Background/Purpose:

Recent reviews have suggested a high prevalence of pulmonary veno-occlusive disease (PVOD) amongst patients with systemic sclerosis (SSc) associated pulmonary hypertension (PH). Interlobular septal thickening (IST) and centrilobular nodules (CLN) are reported to correlate with presence of PVOD, which is associated with worse outcomes in small series. We tested this hypothesis on a large series of systemic sclerosis patients who underwent evaluation for pulmonary hypertension.

Methods:

A retrospective study of patients with systemic sclerosis who underwent CT of the chest within six months of a diagnostic right heart catheterisation. The CTs were blindly scored by two independent radiologists including detailed assessment for extent of interstitial lung disease (using the Goh et al. AJRCCM 2008 staging system), IST and CLN. Each lung quadrant was scored separately for interlobular septal thickening (IST) with score 0-5 and centrilobular nodules (CLN), score 0-3. Survival data were collected on all patients.

Results:

Mean age was 57.8 (range 22-85). 78% were female. 84 patients had LcSSc, 32 had DcSSc and 1 had MCTD. CT scans were performed a mean of 2.7 months from the RHC.

There was limited or no ILD extent (<20%) in 46 patients (43%), ~20% in 28% and extensive (>20%) in 30%. On right heart catheterisation 53% had precapillary PH while 47% did not.

95 scans were reported independently in a blinded fashion by two radiologists. Of the remaining 95 patients, 49 had PAH and 46 did not. Of those with PH, 18 had <20% ILD, 18 had ~20% ILD and 13 had >20% ILD. Amongst patients with PH, there was a weak trend towards worse survival in patients with more lung disease (HR 1.5, 95% CI 0.89,2.52, p=0.13).

IST of any degree was observed in 15% of patients and CLN in 18%. Mean IST score was 1 (on a scale of 0-4) and mean CLN score was 0.63 (scale of 0-2). IST was not associated with extent of ILD (p=0.19 by chi-square), and nor was CLN (p=0.74, by chi-square). IST did not correlate with PVR (R2=2%) whereas CLN did correlate with PVR (R2=15.7%).

By Cox proportional hazards analysis, PVR was a strong predictor of death (p=0.001). Increasing IST was associated with worse survival on univariate analysis (p=0.038) however statistical significance is lost (p=0.11) after adjustment for age.

Increasing CLN is strongly associated with higher mortality (p=0.013) even after adjustment for age, gender, extent of interstitial lung disease and mean pulmonary artery pressure (p=0.047). This is particularly observed in patients without PH (p=0.004 on this multivariate analysis) rather than in patients with PH (where p=0.19 on multivariate analysis). However, CLN is not a significant predictor after adjustment for PVR (p=0.18). 

Conclusion:

Interlobular septal thickening and centrilobular nodules are frequently seen in patients with systemic sclerosis and are each associated with worse survival. However, IST increases with age and CLN increases with worsening pulmonary vascular resistance. In our study they were not independent predictors of worse outcome in systemic sclerosis. It is therefore possible that the significance of these radiological findings is primarily as markers of known prognostic risk factors.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/systemic-sclerosis-associated-pulmonary-hypertension-is-pulmonary-veno-occlusive-disease-as-common-as-they-say/