Interstitial lung disease in systemic sclerosis: a simple staging system.
BACKGROUND
In interstitial lung disease complicating systemic sclerosis (SSc-ILD), the optimal prognostic use of baseline pulmonary function tests (PFTs) and high-resolution computed tomography (HRCT) is uncertain.


OBJECTIVE
To construct a readily applicable prognostic algorithm in SSc-ILD, integrating PFTs and HRCT.


METHODS
The prognostic value of baseline PFT and HRCT variables was quantified in patients with SSc-ILD (n = 215) against survival and serial PFT data.


RESULTS
Increasingly extensive disease on HRCT was a powerful predictor of mortality (P < 0.0005), with an optimal extent threshold of 20%. In patients with HRCT extent of 10-30% (termed indeterminate disease), an FVC threshold of 70% was an adequate prognostic substitute. On the basis of these observations, SSc-ILD was staged as limited disease (minimal disease on HRCT or, in indeterminate cases, FVC >or= 70%) or extensive disease (severe disease on HRCT or, in indeterminate cases, FVC < 70%). This system (hazards ratio [HR], 3.46; 95% confidence interval [CI], 2.19-5.46; P < 0.0005) was more discriminatory than an HRCT threshold of 20% (HR, 2.48; 95% CI, 1.57-3.92; P < 0.0005) or an FVC threshold of 70% (HR, 2.11; 95% CI, 1.34-3.32; P = 0.001). The system was evaluated by four trainees and four practitioners, with minimal and severe disease on HRCT defined as clearly < 20% or clearly > 20%, respectively, and the use of an FVC threshold of 70% in indeterminate cases. The staging system was predictive of mortality for all scorers, with prognostic separation higher for practitioners (HR, 3.39-3.82) than trainees (HR, 1.87-2.60).


CONCLUSIONS
An easily applicable limited/extensive staging system for SSc-ILD, based on combined evaluation with HRCT and PFTs, provides discriminatory prognostic information.
Goh
Nicole S L
NS
Royal Brompton Hospital and National Heart and Lung Institute, London, United Kingdom.
Desai
Sujal R
SR
Veeraraghavan
Srihari
S
Hansell
David M
DM
Copley
Susan J
SJ
Maher
Toby M
TM
Corte
Tamera J
TJ
Sander
Clare R
CR
Ratoff
Jonathan
J
Devaraj
Anand
A
Bozovic
Gracijela
G
Denton
Christopher P
CP
Black
Carol M
CM
du Bois
Roland M
RM
Wells
Athol U
AU
D000328:Adult; D000465:Algorithms; D015331:Cohort Studies; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012595:Scleroderma, Systemic / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D012720:Severity of Illness Index; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity / Q000502:physiology