Point‐of‐care blood glucose measurement errors overestimate hypoglycaemia rates in critically ill patients

Background Hypoglycaemia is associated with morbidity and mortality in critically ill patients, and many hospitals have programmes to minimize hypoglycaemia rates. Recent studies have established the hypoglycaemic patient‐day as a key metric and have published benchmark inpatient hypoglycaemia rates on the basis of point‐of‐care blood glucose data even though these values are prone to measurement errors. Methods A retrospective, cohort study including all patients admitted to Harborview Medical Center Intensive Care Units (ICUs) during 2010 and 2011 was conducted to evaluate a quality improvement programme to reduce inappropriate documentation of point‐of‐care blood glucose measurement errors. Laboratory Medicine point‐of‐care blood glucose data and patient charts were reviewed to evaluate all episodes of hypoglycaemia. Results A quality improvement intervention decreased measurement errors from 31% of hypoglycaemic (<70 mg/dL) patient‐days in 2010 to 14% in 2011 ( p  < 0.001) and decreased the observed hypoglycaemia rate from 4.3% of ICU patient‐days to 3.4% ( p  < 0.001). Hypoglycaemic events were frequently recurrent or prolonged (~40%), and these events are not identified by the hypoglycaemic patient‐day metric, which also may be confounded by a large number of very low risk or minimally monitored patient‐days. Conclusions Documentation of point‐of‐care blood glucose measurement errors likely overestimates ICU hypoglycaemia rates and can be reduced by a quality improvement effort. The currently used hypoglycaemic patient‐day metric does not evaluate recurrent or prolonged events that may be more likely to cause patient harm. The monitored patient‐day as currently defined may not be the optimal denominator to determine inpatient hypoglycaemic risk. Copyright © 2014 John Wiley & Sons, Ltd.