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A Retrospective, Nonrandomized, Before-and-After Study of the Effect of Linens Constructed of Synthetic Silk-like Fabric on Pressure Ulcer Incidence
Abstract
A new, synthetic, silk-like fabric was developed for the purpose of providing bedding and patient gowns that manage moisture, friction, and shear when used between the patient and the healthcare support surface that may affect the development of pressure ulcers (PUs). A retrospective study was conducted to compare the incidence of hospital-acquired PUs in patients admitted to Telemetry, Urology, and Intensive Care Units before and after hospital linens were changed from standard to the synthetic (intervention) linens.
Patient medical record data were abstracted for a period 12 weeks before (control) and 12 weeks following the linen change (intervention). Patient demographic information, Braden Risk Scale score, and PU status and stage were abstracted for a total of 659 patients in the control and 768 patients in the intervention groups. No significant differences in patient weight, age, gender distribution, PU risk (Braden scale scores), or proportion of PUs on admission between groups were found. The most common comorbidity was hypertension (n = 981, 68.7%). On admission, the percentage of patients with PUs in the control and intervention groups was 9.9% (s = 0.3) and 8.7% (s = 0.3), respectively (P = 0.23). Average length of stay was 5.6 days in the control and 5.2 days in the intervention groups (P = 0.08). Sixty-eight (68) of 659 patients (10.3%) in the control and 19 out of 768 patients in the intervention group (2.5%) developed one or more PUs (P <0.001) for an incidence of 11.5% in the control and 3.1% in the intervention group. At discharge, 136 PUs were present in the control and 64 were present in the intervention group (P <0.001). The significant differences in the incidence of hospital-acquired PUs between the two groups suggest that linen type affects PU risk. Additional controlled clinical studies in high-risk patient populations are warranted.
Potential Conflicts of Interest: Ms. McPhail and Dr. Montgomery are employees of Precision Fabrics Group, Inc, Greensboro, NC.
Introduction
Healthcare bed linens and patient gowns come into intimate contact with patients treated in a hospital setting. Hospital bed linens and patient gowns are typically made from cotton-blend fabrics that are inherently deficient in keeping patients’ skin dry and in minimizing skin friction and shear.1-3 Investigating the role of healthcare textile materials in the formation and prevention of pressure ulcers in a retrospective study of the medical records of 22 residents in a long-term care (LTC) facility, Zhong et al1 found that immobility contributed to prolonged interaction between the skin and bedding fabrics, producing correlations between different fabric surfaces and the incidence of pressure ulcers. In a biomechanical study of healthcare bed linens and underpads, Biesecker et al2 determined the coefficient of friction of wet cotton bedding was almost two times greater than dry bedding. In a separate biomechanical study, Pryczynska et al3 highlighted the value of synthetic healthcare bed linens in reducing the effects of moisture, friction, and shear on bedbound patients. The ability to rapidly wick moisture, transport moisture vapor, and dry quickly are important factors in helping fragile skin stay dry and minimizing maceration.1,2 In their overview of moisture-associated skin damage, Gray et al4 described how moisture from perspiration, incontinence, or wound exudate increases friction and shear forces on the skin, which weakens the intercellular bonds in the epidermal layers, causing maceration and epidermal ulceration. As demonstrated in a biomechanical study5 of interface-pressure distribution between various fabrics and a skin-simulating material, friction, the adherent force resisting shearing of the skin, has been shown to result in abraded areas of the dermis, as when patients move or are moved across the coarse surface of a cotton bed sheet.
