|Study Indicates Scleroderma Mortality Rates Being Underestimated|
|Saturday, 25 May 2013 08:39|
Scleroderma patients have a significantly reduced life expectancy that is most likely being underestimated, delegates have heard. Most studies on scleroderma survival are based on prevalent cohorts, where no limit is placed on disease duration at the time of recruitment. This leaves results wide open to “survival bias”.
In a bid to overcome the issue and get to the true figures, Dr Nikpour and colleagues from across Australia evaluated the survival rates of nearly 1,300 scleroderma patients from 13 centres, compared with the general Australian population. Patients were studied as an entire cohort, but also as a separate cohort of patients who had been recruited within 5 years of disease onset.
The figures told a different story. In the whole cohort, there were 27 deaths (15 diffuse and 12 limited disease) over the 8 year study period. Twenty five of these 27 deaths were in the subset of patients with early disease. Ten year survival of patients with diffuse disease in the overall cohort was 90% whereas in the early disease cohort it was 70% -- clear evidence that survival bias was alive and kicking, Dr Nikpour said.
Fifteen of the deaths in the first decade were scleroderma-related and all were caused by either heart or lung manifestations. The remaining 12 deaths were not deemed to be scleroderma related and most were malignancies.
Overall, the study found that the standard mortality ratios were 8.8 for men and 6.4 for women - figures higher than previously reported, Dr Nikpour said.
“Scleroderma carries substantial mortality. The average standard mortality rate of 6.8 in our Australian patients is one of the highest reported and is comparable to some types of malignancies” Dr Nikpour said. The SMR reported here is considerably higher than the SMR of 1.5 recorded in the South Australian registry, she said.
But there may be a variety of explanations for the discrepancy. There could be differences in scleroderma case definition, death case ascertainment and survival bias, she said. Nevertheless the results were a “compelling rationale” for establishing a large multinational inception cohort of patients with scleroderma to follow disease outcomes, she concluded.
Source: Rheumatology Update (2013)