Performance of a Commonly Used Pressure Injury Risk Model Under Changing Incidence

Background: Hospital-acquired pressure injuries (HAPIs) cause patient harm and increase health care costs. We sought to evaluate the performance of the Braden QD Scale-associated changes in HAPI incidence. Methods: Using electronic health records data from a quaternary children's hospital, we evaluated the association between Braden QD scores and patient risk of HAPI. We analyzed how this relationship changed during a hospitalwide quality HAPI reduction initiative. Results: Of 23,532 unique patients, 108 (0.46%, 95% confidence interval [CI] = 0.38%-0.55%) experienced a HAPI. Every 1-point increase in the Braden QD score was associated with a 41% increase in the patient's odds of developing a HAPI (odds ratio [OR] = 1.41, 95% CI = 1.36-1.46, p < 0.001). HAPI incidence declined significantly following implementation of a HAPI-reduction initiative (beta = -0.09, 95% CI = -0.11 - -0.07, p < 0.001), as did Braden QD positive predictive value (beta = -0.29, 95% CI = -0.44 - -0.14, p < 0.001) and specificity (beta = -0.28, 95% CI = -0.43 - -0.14, p < 0.001), while sensitivity (beta = 0.93, 95% CI = 0.30-1.75, p = 0.01) and the concordance statistic (beta = 0.18, 95% CI = 0.15-0.21, p < 0.001) increased significantly. Conclusion: Decreases in HAPI incidence following a quality improvement initiative were associated with (1) significant deterioration in threshold-dependent performance measures such as specificity and precision and (2) significant improvements in threshold-independent performance measures such as the concordance statistic. The performance of the Braden QD Scale is more stable as a tool that continuously measures risk than as a prediction tool.