Systemic sclerosis mortality in the United States: 1979-1998.

The US national mortality rates from systemic sclerosis (SSc) have not been reported since 1979. We studied age, gender and race specific time trends in US national mortality rates of SSc during the period 1979-1998 using poisson regression models. Over the 4.93 billion person-years of observation during the study period, there were 18,126 deaths from SSc, representing a mortality rate of 3.9 per million. The age adjusted mortality rates for men and women were 1.9 and 5.4 per million respectively. There were relatively few deaths in the extremes of age. SSc mortality rates increased with age in both genders and in all racial groups (p<0.001). In multivariable models adjusted for two-way statistical interactions, being African-American, female and of older age were associated with higher death rates. Over the 20 years of observation, overall (age-adjusted) SSc mortality rates showed a 36% increase (p<0.001) and subgroup analyses revealed that the increases were confined to women of both races. This rise occurred during a period in which post-diagnosis survival of SSc is known to have increased, suggesting an increasing incidence of this disease.