Impact of Capillaroscopy in the Investigation of Diffuse Interstitial Pneumonias

Diffuse interstitial lung diseases (DILD) are a group of diseases characterized by inflammation and fibrosis of the lung tissue, with more than 200 identified causes, approximately 20% of which are related to autoimmune diseases such as connective tissue disorders (e.g., scleroderma, lupus). Pulmonary involvement may precede the diagnosis of connective tissue disease, making diagnosis difficult. Capillaroscopy, a non-invasive and reproducible test, is used to detect microvascular abnormalities, especially in scleroderma spectrum diseases, but its precise role in the evaluation of PID is still poorly defined. Studies show that PIDs associated with autoimmunity are more likely to present with capillaroscopic abnormalities. However, current recommendations on the investigation of PIDs do not clearly specify the use of capillaroscopy, and there are no studies establishing its value in systematic screening of all patients with PID. Thus the investigators aim to describe the characteristics of capillaroscopy in patients with a new diagnosis of PID.

The project will be offered to eligible patients for whom a PID has been identified. A review of the medical record information will then be carried out, with additional tests performed as necessary to identify the etiology associated with this IDP. The compilation of information, and especially the performance of additional tests (beyond normal care), is typically completed within three months. In the meantime, and particularly in the first month after signing the consent form, the patient will undergo a capillaroscopy and complete the patient questionnaire. After three months, once all additional tests have been performed and the results compiled, the pulmonologist completes the questionnaire to identify the most likely etiology of the patient's PID. All tests, except for capillaroscopy, are performed as part of routine care.

Inclusion criteria

• Male or female over 18 years of age;
• Have received a new diagnosis of PID within the last six months, confirmed by a pulmonologist;
• Have undergone some specific tests within the last six months (Chest CT scan, respiratory function tests (plethysmography and CO transfer capacity measurement, immunological assessment including: screening for FAN, FR, and anti-CCP);
• French-speaking patient with no comprehension difficulties;
• Person affiliated with or beneficiary of a social security system;
• Free, informed, and written consent signed by the participant and the investigator (no later than the day of inclusion and before any examination required by the research).

Exclusion criteria

• Have previously undergone a capillaroscopy, regardless of the reason;
• Have a diagnosis or high suspicion of connective tissue disease based on initial clinical and paraclinical evaluation;
• Have already started one of the following treatments for pulmonary involvement: systemic corticosteroids, immunosuppressive therapy, antifibrotic therapy;
• Pregnant or breastfeeding women;
• Patients covered by Articles L 1121-5 to L 1121-8 (persons deprived of their liberty by judicial or administrative decision, minors, adults subject to legal protection measures, or persons unable to give their consent).