PPF-ILD DSP survey sample

Two hundred and sixty-five physicians participated in the survey and completed PRFs for 1335 patients with a physician-confirmed ILD diagnosis with PPF (Table 1). The sample was composed of 66.1% pulmonologists, 30.9% rheumatologists and 3.1% internal medicine specialists (only recruited in France). The largest group of patients were based in Germany (24.6%) and the smallest in the UK (13.8%) (Table S3). The ratio of patients to physicians was greatest in France (6.9) and lowest in the UK (3.7).

Table 1 Study sample sizePatient demographics

The mean (standard deviation [SD]) age of patients at the survey date was 60.4 (11.6) years, 91.2% were white, 58.1% were female, 44.0% were non-smokers, and mean (SD) body mass index was 25.3 (3.9) kg/m2 (Table 2). Few patients (5.4%) had a family history of ILD. At the survey date, 25.2% of patients were in full-time employment. Of those not in full-time employment (n = 806), 18.9% were unable to work full-time due to their ILD (either working part-time, retired, on long-term sick leave or unemployed).

Table 2 Patient demographics by type of PPF

Numerically, patient demographics as defined by country or physician specialty were similar (Tables S4–S5). The proportion of patients either working part-time, retired, on long-term sick leave or unemployed due to their ILD was comparable with the main survey population (20.1%) for both patients with CTD-ILD and other types of ILD (21.9% and 18.3%, respectively; Fisher’s exact test p < 0.2387). However, patients with CTD-ILD were significantly younger than those with other types of ILD (58.0 [SD 11.0] and 62.3 [SD 11.7] years, respectively; t-test p < 0.0001), and a greater proportion were female (73.7% and 40.3%, respectively; t-test p < 0.0001) (Table 2, Table S6).

Clinical characteristicsDisease severity

Based on physician-reported disease severity, more patients were reported to have moderate ILD (47.7%) at survey date than mild (42.3%) or severe ILD (10.0%). The proportion of patients with severe ILD varied by reporting physician (rheumatologists 5.8%, pulmonologists 12.5%), country (Germany 0.6%, Spain 15.6%) and type of ILD (Sjögren’s-associated ILD 3.0%, polymyositis/dermatomyositis-associated ILD 14.5%) (Figure S1). For patients with SSc-ILD (n = 263), most patients were classed as having limited disease (73.4%) compared with extensive disease (26.6%) for physician-reported severity of ILD according to Goh’s criteria [27] at survey date (Fig. 2).

Fig. 2

Physician-rated severity of SSc-ILD according to Goh’s criteria. ILD, interstitial lung disease; SSc, systemic sclerosis; UK, United Kingdom

Disease progression

Overall, 19.5% of patients were reported as progressing in the 12 months prior to survey date (moderately progressing 16.6%, severely progressing 2.9%), 52.2% were stable, 26.1% were improving and 2.3% were too early to tell. For those patients deemed to have progression, physicians provided one main reason for their assessment; the most frequent were worsening symptom severity (27.3%), decline in lung function (forced vital capacity [FVC] and diffusing capacity of the lungs for carbon monoxide [DLco]; 25.8%) or increased fibrosis on imaging (14.2%) (Fig. 3). Reasons for progression varied by country and physician specialty (Tables S7 & S8). For example, progression due to symptom severity ranged between 15.0% in Spain to 42.2% in the UK. Progression was reported based on symptom severity for 26.4% of patients seeing a pulmonologist and 32.6% of patients seeing a rheumatologist, and based on decline in FVC or DLco for 27.4% of patients seeing a pulmonologist and 17.4% of patients seeing a rheumatologist. Reasons for progression varied by type of ILD, with symptom severity (30.4%) or increased extent of fibrosis (19.6%) mostly reported for uILD; for RA-ILD, progression was mostly reported due to decline in lung function (29.2%) or symptom severity (25.0%) (Table S9).

