Interstitial Lung Disease in Systemic Sclerosis: A Simple Staging System

Am J Respir Crit Care Med. 2008 Jun 1;177(11):1248-54. doi: 10.1164/rccm.200706-877OC. Epub 2008 Mar 27.

Abstract

Rationale: 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.

Objectives: 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.

Measurements and main 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.

Publication types

  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Algorithms*
  • Cohort Studies
  • Female
  • Humans
  • Lung Diseases, Interstitial / diagnosis*
  • Lung Diseases, Interstitial / etiology
  • Lung Diseases, Interstitial / mortality
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Prognosis
  • Scleroderma, Systemic / complications*
  • Scleroderma, Systemic / diagnostic imaging
  • Scleroderma, Systemic / physiopathology
  • Severity of Illness Index*
  • Survival Analysis
  • Tomography, X-Ray Computed
  • Vital Capacity / physiology