Abstract
Previous studies have shown airflow limitation is common in Sarcoidosis. Recent evidence (Chest 2011; 139:52-59) suggests using fixed percentage predicted (PP) values may discordantly classify patients compared to using fifth percentiles as the lower limit of normal (LLN). We studied PFT patterns, and the effect of classifying by PP and LLN.
Our study assessed the PFT results found in consecutive patients presenting with Sarcoidosis to one medical team over a 14 year period. Eighty-five patients fulfilled the entry criteria. All had PFTs available. Patients were classified into normal, obstructive, restrictive and mixed deficits using the ATS/ERS flowchart for PFT interpretation. Classification by PP and LLN values were compared.
Eleven patients (12.9%) were classified discordantly comparing PP with LLN methods. Six had normal PFTs classified by LLN, but abnormal by PP values. Normal lung function (PP 64.7%, LLN 68.2%) was the commonest pattern. Obstruction was the commonest abnormality (PP 24.7%, LLN 21.7%). Patients with obstructive deficits were more likely to have ever smoked.
The frequency of airflow obstruction in this study was 24.7% when classified by PP, equivalent to findings from a similar cohort (Resp Med 1991; 59-64 - 24.3% using PP), but higher than cohorts studied previously in Japan (8.8%). Classified by LLN, the proportion of our patients with obstruction falls to 21.2%. Overall, the commonest PFT pattern in patients with Sarcoidosis is normality. Expiratory airflow obstruction remains the commonest abnormal pattern, with a slightly higher frequency when classified by PP compared to LLN.
- © 2011 ERS