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THU0235 Identifying and quantifying prognostic factors in systemic sclerosis-related interstitial lung disease using a time-varying covariate survival model
  1. O.A. Moore1,
  2. N. Goh2,
  3. T. Corte3,
  4. H. Rouse4,
  5. O. Hennessy4,
  6. V. Thakkar1,
  7. J. Byron1,
  8. J. Sahhar5,
  9. J. Roddy6,
  10. P. Youssef7,
  11. P. Nash8,
  12. J. Zochling9,
  13. S.M. Proudman10,
  14. W. Stevens1,
  15. M. Nikpour1
  16. and Australian Scleroderma Interest Group
  1. 1Rheumatology, St Vincent’s Hospital
  2. 2Respiratory Medicine, Austin Hospital, Melbourne
  3. 3Respiratory Medicine, Royal Prince Alfred Hospital, Sydney
  4. 4Radiology, St Vincent’s Hospital
  5. 5Rheumatology, Monash Medical Centre, Melbourne
  6. 6Rheumatology, Royal Perth Hospital, Perth
  7. 7Rheumatology, Royal Prince Alfred, Sydney
  8. 8Research Unit, Sunshine Coast Rheumatology, Maroochydore
  9. 9Rheumatology, The Menzies Institute, Hobart
  10. 10Rheumatology, Royal Adelaide Hospital, Adelaide, Australia


Background Interstitial lung disease (ILD) is a leading cause of mortality in systemic sclerosis (SSc). We have shown that total extent of lung disease on high-resolution CT (HRCT) lung, reported using a simple grading system,[1] can determine prognosis in SSc-ILD.

Objectives We assessed factors that predicted deterioration in ILD using a time varying covariate model.

Methods SSc patients with a baseline HRCT around the time of diagnosis of ILD were identified through the Australian Scleroderma Cohort Study (ASCS). All HRCTs and pulmonary function tests (PFTs) performed during follow-up were retrieved. Demographic and disease-related data were prospectively collected in the ASCS database. HRCTs were reported by three blinded raters (two respiratory physicians, one radiologist) following a training session. Scans were graded according to the percentage of lung disease seen; >20% - extensive, <20% - limited, unclear - indeterminate. Indeterminate results were converted to limited or extensive using an FVC threshold of 70%. The composite outcome variable was deterioration (defined as need for home oxygen or lung transplantation) or death. Demographic and disease related data including HRCT grade was compared to outcome using a Weibull hazards regression model with time-varying covariates.

Results Among 172 patients followed for mean±SD of 3.47±2.93 years, there were 33 outcome events. In time-varying covariate models (based on 1309 serial PFTs and 353 serial HRCTs in the 172 patients), serial DLCO/VA (ml/min/mmHg/L) (adjusted hazards ration (aHR) =0.4, 95% CI: 0.3-0.7, p=0.001), FVC (dL) (aHR =0.9, 95% CI: 0.8-0.97, p=0.008) and extensive disease score (aHR =3.3, 95% CI: 1.1-9.9, p=0.03), were strongly predictive of outcome.

Conclusions In follow-up of patients with SSc-ILD findings of extensive disease according to this simple staging system or lower DLCO/VA or FVC are indicative of increased risk of poor disease outcome. Considering the cost and radiation risk of HRCT-lung we would suggest the use of PFTs in the follow-up of these patients.

  1. Goh NSL, Desai SR, Veeraraghavan S, et al. Interstitial Lung Disease in Systemic Sclerosis: A Simple Staging System. American Journal of Respiratory and Critical Care Medicine 2008;177:1248–1254.

Disclosure of Interest None Declared

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