Patients with systemic sclerosis have ‘significantly higher’ mortality despite advances
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Despite advances in understanding and diagnostics, patients with systemic sclerosis still demonstrate “significantly higher” mortality rates compared with the general population, according to Swedish data published in Rheumatology.
“SSc carries one of the highest standardized mortality ratios (SMR) compared to the general population among the rheumatic diseases,” Majd Bairkdar, MD, of the division of clinical epidemiology at the department of medicine at Solna, at the Karolinska Institute, in Stockholm, and colleagues wrote. “Renal involvement, pulmonary arterial hypertension (PAH), and interstitial lung disease (ILD) are the main fatal manifestations of SSc.”
To investigate mortality associated with SSc, Bairkdar and colleagues conducted a population-based, matched cohort study. The information used in the analysis originated from the National Patient Registry, which includes data on hospitalizations for all members of the Swedish national health care system back to 1987. The registry details outpatient specialist visits, including those with rheumatologists. The authors also used the Total Population Register, which includes demographic and census data and the Cause of Death Registry, which collects data surrounding patient death timing and causes.
The researchers identified patients with SSc within the system by finding patients that were aged 18 years or older and had two or more visits with SSc listed as the primary diagnosis. Patients were required to have their first visit between Jan. 1, 2004, and Dec. 31, 2015, and the second visit must have occurred with 12 months of the first. The authors additionally collected comorbidity data from the National Patient Register. Exposure was defined as an incident SSc diagnosis, and the date of follow-up was established as the date of the second “disease-defining” visit for each patient. The researchers followed patients until Dec. 31, 2016, death or until they emigrated.
The analysis included a total of 1,139 patients with SSc and 5,613 matched comparators from the general population. Median follow-up times were 5 years for patients with SSc and 6 years for comparators. During that time, patients with SSc had 268 deaths while individuals without the disease had 554. Survival rates among patients with SSc were 79.8% at 5 years and 67.7% at 10 years, compared with 92.9% and 84.8%, respectively, for the general population (P < .0001). The mortality rate for patients with SSc was 42.1 per 1,000 person years, compared with 15.8 per 1,000 person-years in the comparator group (HR = 3.7; 95% CI, 2.9-4.7).
“This study demonstrates that the previously observed significantly higher mortality among patients with SSc is present also in Sweden today,” Bairkdar and colleagues wrote. “Despite advances in understanding the disease and in diagnostic methods, survival is still severely impacted in Swedish patients diagnosed between 2004 and 2015.”
References:
- Nikpour M, et al. Curr Opin Rheumatol. 2014;doi:10.1097/BOR.0000000000000027.
- Walker UA, et al. Ann Rheum Dis. 2007;doi: 10.1136/ard.2006.062901.