A new synthetic silk-like fabric technology (DermaTherapy®, Precision Fabrics Group, Inc, Greensboro, NC) was developed for the purpose of providing bedding and patient gowns that are cleaner, drier, and smoother than conventional cotton-blend healthcare fabrics. Continuous-filament yarns are woven to produce a silk-like fabric that provides a smooth interface that may help minimize irritation and abrasion of fragile skin. To provide a quick-drying interface between the patient and the support surface, much like performance athletic apparel, very fine filaments within the continuous-filament yarns create micro-channels that are designed to wick moisture away and dry the bedding and skin more quickly than cotton fabrics.6
A 6-month prospective, nonrandomized, controlled trial7 compared the new synthetic silk-like fabric to standard cotton hospital linens in two groups of patients. The first group involved 307 Medical Renal Unit patients at risk for developing pressure ulcers. The incidence of hospital-acquired pressure ulcers was significantly lower (P <0.05) in the intervention (4.6%) than in the control group (12.3%). The second group comprised 275 patients in a Surgical Intensive Care Unit (ICU) who were followed for 8 weeks. The incidence of new pressure ulcers was 7.5% in the regular hospital linen (control) and 0% in the silk-like fabric (intervention) group (P = 0.01). The results of this study were encouraging and warranted additional research in other patient populations at risk for pressure ulcer development.
The purpose of this retrospective study was to compare the incidence of hospital-acquired pressure ulcers in patients admitted to Telemetry, Urology, and ICU before and after hospital linens were changed from standard to silk-like linens. 
Methods and Procedures
A retrospective, before-and-after comparative study was conducted at the 175-bed Wesley Long Hospital, Greensboro, NC from December 2010 to May 2011. On March 5, 2011, the entire Wesley Long Hospital converted from conventional cotton-blend linens, underpads, and gowns to the silk-like bed linens, underpads, and patient gowns. This date was used to retrospectively compare the development of pressure ulcers in Telemetry, Urology, and ICUs (study units) before and after the conversion. As a result of the experiences and results from the prior Surgical ICU study,7 no informed consent was obtained from patients in this study. Investigational Review Board (IRB) approval for the study was obtained from the 17-member Moses Cone Health System IRB.
Available research and statistical calculations suggested the estimated appropriate sample size at 80% power was 174 subjects per group, or a total of 348 patients.8,9
Methodology. The study units were chosen because they were populated by patients at risk for developing pressure ulcers. The study periods for the control and intervention groups were 12 weeks each for a total of 24 weeks. Using convenience sampling methods, all data were collected retrospectively from patient medical records during the period December 1, 2010 through February 28, 2011 for the control and March 7, 2011 through May 30, 2011 for the intervention group.
Inclusion/exclusion criteria. Data from all patients admitted or transferred to the study units during the study periods qualified for abstraction if their length of stay was 48 hours or more. Data from patients assigned to highly specialized beds that required proprietary coverings, or no bed coverings, by bed manufacturers were excluded from the trial, as were data from patients whose stay on the study units overlapped the conversion date. Patients included in the study data were either on the control or intervention linens for their entire stay in the hospital.
Products. Control linens included a conventional, usual-care hospital flat top sheet, fitted bottom sheet, pillowcase, reusable underpad, and patient gown, all made with cotton-blend fabrics. Intervention linens included a flat top sheet, fitted bottom sheet, pillowcase, reusable underpad, and patient gown, all made with the new synthetic silk-like fabric. The intervention underpad was identical to the control underpad with the exception of the top surface fabric (the surface fabric — the layer closest to the patient’s skin — was comprised of the silk-like fabric. The inner “soaker” layer and moisture barrier used in the intervention underpad were the same as used in the control underpad). All underpads were reusable.
Care protocol. All patients received standard care appropriate for their medical needs, including positioning, ongoing management for nutritional stability,10 moist wound dressings for new or existing ulcers, and incontinence management. Standard care also included a daily skin assessment by the nursing staff to determine the presence and stage of the pressure ulcer. If a patient was admitted with a pressure ulcer, it was documented and staged per National Pressure Ulcer Advisory Panel (NPUAP) guidelines11 by staff nurses who are educated annually on assessment and staging of pressure ulcers and use of the Braden Scale.12 Data were collected for skin issues identified as Stage I through Stage IV pressure ulcers, unstageable ulcers, and deep tissue injury (DTI). Daily skin assessment results were recorded per standard hospital protocols.
Data abstraction. Computerized case report forms were used to collect retrospective information for each pressure ulcer, including the wound stage.
