IJCS | Volume 31, Nº4, July / August 2018

390 Borges et al. Adherence score Int J Cardiovasc Sci. 2018;31(4)383-392 Original Article use of medication (higher or lower doses, missing doses), history of invasive or surgical procedures, drug-drug interaction, nutrient-drug interaction (particularly vitamin K), health problems or clinical conditions, other related factors such as considerable psychological distress, weight gain or loss and OAC- related complications. Thus, the score was developed using the variables of several models, classified and compared based on descriptive analysis of the independent variables, as well as interaction tests. Then, a score model for a Brazilian population of patients in OAC-T was developed (Table 3); this was a simple instrument, easily applicable in the clinical setting of OAC-T. Results of the score were presented as odds ratio and respective 95% confidence interval and descriptive analysis. The tests revealed the independent nature of the variables and the impartiality of the event occurrence. Therefore, a score that attributed the same weight for the variables was developed. The proportion of the occurrence of an event will then be calculated by the number of positive variables for adherence and the number of predictive variables established in the model. Simonetti adherence score had a c-statistic of 0.94, indicating satisfactory performance and applicability. Therefore, the score proposed in the present study will contribute to a more accurate evaluation and decision- making process. However, a long-term evaluation of the instrument should be performed in the clinical setting, like any stratification model, in order to evaluate the occurrence of new variables that may affect adherence. Some limitations of the study should be considered. First, since the study was conducted in only one center, the model may not be reproducible in other settings. Second, since the scorewas not applied in an independent population for external validation, the performance of the instrument may not be satisfactory. It is worth pointing out, however, that our next step is to validate the instrument in another group of patients on OAC-T. Despite these limitations, we successfully developed a medication adherence score using a model with good statistical performance. We believe that the score is of public interest and can contribute to the improvement of oral anticoagulation centers. This study aimed to ensure and improve the provision of nursing services to patients on OAC-T in a specialized center, using a specific protocol. Although this characterized a limitation of the study, this would encourage different centers to revise their own protocols and to be informed of how treatment is being performed in other centers. The proposed model of medication adherence score is in conformity with the significant and independent variables identified in the study. This ensures its accessibility and applicability. Using adequate statistical methods, we developed the Simonetti adherence score, and confirmed the hypothesis of this study. Conclusion The medication adherence score here proposed for patients on OAC-T was shown to be an easy-to- use instrument, with high predictive value and good performance. We successfully developed an instrument aimed at measuring and improving adherence of patients to OAC-T bymeans of the proposedmethods and results obtained, confirming the hypothesis of the study. This instrument will help professionals in accurately dealing with and hence improving adherence of patients to OAC-T and consequently improve the quality of life of this population. Author contributions Conception and design of the research: Simonetti SH, Bianchi ERF, Faro ACM. Acquisition of data: Simonetti SH. Analysis and interpretation of the data: Simonetti SH, Bianchi ERF, Faro ACM. Statistical analysis: Simonetti SH. Writing of the manuscript: Simonetti SH, Bianchi ERF, Faro ACM. Critical revision of the manuscript for intellectual content: Simonetti SH, Faro ACM. Supervision / as the major investigador: Simonetti SH. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Study Association This article is part of the thesis of Doctoral submitted by Sérgio Henrique Simonetti, fromUSPNursing School.