Clinical care in interstitial lung disease: a critical appraisal of clinical guidance documents

Abstract

Introduction

Interstitial lung diseases (ILDs) are complex, requiring multifaceted care for optimal management of patients’ symptoms and health outcomes. This systematic review evaluated the content coverage of currently available clinical guidance documents ILD.

Methods

A systematic search was performed to identify clinical guidance documents published between 2011 and March 2025 in the Embase, Ovid Medline and Trip databases. Document characteristics, quality and contents covered were independently assessed by two reviewers.

Results

A total of 79 ILD clinical guidance documents were identified, with clinical practice guidelines (n=50) having superior quality based on the Institute of Medicine standards. The content of most documents (84%) focused on ILD aetiology, with connective tissue disease (44%) being the most discussed. Only 46% of documents covered pulmonary manifestations, which often encompassed pulmonary hypertension (30%) and hypoxaemia (28%). Extrapulmonary morbidities were covered in 28% of documents, with gastro-oesophageal reflux disease (23%) and obstructive sleep apnoea (10%) being commonly presented. Behavioural and lifestyle factors were covered in 34% of documents, with most addressing physical inactivity (30%). Additionally, 51% of documents covered overall diagnostic approach for ILD, 35% lung transplantation, 22% acute exacerbations and 19% palliative care.

Conclusion

Despite growing awareness of ILD, most clinical guidance documents have limited coverage for domains of patient care outside of diagnosis and pharmacotherapies. Future clinical guidance documents on ILD should address the content gaps to deliver comprehensive care for patients with ILD, with engagement of different stakeholders from various regions.

Shareable abstract

This systematic review shows most ILD clinical guidance documents focus on diagnosis and pharmacotherapies, with limited coverage of other aspects of patient care. Future guidance documents need to address the gaps for comprehensive ILD care. https://bit.ly/44B60XJ

Introduction

Interstitial lung diseases (ILDs) are a large group of inflammatory and fibrotic lung conditions with a wide variety of aetiologies. There has been a notable rise in the disease burden of ILD over the last couple of decades, despite regional differences in its prevalence [1, 2]. In 2019, the global incidence of ILD was estimated at 24.2 million [1]. Of the different ILD subtypes, idiopathic pulmonary fibrosis (IPF), connective tissue disease-associated ILD (CTD-ILD) and sarcoidosis are commonly encountered clinically [3]. Patients with ILD experience high morbidity and mortality, particularly those with IPF or progressive pulmonary fibrosis [4–6]. With the availability of antifibrotic drugs, nintedanib and pirfenidone, the 5-year cumulative survival rate of patients with IPF remains poor at <50% [4–7].

In addition to manifestations and complications from the lung disease, health-related quality of life and health outcomes in patients with ILD can be affected by their comorbidities [8]. Psychosocial support and lifestyle factors can also impact the well-being and disease-coping capacity of patients with ILD [9]. Thus, there is increasing recognition of the importance of comprehensive care addressing the different needs of this population. Clinical guidance documents such as guidelines and position statements are important in guiding clinical decision-making and care standards through evidence-based and expert consensus recommendations. However, it is unknown whether existing clinical guidance documents have relevant content and recommendations for the delivery of comprehensive care in ILD. This study aimed to systematically review clinical guidance documents for ILD, with a comprehensive evaluation of the content coverage for patient care.

Methods

We performed a systematic review, with the protocol being registered prospectively on PROSPERO (registration ID: CRD42023426233) (appendix 1)

Search methods

A systematic literature search of clinical guidance documents published from January 2011 to March 2025 was performed using three databases, namely Ovid Medline, Embase and Trip. The full search strategy can be found in the online supplement (appendix 2). The databases were selected for their relevance and complementary nature for this review. Ovid Medline and Embase are two of the largest biomedical databases for English publications and some translated foreign publications, while the Trip database is a clinical search engine on evidence-based medicine and clinical guidelines.

Eligibility criteria

We included English-language clinical guidance documents that were produced or commissioned by professional societies for the diagnosis and management of adults with ILD. Only clinical guidance documents published since the year 2011 were included to ensure their relevance to contemporary practice [10]. Clinical guidance documents were defined as including, but not limited to, guidelines, consensus statements, recommendations, guidance statements, position papers or professional standard statements that were produced or commissioned by professional society/societies. When updates of the clinical guidance documents were available, data from different versions of the clinical guidance document were collated.

Document selection, extraction and quality assessment

Two reviewers (M.H.V. Ng and P.V. Wettesinghe) independently performed document selection, as well as data extraction and quality assessment of included clinical guidance documents, with disagreement being resolved by a third reviewer (Y.H. Khor).

