Introduction: The idiopathic inflammatory myopathies are rare diseases for which data regarding the natural
history, response to therapies and factors affecting mortality are needed. We performed this study to examine the
effects of treatment and clinical features on survival in polymyositis and dermatomyositis patients.
Methods: A total of 160 consecutive patients (77 with polymyositis and 83 with dermatomyositis) seen at the
University of Michigan from 1997 to 2003 were included. Medical records were abstracted for clinical, laboratory
and therapeutic data, including initial steroid regimen and immunosuppressive use. State vital records were utilized
to derive mortality and cause of death data. Survival was modeled by left-truncated Kaplan-Meier estimation and
Cox regression.
Results: The 5- and 10-year survival estimates were 77% (95% CI = 66 to 85), and 62% (95% CI = 48 to 73),
respectively, and the rates were similar for polymyositis and dermatomyositis. Survival between the sexes was
similar through 5 years and significantly lower thereafter for males (10-year survival: 18% male, 73% female; P =
0.002 for 5- to 10-year interval). The sex disparity was restricted to the polymyositis group. Increased age at
diagnosis and non-Caucasian race were associated with lower survival. Intravenous versus oral corticosteroid use
was associated with a higher risk of death among Caucasians (HR = 10.6, 95% CI = 2.1 to 52.8). Early survival
between patients treated with methotrexate versus azathioprine was similar, but survival at 10 years was higher for
the methotrexate-treated group (76% vs 52%, P = 0.046 for 5- to 10-year interval).
Conclusions: Patients treated initially with intravenous corticosteroids had higher mortality, which was likely
related to disease severity. Both methotrexate and azathioprine showed similar early survival benefits as first-line
immunosuppressive drugs. Survival was higher between 5 and 10 years in the methotrexate-treated group, but
could not be confirmed in multivariable modeling for the full follow-up period. Other important predictors of longterm
survival included younger age, female sex and Caucasian race.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90025/1/IIM_ART2012.pdf1611
