Changes in compliance with cardiovascular medication after a breast cancer diagnosis: a latent class trajectory analysis using French nationwide data

BACKGROUND: Managing cardiovascular risk is key for breast cancer survivors, many of whom have pre-existing conditions like hypertension and hyperlipidaemia. Research suggests compliance with cardiovascular medication declines after a breast cancer diagnosis. However, these studies rely on population-level averages, which mask patient heterogeneity and longitudinal variations in compliance. This study aimed to identify compliance trajectories with cardiovascular medication around a breast cancer diagnosis and describe associated characteristics. METHODS: Using the French National Health Data System, we constructed a cohort of women diagnosed with incident breast cancer (2016-2020) who received at least 2 cardiovascular drug classes before diagnosis for primary prevention, defined as treatment of cardiovascular risk factors in the absence of established cardiovascular disease. Compliance trajectories were analysed over 3 years using group-based trajectory modelling. RESULTS: Among 35,399 women, 6 trajectories were identified: stable high compliance (49.9%), moderate stable (21.2%), low stable (12.8%), sharp decline post-diagnosis (9.8%), treatment discontinuation post-diagnosis (3.4%), and very low and declining (2.9%). Declining trajectories were associated with higher rates of metastases and chemotherapy. CONCLUSION: This study revealed substantial heterogeneity in compliance responses post-diagnosis. While most women maintained stable compliance, a significant subset experienced sharp declines, likely linked to cancer severity. Early interventions post-diagnosis could reduce cardiovascular risk and improve outcomes.