Investigators used death certificate data to determine the annual average decline of deaths attributed to systemic sclerosis.
Age-adjusted systemic sclerosis (SSc)—related mortality dropped by about 3% per year in the United States, according to a paper published in ERJ Open Research.
Investigators from Thailand and Denver, Colorado, used death certificates and data from the U.S.’ National Center for Health Statistics in order to determine any trends in SSc and SSc-related pulmonary arterial hypertension (PAH) mortality both overall and within specific subgroups of the population. They expected the longitudinal nature of their data to reveal changing patterns for SSc-related mortality, which could lead to better treatment for vulnerable populations, they wrote.
The investigators found 25,175 death records from 2003 to 2016 that contained a code for SSc, and included those patients in their analysis. SSc was listed on death records as the single underlying cause-of-death (UCOD) for about three-fourths of cases, and SSc was listed as one of the multiple causes-of-death (MCOD) for the remainder of cases. Death certificates can include up to 20 MCODs, the study authors noted.
The investigators also observed that the proportion of SSc as the UCOD vs MCOD remained stable throughout the duration of the study period, but they found that it declined as age increased. The 3 most common UCOD other than SSc itself were circulatory system, malignant neoplastic disorders, and diseases of the digestive system, they added.
Most of these deaths occurred in a hospital, according to the study authors, though about 10% happened in the patients’ homes and 4% happened in long-term care facilities. The mean age of patients at death was 62 years for men and 67 years for women. The patients aged 75 years or older had the highest mortality rate during the study period, the investigators said.
The study authors also learned that SSc mortality rates declined at an average annual rate of 3%. For example, SSc-related mortality rate was 6.6 per 1,000,000 in 2003 but 4.3 per 1,000,000 by 2016. There was also a decline in mortality from SSc during the study period for patients aged between 35 and 54 years and aged 55 to 75 years, the study authors said.
Both men and women saw a decline throughout the study period in SSc-related mortality rate, the study authors said. For women, the rate dropped from 10.3 per million in 2003 to 7.2 per million by 2016. For men, they said, that rate dropped from 2.7 per million in 2003 to 1.5 per million in 2016. But in any given year, they highlighted, women had a higher age-adjusted SSc-related mortality compared to men by a ratio of 4:1.
The study authors also compared mortality rates by race, and found that white (9.7 per million) and black (8.6 per million) patients had the highest age-adjusted SSc-related mortality rates. However, they noted that all racial groups had similar declines in the average annual mortality rates due to SSc throughout the observation period.
Geographically, the study authors found that Midwesterners had the highest age-adjusted SSc-related mortality throughout the study period. The states with the highest rates included South Dakota (8.9 per million), Montana (8.8 per million), and Vermont (8.8 per million). The SSc-related mortality rate decreased similarly across regions and states, the investigators said.
For patients that died from SSc-related causes, PAH was prevalent in about a quarter of cases. The study authors said the odds of PAH were higher in female and black patients, those who were in the 55- to 74-year age bracket, and patients with pulmonary embolism, cardiomyopathy, and interstitial lung disease. There was no significant change in the annual percentage of SSc-related PAH mortality throughout the study period, the investigators reported.
“The study suggests that SSc-related mortality is decreasing in the U.S.,” the study authors concluded. “The finding that PAH, particularly in black women, and cardiovascular complications are the leading contributing causes of SSc death have significant implications for planning the future allocation of health resources.”
Ratanawatkul P, Solomon JJ, Kim D, et al. Trends in systemic sclerosis and systemic sclerosis-related pulmonary arterial hypertension mortality in the USA. ERJ Open Res. 2020;6(2):00309-2019. doi:10.1183/23120541.00309-2019