Estimation of age- and comorbidities-adjusted percentiles of high-sensitivity cardiac troponin T levels in the elderly.

Abstract

Cardiac troponin level measured by high-sensitivity assays (hs-cTn) in the elderly is frequently found higher than the 99th percentile upper reference limit, making the diagnosis of acute coronary syndromes (ACS) difficult. This study aimed at: 1) identifying determinants of hs-cTnT levels in an unselected population of elderly subjects; and 2) assessing the prognosis value of increased hs-cTnT in elderly people free of ACS. Hs-cTnT was measured in 591 individuals aged over 65 years without suspicion of ACS. Comorbidities were assessed using the Cumulative Illness Rating Scale for Geriatrics (CIRS-G). C-reactive protein, α1-acid glycoprotein, albumin and creatinine were measured. Factors influencing hs-cTnT levels were assessed through linear regression and quantile regression was used to model percentiles of hs-cTnT. Risk of mortality was assessed through Cox regression. Age, gender, cardiac CIRS-G, estimated glomerular filtration rate (p<0.001 for all), albumin (p<0.028) and α1-acid glycoprotein (p=0.002) were independent predictors of hs-cTnT. After exclusion of outliers, the median was 15 ng/L and 99th percentile was 64 ng/L. After controlling for comorbidities, the 99th percentile increased from 24 ng/L at age 65 to 53 ng/L at age 90 in females and from 33 ng/L to 75 ng/L in males. In multivariate analysis, hs-cTnT level was significantly related to mortality. Hs-cTnT level is associated with inflammation and renal function in the elderly. Independently of comorbidities, hs-cTnT concentration increases exponentially with age after 65 years. Decision limits adapted to age and sex may be useful to patient management.