Information from patient records was abstracted and entered into a Microsoft Access data collection tool by a study nurse (RN). Information collected included patient demographic data (weight, age, gender, and medical diagnosis), patient comorbidities (hypertension, pulmonary, diabetes, atherosclerosis, neoplasm, heart failure, renal failure, dementia, chronic kidney disease, cerebral vascular accident [CVA], myocardial infarction, infectious disease, drugs/alcohol, thrombophlebitis, pain, asthma, osteoporosis, and peripheral vascular disease), albumin level, and Braden Scale total and subscores. If a pressure ulcer was present on admission, that information and the ulcer stage also were abstracted.12 No attempt was made to segregate patient data by unit type.
Follow-up variables abstracted included admission and discharge date (number of days in unit), and whether the patient developed a pressure ulcer and ulcer stage.
Data storage. Information that might identify the patient was not included. Two files were used to de-identify patient criteria. The first file included the patient’s medical record number and was linked to the subjects’ study identification number. The Microsoft Excel file, linking patient medical record number and participant study identification number, was maintained in a secure location within the Cone Health System, accessible only to authorized individuals. A second separate file, which involved the Microsoft Access data collection tool, was linked only to participant study identification number. The second file including only de-identified patient data also was stored in a secure location accessible only to the study’s principal and associate investigators.
Data analysis. The primary endpoint was the incidence rate of hospital-acquired pressure ulcers. Descriptive statistics were used to summarize all demographic, comorbidity, and outcome variables, including number of hospital-acquired and present-on-admission pressure ulcers. Control and intervention groups were compared using the t-test statistical method assuming equal variances.13 In this study, the unpaired t-test was applied to find the difference between the means of sample variables of the two independent samples. A test of statistical significance was derived and compared with a set of t-distribution tables to see whether the null hypothesis should be rejected or not, the probability of which is quantified by the calculation of a P value. Statistical significance was indicated when P <0.05 — ie, there is a 95% or greater chance the differences in the means, or averages, were not due to chance. Statistical calculations were performed using StatPlus® Professional Software v2009 (AnalystSoft, Inc, Alexandria, VA).
Results
Data were abstracted from a total of 1,427 patients, 659 (297 men, 362 women) in the control and 768 (330 men, 438 women) (P = 0.20) in the intervention group. The study was sufficiently sized to detect clinically important differences in endpoints. On admission, with the exception of age, no significant differences in demographic variables (weight, age, and albumin level) between the two groups were observed. The average age of the control and intervention groups was 69.5 (s = 33.5) and 66.4 (s = 17.0) years, respectively (P = 0.01) and average weight was 81.1 Kg (s = 25.3) and 80.4 Kg (s = 24.5), respectively (P = 0.31). On admission, average albumin levels in the control and intervention groups were 3.02 g/dL (s = 0.6) and 3.03 g/dL (s = 0.6), respectively (P = 0.41) (see Table 1).
The majority of patients had several comorbidities, including hypertension (981, 68.7%), pulmonary disease (534, 37.4%), diabetes (515, 36.1%), neoplasm (406, 28.5%), and atherosclerosis (368, 25.8%), but few significant differences between patients in the control and intervention groups were observed (see Table 2). Atherosclerosis, renal failure, and dementia were more common in the control group, whereas hypertension and infectious disease were more common in the intervention group. Differences in the overall Braden Scale score and Braden subscales between control and intervention group patients were small (see Table 3) and significantly different for the Activity subscale only. The average total Braden scores for the control and intervention groups at admission were 17.3 (s = 3.0) and 17.1 (s = 2.9), respectively (P = 0.10) (see Table 3).
