Pulmonary Function Parameters Other Than Vital Capacity Should Be Considered in Screening for Interstitial Lung Disease in Patients With Systemic Sclerosis: Comment on the Article by Suliman et al

Insight into the relationship between forced vital capacity and transfer of the lungs for carbon monoxide in patients with idiopathic pulmonary fibrosis

BACKGROUND

Forced vital capacity (FVC) is routinely used to quantify the severity and identify the progression of idiopathic pulmonary fibrosis (IPF). Although less commonly used, lung transfer of carbon monoxide (TLCO) correlates better with the severity of IPF than does FVC.

METHODS

Aiming at studying how FVC behaves in relation to TLCO, we analysed cross-sectional data from 430 IPF patients, of which 221 had at least 2 assessments (performed 2.4 ± 1.9 years apart) available for longitudinal analyses. Thresholds for identifying "abnormal" FVC and TLCO values were the statistically-defined lower limits of normal (LLN). For patients with longitudinal data, mean annual absolute declines of FVC and TLCO were calculated.

RESULTS

The correlation between FVC and TLCO (%predicted) was weak (R2=0.21). FVC was "abnormal" (i.e.,

CONCLUSION

In IPF, a "normal" FVC should be viewed with caution as it is most often associated with an "abnormal" TLCO, a parameter that is strongly correlated with the morphological extent of the disease. Only 1/3 of the patients with a FVC-based progression criterion also had a TLCO progression criterion. In contrast, 2/3 of patients with a TLCO progression criterion also had a FVC progression criterion.

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Key Words

• Forced vital capacity
• Idiopathic pulmonary fibrosis
• Pulmonary function tests
• Transfer of the lungs for carbon monoxide

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MESH Headings

• Humans
• Carbon Monoxide
• Cross-Sectional Studies
• Lung
• Vital Capacity
• Idiopathic Pulmonary Fibrosis/diagnosis

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Affiliation(s)

Thibaud Soumagne Service de Pneumologie et Soins intensifs respiratoires, Hôpital Européen Georges-Pompidou, Assistance Publique des hôpitaux de Paris, Paris, France
Sébastien Quétant Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
Alicia Guillien Épidemiologie environnementale appliquée à la reproduction et à la santé respiratoire, INSERM, CNRS, Université Grenoble Alpes, Institut pour l'Avancée des Biosciences (IAB), U1209, Grenoble, France
Loïc Falque Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
David Hess Programme Colibri, Association pour la complémentarité des connaissances et des pratiques de la pneumologie (aCCPP), 19 avenue Marcelin Berthelot, 38100, Grenoble, France
Bernard Aguilaniu Programme Colibri, Association pour la complémentarité des connaissances et des pratiques de la pneumologie (aCCPP), 19 avenue Marcelin Berthelot, 38100, Grenoble, France; Université Grenoble Alpes, Grenoble, France
Bruno Degano Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Laboratoire HP2, INSERM U1300, Université Grenoble Alpes, Grenoble, France.

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Feasibility of online home spirometry in systemic sclerosis-associated interstitial lung disease: a pilot study

OBJECTIVES

Frequent monitoring of forced vital capacity at home may be of added value in patients with SSc-associated interstitial lung disease (SSc-ILD) to monitor disease progression and guide treatment decisions. The aim of this study was to evaluate the feasibility and optimal frequency of online home spirometry using a home monitoring application in patients with SSc-ILD.

METHODS

This was a prospective, observational study in patients with SSc-ILD. Patients evaluated for 3 months the online home monitoring application ILD-online integrated with a Bluetooth-connected spirometer. Patients performed daily home spirometry for 6 weeks and weekly home spirometry for 6 weeks. In addition, patients completed an evaluation questionnaire after 3 months and online patient-reported outcomes at baseline and 3 months.

RESULTS

Ten consecutive patients participated. Mean adherence to home spirometry was 98.8% (s.d. 1.5). Home and hospital spirometry were highly correlated. The mean coefficient of variation was lower for weekly [2.45% (s.d. 1.19)] than daily [3.86% (s.d. 1.45)] forced vital capacity measurements (P = 0.005). All patients considered the home monitoring application and spirometer easy to use and no patients considered home spirometry burdensome. All patients would recommend home monitoring to other patients with SSc.

CONCLUSIONS

Home spirometry using an online home monitoring application is feasible in patients with SSc-ILD, with high adherence and patient satisfaction. Larger long-term studies are needed to assess whether home spirometry can detect the progression of ILD in patients with SSc.

Short-Term Lung Function Changes and Predictors of Progressive Systemic Sclerosis-Related Interstitial Lung Disease

BACKGROUND

Systemic sclerosis (SSc) involves multiple organ systems and has the highest mortality among connective tissue diseases. Interstitial lung disease is the most common cause of death among SSc patients and requires closer studies and follow-ups. This study aimed to identify lung function changes and predictors of progressive disease in systemic sclerosis-related interstitial lung disease (SSc-ILD).

METHODS

A retrospective study extracted SSc patients from an electronic database January 2002-July 2019. Eligible cases were SSc patients >age 15 diagnosed with SSc-ILD. Factors associated with progressive disease were analyzed by univariate and multivariate logistic regression analyses.

RESULTS

Seventy-eight SSc-ILD cases were enrolled. Sixty-five patients (83.3%) were female, with mean age of 44.7±14.4, and 50 (64.1%) were diffuse type SSc-ILD. Most SSc-ILD patients had crackles (75.6%) and dyspnea on exertion (71.8%), and 19.2% of the SSc-ILD patients had no abnormal respiratory symptoms but had abnormal chest radiographic findings. The most common diagnosis of SSc-ILD patients was non-specific interstitial pneumonia (43.6%). The lung function values of diffusing capacity of the lung for carbon monoxide (DLCO) and DLCO per unit alveolar volume declined in progressive SSc-ILD during a 12-month follow-up. Male and no previous aspirin treatment were the two significant predictive factors of progressive SSc-ILD with adjusted odds ratios of 5.72 and 4.99, respectively.

CONCLUSION

This present study showed that short-term lung function had declined during the 12-month follow-up in progressive SSc-ILD. The predictive factors in progressive SSc-ILD were male sex and no previous aspirin treatment. Close follow-up of the pulmonary function tests is necessary for early detection of progressive disease.

Interstitial lung disease in systemic sclerosis: challenges in early diagnosis and management

Interstitial lung disease (ILD) is a group of lung diseases characterized by thickening of the interstitium surrounding pulmonary alveolar walls. It is related to specific radiographic features in lung imaging and/or the presence of restrictive disorders in pulmonary function tests (PFTs). ILD is one of the leading causes of death in systemic sclerosis patients. Major risk factors of ILD associated with SSc (SSc-ILD) include male sex, diffuse type of cutaneous SSc and presence of anti-Scl-70 antibodies.

SSc-ILD is challenging to diagnose at an early stage as the symptoms are non-specific. The greatest risk of its development is during the 4–5 years after the initial diagnosis of systemic sclerosis. Clinical vigilance at the time, including regular pulmonary function tests and/or high-resolution com-puted tomography (HRCT), is needed. The aim of this paper is to summarize the current knowledge on early diagnostic methods and progression risk factors for SSc-ILD.