Long-term biological variation of high-sensitivity cardiac troponin T using minimal important differences and reference change values in stable outpatients with cardiovascular disease

Objective To evaluate the long term biological variation of high-sensitivity cardiac troponin T (hs-cTnT) in stable outpatients with cardiovascular disease (CVD). Methods After applying 8 exclusion criteria to 965 patients, hs-cTnT was measured at index visit and at a 12-month interval in 169 stable outpatients presenting for routine follow-up visits for any CVD. Stability was defined as absence of any endpoint within the follow-up period. Reference change values (RCVs) and minimal important differences (MIDs) were determined to assess biological variation of hs-cTnT. Results MID and RCV for the 12 months interval in patients were 3.8 ng/L or 44.2%, respectively. MID and transformed MID values were lower than the corresponding RCV with a value of 5.1 ng/L for the transformed RCV and 28.1% for the transformed MID. Similar patterns were shown in different subgroups as sex, age, and renal function . We observed a baseline hs-cTnT value dependent change of MID and RCV with increasing values for MID and decreasing values for RCV which converge to stable values between a baseline hs-cTNT value of 11 to 25 ng/L. Conclusions Biological variation of hs-cTnT over 12 months in stable outpatients depends on the concentration at index visit, and is consistent among important prespecified subgroups. MID shows a low biovariability over 12 months. Clinical Trials Identifier: NCT01954303