Interstitial lung diseases (ILDs) comprise a heterogeneous group of acute and chronic lung diseases that cause progressive scarring of the lung tissue, compromising respiratory function and blood oxygenation [1]. 

An important subset of patients with fibrotic interstitial lung disease (ILD) experience a decline in lung function with progressive symptoms, poor response to treatment and reduced quality of life and early mortality [2].

Pulmonary function testing (PFTs) is essential to management and usually show a pattern of a restrictive ventilatory defect with an abnormal diffusion capacity, but are predominantly a guide to severity of disease and response to treatment and only rarely will point to a specific form of ILD [3].

In clinical practice, progression of ILD is typically monitored through pulmonary function tests and evaluation of symptoms. In-clinic measurements of FVC are essential to monitor how a patient's disease is progressing, but are limited by the test variability and, potentially, by confounding effects of comorbidities such as emphysema [4].

Besides a thorough history and clinical examination, the protocol should include a 6-minute walk test and pulmonary function tests for evaluation of ILD Patients [3].

There is paucity of studies on the Pulmonary Function Test (PFT) and 6 Minutes’ Walk Test Findings of patients diagnosed with interstitial lung diseases (ILD), in this hilly area of northern India. The present study was done to evaluate the Pulmonary Function Test (PFT) and 6 Minutes’ Walk Test Findings of Interstitial Lung Diseases (ILDs) patients.

Aims & Objectives

To study the Pulmonary Function Test (PFT) and 6 Minutes’ Walk Test Findings of Interstitial Lung Diseases (ILDs) patients.

The present study was conducted at Indira Gandhi Medical College, Shimla which is a tertiary care center of Himachal Pradesh, located in North India in Asian Continent and covers the majority of the population of this state. All consecutive patients of Interstitial Lung Diseases (ILDs), attending the outpatient services of the Department of Pulmonary Medicine, IGMC Shimla from July 2018 to June 2019 were screened for enrolment in the study. All types of ILDs were enrolled in the study.

Inclusion Criteria

• Stable ILD patients: diagnosis of ILD according to ATS/ERS guidelines based on an overall assessment of high-resolution computed tomography (HRCT) scan, lung function tests, (bronchoscopy and biopsy, if available.)

• Age >18 years, written consent.

Exclusion Criteria

• Subjects with evidence of left heart disease, Chronic kidney disease, Liver disease

• Chronic lung diseases other than ILDs

• Patients with HIV.

• Pregnant

Patients presenting with respiratory symptoms such as cough, shortness of breath and diagnosed cases of ILD were evaluated.

All consecutive ILD patients were subjected to focused history and physical examination as structured questionnaire record information related to; Demographics, Duration of ILD, Pulmonary Function Test (PFT) and 6 Minutes’ Walk Test Findings etc.

The data was collected, entered in the MS Excel sheet and analyzed using Epi info V7 software. Continuous variables were reported as mean ± SD or median and interquartile range depending on the distribution of the variables. Categorical variables were recorded as counts and percentages. Differences between means of continuous variables were compared using the unpaired student’s’ test. A p-value of < 0.05 was considered as statistically significant.

Among the study population, 50 patients 27 (54%) were female and 23 (46%) were male. The mean age of the study population was 57.821+5.03years. The mean age of males and females was 62.561+3.84 years and 53.771+5.07 years respectively. The mean duration of symptoms of ILD was 3.034+2.62 years. There was no significant difference between males and females regarding the duration of illness (2.76+2.46 years versus 3.39+2.77 years, p = 0.40) (Table 1).

The mean six minutes’ walk distance was 311.4±122.5meters. The mean six minutes’ walk distance was significantly higher in males than in females, 350.19±110.41 meter and 277.77±124 meter respectively, (p = 0.034). Thirty (60%) patients walked less than 350 meters. The restrictive pulmonary function abnormality was the commonest form observed in 30 (60%) patients, followed by obstructive pulmonary dysfunction 5 (10%) while small percentage had mixed abnormality 3(6%). There was no significant male-female difference with regards to Pulmonary Function Test (Table 2).

Progression of ILD is typically monitored through pulmonary function tests, 6 minutes’ walk Test and evaluation of symptoms in clinical practice.

In the present study mean age of the study population was 57.821±5.03 with male and female mean age 62.561±3.84 and 53.771±5.07 respectively. Females were more than male and younger with a mean duration of ILD of 3.034±2.62 years. A similar finding was also reported in the study conducted by Agarwal. et al. [5], In the ILD registry of Indian data, it was reported that ILDs occur at a younger age compared to the western countries and females are affected more [6].

In our study, baseline PFT was performed and a majority of the patients had restrictive physiology of 30 (60%), with male and female 12 (50.17%) and 18 (66.67%) respectively. In a study done by Agarwal. et al. 5, majority of patients were also had restrictive physiology. In our study, the result was not statistically significant between male and females, as we included different types of ILD, but in their study, only IPF patients were included and the sample size was also small in their study.

Table 1: Age and Gender Distribution of the Study Population (N = 50)

Table 2: PFTs and 6 Minutes’ Walk Test in ILD Patients

Six-minute Walk distance was performed in our study the mean value was 311.42±122.55 (SD with male and female had 350.19±110.41 and 277.77±124 respectively. P=0.03. Similar comparable results were noted in the study by Agrawal et al. [7], In their study the aim was to study the correlation of PH in patients with ILD with spirometry and six-minute walk distance, the mean distance walk was 258.88 meter which is less as compared to our study.

The restrictive pulmonary function abnormality was the commonest form observed in most of ILD patients and mean six minutes’ walk distance was significantly higher in males than in females. Besides a thorough history and clinical examination, the protocol should include a 6-minute walk test and pulmonary function tests for evaluation of ILD Patients.

Limitations of the Study

The small number of the population were included in this study represents a methodological limitation and study over a larger population is recommended.

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