Identified documents were assessed for eligibility using sequential review of titles and abstracts followed by full-text articles. Data of included clinical guidance documents were extracted using a standardised form, which encompassed 1) document characteristics (document type, publication year, funding source, responsible societies, author representation, stakeholder involvement, target audience), 2) the targeted ILD subtypes, and 3) document content coverage related to the diagnosis and management of ILD.

The quality of included clinical guidance documents was evaluated according to compliance with the Institute of Medicine standards for optimal development of clinical practice guidelines [11]. This assessment includes eight criteria, as follows: transparency of funding, management of conflict of interests, development group composition, use of systematic reviews for evidence synthesis, evidence grading for strength rating of recommendations, articulation of recommendations, the presence of external review and document updates. Given the different methodologies used for developing position statements, the quality assessment was adapted by substituting systematic reviews with literature reviews for evidence synthesis and removing the criterion on rating evidence foundation and strength of recommendations.

Data synthesis and analyses

Characteristics and content coverage of included clinical guidance documents were reported using summary statistics as counts and percentages. Key content areas for ILD care covered in the clinical guidance documents were categorised according to the framework of the treatable traits approach, which delivers individualised multidimensional assessment and management [8]. These included ILD aetiology, pulmonary morbidities, extrapulmonary morbidities and behaviour and lifestyle factors, which were subdivided into descriptions of diagnostic or identification approaches, and treatments, and only mentioned without details. Other topics synthesised were the ILD diagnostic process (including clinical assessment and investigations for diagnosing ILD), acute exacerbation, palliative care and lung transplantation.

Results

ILD clinical guidance document characteristics

Of the 2340 documents identified, 141 underwent full-text assessment (figure 1). 79 ILD clinical guidance documents were selected for inclusion, with two being published as a series [12–18], resulting in a total of 84 individual documents being reviewed. Primary documents referred to standalone documents or the first documents of multi-document series, while secondary documents referred to the subsequent documents of multi-document series. Most included documents were clinical practice guidelines (n=50, 63%) [10, 12, 17, 19–65] and were published since 2016 (n=67, 85%) [12, 17, 27–84] (figure 2 and table 1). The remaining 29 documents were position statements [66–94]. Approximately half of the included documents were national in authorship (n=41, 52%), while the remaining involved authors from different countries (n=38, 48%). The majority of included documents were supported by healthcare professional associations (n=64, 81%), most commonly the American Thoracic Society (n=14, 18%), the European Respiratory Society (n=11, 14%) and the Japanese Respiratory Society (n=10, 13%) (table S1). Table S2 presents detailed characteristics of the included documents. There were 48 ILD-specific documents and 31 non-ILD-specific documents, which were dedicated to different connective tissue diseases (n=16), other related conditions such as cough, pulmonary hypertension and sarcoidosis (n=8), and single intervention types such as lung transplantation and pulmonary rehabilitation (n=7).

FIGURE 1.

PRISMA flow chart.

FIGURE 2.

a) Publication trend, b) continental representation of contributing authors (numbers in the figure represent the numbers of documents with authors from respective continents; for North America there were only representatives from Canada and USA), and c) quality assessment using the Institute of Medicine standards for included interstitial lung disease (ILD) clinical guidance documents. COI: conflict of interest; CPG: clinical practice guidelines; N/A: not applicable; PS: position statement.

TABLE 1.

Summary of characteristic of clinical guidance documents for interstitial lung disease (ILD)

Document characteristics (n=79)	Number (%)
Document type
Clinical practice guideline	50 (63)
Position statement	29 (37)
Publication year
2011–2015	12 (15)
2016–2020	33 (42)
2021–2025	34 (43)
Countries
Single nation	41 (52)
Multiple nations	38 (48)
Document focus
ILD-specific	48 (61)
Non-ILD-specific	31 (39)
Funding sources
Healthcare professional associations	64 (81)
Patient advocacy associations	7 (9)
Governmental bodies	4 (5)
Pharmaceutical industry	2 (3)
Not disclosed	9 (11)

Of the 84 individual documents, most had contributions from at least one pulmonology physician (n=71, 85%) (figure S1 and table S3). Other common contributing expert authors included nonpulmonology physicians (n=53, 63%), pathologists (n=33, 39%) and radiologists (n=32, 38%). The involvement of allied health professionals, nurses and nonclinician researchers was low. There was at least one author from Europe and North America (USA or Canada) for 47 (56%) and 34 (40%) of the included documents, respectively, with lower representation from other continents (figure 2). The first (n=58, 69%) and senior authors (n=60, 71%) for most included documents were male. Less than half of the included documents had nonhealthcare professional stakeholder involvement (n=38, 45%), including individual patients (n=28, 33%), patient advocacy group representatives (n=9, 11%) and caregivers (n=3, 4%) (figure S1). All 79 included documents were aimed towards clinicians, with common secondary target audiences being patients (n=11, 14%) and policymakers (n=9, 11%) (table S4).

