What does this research mean for the field?

The TAAW tool demonstrates excellent internal consistency (Cronbach's alpha = 0.98) and high test–retest reliability (ICC = 0.96) for assessing warfarin adherence in Brazilian patients. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To create and validate a multidimensional tool that measures adherence to warfarin therapy among Brazilian patients.

February 8, 2026Open Access

Development and validation of a tool assessing adherence to warfarin therapy (TAAW) by Brazilian patients

Key Result

The TAAW tool showed excellent reliability (Cronbach's alpha=0.98, ICC=0.96) and validity (Spearman's rho=0.91) in assessing adherence to warfarin therapy in Brazilian patients.

Key Points

To create and validate a multidimensional tool that measures adherence to warfarin therapy among Brazilian patients.
Developed a Tool for Assessing Adherence to Warfarin Therapy (TAAW) covering various related aspects.
Guided by concept mapping, expert assessments, and pre-testing with participants.
Conducted psychometric evaluations including exploratory factor analysis and reliability testing.
Out of 35 initial items, 21 were finalized covering warfarin intake, self-care, and health monitoring.
TAAW showed excellent internal consistency (Cronbach's alpha = 0.98) and high reliability (Intraclass Correlation Coefficient = 0.96).
The tool correlated strongly with therapeutic range time (Spearman's rho = 0.91), confirming its effectiveness in assessing adherence.

Structured PICO

Is the newly developed Tool for Assessing Adherence to Warfarin Therapy (TAAW) a valid and reliable instrument for Brazilian patients?

Population

Brazilian patients on warfarin therapy (pre-testing phase included 30 participants)

Intervention

Tool for Assessing Adherence to Warfarin Therapy (TAAW), a 21-item multidimensional instrument

Outcome

Psychometric validity and reliability of the TAAW tool (including internal consistency, test-retest reliability, and correlation with time in therapeutic range)patient reported

The TAAW is a highly reliable and valid 21-item tool for assessing warfarin adherence in Brazilian patients, correlating strongly with clinical time in therapeutic range.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

Abstract Aim To develop and validate a multidimensional tool to assess adherence to warfarin therapy by Brazilian patients. Methods A Tool for Assessing Adherence to Warfarin Therapy (TAAW) was designed to encompass warfarin intake and other treatment‐related aspects, including causal and effect items of adherence. The development process included: (i) construction of a concept map; (ii) elaboration of a preliminary version; (iii) expert assessment; (iv) semantic analysis through pre‐testing with 30 participants; and (v) psychometric validation, including exploratory factor analysis, internal consistency, test–retest reliability and hypothesis testing. Results Of the 35 initially drafted items, 14 were discarded and 19 modified, resulting in a final version with 21 items distributed across three dimensions: warfarin intake (n = 10), self‐care associated with warfarin use (n = 7) and health monitoring (n = 4). The TAAW tool demonstrated a unidimensional structure, excellent internal consistency (Cronbach's alpha = 0.98), high test–retest reliability (Intraclass Correlation Coefficient = 0.96) and strong correlation with the time in therapeutic range (Spearman's rho = 0.91), confirming its validity and reliability. Conclusion The validated TAAW is a robust instrument for assessing adherence to warfarin therapy in clinical and research settings. Its comprehensive approach allows for the identification of adherence patterns, enabling healthcare professionals to implement targeted interventions and optimize anticoagulation outcomes.