Staffing and Patient-related Factors Affecting in-patient Fall-related Injury in a Psychiatric Hospital: A 5-year Retrospective Matched Case-control Study

Background: Incidence of fall-related injury of psychiatric in-patients was more frequent and the severity greater than in general units. Also, the risk factors were different and more complicated. The aim of this study was to investigate the staffing factors and patient-related factors that increase the likelihood of fall-related injury among psychiatric in-patients. Methods: A five-year retrospective matched case-control study was used to select cases of in-patient fall which were reported to the hospital risk management system. The total sample consisted of 240 patients. Conditional logistic regression was used to analyze the data. Results: Of the eighty fall-related injuries, 86.3% resulted in temporary harm and required intervention. The multivariate model showed that the three strongest predictors were having an acute psychotic condition (adjusted matched odds ratio (aOR)=5.40; 95%CI 4.22-6.90; p< 0.001), proportion of nurse staffing equal to nurse assistants (aOR=5.52; 95%CI 2.64-11.55; p<0.001), and taking atypical antipsychotic drug (aOR=3.92; 95%CI 3.22-4.76; p<0.001). In addition, the following factors all increased the risk of fall-related injury significantly: using more than four drugs, having a medical illness, having comorbid psychiatric disorder, taking lithium, anti-Parkinson, benzodiazepine, and anti-convulsant drugs. Regarding staffing factors, patient numbers in the unit of 25-50, and ≥ 51, also significantly increased risk for fall than having patient numbers of 25 or fewer. Nurse to patient ratios of 1:16-30, and 1: 31-45 significantly increased the fall risk compared to ratios of 1: 1-15. Conclusions: The risk factors found are expected to be of use for assessing fall risk and managing staff workload in psychiatric units.