Preliminary diagnostic guidelines for macrophage activation syndrome complicating systemic juvenile idiopathic arthritis.
OBJECTIVE
To develop diagnostic guidelines for macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (S-JIA).


METHODS
We followed the classification criteria approach that is based on the comparison of patients with the index disease with patients with a "confusable" disease. The former group included 74 patients with S-JIA-associated MAS reported in the literature or seen by the authors; the latter group included 37 patients with S-JIA who had 51 instances of "high disease activity" seen by the authors. The relative power of clinical, laboratory, and histopathologic variables in discriminating patients with MAS from patients with high disease activity was evaluated by calculating the sensitivity rate, specificity rate, area under the receiver operating characteristic curve, and diagnostic odds ratio (DOR). The combinations of variables that led to best separation between patients and control subjects were identified through "the number of criteria present" method.


RESULTS
The strongest clinical discriminators were hemorrhages (DOR = 67) and central nervous system dysfunction (DOR = 63); the strongest laboratory discriminators were decreased platelet count (DOR = 1092), increased aspartate aminotransferase (DOR = 247), leukopenia (DOR = 70), and hypofibrinogenemia (DOR = 165). The best separation between patients and control subjects occurred when any 2 or more laboratory criteria (DOR = 1309) were simultaneously present; the second best performance was provided by the presence of any 2, 3, or more clinical and/or laboratory criteria (DOR = 765 and 743, respectively).


CONCLUSIONS
We identified preliminary diagnostic guidelines for MAS complicating S-JIA. These guidelines deserve prospective validation.
Ravelli
Angelo
A
Department of Pediatrics, Division of Pediatrics II, University of Genoa, Istituto G. Gaslini, Largo G. Gaslini 5, 16147 Genoa, Italy. angeloravelli@ospedale-gaslini.ge.it
Magni-Manzoni
Silvia
S
Pistorio
Angela
A
Besana
Cristina
C
Foti
Tiziana
T
Ruperto
Nicolino
N
Viola
Stefania
S
Martini
Alberto
A
D000293:Adolescent; D001171:Arthritis, Juvenile / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008262:Macrophage Activation; D008297:Male; D012680:Sensitivity and Specificity; D013577:Syndrome