Quality of ILD clinical guidance documents

Figure S2 summarises quality assessments of included documents according to the Institute of Medicine standards, with details presented in table S5. Overall, clinical practice guidelines had satisfactory quality, with six out of eight criteria being fulfilled in >80% of documents, with the two lower-scoring criteria due to the lack of clear documentation of external review (n=36, 72%) and update frequency or plan (n=15, 30%). On the other hand, position statements had varying quality performance, with only one out of the seven criteria, conflict of interest declaration, being fulfilled in >80% of the documents. Only seven (24%) [71, 72, 76, 77, 90–92] position statements had a documented update frequency or plan. In addition, only 13 (45%) [67, 73, 76, 80–82, 86, 87, 89, 90, 92–94] position statements fulfilled the literature review criterion.

Content coverage of ILD clinical guidance documents

Most ILD clinical guidance documents (out of n=79) covered content related to ILD aetiology (n=66, 84%; clinical practice guidelines: n=42, 84%; position statements: n=24, 83%) (figures 3 and 4). Contents for other areas were covered in less than 50% of ILD clinical guidance documents: pulmonary morbidities (clinical practice guidelines: n=22, 44%; position statements: n=14, 48%), extrapulmonary morbidities (clinical practice guidelines: n=11, 22%; position statements: n=11, 38%) and behavioural and lifestyle factors (clinical practice guidelines: n=15, 30%; position statements: n=12, 41%).

FIGURE 3.

Summary of content coverage of clinical guidance guidelines. ILD: interstitial lung disease; NICE: National Institute for Health and Care Excellence. ^#: multi-part documents.

FIGURE 4.

Summary of content coverage of position statements. ILD: interstitial lung disease; NICE: National Institute for Health and Care Excellence. #: multi-part documents.

Among the included clinical guidance documents, the most commonly covered topic for ILD aetiology was connective tissue disease, followed by idiopathic pulmonary fibrosis, with both diagnostic and treatment approaches covered (figure 5). For other ILD aetiology topics, the identification approaches were covered more often than their treatment strategies, particularly for environmental exposures. For pulmonary morbidities, pulmonary hypertension and hypoxaemia were the most common topics covered in the documents, with others including respiratory symptoms such as chronic breathlessness and cough, pulmonary infection, lung cancer and co-existing emphysema (figure 5). Overall, most documents guided the treatment of pulmonary morbidities rather than their identification or diagnosis. Among the different extrapulmonary morbidities, gastro-oesophageal reflux disease was most covered in the documents, followed by obstructive sleep apnoea, anxiety and depression, with the majority focusing on their treatment approaches (figure 5). While behavioural and lifestyle factors were infrequently covered in the documents, interventions for physical inactivity, such as pulmonary rehabilitation, were often discussed (figure 5).

FIGURE 5.

Summary of content coverage. CTD: connective tissue disease; GORD: gastro-oesophageal reflux disease; ILD: interstitial lung disease; IPF: idiopathic pulmonary fibrosis; OSA: obstructive sleep apnoea; PH: pulmonary hypertension. ^#: pulmonary infection category includes vaccinations against respiratory infection.

In addition, the overall diagnostic process for ILD was covered in 40 documents (51%) (clinical practice guidelines: n=25, 50%; position statements: n=15, 52%), with 28 (35%) covering lung transplantation as an intervention (clinical practice guidelines: n=15, 30%, position statements: n=13, 45%), 17 (22%) covering acute exacerbation (clinical practice guidelines: n=9, 18%; position statements: n=8, 28%) and 15 (19%) covering palliative care involvement (clinical practice guidelines: n=7, 14%; position statements: n=8, 28%).

Discussion

Despite the availability of a range of clinical guidance documents for ILD, this systematic review identifies variations in the development and quality, with important remaining gaps in their content coverage. Most contributing experts for ILD clinical guidance documents were based in Europe and North America, with low involvement of nonphysician healthcare professionals and patient representatives. The vast majority of ILD clinical guidance documents focused on different aetiologies and the overall diagnostic process for ILD, with a small number providing guidance on comprehensive care for other disease aspects.

