Stability of the INR in Relation to Personality Traits in Patients On Stable Oral Anticoagulant Therapy.

Abstract 4178

Maintenance of a stable anticoagulation as determined by the international standardized ratio (INR) remains difficult despite increasing knowledge on genetic variations of metabolism and improved therapeutic approaches. We hypothesised that personality traits of patients may influence the stability of the INR, obtained during stable therapy with vitamin-K antagonist (VKA). We assumed that the standard deviation (SD) of the INR over a time period of 6 months represents the stability of the anticoagulant treatment.

Patients (n=28) treated with VKA for more than one year in our outpatient care unit, completed a widely used personality inventory (Freiburger Persönlichkeitsinventar, FPI-R) and a questionnaire referring to general health and quality of life (SF12). Correlations between factors of FPI-R and SF12 with the standard deviation (SD) of the INR were analysed by means of the spearman correlation coefficient.

76% of all INRs of the patients were within the therapeutic range of 2 to 4 and the SDs of the patients INRs ranged from 0.23 to 1.17. The higher the social competence (FPI-R) of a person the lower was the SD of the INRs (p=0.0003). The less calm and relaxed a person felt in the past (SF12), the lower was the SD of the INRs (p=0.013). No other personality dimensions or domains of the SF-12 correlated with the variance of the INRs.

A high social competence and low score of a person feeling calm and relaxed leads to a more stable anticoagulation of patients treated with VKAs. The first finding may relate to subjects with good cooperation and social responsibility resulting in a stable anticoagulant therapy. Patients who feel troubled and worried by higher variations of INR values may cause the second finding. The data suggest that personality traits play a role for reaching a stable INR.