Interstitial lung disease (ILD) is a group of lung diseases that result in inflammation, scarring and changes to the tissue on the inside of the lungs. ILD is an umbrella term for more than 200 illnesses, such as drug-induced pulmonary fibrosis, hypersensitivity pneumonitis, occupational lung diseases, connective tissue disease associated ILD and idiopathic interstitial pneumonias [1]. The combined morbidity and mortality of these diseases is significant because of the progressive decline in the function of the lungs, the poor gas exchange, and reduced quality of life [2]. ILD may be insidiously developed with slow onset of exertional dyspnea and a chronic, dry cough being most common clinical symptoms. Physical examination might show bilateral fine inspiratory crackles and pulmonary function testing will usually show a restrictive ventilatory pattern with diminished forced vital capacity and diffusion capacity [3]. The symptoms of other respiratory diseases like chronic obstructive pulmonary disease and heart failure are comparable making diagnosis often delayed, which leads to the disease to be presented at a higher level and less available treatment [4]. The best known form of fibrosing ILD is idiopathic pulmonary fibrosis (IPF) which has been associated with scaring of the lung and long term worse outcomes. Other important ILD include NSIP, organizing pneumonia, sarcoidosis and hypersensitivity pneumonitis, all of which have different clinical courses and therapies [5]. Therefore, it is crucial that the underlying ILD subtype is identified, to inform prognosis and choice of management.

Chest Computed Tomography (CT or high-resolution computed tomography [HRCT]) is a significant part player in the evaluation and classification of ILD. HRCT can provide detailed visualisation of changes in the parenchyma and may be helpful in helping to diagnose characteristic radiological patterns such as usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), organizing pneumonia, and fibrotic hypersensitivity pneumonitis [6][7]. The NSIP looks different than the UIP with relative preservation of lung architecture and bilateral ground glass opacities, whereas the UIP pattern is characterized by reticulation, honeycombing and traction bronchiectasis, which predominate in the basal and subpleural regions. Although advances have been made in imaging techniques, the diagnosis of ILD is still difficult because the radiological characteristics of different diseases may be similar. The use of a multidisciplinary diagnostic approach that takes into account clinical, radiological and pathological data, is recommended for the effective classification of the disease [9]. The early identification of radiologic patterns can help avoid unnecessary invasive procedures and enhance clinical decision making [10]. The clinical expression of ILD and the distribution of ILD cases by geography may be different, depending on genetic susceptibility, exposure to the environment, occupational exposure and health care availability [11][12]. A lack of awareness, poor referral and lack of specialized investigations are factors that may contribute to delayed diagnosis and aggravate disease complications in developing countries [13]. Hence, there is a need to understand the disease pattern and improve the health of a patient by analysing the local clinical characteristics and radiological findings.

Objective

This study aimed to evaluate the clinical profile and radiological patterns of interstitial lung disease among patients presenting at a tertiary care center.

This analytical cross-sectional study was conducted among 180 patients diagnosed with interstitial lung disease (ILD) at Al Aleem medical college Lahore from may 2025 to may 2026. A total of 180 patients with confirmed or clinically suspected interstitial lung disease were included using consecutive sampling. Patients of either gender who were diagnosed with ILD based on clinical evaluation, pulmonary function testing, and radiological assessment were eligible for inclusion. Patients with incomplete clinical records, inadequate radiological imaging, previously diagnosed pulmonary malignancy, active pulmonary infection, or other conditions causing secondary interstitial changes without confirmed ILD were excluded. Each patient underwent a detailed clinical evaluation including demographic assessment, presenting complaints, symptom duration, relevant medical history, exposure history, and physical examination findings. The diagnosis and classification of ILD were based on clinical features and high-resolution computed tomography (HRCT) findings. Radiological patterns were categorized according to recognized ILD patterns, including usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), organizing pneumonia, hypersensitivity pneumonitis, and other fibrotic or non-fibrotic patterns. HRCT parameters including distribution of lesions, presence of reticulation, ground-glass opacities, honeycombing, traction bronchiectasis, architectural distortion, and extent of fibrosis were recorded. The severity of radiological involvement was assessed according to the extent and pattern of pulmonary abnormalities. Data Collection Data were collected using a structured data collection proforma. Patient-related variables included age, gender, body mass index, smoking status, occupational and environmental exposure history, duration of symptoms, presenting complaints, and associated comorbidities. Clinical characteristics including dyspnea severity, cough, chest pain, fatigue, oxygen requirement, respiratory examination findings, and functional limitation were documented. Relevant laboratory and pulmonary investigations, including complete blood count, inflammatory markers, autoimmune screening where available, pulmonary function test parameters, forced vital capacity (FVC), and diffusion capacity for carbon monoxide (DLCO), were recorded. Radiological variables included HRCT pattern, distribution of abnormalities, presence of fibrosis, honeycombing, ground-glass opacities, septal thickening, traction bronchiectasis, and other associated findings. ILD subtypes were categorized based on combined clinical and radiological assessment. Disease severity indicators, including pulmonary function impairment and extent of radiological involvement, were also documented. All collected information was entered into a structured database for statistical analysis while maintaining patient confidentiality. Statistical Analysis Data were analyzed using SPSS version 26.0. Continuous variables including age, duration of symptoms, pulmonary function parameters, and laboratory values were presented as mean ± standard deviation or median with interquartile range according to data distribution. Normality of continuous variables was assessed using the Shapiro–Wilk test. Categorical variables including gender, presenting symptoms, smoking status, comorbidities, and HRCT patterns were expressed as frequencies and percentages. Adjusted odds ratios (aOR) with 95% confidence intervals (CI) were reported, and a p-value <0.05 was considered statistically significant.

