Introduction: There is inter-observer variability in requesting pulmonary function (PFT) in ILD. Monitoring is essential to the management of the pathology.

Aim: Explore the pattern of referral and PFTs using z-scores to classify severity, which guides management and treatment.

Method: Diagnosed ILD patients were classified as per National Institute for Clinical Excellence (NICE) Z-score limits (n-120) as mild, moderate, and severe, respectively. Consultant referral patterns and testing intervals (both by severity and sub-class of ILD (UIP, Sarcoidosis, CTD, Chemical Exposure, NSIP, Other IP) were assessed for statistical significance. All required local hospital ethics approvals were completed, respectively.

Results: There was no significant difference between the median interval for consultant referrals and pulmonary function tests (PFTs). There was no significant difference between median PFTs intervals when severity was considered (p= 0.90). However, there was a significant difference (mild vs moderate p=0.05; mild vs severe p=0.21) between consultant requests for mild patients compared to moderate and severe. When the median interval for pulmonary function testing was compared by ILD sub-class there was no significant difference (p=0.34).

Conclusion: Intervals between referrals and lung function tests were similar in the ILD cohort. Severity was not a determining factor for the frequency of lung function testing. Although, referrals from consultants for moderate and severe patients were more frequent than for mild patients. Although median lung function testing intervals were varied when sub-classes of ILD were compared, there was no significant difference across the groups.