Adherence evaluation of endocrine treatment in breast cancer: methodological aspects

BMC Cancer. 2012 Oct 15;12:474. doi: 10.1186/1471-2407-12-474.

Abstract

Background: Current studies on adherence to endocrine therapy in breast cancer patients suffer from methodological limitations due to a lack of well-validated methods for assessing adherence. There is no gold standard for measuring adherence. The aim of our study was to compare four different approaches for evaluating adherence to anastrozole therapy for breast cancer with regard to concordance between methods.

Methods: Outpatients with early breast cancer treated with anastrozole completed the multi-method assessment of adherence. We implemented a self-report scale (the Simplified Medication Adherence Questionnaire), physician- ratings, refill records and determination of anastrozole serum concentration.

Results: Comparison of the four approaches using Spearman rank correlation revealed poor concordance across all methods reflecting weak correlations of 0.2-0.4. Considering this data incomparability across methods, we still observed high adherence rates of 78%-98% across measures.

Conclusion: Our findings contribute to the growing body of knowledge on the impact that methodological aspects exert on the results of adherence measurement in breast cancer patients receiving endocrine treatment. Our findings suggest that the development and validation of instruments specific to patients receiving endocrine agents is imperative in order to arrive at a more accurate assessment and to subsequently obtain more precise estimates of adherence rates in this patient population.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Anastrozole
  • Antineoplastic Agents, Hormonal / blood
  • Antineoplastic Agents, Hormonal / therapeutic use
  • Breast Neoplasms / drug therapy*
  • Data Collection / methods
  • Data Collection / standards
  • Data Collection / statistics & numerical data
  • Female
  • Humans
  • Medication Adherence / statistics & numerical data*
  • Middle Aged
  • Nitriles / blood
  • Nitriles / therapeutic use*
  • Reproducibility of Results
  • Surveys and Questionnaires / standards*
  • Time Factors
  • Triazoles / blood
  • Triazoles / therapeutic use*

Substances

  • Antineoplastic Agents, Hormonal
  • Nitriles
  • Triazoles
  • Anastrozole