Background: Various studies have described decreased serum angiotensin-converting enzyme (ACE) activity in patients with pneumonia. The aim of the present study was to evaluate the role of ACE in pneumonia by comparing ACE insertion/deletion (I/D) genotype corrected serum ACE activity and to establish whether the severity of the disease correlates with lower ACE activity.
Methods: This was a prospective hospital-based observational study including 134 patients with pneumonia. Serum ACE activity was determined at admission, on days 2, 3, 5 and 10 of hospital stay, and at recovery. Based on ACE genotype and reference values, corresponding Z-scores were calculated. Disease severity, quantified by the acute physiology score (APS), and clinical outcome were compared between tertile groups of the Z-scores.
Results: A significant decrease in serum ACE activity during an episode of pneumonia with return to control range during recovery was observed for all three genotypes (II, ID and DD). The calculated Z-scores showed a negative correlation with APS scores (p=0.050). No significant association between decreased serum ACE activity and clinical outcome was observed.
Conclusions: Serum ACE activity is significantly decreased during the acute phase of pneumonia. Despite correction for ACE I/D genotype, decreased ACE activity did not show a prognostic value. Further studies are needed to examine the mechanisms behind and diagnostic value of decreased ACE activity in community-acquired pneumonia.