Background: The Drug Burden Index (DBI) is a pharmacotherapy risk assessment tool explored to evaluate its association with unplanned hospital-related outcomes.
Objective: To evaluate the DBI association with unplanned hospital readmissions, develop a prediction model for unplanned readmissions. To investigate DBI association with length of hospital stay (LOS).
Setting: Unplanned readmission data were collected for 1000 adult hospitalized patients at Antrim Area Hospital in Northern Ireland.
Method: The study was designed as a retrospective analysis. Logistic regression models were developed to determine the prediction power. Discriminative ability testing was carried out using the Receiver Operating Characteristic (ROC) curve. Youden's index formula was used to detect the cut-off points. Analysis of covariance (ANCOVA) was performed to determine whether LOS differed based on the DBI score. Finally, negative binomial regression was used to predict LOS based on DBI.
Results: Of the 1000 patient records, 43% were females, and a total of 885 (88.5%) were exposed to sedative and anticholinergic medications (DBI>0). Readmission rates at 7, 14, 30 and 90 days were 5.4%, 9.0%, 15.0% and 28.8% respectively. The odds ratio (OR) of readmission within seven days for patients with DBI>1 was 3.42 times higher than those who had their DBI=0 (OR= 3.42, 95% CI: 1.6–7.3; P= 0.001). The DBI category significantly predicts 7-day readmission (P=0.002), the area under the curve for the ROC curve was 0.65 (95% CI: 0.58 - 0.71; P<0.001). For 14-day readmissions, patients with a DBI >1, compared with DBI=0, had a reported higher Odds Ratio (OR = 2.19, 95% CI: 1.1– 4.4; P= 0.025). However, the DBI category prediction power for 14-day readmission was not significant (P=0.069). DBI failed to show an association with 30- and 90-day readmissions. The adjusted estimated marginal difference for LOS of patients with DBI>1 vs. DBI=0 was 2.7 (95%CI: 0.89 – 4.5; P=0.003).
Conclusion: DBI was a statistically significant tool to predict 7-days unplanned readmission. DBI was not a statistically significant predictor for readmission over longer periods. Higher DBI was associated with a longer LOS.
Impact on Practice Statements: Readmission within seven days of a patient's discharge can be predicted by the DBI, and a longer hospital stay was also associated with higher DBI. Accordingly, the hospital teams can consider reporting DBI scores and performing tailored discharge plans for patients who are at risk for seven days of unplanned readmission.
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