Fibrosis as measured by the biomarker, tissue inhibitor metalloproteinase-1, predicts mortality in Age Gene Environment Susceptibility-Reykjavik (AGES-Reykjavik) Study

BACKGROUND: Fibrosis is a key pathological process in many chronic inflammatory disease states. AIMS: We hypothesized that tissue inhibitor metalloproteinase-1 and matrix metalloproteinase-9 (TIMP-1 and MMP-9), biomarkers of fibrosis, would predict all-cause mortality and we assessed the incremental value of these biomarkers when adjusting for clinical and other biomarkers. METHODS: The cohort included 5511 community-dwelling participants in the AGES-Reykjavik Study. The baseline Cox proportional hazards regression model was based on the Framingham Risk Score variables; we added TIMP-1, MMP-9, serum high-sensitivity C-reactive protein (hsCRP), and estimated glomerular filtration rate (eGFR). The primary outcome was all-cause 10-year mortality. Cause of death was categorized as cardiovascular death (CVD), cancer death, and other causes. RESULTS: Participants averaged 76 years and 43% were male. Ten-year mortality was 41% (2263 deaths). Of these, 915 (16.6%) died of cardiovascular disease (CVD), 543 (9.9%) with cancer, and 805 (14.6%) from other causes. For 10-year mortality, age was the strongest predictor (log likelihood χ2 = 798.7, P < 0.0001), followed by TIMP-1 (χ2 = 125.2, P < 0.0001), female gender, current smoker, diabetes mellitus, total cholesterol, eGFR (χ2 16.7, P < 0.0001), body mass index, and hsCRP (χ2 11.3, P = 0.0008) in that order. TIMP-1 and hsCRP had the highest continuous net reclassification improvement over the baseline model for 5-year survival [net reclassification index (NRI) 0.28 and 0.19, respectively, both P < 0.0001] and for 10-year survival (NRI 0.19 and 0.11, respectively, both statistically significant). CONCLUSION: TIMP-1 is the strongest predictor of all-cause mortality after age. The metabolic pathways regulating extracellular matrix homeostasis and fibrogenic processes appear pathologically relevant and are prognostically important.