Characterisation of the Patient Population Attending the Interstitial Lung Disease Clinic at Hospital Garcia de Orta: Implications for Pulmonary Rehabilitation ^†

Abstract

Interstitial lung diseases (ILDs) are chronic respiratory disorders often leading to dyspnoea, reduced exercise tolerance, and poor quality of life. Pulmonary rehabilitation (PR) improves symptoms and function but remains underused in Portugal, with only ~1% of eligible patients enrolled. This study retrospectively analysed 61 ILD patients at Hospital Garcia de Orta (July–December 2024) to identify PR candidates. Most had idiopathic pulmonary fibrosis (44%), exertional dyspnoea (67.2%), and moderate lung impairment (49%). Comorbidities and risk factors were common. Findings highlight a significant gap between clinical need and access, reinforcing the urgency of structured referral strategies to expand PR availability.

1. Introduction

Interstitial lung diseases (ILDs) comprise a heterogeneous group of conditions characterised by inflammation and/or fibrosis of the pulmonary interstitium, commonly resulting in progressive dyspnoea, exercise intolerance, and a substantial deterioration in quality of life [1,2,3].

Although pharmacological treatment has advanced in recent years, particularly with the introduction of antifibrotic agents for progressive phenotypes such as idiopathic pulmonary fibrosis (IPF), non-pharmacological approaches, notably pulmonary rehabilitation (PR), remain underutilised [4]. PR is a core component in the management of chronic respiratory diseases. It is cost-effective, safe, and proven to improve dyspnoea, exercise capacity, and health-related quality of life [3,5].

In Portugal, access to PR is extremely limited. Fewer than 1% of patients with chronic obstructive pulmonary disease (COPD), the primary population currently included in PR programmes, are enrolled [6]. Despite robust evidence supporting the efficacy of PR in chronic respiratory diseases, including ILDs [3], its implementation across the country remains inadequate. Existing services are concentrated in large urban hospitals, contributing to disparities in access. Structural, logistical, and awareness-related barriers further hinder effective implementation [6,7].

Additional factors, such as patient scepticism regarding symptomatic improvement and fear of exertion-induced dyspnoea, also limit participation [6]. Furthermore, there is a paucity of local data on the clinical and functional characterisation of ILD patients in specialist outpatient settings, impeding the development of targeted intervention strategies. Defining clinical, functional, and sociodemographic profiles is critical to optimise referral processes and adapt PR programmes to the Portuguese healthcare context, ultimately aiming to enhance outcomes in this population. Community-based and hybrid models emerge as viable strategies to expand coverage, reduce inequities, and improve clinical outcomes in ILDs and other respiratory conditions.

This study aims to characterise the clinical and functional profile of ILD patients followed in the specialised Interstitial Lung Disease Outpatient Clinic at Hospital Garcia de Orta and to identify those eligible for PR referral. The goal is to inform and optimise referral practices and support the implementation of PR programmes within this population.

2. Materials and Methods

This was a retrospective, descriptive study aimed at characterising the clinical and functional profiles of patients followed in the Interstitial Lung Disease Outpatient Clinic of Hospital Garcia de Orta, with the purpose of identifying those who might benefit from pulmonary rehabilitation (PR).

All patients with a confirmed diagnosis of ILD and active follow-up between July and December 2024 were included. Eligibility criteria comprised a documented ILD diagnosis, clinical follow-up within the specified timeframe, and availability of relevant electronic health records.

Data were collected from the electronic clinical record system (SClínico), ensuring anonymity and compliance with the General Data Protection Regulation (GDPR). Extracted data included the following: demographic information (age and sex); clinical ILD diagnosis according to established criteria and coding; symptomatology (dyspnoea on exertion and chronic cough); respiratory functional assessments (spirometry, lung volumes, and diffusing capacity for carbon monoxide—DLCO), when available; risk factors (history of smoking, relevant occupational or environmental exposures); and associated comorbidities, with emphasis on cardiovascular disease, diabetes mellitus, and obstructive sleep apnoea.

The study received approval from the Ethics Committee of Hospital Garcia de Orta on 3 July 2024. All data were anonymised, and no personally identifiable information was collected.

Data analysis was descriptive, using absolute and relative frequencies for categorical variables and mean with standard deviation for continuous variables. Interpretation focused on identifying clinical features consistent with eligibility for PR, including persistent symptoms, pulmonary function impairment, and comorbidities contributing to functional limitation.

3. Results and Discussion

This retrospective study analysed a cohort of 61 ILD patients followed in a specialised clinic between July and December 2024. The cohort had a mean age of 74.7 years, with a slight predominance of females (54%). IPF was the most prevalent diagnosis (44%), followed by other progressive and chronic fibrosing ILDs, consistent with the literature identifying IPF as the most common ILD in elderly populations [3].

Persistent respiratory symptoms, particularly exertional dyspnoea (67.2%) and chronic cough (27.8%), were highly prevalent, indicating frequent functional impairment. Nearly half of the patients had moderate disease severity according to spirometry and DLCO, while 1.6% had severe disease. These findings support the appropriateness of PR, which is recommended for patients with persistent symptoms and functional limitation [6].

Relevant risk factors were identified in 59% of patients, including a history of smoking (40.9%) and environmental/occupational exposures (32.7%), highlighting the influence of external factors in ILD pathogenesis and progression. Common comorbidities included diabetes mellitus (18%), obstructive sleep apnoea (18%), and cardiovascular disease (14.7%), increasing clinical complexity. These findings align with Butler et al. [1], who reported that musculoskeletal, endocrine, and cardiovascular comorbidities were associated with reduced functional gains in PR, underscoring the need for tailored exercise prescriptions.

Notably, 95.1% of patients in this cohort met the clinical criteria for PR referral, and none were referred for PR, revealing a significant mismatch between clinical need and service availability (no PR programme available at HGO). Despite robust evidence demonstrating significant improvements in six-minute walk distance (6MWD) and health-related quality of life with PR [3,8], referral rates remain extremely low in Portugal. Only around 1% of eligible patients are enrolled in structured PR programmes, similar to rates observed in other countries [5].

Evidence also supports improved survival associated with functional gains in the incremental and endurance shuttle walk tests (ISWT and ESWT) among PR participants [9]. Observational studies further suggest reduced five-year mortality in patients demonstrating a positive functional response to PR, although randomised controlled trials are needed to confirm this benefit [10].

Given the high proportion of eligible patients identified in this study, the systematic implementation of clinical screening tools and structured referral pathways in ILD clinics is essential. Regular assessment of dyspnoea, pulmonary function, and exercise capacity would enable early identification of PR candidates and promote equitable access to this beneficial intervention.

Limitations of this study include its retrospective design based on electronic health records, with no objective functional testing such as the 6MWD. The single-centre and small sample size also limit the generalisability of findings. Nevertheless, the results provide a realistic overview of clinical practice in a specialised centre and highlight the urgent need to expand access to PR as a core component of ILD management.

4. Conclusions

In this cohort, a substantial proportion of ILD patients met clinical criteria for referral to pulmonary rehabilitation. Recent evidence confirms that PR improves functional capacity, reduces symptoms, and enhances quality of life, with possible survival benefits [11].

However, access to this intervention remains critically limited in Portugal. The following measures are recommended: systematic integration of PR screening into ILD clinics; development of structured referral pathways; implementation of alternative models such as home-based or hybrid programmes with remote supervision; and ongoing training and awareness initiatives targeting both healthcare professionals and patients.

Adopting these strategies, in line with international best practices, may increase referral rates and improve clinical outcomes and quality of life for this vulnerable population [12,13].