Data Collection
Each EMR was reviewed, and the following data were abstracted: (1) patient age; (2) date of first hospital discharge during 2006; (3) final MFS score and subscores recorded during the index hospitalization; (4) date of the first fall requiring acute medical evaluation; (5) severe bleeding associated with the fall; (6) date of the subject’s death; and (7) date of the last recorded follow-up. The occurrence of a postdischarge fall and of fall-associated severe bleeding was determined by review of all hospitalizations, clinic visits, emergency department (ED) visits, outside records scanned into the EMR, and visiting nurse reports. The MFS score was converted to a MMS by subtracting points given for the presence of an IV line during the hospitalization, as such a fall risk would end at discharge.
Endpoints
The primary endpoint for the study was the occurrence of a fall following hospital discharge, resulting in evaluation of the subject in an outpatient clinic or ED within 24 hours. The primary comparison was between subjects aged ≥ 65 years with a MMS ≥ 55 and subjects aged ≥ 65 years with a MMS < 55.
A secondary endpoint was the occurrence of severe bleeding associated with a fall. Severe bleeding was defined as fatal bleeding; and/or symptomatic bleeding in a critical area or organ, such as intracranial, intraspinal, intraocular, retroperitoneal, intra-articular, pericardial, or intramuscular with compartment syndrome; and/or bleeding causing a fall in hemoglobin level of ≥ 2 g/dL or leading to transfusion of ≥ 2 units of whole blood or red blood cells.9
Statistical Analysis
An estimated analyzable sample size (df = 1, α = 0.05, and a critical value for χ2 of 3.841) of 180 subjects was based on CDC age-related fall rates, MFS-related fall rates, and published sensitivity and specificity values of the MFS.7,10,11 An estimated exclusion rate of 25% to 30% based on published rates of AF-related hospital mortality; transient (persisting < 24 hours) AF; patients with AF declining recommended anticoagulation therapy; and hospital admissions lasting < 24 hours (coded as observations) yielded a total estimated study sample size of 240 to 257 subjects.