Determinants of non-adherence to adjuvant endocrine treatment in women with breast cancer: the role of comorbidity

W Wulaningsih,M Lambe,A Wigertz,J Ahlgren,L Holmberg,H Garmo,M Van Hemelrijck,Y Folkvaljon

doi:10.1007/s10549-018-4890-z

Abstract

PurposeTo examine factors associated with non-adherence during 5 years of endocrine treatment, including the possible influence of comorbidity burden and specific medical conditions.MethodsFrom all women diagnosed with stage I–III, ER-positive breast cancer in Stockholm-Gotland, Uppsala–Örebro and Northern Sweden between 2006 and 2009, we included 4645 women who had at least one dispensation of tamoxifen or aromatase inhibitors (AIs) and 5 years of follow-up without distant recurrence. A medical possession ratio of < 80% was used to define non-adherence. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of non-adherence.ResultsDuring follow-up, 977 (21%) women became non-adherents. Non-adherence was associated with greater comorbidity burden assessed by Charlson comorbidity index (CCI) during follow-up (OR 1.43; 95% CI 1.08–1.88 for ≥ 2 additional scores compared to 0), pre-diagnostic HRT use (OR 1.99; 1.58–2.49), not married (OR 1.42; 1.23–1.64), high educational level (OR 1.25; 1.02–1.53 compared to lowest level), and use of symptom-relieving drugs. HER-2 positivity (OR 0.61; 0.45–0.81) and adjuvant chemotherapy (OR 0.42; 0.35–0.52) were associated with lower odds of non-adherence. Similar patterns were observed for the presence of lymph node metastasis, higher tumour grade, and use of AIs compared to tamoxifen. Myocardial infarction and chronic pulmonary disease was suggested as leading conditions associated with non-adherence in women with increasing CCI.ConclusionWe identified subgroups of women with breast cancer at increased risk of non-adherence. Our findings related to comorbidity suggest the importance of focusing on the presence of specific co-existing conditions when monitoring adherence.

Highlights

Adjuvant endocrine treatment (ET) is part of the standard therapy for oestrogen receptor (ER)-positive breast cancers [1]
The Swedish Prescribed Drug Register encompasses prescribed medications dispensed in Swedish pharmacies and includes information on dates of dispensation, number of defined daily doses (DDD) and classification of the drugs based on the Anatomic Therapeutic Chemical (ATC) system
In Swedish women undergoing adjuvant endocrine treatment for ER-positive non-metastatic breast cancer, we found a broad range of factors associated with non-adherence to ET including age, region, increases in comorbidity burden, marital status, educational level, use of hormone replacement therapy (HRT) and symptomrelieving drugs, tumour characteristics, adjuvant chemotherapy and type of ET

Summary

Introduction

Adjuvant endocrine treatment (ET) is part of the standard therapy for oestrogen receptor (ER)-positive breast cancers [1]. Breast Cancer Research and Treatment (2018) 172:167–177 suggested several key determinants, including patient age, out-of-pocket costs, changes of therapy, follow-up and treatment side effects [6, 7]. These studies differed with regard to assessment methods, length of follow-up and factors under study [6, 8] while findings from earlier studies have linked multimorbidity with lower adherence to ET, [9] results from most studies have been based on comorbidities assessed at baseline and did not investigate specific types of co-existing disease or changes in comorbidity burden over time

Objectives

Methods

Results

Discussion

Conclusion