The characteristics and prognostic factors on initial presentation to healthcare facilities associated with poor outcomes in acute or acute‐on‐chronic digoxin poisoning in Hong Kong

Abstract Background Digoxin is a commonly used cardiovascular drug but has a narrow therapeutic window, and its poisoning could be fatal. Prognostic factors of digoxin poisoning were proposed largely based on the toxicokinetics of digoxin. Higher levels of evidence on this topic were limited. Objective The study aimed to identify patient characteristics and risk factors associated with poor outcomes in acute or acute‐on‐chronic digoxin poisoning and to review the poor outcome rates, the time intervals between acute or acute‐on‐chronic digoxin poisoning and healthcare facility attendances, the overall mortality rate, and antidote usage of digoxin poisoning in Hong Kong. Methods A retrospective cohort study was conducted using data from the Hong Kong Poison Information Centre from 1 January 2008 to 31 December 2022. Included were adult patients with acute or acute‐on‐chronic digoxin poisoning who presented to outpatient facilities. Excluded were individuals under 18 years, pregnant, had incomplete or unrelated medical records. Univariate and multivariable logistic regression analyses were used to identify predictors of poor outcomes. Results During the study period, 57 adult cases of digoxin poisoning were identified for further analysis. Among these patients, 36 (63%) had good outcomes (no effect, minor effect, or moderate effect from the poisoning) while 21 (37%) had poor outcomes (major effect or death), and there were 8 (14%) deaths in total. Multivariable analysis and analysis of the receiver operating characteristic curve revealed that poor outcomes were significantly associated with an initial systolic blood pressure below 123.5 mmHg ( p = 0.034), an initial pulse rate below 59.5 beats per minute ( p = 0.009), and a serum potassium level above 4.64 mmol/L ( p = 0.018). Conclusions In adult patients with acute or acute‐on‐chronic digoxin poisoning, the initial systolic blood pressure, pulse rate, and potassium levels are the most important predictors of poor outcomes upon initial presentation. These findings allow early recognition of patients with poor outcomes for further management.