FRI0245 PULMONARY ARTERIAL HYPERTENSION IN SYSTEMIC SCLEROSIS IS NEARLY ALWAYS ACCOMPANIED BY A LOW DIFFUSING CAPACITY
Authors: A. Hu, T. Nevskaya, M. Baron, J. Pope
Journal: Annals of the Rheumatic Diseases (2020)

Background: Scleroderma (systemic sclerosis; SSc) has high morbidity and mortality. Pulmonary hypertension (PH) and pulmonary arterial hypertension (PAH) is common with a high mortality (1). SSc patients are screened with pulmonary function tests (diffusing capacity of the lung for carbon monoxide; DLCO) (2). Objectives: The DLCO%predicted was analyzed comparing patients with and without PAH to determine if it is always low at time of PAH diagnosis. Methods: The Canadian Scleroderma Research Group (CSRG) database was used containing more than 1300 SSc patients with a mean disease duration of 8 years. All patients with at least one follow up visit and DLCO recorded at least twice were eligible for enrolment into this nested case control study. Diagnosis of PH was verified using several algorithms within the database including R heart catheterization, use of PH medications and physician response of ‘yes’ to question has this patient been diagnosed with pulmonary hypertension. Sensitivity, specificity and positive (PPV) and negative predictive values (NPV) were calculated for DLC0%predicted &lt;50% and presence of PH/PAH. Results: At time of PH diagnosis, the mean DLCO% predicted was 47% (N=30) vs no PH 73% (N=960) P&lt;0.0001, and proven documented PAH also showed the differences (PAH, N=22 DLCO% predicted 51% vs. PAH negative (N=968) DLCO% pred 72%, P&lt;0.0001) (Table 1). The OR of a DLCO%predicted less than 60 was 4.7 for PAH and 7.6 for PH (both P&lt;0.001) and even higher if DLCO&lt;50% (OR 11.5 for PH and 7.6 for PAH). Table 2 shows the PPV of DLCO at varying levels. Table 1. DLCO comparison between PH+ and PH- SSc patients and between PAH+ and PAH- SSc patients, at the time of diagnosis. PH+ (n=30) PH- (n=960) P-value PAH+ (n=22) PAH- (n=968) P-value mean±SD 47.17±17.53 72.74±20.79 &lt;0.0001 51.23±17.55 72.44±20.99 &lt;0.0001 Range 18-81 13-147 25-81 13-147 Table 2. Sensitivity, specificity and predictive values in SSc-PH and -PAH for DLCO at various cut points. OR PPV Specificity NPV Sensitivity DLCO&lt;50% 11.5 (CI 95% 5.4-24.8),p&lt;0.0001 13.2% 87.0% 98.7% 63.3% PH DLCO&lt;60% 7.6 (CI 95% 3.3-17.2), p&lt;0.0001 7.9% 73.3% 98.9% 73.3% DLCO&gt;80% 0.06 (CI 95% 0.008-0.46), p=0.007 0.3% 64.5% 95.5% 3.3% DLCO&lt;50% 7.6 (CI 95% 3.2-17.9), p&lt;0.0001 8.3% 86.4% 98.8% 54.5% PAH DLCO&lt;60% 4.7 (1.9-11.3), p&lt;0.001 5.0% 72.7% 98.9% 63.6% DLCO&gt;80% 0.1 (0.01-0.7), p=0.018 0.3% 64.8% 96.8% 4.5% Conclusion: A low DLCO is associated with a high odds of PH/PAH in SSc and the NPV is very high at both DLCO&lt;50% predicted and &lt;60% predicted. This may aid in determining who should recieve a right heart catheterization in SSc patients. References: [1]Mukerjee D et al (2003) Prevalence and outcome in systemic sclerosis associated pulmonary arterial hypertension: application of a registry approach. Ann Rheum Dis 62(11):1088-93 [2]Khanna D et al (2013) Recommendations for screening and detection of connective tissue disease-associated pulmonary arterial hypertension. Arthritis Rheum 65(12):3194-201 Disclosure of Interests: None declared