Hospital-Acquired Pressure Injury: Risk-Adjusted Comparisons in an Integrated Healthcare Delivery System

Abstract

Background: Although healthcare organizations have decreased hospital-acquired pressure injury (HAPI) rates, HAPIs are not eliminated, driving further examination in both nursing and health services research.

Objective: The objective was to describe HAPI incidence, risk factors, and risk-adjusted hospital variation within a California integrated healthcare system.

Methods: Inpatient episodes were included in this retrospective cohort if patients were hospitalized between January 1, 2013, and June 30, 2015. The primary outcome was development of a HAPI over time. Predictors included cited HAPI risk factors in addition to incorporation of a longitudinal comorbidity burden (Comorbidity Point Score, Version 2 [COPS2]), a severity-of-illness score (Laboratory-Based Acute Physiology Score, Version 2 [LAPS2]), and the Braden Scale for Predicting Pressure Ulcer Risk.

Results: Analyses included HAPI inpatient episodes (n = 1661) and non-HAPI episodes (n = 726,605). HAPI incidence was 0.57 per 1,000 patient days (95% CI [0.019, 3.805]) and 0.2% of episodes. A multivariate Cox proportional hazards model showed significant (p < .001) hazard ratios (HRs) for the change from the 25th to the 75th percentile for age (HR = 1.36, 95% CI [1.25, 1.45]), higher COPS2 scores (HR = 1.10, 95% CI [1.04, 1.16]), and higher LAPS2 scores (HR = 1.38, 95% CI [1.28, 1.50]). Female gender, an emergency room admission for a medical reason, and higher Braden scores showed significant protective HRs (HR < 1.00, p < .001). After risk adjustment, significant variation remained among the 35 hospitals.

Discussion: Results prompt the consideration of age, severity of illness (LAPS2), comorbidity indexes (COPS2), and the Braden score as important predictors for HAPI risk. HAPI rates may be low; however, because of significant individual site variation, HAPIs remain an area to explore through both research and quality improvement initiatives.

FIGURE 1

Cumulative incidence plot for hospital-acquired pressure injury hazard over 0–30 days of hospitalization.

FIGURE 2

Hazard ratio graph with 95% confidence intervals based on the multivariate Cox proportional hazards model (Table 4). The admission category of non-ED/surgical (N-ED/S) is the reference group and is not displayed. Admit ED/S = admission from the emergency department and a surgery during the episode; Admit ED/M = admission from the emergency room for a medical reason and did not have surgery during the episode; Admit N-ED/M = admitted directly to the hospital (not through the emergency department) for a medical reason; Full code = designation as a full code for the episode; LAPS2 = the Laboratory-based Acute Physiology Score, Version 2 (This is a score measuring acute physiologic instability during the 72 hours preceding admission—the higher the score, the greater the mortality risk due to acute physiologic derangement.); COPS2 = Comorbidity Point Score, Version 2 (This is a longitudinal score based on 12 months of patient data—the higher the score, the greater the mortality risk due to comorbid illness.); Braden = the lowest Braden score in the first 24 hours since admission (lower Braden scores indicate a greater risk for pressure injury development).

FIGURE 3

Risk-adjusted hospital effect for hospital-acquired pressure injury (HAPI). The x-axis shows individual hospitals, and the y-axis shows the risk-adjusted hospital random effect on the probability of experiencing a HAPI for each hospital (vertical bars). The horizontal lines denote 1 SD marks. The HAPI risk increases by >90% for hospitals with effects above 1 SD.