Evolving Factors in Hospital Safety: A Systematic Review and Meta-Analysis of Hospital Adverse Events

This study aimed to estimate the frequency of hospital adverse events (AEs) and explore the rate of AEs over time, and across and within hospital populations.

Validated search terms were run in MEDLINE and EMBASE; gray literature and references of included studies were also searched. Studies of any design or language providing an estimate of AEs within the hospital were eligible. Studies were excluded if they only provided an estimate for a specific AE, a subgroup of hospital patients or children. Data were abstracted in duplicate using a standardized data abstraction form. Study quality was assessed using the Newcastle-Ottawa Scale. A random-effects meta-analysis estimated the occurrence of hospital AEs, and meta-regression explored the association between hospital AEs, and patient and hospital characteristics.

A total of 45,426 unique references were identified; 1,265 full-texts were reviewed and 94 studies representing 590 million admissions from 25 countries from 1961 to 2014 were included. The incidence of hospital AEs was 8.6 per 100 patient admissions (95% confidence interval [CI], 8.3 to 8.9; I2 = 100%, P < 0.001). Half of the AEs were preventable (52.6%), and a third resulted in moderate/significant harm (39.7%). The most evaluated AEs were surgical AEs, drug-related AEs, and nosocomial infections. The occurrence of AEs increased by year (95% CI, -0.05 to -0.04; P < 0.001) and patient age (95% CI = -0.15 to -0.14; P < 0.001), and varied by country income level and study characteristics. Patient sex, hospital type, hospital service, and geographical location were not associated with AEs.

Hospital AEs are common, and reported rates are increasing in the literature. Given the increase in AEs over time, hospitals should reinvest in improving hospital safety with a focus on interventions targeted toward the more than half of AEs that are preventable.