A Retrospective Analysis of Pressure Ulcer Incidence and Modified Braden Scale Score Risk Classifications
The Braden Scale is the most widely used pressure ulcer risk assessment in the world, but the currently used 5 risk classification groups do not accurately discriminate among their risk categories. To optimize risk classification based on Braden Scale scores, a retrospective analysis of all consecutively admitted patients in an acute care facility who were at risk for pressure ulcer development was performed between January 2013 and December 2013.
Predicted pressure ulcer incidence first was calculated by logistic regression model based on original Braden score. Risk classification then was modified based on the predicted pressure ulcer incidence and compared between different risk categories in the modified (3-group) classification and the traditional (5-group) classification using chi-square test. Two thousand, six hundred, twenty-five (2,625) patients (mean age 59.8 ± 16.5, range 1 month to 98 years, 1,601 of whom were men) were included in the study; 81 patients (3.1%) developed a pressure ulcer. The predicted pressure ulcer incidence ranged from 0.1% to 49.7%. When the predicted pressure ulcer incidence was >10.0% (high risk), the corresponding Braden scores were <11; when the predicted incidence ranged from 1.0% to 10.0% (moderate risk), the corresponding Braden scores ranged from 12 to 16; and when the predicted incidence was <1.0% (mild risk), the corresponding Braden scores were >17. In the modified classification, observed pressure ulcer incidence was significantly different between each of the 3 risk categories (P <0.05). However, in the traditional classification, the observed incidence was not significantly different between the high-risk category and moderate-risk category (P >0.05) and between the mild-risk category and no-risk category (P >0.05). If future studies confirm the validity of these findings, pressure ulcer prevention protocols of care based on Braden Scale scores can be simplified.
The Braden Scale is an assessment tool for pressure ulcer risk that was developed in 1987.1,2 A series of studies subsequently showed the Braden Scale is both reliable and valid, with correlation coefficients (ICC) of ~0.9 for reliability3 and the area under curves (AUC) for receiver operating characteristic (ROC) of 0.707 for validity.4 A recent systematic review5 compared the reliability and validity of the Braden Scale, the Norton Scale, and the Waterlow Scale and concluded the Braden Scale demonstrated the best reliability and validity indicators in a variety of settings and was a better predictor of pressure ulcers than nurse judgment. These findings underscore why the Braden Scale is the most widely used pressure ulcer risk assessment scale in the world.
The Braden Scale is composed of 6 subscales: sensory perception, skin moisture, activity, mobility, nutrition, and friction and shear; Braden sum scores range from 6 to 23.1,2 The first study of the predictive validity1,2 of the Braden Scale determined a total score of 16 resulted in the best balance between sensitivity and specificity; known as the cut-off point, this value represents the point at which pressure ulcer risk begins. Although Braden and Bergstrom6 initially proposed 3 general risk categories based on total scores (mild [15–16], moderate [12–14], and severe [<11]), the version used by Braden6 in 2002 divides pressure ulcer risk into 5 categories, with scores of 6–9 indicating very high risk, 10–12 high risk, 13–14 as moderate risk, 15–18 at risk, and 19–23 no risk.7
The purpose of this study was to assess the feasibility of redefining the risk classification of Braden Scale.
Patient population. A retrospective analysis was conducted between January 2013 and December 2013 among consecutive patients admitted to a 3,000-bed teaching hospital. Inclusion criteria stipulated patients be at risk for pressure ulcer on admission or when they entered the intensive care unit (ICU) and were recognized to be at risk (ie, patients with spinal cord injury, patients undergoing cardiac surgery, patients experiencing a long operation time). Patients were excluded if they were admitted with a pressure ulcer or died before a pressure ulcer developed.
The study was approved by the medical ethics committee of the authors’ hospital. Patient confidentiality was maintained.
Data collection. Data were retrospectively collected from electronic and paper medical records and recorded in an Excel form predesigned by 2 of the authors. The form included 3 parts: 1) demographic characteristics, which included patients’ age, gender, weight, and disease; 2) Braden scores, including item scores; and 3) pressure ulcer information (pressure ulcer occurrence [yes or no], ulcer severity determined by National Pressure Ulcer Advisory Panel7 [NPUAP] classification system,7 number of the ulcers, anatomical location, and outcomes). Microsoft Office Excel was used to collect the data. All data were collected by a nurse experienced in pressure ulcer care and verified by another nurse.
Statistical analysis. Measurement data were described as mean ± standard deviation. A logistic regression model (Logit [P] =-0.425 x Braden Scale + 2.538) was used to predict pressure ulcer risk using only Braden score. Using this model, the predicted incidence was calculated. The risk classification of the Braden Scale then was modified based on the predicted incidence. The observed pressure ulcer incidence was compared between different risk categories in the modified classification and the traditional classification by chi-square test; odds ratios (OR) with 95% confidence intervals (CI) also were calculated. Statistical analyses were performed using IBM SPSS software (version 19.0, Chicago, IL).
