Time in Therapeutic Range (TTR) compliance

We are proud that patients on our INRstar database show higher than average Time in Therapeutic Range (TTR). We have more than 260,000 anticoagulation patients on the database and 72% of those patients have a TTR >65%. The average TTR for an INRstar testing location is 74.4%.

TTR works out the estimated time each patient is spending in range over a period of time and relies on the Rosendaal principle that there is a linear relationship between successive INR blood results. Recommendations from NICE for patients with atrial fibrillation (AF)* published in July 2014 suggest that good quality care is represented by a TTR in excess of 65%, over a maintenance period of at least 6 months.
*Atrial fibrillation: the management of atrial fibrillation. NICE guidelines [CG180] Published date: June 2014

Surpassing NICE Guidelines

TTR results give an overall assessment of the efficacy of a clinic and indicate whether patients may benefit from a switch to one of the newer oral anticoagulant drugs (NOACs or ODIs). INRstar can calculate TTR both for an individual patient (iTTR), and also across an anticoagulation service.

As NICE confirms for patients with AF, an iTTR figure greater than 65% generally implies good control, and patients may be left on a traditonal oral anticoagulant so long as both they and their clinician are happy with the current situation. Patients whose iTTR falls below that figure may be considered for a switch to one of the NOACs, but if the iTTR figure falls below 40% then definitive action is required.

TTR is now recognised as the ‘gold standard’ of anticoagulation care and is valued as the best quantitative measure of INR. INRstar has worked hard to ensure that we can provide benchmarking services for our users in an easily accessible format. Dr Robert Treharne Jones, Clinical Director, LumiraDx Care Solutions