Fig. 3

Physician-reported reasons for disease progression in the last 12 months. CT, computed tomography; DLco, diffusing capacity of the lungs for carbon monoxide; FVC, forced vital capacity; HRCT, high-resolution CT; ILD, interstitial lung disease

Of those patients diagnosed with ILD less than 1 year before survey date, 16.8% of patients were reported to have moderately or severely progressing disease compared with 21.0% of patients diagnosed more than 1 year before (Figure S2). Physicians expected that over the next 12 months from the survey date, progression would stabilise for more than half (61.4%) of all patients. This ranged from 48.1% of patients with uILD to 70.3% of patients with RA-ILD. Expected progression in the next 12 months from the survey date based on physician perspective was aligned with clinical parameters, with patients considered as progressing presenting with lower FVC and DLco (Figure S3).

Comorbidities

A total of 61.8% of patients had at least one comorbidity; the mean (SD) number of comorbidities per patient was 1.3 (1.5) and ranged from 0 to 12. The most frequent physician-reported comorbidities were anxiety (16.9%), gastroesophageal reflux (15.5%), depression (13.4%), diabetes without chronic complications (10.0%) and pulmonary hypertension (9.0%). There was some variation in comorbidities reported according to country, physician specialty and type of ILD (Tables S10–S12). For example, anxiety was most frequently reported in Italy (24.7%) and France (22.5%) (lowest in Germany at 3.1% of patients) and pulmonary hypertension was reported for 14.5% of patients with SSc-ILD and 6.0% each of patients with RA-ILD and polymyositis/dermatomyositis-ILD.

Treatment

Mean (SD) age at initial treatment was 57.8 (12.3) years (n = 1,000). A total of 77.8% of patients were receiving treatment for their ILD at the survey date; of those, low-dose prednisone (41.5%), nintedanib (30.9%) and mycophenolate (19.1%) were the most frequent treatments (Table 3). Of those prescribed low-dose prednisone (n = 431), 21.3% were prescribed low-dose prednisone only and 78.7% were prescribed low-dose prednisone plus other treatment; of those prescribed nintedanib (n = 321), 34.0% were prescribed nintedanib only and 66.0% were prescribed nintedanib plus other treatments; of those prescribed mycophenolate (n = 198), 16.2% were prescribed mycophenolate only and 83.8% were prescribed mycophenolate plus other treatments.

Table 3 Patient treatment history

For those with available data (n = 705; 67.9%), mean (SD) current treatment duration was 1.6 (3.9) years at survey date. The proportion of patients currently prescribed treatment varied by country (ranging from Germany 88.4% to France 71.7%), physician specialty (pulmonologists 60.0%, rheumatologists 43.2%) and type of ILD (polymyositis/dermatomyositis-associated ILD 88.0%, uILD 54.1%) (Tables S13–S15).

If current treatment was deemed to be inadequate as judged by the treating physician, the most frequently reported next steps included switching to a different treatment (18.8%), increasing the dose (17.1%), or adding a treatment to the existing regimen (16.6%), although 18.3% of physicians did not know what the next course of action would be (Table 3). A numerically higher proportion of physicians in the UK would switch treatment compared with physicians in Germany (29.6% and 13.8%, respectively) (Figure S4).

Some patients (6.6%) were not receiving treatment for their ILD at survey date but had previously been treated (Table 3). Of these, 44.3% had discontinued low-dose prednisone, 33.0% discontinued high-dose prednisone, and 20.5% discontinued nintedanib. The main reasons given by physicians for discontinuing treatment were side effects (26.1%) and poor adherence to prescribed treatment (23.9%). Overall, 15.6% of patients had never been prescribed treatment for their ILD (Table 3). The most common reason for never receiving treatment as reported by physicians was the disease being considered manageable without treatment (48.6%), which was consistent across countries, physician specialty and type of ILD.

Patient journeyClinical milestones

A total of 534 patients (40.0%) had data available regarding their diagnostic journey (Fig. 4). For these patients, the mean (SD) age at first symptom of ILD was 56.9 (12.0) years, mean age at first HCP visit was 57.6 (12.1) years, and mean age at confirmed ILD diagnosis was 58.2 (12.2) years (Tables S16–S18). In total, there was an average of 15.5 months between first ILD symptoms and ILD diagnosis.

