Effect of comorbidity and multimorbidity on adherence to follow-up recommendations among long-term breast cancer survivors.

Objectives: To study the impact of comorbidities, multimorbidity, and multimorbidity clusters on adherence to recommended follow-up guidelines among long-term breast cancer survivors.

Study Design: Retrospective cohort study based on 2078 women diagnosed with breast cancer from 2000 to 2006 and followed up from 2012 to 2016.

Main Outcome Measures: Adherence to breast cancer follow-up recommendations (annual medical visit and imaging) was determined. Comorbidities were classified as acute/chronic. Multimorbidity was defined as the presence of two or more chronic comorbidities aside from breast cancer. Five multimorbidity clusters were considered. Multivariate logistic regression models were fitted to determine the relationship between adherence to recommendations and the presence of comorbidities and multimorbidity, considering both sociodemographic and clinical characteristics.

Results: Overall adherence to recommendations was 79.5 %. Adherence was lower among long-term breast cancer survivors with no comorbidities (75.8 %). Among multimorbidity clusters, adherence was highest in the anxiety and fractures cluster (84.3 %) and was lowest in the musculoskeletal and cardiovascular cluster (76.4 %). In adjusted multivariate models, multimorbidity was associated with higher levels of adherence (OR = 1.52 95 %CI 1.16-1.99), and adherence was highest in the metabolic and degenerative cluster (OR = 2.2 95 %CI 1.4-3.5).

Conclusion: Adherence to follow-up recommendations was higher among long-term breast cancer survivors with multimorbidity than among those without. Adherence also differed by multimorbidity cluster. These results suggest suboptimal adherence to the current follow-up recommendations in certain groups, suggesting the need to adapt clinical practice guidelines to reflect patients' comorbidities and different characteristics.