Among 180 patients with interstitial lung disease, the mean age was 58.6 ± 14.2 years, with the majority of patients aged ≥60 years (95, 52.8%), followed by those aged 40–59 years (67, 37.2%). Males represented 108 (60.0%) cases, while females accounted for 72 (40.0%). The mean duration of symptoms was 18.4 ± 10.6 months. Smoking history was present in 61 (33.9%) patients, whereas occupational exposure was reported in 46 (25.6%) cases. Progressive dyspnea was the most common presenting complaint, observed in 165 (91.7%) patients, followed by dry cough in 139 (77.2%) and fatigue in 86 (47.8%). Hypertension was present in 58 (32.2%) patients and diabetes mellitus in 42 (23.3%). Resting oxygen requirement was observed in 49 (27.2%) patients.

Table 1. Baseline Demographic and Clinical Characteristics of Patients with Interstitial Lung Disease (n = 180)

Patients had a mean respiratory rate of 24.8 ± 5.1 breaths/min and oxygen saturation of 89.6 ± 6.8%. Fine inspiratory crackles were present in 152 (84.4%) patients, while reduced exercise tolerance was observed in 143 (79.4%). Mean FVC, FEV1, and DLCO were 61.5 ± 15.8%, 66.2 ± 16.4%, and 48.9 ± 14.6% predicted, respectively. A restrictive pattern was observed in 137 (76.1%) patients.

Table 2. Clinical and Pulmonary Function Characteristics of Patients with Interstitial Lung Disease (n = 180)

The distribution of ILD subtypes revealed that idiopathic pulmonary fibrosis was the most frequent subtype, affecting 62 (34.4%) patients. Connective tissue disease-associated ILD was observed in 38 (21.1%) cases, followed by hypersensitivity pneumonitis in 27 (15.0%) and nonspecific interstitial pneumonia in 24 (13.3%) patients. Other identified subtypes included sarcoidosis in 11 (6.1%), organizing pneumonia in 9 (5.0%), drug-induced ILD in 5 (2.8%), and other ILD patterns in 4 (2.2%) cases. Overall, fibrotic forms of ILD represented the predominant disease category in this patient population.

Table 3. Distribution of Interstitial Lung Disease Subtypes Based on Clinical and

Radiological Assessment (n = 180)

The most frequent HRCT pattern was UIP, observed in 69 (38.3%) patients, followed by NSIP in 41 (22.8%) cases. Reticulation was the commonest radiological finding (142, 78.9%), followed by traction bronchiectasis (96, 53.3%) and honeycombing (67, 37.2%). Bilateral involvement was present in 169 (93.9%) patients, with subpleural predominance in 124 (68.9%) cases.

Table 4. High-Resolution Computed Tomography (HRCT) Radiological Patterns

in Patients with Interstitial Lung Disease (n = 180)

Fibrotic HRCT patterns were significantly associated with older age, male gender, prolonged symptoms, and impaired lung function. Patients aged ≥60 years had higher fibrosis frequency (71, 63.4% vs. 24, 34.8%; p<0.001). Fibrosis was also associated with symptom duration >12 months (82, 72.6%; p<0.001), FVC <50% predicted (35, 31.0%; p<0.001), reduced DLCO (39, 34.5%; p=0.012), and oxygen requirement (38, 33.6%; p=0.009).

