Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: Pulmonary hypertension (PH) is a leading cause of death in patients with systemic sclerosis (SSc). Transthoracic echocardiogram and pulmonary function testing are standard noninvasive screening methods for PH. However, both are limited in their ability to distinguish between SSc patients with and without PH. The gold standard diagnostic test for PH is right heart catheterization (RHC), which although accurate, is expensive, invasive, and has associated risks. Finding an accurate, noninvasive technique to screen for PH in the SSc population is an important unmet need.
The submaximal heart and pulmonary evaluation (step test) is a standardized, noninvasive, submaximal stress test that consists of a 5.5 inch high step that patients step up and down on for 3 minutes. During the test, end tidal carbon dioxide, which is positively correlated with cardiac output and pulmonary blood flow and inversely correlated with the minute ventilation to carbon dioxide production ratio (VE/VCO2) and reflects the severity of PH, is monitored. Our primary aim was to determine whether SSc patients with PH would have a lower change in end tidal carbon dioxide (DPETCO2) from rest to end-exercise on the step test than SSc patients without PH. Our secondary aim was to determine whether SSc patients with PH would have a higher VE/VCO2 than those without PH. We also examined differences in validated self-report questionnaires and biomarkers between SSc patients with and without PH. We hypothesized that SSc patients with PH would have a lower DPETCO2 and higher VE/VCO2 than SSc patients without PH.
Methods: This is a cross-sectional study of 27 patients with limited or diffuse cutaneous SSc who underwent an RHC within 24 months of study entry. All patients were administered the step test between May 2012 and August 2013. DPETCO2 and VE/VCO2 were compared between patients with and without PH, defined as a mean pulmonary artery pressure ≥ 25 mmHg on RHC. Differences in self-report data and biomarkers were also compared between groups. Statistical analysis was performed using Kruskal-Wallis, chi square, and Fisher exact tests, as appropriate.
Results: See Table 1 for patient characteristics. SSc patients with PH had a statistically significantly lower median DPETCO2 than SSc patients without PH (-2.1 [-5.1 – +0.7] vs. 1.2 [-0.7 – +5.4], p=0.035) and a statistically significantly higher median VE/VCO2 (53.4 [39-64.1] vs. 36.4 [31.9-41.1], p=0.035) than SSc patients without PH. There were no statistically significant differences in self-report data or biomarkers between groups (Table 1).
Conclusion: DPETCO2 and VE/VCO2 as measured by the step test are statistically significantly different between SSc patients with and without PH. Neither traditional self-report outcome measures nor biomarkers differed between groups. Further prospective studies are needed to evaluate the step test as a screening tool for PH in the SSc population.
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Table 1: Patient Characteristics, Self-Report Questionnaire Scores, and Biomarker Levels |
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Patient Characteristics |
PH (N = 18) |
No PH (N = 9) |
p-value |
|
Age – yr |
61.9 (52.9-69.2) |
65.7 (56.4-70.3) |
0.64 |
|
Female sex |
13 (72%) |
5 (56%) |
0.39 |
|
White race |
13 (72%) |
7 (78%) |
0.76 |
|
Limited cutaneous SSc |
13 (72%) |
6 (67%) |
0.77 |
|
Disease duration – yr |
17.5 (6.4-26.1) |
11.5 (4.02-19.4) |
0.22 |
|
Time between RHC and step test – months |
9.9 (7.2-16.5) |
12.5 (4.6-22.5) |
0.64 |
|
Anti-centromere antibody positive |
6/17 (35%) |
3 (33%) |
0.92 |
|
Anti-Scl-70 antibody positive |
2/17 (12%) |
4 (44%) |
0.06 |
|
Anti-RNA polymerase III antibody positive |
1/16 (6%) |
0/7 (0%) |
0.99 |
|
Raynaud’s phenomenon |
17 (94%) |
9 (100%) |
0.47 |
|
Digital ulcerations |
10 (56%) |
6 (67%) |
0.58 |
|
Renal crisis |
0 (0%) |
0 (0%) |
|
|
Sclerodactyly |
16 (89%) |
8 (89%) |
|
|
Interstitial lung disease |
10 (56%) |
5 (56%) |
|
|
Gastroesophageal reflux disease |
16 (89%) |
9 (100%) |
0.30 |
|
Calcinosis |
7 (39%) |
4 (44%) |
0.78 |
|
Telangiectasias |
13 (72%) |
7 (78%) |
0.76 |
|
Proximal lower extremity weakness |
1 (6%) |
0 (0%) |
0.47 |
|
Arthritis |
9 (50%) |
5 (56%) |
0.79 |
|
Tobacco use |
|
|
0.41 |
|
Never |
11 (61%) |
4 (44%) |
|
|
Former |
7 (39%) |
5 (56%) |
|
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Self-Report Questionnaires |
PH (N = 18) |
No PH (N = 9) |
|
|
Cambridge Pulmonary Hypertension Outcome Review |
|
|
|
|
Symptom Scale |
8 (4-12) |
6 (5-10) |
0.90 |
|
Energy Subscale |
4 (2-6) |
5 (2-6) |
0.68 |
|
Breathlessness Subscale |
3.5 (1-4) |
2 (2-4) |
0.56 |
|
Mood Subscale |
1 (0-2) |
0 (0-2) |
0.72 |
|
Functioning Scale |
8.5 (6-15) |
7 (5-11) |
0.74 |
|
Quality of Life Scale |
5 (2-8) |
5 (2-7) |
0.80 |
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Scleroderma Health Assessment Questionnaire |
|
|
|
|
HAQ-DI component |
0.88 (0.25-1.50) |
0.75 (0.13-1.25) |
0.74 |
|
Raynaud’s phenomenon VAS |
15 (0-40) |
10 (2-35) |
0.91 |
|
Digital tip ulceration VAS |
0.5 (0-8) |
1 (0-14) |
0.67 |
|
Pulmonary symptom VAS |
39.5 (10-52) |
15 (11-50) |
0.94 |
|
Gastrointestinal symptom VAS |
12.5 (0-50) |
12 (10-30) |
0.80 |
|
Overall disease severity VAS |
50 (21-68) |
38 (27-56) |
0.88 |
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Borg Dyspnea Index |
3 (1-4) |
3 (2-4) |
|
|
Biomarkers |
PH (N = 18) |
No PH (N = 9) |
|
|
Vascular endothelial growth factor – pg/mL |
346.4 (260.1-427.2) N = 17 |
265.2 (228.9-468.2) |
0.55 |
|
Hypoxia-inducible factor 1α – units |
23.62 (22.98-23.80) N = 17 |
23.29 (22.99-23.53) |
0.40 |
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Interleukin-6 – pg/mL |
4.46 (3.72-10.54) N = 17 |
5.45 (3.19-6.3) |
0.77 |
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N-terminal pro brain natriuretic peptide – fmol/mL |
1152.2 (503.7-2207.6) N = 17 |
566.6 (296.2-902.3) |
0.08 |
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Data presented as mean (SD), median (IQR), and frequency (percentage) |
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HAQ-DI = Health Assessment Questionnaire – Disability Index; VAS = Visual Analogue Scale |
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Disclosure:
E. J. Bernstein,
None;
J. K. Gordon,
None;
R. F. Spiera,
roche-genetech,
2;
W. T. Huang,
None;
E. M. Horn,
None;
L. A. Mandl,
None.
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