Long-term outcome in polymyositis and dermatomyositis.
BACKGROUND
Although polymyositis and dermatomyositis are regarded as treatable disorders, prognosis is not well known, as in the literature long-term outcome and prognostic factors vary widely.


OBJECTIVE
To analyse the prognostic outcome factors in polymyositis and adult dermatomyositis.


METHODS
We determined mortality, clinical outcome (muscle strength, disability, persistent use of drugs and quality of life) and disease course and analysed prognostic outcome factors.


RESULTS
Disease-related death occurred in at least 10% of the patients, mainly because of associated cancer and pulmonary complications. Re-examination of 110 patients after a median follow-up of 5 years showed that 20% remained in remission and were off drugs, whereas 80% had a polycyclic or chronic continuous course. The cumulative risk of incident connective tissue disorder in patients with myositis was significantly increased. 65% of the patients had normal strength at follow-up, 34% had no or slight disability, and 16% had normal physical sickness impact profile scores. Muscle weakness was associated with higher age (odds ratio (OR) 3.6; 95% confidence interval (CI) 1.3 to 10.3). Disability was associated with male sex (OR 3.1; 95% CI 1.2 to 7.9). 41% of the patients with a favourable clinical outcome were still using drugs. Jo-1 antibodies predicted the persistent use of drugs (OR 4.4, 95% CI 1.3 to 15.0).


CONCLUSIONS
Dermatomyositis and polymyositis are serious diseases with a disease-related mortality of at least 10%. In the long term, myositis has a major effect on perceived disability and quality of life, despite the regained muscle strength.
Bronner
I M
IM
Department of Neurology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
van der Meulen
M F G
MF
de Visser
M
M
Kalmijn
S
S
van Venrooij
W J
WJ
Voskuyl
A E
AE
Dinant
H J
HJ
Linssen
W H J P
WH
Wokke
J H J
JH
Hoogendijk
J E
JE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood; D003882:Dermatomyositis / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D017285:Polymyositis / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D011379:Prognosis; D011788:Quality of Life; D016019:Survival Analysis
D001323:Autoantibodies; D007166:Immunosuppressive Agents