What’s New in the Patient Safety World

January 2013

Bed Alarms Fail the Test



Many hospitals have invested in bed alarm system to help reduce patient falls. The theory behind them is simple: a sensor responds to the weight of the patient in the bed. If the patient attempts to get out of the bed, the sensor detects the reduction in weight/pressure and alarms in the nursing station. But, much to our surprise, such bed alarm systems had never been studied using well-designed scientific methodology to determine whether they truly reduced falls or injuries.


Now a study has demonstrated that an intervention designed to increase bed alarm use in an urban community hospital increased alarm use but had no statistically or clinically significant effect on fall rates, fall-related events or physical restraint use (Shorr 2012). Using a cluster randomized methodology the “intervention” nursing units received education, training and technical support on use of the bed alarm system. The “control” units did have bed alarms but received no training or support on their use. The study population included over 27,000 inpatients in general medical, surgical, and specialty units. Prevalence of alarm use was 64.41 days per 1000 patient-days on intervention units and 1.79 days per 1000 patient-days on control units. But there was no difference in change in fall rates per 1000 patient-days or in the number of patients who fell, injurious fall rates, or the number of patients physically restrained on intervention units compared with control units.


Our only prior column that mentioned bed alarms (June 19, 2007 Patient Safety Tip of the Week “Unintended Consequences of Technological Solutions”) noted a case when a hospital purchased a new alarm system that would send an alarm when the patient got out of bed. It turned out that on some units there were not enough electrical outlets for both the new bed alarms and the nurse call buttons. So a decision was made in some cases to swap out these two devices. You can guess what happened: nursing staff responded to the “out-of-bed” alarm only to find the patient lying on the floor with an injury because he tried to get out of bed after no one responded when he pushed the nurse call button!


Like so many other things in medicine, what sounds good often turns out not to be so good. Unfortunately, because we often adopt interventions without appropriate scrutiny we end up spending much time, money and other resources without reaping the expected benefits.







Shorr RI, Chandler AM, Mion LC, et al. Effects of an Intervention to Increase Bed Alarm Use to Prevent Falls in Hospitalized Patients: A Cluster Randomized Trial. Ann Intern Med 2012; 157(10): 692-699






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