Table 5. Association between Patient Characteristics and Fibrotic HRCT Pattern

in Interstitial Lung Disease (n = 180)

The mean age was 58.6 ± 14.2 years for 180 patients with interstitial lung disease (ILD) in the present study, of which 52.8% were ≥60 years of age. There was a male predominance, with male being 60.0% of cases. Previous studies have reported similar associations, with increased ILD occurring in older patients and males, with a particular association with fibrotic variants including fibrotic idiopathic pulmonary fibrosis. This pattern could be associated with cumulative exposure to environmental factors, tobacco use, and with age-related lung repair function changes [14]. In our study, the most prevalent symptom was progressive dyspnea (91.7%), followed by cough (77.2%). In 84.4% of cases, fine inspiratory crackles were seen. Previous studies have also shown that the main clinical features of ILD are exertional dyspnea, chronic dry cough and typical inspiratory crackles. These symptoms are indicative of the development of interstitial thickening and fibrosis which leads to decreased lung compliance and gas exchange [15]. In our study, pulmonary function assessment was characterized by a mean FVC of 61.5 ± 15.8% predicted, mean DLCO of 48.9 ± 14.6% predicted and restrictive ventilatory pattern in 76.1% of patients. The same has been reported in other studies, in which restricted lung physiology and decreased diffusion capacity were commonly seen in ILD patients and were shown to be important indicators of disease severity and functional status [16][17]. In terms of the distribution of ILD subtypes, idiopathic pulmonary fibrosis (34.4%) was the most frequent subtype, followed by connective tissue disease-associated ILD (21.1%) and hypersensitivity pneumonitis (15.0%). Indeterminate pulmonary fibrosis (IPF) has been previously recognized as a common fibrotic ILD type with significant clinical implications. The overall pattern of fibrotic disorders reiterates the need for prompt recognition and classification due to the fact that worsening respiratory function and decreased outcomes are linked to progressive fibrosis [18]. The most common radiological pattern on HRCT was UIP (38.3%) followed by NSIP (22.8%). Common features were reticulation (78.9%), traction bronchiectasis (53.3%) and honeycombing (37.2%). Similar HRCT features have been previously reported, including UIP being associated with basal and subpleural fibrosis, honeycombing, and traction bronchiectasis. In addition to the above, HRCT is still a crucial imaging modality as it offers detailed evaluation of the distribution of fibrosis, and can also aid in the distinction of major patterns of ILD without the need for invasive procedures in all cases [19]. In this study, bilateral involvement was seen in 93.9% of patients, subpleural involvement in 68.9% and basal predominance in 65.6%. Previously, it was also reported that the fibrotic ILDs, particularly UIP pattern ILDs, are frequently bilateral, basal and peripheral in distribution. The typical progression of fibrosis in the lung parenchyma is reflected by these radiological features [20]. The present analysis revealed that the fibrotic pattern of HRCT was significantly correlated with age, longer symptom duration, lower FVC, lower DLCO, and requirement of oxygen. An increased prevalence of fibrotic changes was seen in patients aged ≥60 years, >12 months of symptoms and with impaired pulmonary function. One previous study reported that advanced age, reduced lung function, and having had a long course of disease were associated with higher levels of radiological fibrosis and disease severity [21]. This study had a number of limitations. The results of this study could not fully represent the large population of people with ILDs in different health care settings, as it is a single-center study. Due to the cross-sectional design, it was not possible to evaluate the progression of the disease, reaction to treatment or long-term effects. Diagnosis and classification of ILD was primarily done based on clinical and radiological evaluation in all patients and confirmed histopathologically in some. However, differences in referral practices and access to more sophisticated diagnostic tests could have affected the distribution of the ILD subtypes. Larger multicenter studies with longer follow-up time are recommended for future studies to offer more detail to the progression of the disease and the prognostic factors.

It is concluded that interstitial lung disease predominantly affects older adults, with male predominance and progressive dyspnea being the most common clinical presentation. Idiopathic pulmonary fibrosis was the most frequent ILD subtype, while the usual interstitial pneumonia pattern represented the most common HRCT finding. Reticulation, traction bronchiectasis, and honeycombing were frequently observed radiological features. Advanced age, prolonged symptom duration, reduced pulmonary function, and oxygen requirement were associated with greater fibrotic involvement. Comprehensive clinical assessment combined with HRCT evaluation remains essential for early diagnosis, classification, and management of patients with interstitial lung disease.