Patient characteristics. Two thousand, six hundred, twenty-five (2,625) patients (mean age 59.8 ± 16.5 years, range 1 month to 98 years; 1,601 men [~61%]) were included in the study. The patients came from 7 clinical departments: neurosurgery, ICU, orthopedics, neurology, respiratory medicine, spine surgery, and cardiothoracic surgery. Mean traditional Braden score was 15.3 ± 2.3 (range 6–22) (see Figure 1).
Pressure ulcer incidence. Among the 2,625 patients, 81 developed a pressure ulcer for an overall incidence of 3.1% (95% CI 2.5%–3.8%). Among the 81 patients with a pressure ulcer, 23 (28.4%) developed a Stage I pressure ulcer, 47 (58.0%) developed a Stage II, and 2 developed a Stage III (2.4%); 9 (11.1%) developed more than one pressure ulcer (6 had a Stage I and a Stage II; 3 had a Stage II and Stage III). The most common locations for pressure ulcers were the sacrum, coccyx, heels, and ischial tuberosities.
Predicted pressure ulcer incidence. The logistic regression model for the Braden Scale predicting pressure ulcer incidence is listed in Table 1. According to logistic regression, the predicted pressure ulcer incidence for Braden scores 6 to 22 was 49.7%, 39.2%, 29.7%, 21.6%, 15.3%, 10.5%, 7.2%, 4.8%, 3.2%, 2.1%, 1.4%, 0.9%, 0.6%, 0.4%, 0.3%, 0.2%, and 0.1%, respectively (see Table 2).
Modified risk classification. When the predicted pressure ulcer incidence was >10.0%, the corresponding Braden Scale scores were <11; when the predicted incidence ranged from 1.0% to 10.0%, the corresponding Braden Scale scores ranged from 12 to 16; and when the predicted incidence was <1.0%, the corresponding Braden Scale scores were >17 (see Table 2). Therefore, the authors defined Braden Scale scores ≤11 as high risk, 12–16 as moderate risk, and ≥17 as mild risk.
Comparison of different risk categories. In the modified classification, the observed pressure ulcer incidences were significantly different among the 3 risk categories (P <0.05). However, in the traditional classification, the observed incidences were not significantly different between the high-risk category and the moderate-risk category (P >0.05) and between mild-risk category and no-risk category (P >0.05) (see Table 3 and Figure 2).
In this study, predicted pressure ulcer incidence was used to define risk classification. Using the modified classification, the observed pressure ulcer incidence was significantly different between the 3 risk categories, suggesting the modified classification is valid and clearly distinguishes the different incidence in 3 risk levels. However, using the traditional risk classification, the observed incidence was not significantly different between the high-risk category and moderate-risk category (P >0.05) and between the mild-risk category and no-risk category (P >0.05). Based on these study results, it appears separating the high-risk category from the moderate-risk category and separating the mild-risk category from the no-risk category may be unnecessary.
Initially, Braden and Bergstrom8 proposed a 3-category scale: mild risk (15–16), moderate risk (12–14), and severe risk (< 11). Their initial categories closely match the current findings.
Cordrey9 developed pressure ulcer prevention interventions based on Braden Scale risk level. When at risk (15–18), patients should use a cushion on a chair when sitting, limit sitting time to a maximum of 2 hours if the patient is unable to reposition him/herself, use a draw sheet or mechanical lift to move patient, and limit friction and shear. When at moderate risk (13–14), patients should use positioning aids as needed, be checked frequently if incontinent, limit sitting time to 1 hour or less, and have prealbumin levels checked every 4 days. When at high risk (10–12), patients should utilize passive range of motion for all extremities. When at very high risk (5–9), patients should use a product such as Flexicare Eclipse (Hill-Rom, Batesville, IN). However, these preventive interventions are complex and difficult to remember, and their effectiveness has not been confirmed in clinical studies. In the modified risk classification discussed herein, pressure ulcer risk is classified according to 3 levels, simplifying prevention interventions strategies (see Table 4).
Another reason to reconsider traditional classification is scores of 19–23 were classified as no risk. However, in the current study, the actual observed pressure ulcer incidence among patients with that risk score was 1.4% (95% CI: 0.03%-7.9%) (ie, patients were still at risk). Thus, the current authors believe a score of 19–23 should not be regarded as no risk.
According to research,10-13 pressure ulcer incidence ranges from 1% to 50% and varies greatly among medical centers. In the current study, pressure ulcer incidence was 3.1%. The modified risk classification was based on the predicted pressure ulcer incidence, which may or may not be different in other medical centers.
This was a retrospective study with the inherent limitations related to patient record accuracy and completeness. In addition, patients from only 1 medical center were included and the sample size was too small to analyze scores by ulcer stage. The results of this study should be confirmed in additional prospective multicenter studies.
Based on the findings, the risk classification of patients using Braden Scale scores should comprise only 3 levels: high risk, with a total score ≤11; moderate risk, with a total score of 12 to 16; and mild risk, with a total score ≥17. This 3-level risk categorization may be more convenient and feasible in clinical practice.
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Potential Conflicts of Interest: This work was supported by the Nantong Municipal Science and Technology Bureau (grant BK2013014).