Impact of interstitial lung disease on the survival of systemic sclerosis with pulmonary arterial hypertension

Systemic sclerosis is associated with increased in-patient mortality in patients hospitalized for heart failure

AIMS

We aimed to analyse the characteristics and in-hospital outcomes of patients hospitalized for heart failure (HF) with co-morbid systemic sclerosis (SSc) and compare them to those without SSc, using data from the National Inpatient Sample from years 2016 to 2019.

METHODS AND RESULTS

International Classification of Diseases, Tenth Revision diagnosis codes were used to identify hospitalized patients with a primary diagnosis of HF and secondary diagnoses of SSc from the National Inpatient Sample database from 2016 to 2019. Patients were divided into two groups: those with and without a secondary diagnosis of SSc. Baseline characteristics including demographics and co-morbidities, outcomes of mortality, length of stay (LOS), and costs were compared between the two groups. Multivariable logistic regression analysis was performed to adjust for confounders and assess the impact of SSc on in-hospital mortality, cost, and LOS. A total of 4 709 724 hospitalizations for HF were identified, with 8150 (0.17%) having a secondary diagnosis of SSc. These patients were predominantly female (82.3% vs. 47.8%; P = 0.01), younger (mean age of 67.4 vs. 71.4; P < 0.01), and had significantly lower rates of traditional cardiovascular risk factors such as coronary artery disease (35.8% vs. 50.6%; P < 0.01), hyperlipidaemia (39.1% vs. 52.9%; P < 0.01), diabetes (22.5% vs. 49.1%; P < 0.01), obesity (13.2% vs. 25.0%; P < 0.01), and hypertension (20.2% vs. 23.8%; P < 0.01). Higher rates of co-morbid pulmonary disease in the form of interstitial lung disease (23.1% vs. 2.0%; P < 0.01) and pulmonary hypertension (36.6% vs. 12.7%; P < 0.01) were noted in the SSc cohort. Unadjusted in-hospital mortality was significantly higher in the HF with SSc group [5.1% vs. 2.6%; odds ratio: 1.99; 95% confidence interval (CI): 1.60-2.48; P < 0.001]. Unadjusted mortality was also higher among female (86.7% vs. 47.0%; P < 0.01), Black (15.7% vs. 13.0%; P < 0.01), and Hispanic (13.3% vs. 6.9%; P < 0.01) patients in the SSc cohort. After adjusting for potential confounders, SSc remained independently associated with higher in-hospital mortality (adjusted odds ratio: 1.81; 95% CI: 1.44-2.28; P < 0.001). Patients with HF and SSc also had longer LOS (6.4 vs. 5.4; adjusted mean difference [AMD]: 0.37, 95% CI: 0.05-0.68; P = 0.02) and higher hospitalization costs ($67 363 vs. $57 128; AMD: 198.9; 95% CI: -4780 to 5178; P = 0.93).

CONCLUSIONS

In patients hospitalized for HF, those with SSc were noted to have higher odds of in-hospital mortality than those without SSc. Patients with HF and SSc were more likely to be younger, female, and have higher rates of co-morbid interstitial lung disease and pulmonary hypertension at baseline with fewer traditional cardiovascular risk factors.

[The importance of data in Pulmonary Arterial Hypertension: from international registries to Machine Learning]

Real-world registries have been critical to building the scientific knowledge of rare diseases, including Pulmonary Arterial Hypertension (PAH). In the past 4 decades, a considerable number of registries on this condition have allowed to improve the pathology and its subgroupś definition, to advance in the understanding of its pathophysiology, to elaborate prognostic scales and to check the transferability of the results from clinical trials to clinical practice. However, in a moment where a huge amount of data from multiple sources is available, they are not always taken into account by the registries. For that reason, Machine Learning (ML) offer a unique opportunity to manage all these data and, finally, to obtain tools that may help to get an earlier diagnose, to help to deduce the prognosis and, in the end, to advance in Personalized Medicine. Thus, we present a narrative revision with the aims of, in one hand, summing up the aspects in which data extraction is important in rare diseases -focusing on the knowledge gained from PAH real-world registries- and, on the other hand, describing some of the achievements and the potential use of the ML techniques on PAH.

