The main objective of this study is to evaluate, for a 6-month observation period, the concordance in terms of clinical decision making concerning therapeutic adjustment as determined by a weekly capillary International Normalised Ratio (INR) monitoring strategy versus the usual strategy in a population of dependent elderly people in nursing homes, treated with anti-vitamin K (AVK).

The secondary objectives of this study are to:

A. Estimate the intra-patient variability of capillary INR measures.

B. Estimate the time spent in the target INR (TTR) window of dependent elderly patients in nursing homes, under AVK treatment, and with a capillary INR monitoring strategy.

C. Estimate the number of venous thromboembolic events and bleeding events over the 6-month observation period.

Inclusion Criteria:

• The patient resides at the establishment for the dependent elderly (nursing home (EHPAD)) in Pont-Saint-Esprit, France
• The patient must be insured or beneficiary of a health insurance plan
• The patient treated with vitamin K antagonist for over six months
• The patient must have given his/her informed and signed consent
• For adults under guardianship, the legal guardian must have given free and informed consent and signed the consent

Exclusion Criteria:

• The patient is under judicial protection
• The general practitioner in charge of the patient at the EHPAD does not want to participate in the study
• It is impossible to correctly inform the patient, or his/her legal guardian
• The patient, or his/her legal guardian, refuses to sign the consent
• The patient is participating in another interventional study, or has participated in another interventional study within the past three months
• The patient is in an exclusion period determined by a previous study