more than 100 times more likely to have high protein in their urine, also known as proteinuria. Additionally, they had a 20-fold higher chance of having chronic kidney disease and a 13-fold higher chance of high blood pressure than those not affected by kidney failure.
Other risk factors significantly associated with renal crisis were anemia, or low levels of red blood cells in the blood; an elevated erythrocyte sedimentation rate, indicative of inflammation; and low platelet counts, or thrombocytopenia.
Researchers also found that hypothyroidism, when the thyroid gland cannot produce enough thyroid hormone, also correlated with the development of renal crisis in SSc patients.
In addition, the presence of anti-RNA polymerase III antibodies and antinuclear antibodies in SSc patients was also associated with SRC development.
According to the team, displaying two or more of these risk factors at the time of SSc diagnosis predicted, with 94% specificity, the eventual onset of renal crisis.
“Improved understanding of SRC risk factors at the time of SSc diagnosis could better instruct future clinical surveillance and prospective research,” the researchers wrote.
The team also suggested that “this population may benefit from follow-up at closer intervals, more aggressive BP [blood pressure] monitoring, more stringent avoidance of steroids, and potential future therapies.”
Researchers emphasized that studies on the use of angiotensin-converting enzyme, or ACE, inhibitors, angiotensin-receptor blockers, and calcium channel blockers before a renal crisis is diagnosed can improve our understanding of the benefits and potential risks of these therapies as preventive treatments.