Impact of Systemic Sclerosis-Associated Interstitial Lung Disease With and Without Pulmonary Hypertension on Survival: A Large Cohort Study of the German Network for Systemic Sclerosis

BACKGROUND

Pulmonary involvement is the leading cause of death in systemic sclerosis (SSc) and may manifest as interstitial lung disease (ILD), pulmonary arterial hypertension (PAH), or in combination of both (ILD with pulmonary hypertension [ILD-PH]). The aim of this analysis was to determine prevalence, clinical characteristics, and survival of these different forms within the registry of the German Network for Systemic Sclerosis.

RESEARCH QUESTION

Does SSc-associated ILD-PH or ILD without PH affect survival differently, and are there any risk factors that have an additional impact?

STUDY DESIGN AND METHODS

Clinical data of 5,831 patients with SSc were collected in the German Network for Systemic Sclerosis registry. Kaplan-Meier estimates were used to compare overall survival in patients with SSc-associated ILD-PH and ILD without PH with patients without pulmonary involvement and those with PAH. The Cox proportional hazard model was used to analyze the influence of pulmonary involvement and other potential predictors on patient survival.

RESULTS

Clinical data of 3,257 patients with a mean follow-up time of 3.45 ± 1.63 years have been included in our analysis. At baseline, ILD was present in 34.5%, whereas PH without ILD had a lower prevalence with 4.5%. At the end of follow-up, 47.6% of patients with SSc had ILD, 15.2% had ILD-PH, and 6.5% had PAH. ILD was more frequent in the diffuse cutaneous form (57.3%), whereas PAH did not differ significantly between SSc subtypes. Significant differences in baseline characteristics between PAH vs ILD-PH vs ILD without PH were found for age at diagnosis, sex, SSc subsets, antibody status, FVC, diffusing capacity of the lung for carbon monoxide, and therapy. Overall survival at 5 years was 96.4% for patients without pulmonary involvement and differed significantly between patients with ILD without PH, PAH, and being worst in patients with ILD-PH. Female sex (hazard ratio [HR], 0.3), higher BMI (HR, 0.9), and higher diffusing capacity of the lung for carbon monoxide values (HR, 0.98) were associated with a lower mortality risk.

INTERPRETATION

ILD is the most prevalent pulmonary involvement in SSc, whereas the combination of ILD and PH is associated with the most detrimental survival.

Reproducibility of pulmonary function tests in patients with systemic sclerosis

Systemic sclerosis (SSc) is a rare autoimmune disease in which interstitial lung disease (ILD) is the leading cause of morbidity and mortality. Clinical management of the lung disease is mainly based on pulmonary function testing (PFT) and their changes over time. Little is known about the reproducibility of PFT testing in SSc patients. The aim of this study was to assess the test-retest reliability and reproducibility of PFTs in SSc patients with or without ILD over 30 days in order determine the potential physiologic variation over the time. We performed prospective observational study of SSc patients. The FVC, FEV1/FVC ratio, DLCO and KCO parameters were assessed in this population at four different timepoints; T0 (time 0) and H3 (T0 + 3 h) defined test-retest reliability, D15 (T0 + 15 days) and D30 (T0 + 30 days) for reproducibility. A mixed linear model was used to test the effect of time (and therefore reproducibility) on patients and we looked for an interaction. We included 25 SSc patients divided in two groups, 14 with ILD and 11 non-ILD. Interactions between time and group were not significant and were not reported. Time and group did not significantly influence the different measures of the PFT: FVC [p values time and group effect respectively (0.33; 0.34)], FEV1/FVC ratio (0.093; 0.056) and DLCO (0.99; 0.13) in the ILD and non ILD group (Table S2). The analyse with interactions between time and group were not significant and are not reported. We also used a Bland Altman test to assess reproducibility for FVC (L) and DLCO (mMKpa/min/L), Figs. 1 and 2 respectively. The measurements were therefore reproducible over time and in each group. PFT parameters are reproducible over time in a clinically stable population of SSc (no significant effect of the time T0, H3, D15 and D30) and there is no significant distinction between patients with ILD and no ILD. These respiratory functional data can further underline their use in clinical practice.

