Matrix metalloproteinase-9 predicts pulmonary status declines in α1-antitrypsin deficiency

Respiratory Research

Table 4 MMP-9 as a longitudinal predictor of respiratory outcomes: lung function, lung density, functional status, and COPD exacerbations

Outcome Measures	Annualized Δ (95% CI)*	P-value
Spirometry
FEV₁, ml	+14 (-4 to +33)	0.13
FVC, ml	+72 (+6 to +138)	0.03
FEV₁/FVC ratio	-0.6% (-1.3% to -0.1%)	0.053
Total Lung Capacity, ml	+69 (+10 to +126)	0.02
Transfer Factor (TLco), mmol/min/kpa	-0.1 (-0.2 to -0.004)	0.04
CT Densitometry
Adjusted Lung Density^†	-0.6 (-1.1 to -0.2)	0.003
Resting Oxygenation Saturation (room air)	-0.5% (-0.7% to -0.3%)	<0.001
Incremental Shuttle Walk Test Distance
Distance Walked, meters	-6 (-15 to +2)	0.16
Acute Exacerbations of COPD, number	+0.27 (+0.10 to +0.45)	0.003

All analyses controlled for age, gender, race-ethnicity, leukocyte count, and tobacco pack-year history. Analysis of total lung capacity also controlled for method of lung capacity assessment (box plethysmography vs helium dilution).
*Annualized longitudinal change (Δ) predicted by a 25^th - 75^th percentile interquartile range higher level of MMP-9.
^†Measured in Hounsfield Units at the 15^th percentile.

ISSN: 1465-993X