Fig. 4

Patient journey for ILD in Europe. HCP, healthcare professional; ILD, interstitial lung disease; PCP, primary care physician

Patient journey varied by country, reporting physician and type of ILD. For example, patients in Germany were generally younger across all milestones (e.g., mean age [SD] 52.2 [9.5] years at first symptom of ILD compared with 60.0 [11.2] years for patients in Spain). Pulmonologists reported that patients were older at first ILD symptom (mean [SD] 59.4 [11.5] years) and first HCP visit (60.2 [11.5] years) than those reported by rheumatologists (54.6 [11.2] years and 54.9 [11.2] years, respectively). Patients with Sjögren’s-associated ILD had a confirmed diagnosis of ILD at a mean (SD) age of 48.2 (14.0) years, whereas patients with SSc-ILD were mean age 62.8 (12.4) years at diagnosis.

There was a mean (SD) delay of 7.8 (22.7) months between first ILD symptom and first HCP visit, with a further delay of 7.7 (12.8) months between first HCP visit and ILD diagnosis. This varied by country, with mean (SD) delay between first HCP visit and ILD diagnosis of 5.5 (7.2) months in France and 10.5 (14.5) months in Spain. Patients seeing a pulmonologist generally had a longer mean delay between first HCP visit and confirmed diagnosis of ILD (mean [SD] 9.1 [14.0] months). The mean delay between first HCP visit and ILD diagnosis varied between type of ILD; however, there was also wide variation within each type of ILD.

Symptom burden and diagnosis

Of those patients reporting or presenting with symptoms at the survey date (n = 1,007), 72.8% of them experienced symptoms of ILD prior to a confirmed diagnosis. The most frequent symptoms experienced prior to an ILD diagnosis were dyspnoea on exertion (80.5%), cough (57.8%) and dyspnoea following exertion (37.0%). Among the 1,007 patients reporting symptoms in the 4 weeks prior to survey date, the most frequent were dyspnoea on exertion (78.4%) and cough (49.4%).

Overall, 232 patients (17.4%) were diagnosed with another condition prior to ILD diagnosis; of these, chronic obstructive pulmonary disease (COPD) was suspected or investigated in 39.2% of patients and asthma in 22.4% of patients. Rates for conditions suspected or investigated prior to ILD diagnosis varied by country, reporting physician specialty and type of ILD (Tables S19–S21). In Germany (n = 54), COPD was the most frequently suspected or investigated condition (77.8%), whereas in Spain (n = 52), asthma (32.7%) was the most frequent. For pulmonologists (n = 164), COPD (36.6%), asthma (25.6%) and heart failure (10.4%) were the most frequently suspected or investigated conditions. For rheumatologists (n = 60), these were COPD (48.3%), anxiety (21.7%) and bronchitis (20.0%). COPD was the most frequently suspected or investigated condition across the different types of ILD, except for fibrotic hypersensitivity pneumonitis (n = 55; asthma, 43.6%) and SSc-ILD (n = 31; anxiety and COPD, both 25.8%).

Consultation and referral history

Most patients first consulted a primary care physician (57.0%) regarding their ILD symptoms. A total of 71.8% of patients were referred from another HCP, most frequently by a primary care physician (54.9%) (Fig. 5). The most common reasons for referral were that the referring HCP did not specialise in respiratory conditions (56.7%), a lack of understanding around ILD (25.1%) and the need for additional diagnostic testing (24.5%). A pulmonologist was the diagnosing physician in 62.6% of cases, and additional physicians were involved in the diagnosis of 24.9% of all cases. According to the physician surveys (n = 265), 83.4% of respondents were part of a multidisciplinary team, and within those teams most had a role in diagnosis and ongoing management (91.4%). This varied across countries, with the use of a multidisciplinary team for diagnosis reported in 40.6% of patients in Italy and 4.0% of patients in Germany.

Fig. 5

Physician-reported patient referral. HCP, healthcare professional; ILD, interstitial lung disease; PCP, primary care physician