Clinical characteristics and survival of pulmonary arterial hypertension with or without interstitial lung disease in systemic sclerosis

OBJECTIVES

To describe the clinical phenotype and prognosis of people in the Australian Scleroderma (SSc) Cohort Study with pulmonary arterial hypertension (PAH) with or without interstitial lung disease (ILD).

METHODS

Participants meeting ACR/EULAR criteria for SSc were divided into four mutually exclusive groups: those meeting criteria for PAH (PAH-only), ILD (ILD-only), concurrent PAH and ILD (PAH-ILD) or neither PAH nor ILD (SSc-only). Logistic or linear regression analyses were used for associations between clinical features, health-related quality of life (HRQoL) and physical function. Survival analysis was performed using Kaplan-Meier estimates and Cox-regression modelling.

RESULTS

Of 1561 participants, 7% fulfilled criteria for PAH-only, 24% ILD-only, 7% PAH-ILD and 62% SSc-only. People with PAH-ILD were more frequently male, with diffuse skin involvement, higher inflammatory markers, older age of SSc onset and higher frequency of extensive ILD than the cohort overall (p < 0.001). People of Asian race more frequently developed PAH-ILD (p < 0.001). People with PAH-ILD or PAH-only had worse WHO functional class and 6-min-walk-distance than ILD-only (p < 0.001). HRQoL scores were worst in those with PAH-ILD (p < 0.001). Survival was reduced in the PAH-only and PAH-ILD groups (p < 0.01). Multivariable hazard modelling demonstrated the worst prognosis in extensive ILD and PAH (HR = 5.65 95% CI 3.50-9.12 p < 0.01), followed by PAH-only (HR = 4.21 95% CI 2.89-6.13 p < 0.01) and PAH with limited ILD (HR = 2.46 95% CI 1.52-3.99 p < 0.01).

CONCLUSIONS

The prevalence of concurrent PAH-ILD in the ASCS is 7%, with poorer survival in those patients with PAH-ILD compared to ILD or SSc alone. The presence of PAH confers a poorer overall prognosis than even extensive ILD; however, further data are required to better understand the clinical outcomes of this high-risk patient group.

Pulmonary hypertension in systemic sclerosis with usual interstitial pneumonia

Retrospective study comparing pulmonary hypertension risk in systemic sclerosis (SSc) and non-SSc interstitial lung disease patients with usual interstitial pneumonia (UIP) and non-specific interstitial pneumonia (NSIP). Retrospective analysis of 144 interstitial lung disease patients, 53 SSc (32 UIP and 21 NSIP) and 91 non-SSc (47 UIP and 44 NSIP). Pulmonary hypertension was diagnosed as pulmonary systolic artery pressure (PAPs) > 25 mmHg. All SSc and non-SSc patients with pulmonary hypertension were classified WHO Group 3. Pulmonary hypertension was identified in 21/32 (65.6%), 9/21 (42.8%), 14/47 (29.7%), and 28/44 (45.4%) SSc-UIP, SSc-NSIP, control-UIP, and control-NSIP groups, respectively. PAPs mean of SSc-UIP group was higher than control-UIP group (32.6 ± 9.8 vs 28.5 ± 6.6, p-value = 0.02). PAPs mean of SSc-NSIP group was lower than control-NSIP group (27.0 ± 7.1 vs 33.9 ± 8.8, p = 0.002). Frequency of patients with PAP > 25 mmHg in SSc-UIP group was 60% higher in comparison to control-UIP (OR = 1.62, 95% CI 0.51-5.16) and SSc-NSIP (OR = 1.60, 95% CI 0.45-5.70) groups. Logistic regression analysis estimating the linear trend per ten-unit increase in PAPs levels demonstrated an increment for the SSc-UIP group compared to the control-UIP (OR = 2.64, 95% CI 1.25-5.58, p = 0.01) and the control-NSIP (OR = 6.34, 95% CI 2.82-14.3, p < 0.001) groups. The case-control study confirms that pulmonary hypertension is frequently found in SSc patients and demonstrates, for the first time, a significant increased risk of pulmonary hypertension among SSc-UIP patients.