Preventable and mitigable adverse events in cancer care: Measuring risk and harm across the continuum.

BACKGROUND: Patient safety is a critical concern in clinical oncology, but the ability to measure adverse events (AEs) across cancer care is limited by a narrow focus on treatment-related toxicities. The objective of this study was to assess the nature and extent of AEs among cancer patients across inpatient and outpatient settings.
METHODS: This was a retrospective cohort study of 400 adult patients selected by stratified random sampling who had breast (n = 128), colorectal (n = 136), or lung cancer (n = 136) treated at a comprehensive cancer center in 2012. Candidate AEs, or injuries due to medical care, were identified by trained nurse reviewers over the course of 1 year from medical records and safety-reporting databases. Physicians determined the AE harm severity and the likelihood of preventability and harm mitigation.
RESULTS: The 400-patient sample represented 133,358 days of follow-up. Three hundred four AEs were identified for an overall rate of 2.3 events per 1000 patient days (91.2 per 1000 inpatient days and 0.9 per 1000 outpatient days). Thirty-four percent of the patients had 1 or more AEs (95% confidence interval, 29%-39%), and 16% of the patients had 1 or more preventable or mitigable AEs (95% confidence interval, 13%-20%). The AE rate for patients with breast cancer was lower than the rate for patients with colorectal or lung cancer (P ≤ .001). The preventable or mitigable AE rate was 0.9 per 1000 patient days. Six percent of AEs and 4% of preventable AEs resulted in serious harm. Examples included lymphedema, abscess, and renal failure.
CONCLUSIONS: A heavy burden of AEs, including preventable or mitigable events, has been identified. Future research should examine risk factors and improvement strategies for reducing their burden. Cancer 2017;123:4728-4736.