ILDs have been the subject of increasing attention and rapid growth of research in the past two decades in recognition of the disease burden and poor prognosis. Not surprisingly, the number of clinical guidance documents on ILD increased over time. Clinical guidance documents facilitate the translation of research evidence to implement the best standard care for optimal health outcomes and provide a standardised approach for ongoing research activities to advance the field [95]. However, given the resources required for the development and timely completion of high-quality clinical guidance documents, it is often necessary to limit the number of questions and topics covered by prioritising areas of greatest uncertainty or impact on current practice, which may have influenced the content covered. This is particularly relevant for ILD, given its complexity and heterogeneity with various aetiologies and disease courses.

Currently available ILD clinical guidance documents had good coverage of the overall diagnostic process for ILD and different common aetiologies, with a few of them focusing on specific aetiologies. These documents provide the basis required in supporting clinical decisions for timely accurate diagnosis of ILD. The guidance on comprehensive care for ILD received less attention, despite its complexity requiring multidisciplinary involvement. Similarly, only a few ILD clinical guidance documents covered acute exacerbation and palliative care. This may be due to the relatively less evidence in these areas, which have only emerged as critical aspects of ILD in recent years. Importantly, comprehensive care for ILD is identified as a key unmet care need among patients with ILD [96], which should be considered in the future development of ILD guidance documents.

We identified both ILD- and non-ILD-specific clinical guidance documents, with the latter addressing systemic diseases with ILD as a manifestation, as well as different comorbidities and interventions relevant to patients with ILD. This may contribute to variations in content coverage across the included documents. It is noteworthy that some of the non-ILD-specific clinical guidance documents were not published in journals targeting respiratory medicine audiences, which can be a potential barrier for implementation. Disease-specific clinical guidance documents typically focus on recommendations for the best outcomes of a specific condition; however, the potential interactions of interventions for different diseases may not be considered. Furthermore, cumulative burden from interventions targeting individual diseases in patients with ILD can be excessive [97]. Given that systematic disease and multimorbidity are common in patients with ILD [98, 99], increased interdisciplinary collaboration in the development of ILD-specific clinical guidance documents may help the integration for implementation of multidisciplinary comprehensive care.

Among the included documents, clinical practice guidelines had superior quality according to the Institute of Medicine standards, compared to position statements. This is largely attributed to differences in the evidence synthesis process between these two different types of guidance documents. Given that this step is critical in providing evidence-based guidance for clinical care, description of literature review methodology used is needed in future position statements, even though systematic reviews are not prerequisites. Similar to previous evaluation of clinical guidance documents for respiratory and other diseases [100–102], there was low reporting of planned document updates. Although maintaining updated clinical guidance documents is crucial for incorporating the latest evidence, setting scheduled updates is challenging as new development is unpredictable and requires substantial resources [103]. Despite the document development group composition criterion being well-scored for both clinical practice guidelines and position statements, there was low representation from selected regions, which can influence the implementation of recommended clinical guidance due to geographical and cultural disparities.

To our knowledge, this is the first systematic review of ILD clinical guidance documents to identify areas for improvement, informing future development of guidance documents. However, only English-language clinical guidance documents were included in this review. Thus, clinical practice guidelines and position statements for ILD that are published in other languages may have been missed. Nevertheless, we performed a comprehensive search using different databases, including the TRIP database (www.tripdatabase.com), which is the largest medical search engine that focuses on evidence-based medical literature such as clinical guidance documents. Of note, it is beyond the scope of this review to individually search and identify clinical guidance documents for each aetiology, comorbidity and intervention for ILD. Quality assessment of the included documents was based on published data, which did not consider information that may only be available internally.

Conclusion

This comprehensive systematic review provides critical appraisal of the quality and content coverage of ILD clinical guidance documents to identify areas of improvement and gaps for future development. The increased number of clinical guidance documents highlights the efforts to improve the quality and standard of care for patients with ILD. However, most clinical guidance documents remain focused on the ILD aetiologies and the overall diagnostic approach, with limited coverage for other domains of patient care. Future clinical guidance documents on ILD need to address the content gaps to support the provision of comprehensive care needed in patients with ILD. In addition, engagement with different stakeholders and representation from different regions can be considered to ensure the relevance of ILD clinical guidance documents for implementation globally across different regions with varying local environments and resources.

Supplementary material

Please note: supplementary material is not edited by the Editorial Office, and is uploaded as it has been supplied by the author.

Supplementary material

ERR-0064-2025.SUPPLEMENT