On admission, the percentage of patients with pressure ulcers in the control and intervention groups was 9.9% (s = 0.3) and 8.7% (s = 0.3), respectively (P = 0.23) (see Table 4). A total of 65 control patients were admitted with 90 pressure ulcers (9.9%), compared to a total of 67 intervention patients admitted with 80 pressure ulcers (8.7% of patients) (P = 0.23) (see Table 4). During the study, 68 out of 659 patients (10.3%, s = 0.3) in the control and 19 out of 768 patients in the intervention group (2.5%, s = 0.2) developed a pressure ulcer (P <0.001) during an average length of stay of 5.56 days (s = 4.6) for control and 5.21 days (s = 4.1) for intervention patients (P = 0.08). Thirty-seven patients (37, 5.6%) in the control and 18 patients (2.3%) in the intervention group developed a Stage I pressure ulcer (P <0.001). Thirty-nine (39) patients (5.9%) in the control and six (6) patients (0.8%) in the intervention group developed a Stage II or greater pressure ulcer (P < 0.001) for a total incidence of 11.5% in control and 3.1% in the intervention group. The average number of pressure ulcers per patient was 0.137 (s = 0.5) on admission and 0.206 (s = 0.6) on discharge in the control group (P = 0.01). The average number of pressure ulcers per patient in the intervention group was 0.106 (s = 0.4) on admission and 0.083 (s = 0.3) at discharge (P = 0.11) The average number of new pressure ulcers per patient was 0.134 (s = 0.4) in the control and 0.025 (s = 0.2) in the intervention group (P <0.001). At discharge, 13.4% (s = 0.3) of control and 6.8% (s= 0.3) of intervention patients (P <0.001) had an ulcer (see Table 4).
No adverse effects or reactions related to the use of the intervention products were reported during the study.
Discussion
Prior published studies involving patients in acute care hospitals have determined the overall incidence of pressure ulcers can range from 0.9% to 25.0%. On the low end of the range, in a retrospective study of adult medical-surgical and critical-care patients admitted to a 543-bed facility over a year’s time, including routine quality control reports on patients with facility-acquired pressure ulcers, Jackson14 reported an overall pressure ulcer incidence of 368 in 41,840 admissions, or 0.9%. Patients studied by Jackson were, on average, 62 years in age and 60%/40% male/female. All pressure ulcer stages — Stage I through Stage IV, DTI, and unstageable — were considered. On the high end of the range, in an audit study of patients at a community hospital, Oot-Giromini15 found the incidence of hospital-acquired pressure ulcers for 176 patients was 25%. The demographic in this study included all units, except maternity, nursery, and ambulatory surgery, at all pressure ulcer stages. In the current study, 10.3% of the control group and 2.5% of intervention group patients developed a pressure ulcer during a length of stay of approximately 5 days, well within published ranges.
Control patients in the current study were admitted with 22.8% more pressure ulcers per patients than intervention patients (0.137 [s = 0.5] versus 0.106 [s = 0.4], respectively [P = 0.08]). The control group also had a higher incidence of hospital-acquired ulcers than the intervention group. Even though admission Braden Scale scores were not significantly different, these findings suggest the control group was at more risk for pressure ulcer development than the intervention group.
The medical literature has shown higher rates of pressure ulcers in critical care areas of the hospital (ie, telemetry, urology, and ICU), where the incidence of hospital-acquired pressure ulcers can range from 15% to 40%.16,17 In a nested case-control study performed by Baumgarten et al16 at two teaching hospitals involving 792 total cases, 195 patients (24.6% of total cases), including 117 ICU patients (14.8% of total cases and 60% of those patients with pressure ulcers), developed hospital-acquired pressure ulcers. The patient demographic in this study was 40% male/60% female, with participant age 65 years. One of Baumgarten et al’s key findings was the odds of developing a pressure ulcer were twice as high for patients with an ICU stay than those without.
Incidence rates in specific medical units were surveyed in a cross-sectional cohort study assessing pressure ulcer prevalence18; 92,408 US patients were surveyed in all care settings. Of those surveyed, 94% were in acute care, 2.3% in long-term care, 1.7% in rehab facilities, 1.6% in long-term acute care, and 0.3% in home care. The International Pressure Ulcer Prevalence Survey (IPUP)17 found the prevalence of facility-acquired pressure ulcers was 5.1% for telemetry units (cardiac, general, medical, surgical, n = 718), 5.1% for urology units (n = 46), and 10.1% for ICUs (surgical, general, medical, n = 873). In the current study involving patients from telemetry, urology, and ICUs, 10.3% of control and 2.5% of intervention patients developed pressure ulcers, with an incidence of 11.5% in control and 3.1% in the intervention group. Control patients in this study developed pressure ulcers at a rate similar to ICU patients in the IPUP survey; however, the intervention group incidence rate for facility-acquired pressure ulcers was well below any of the critical care units reported by IPUP.
The results of this study are similar to those reported earlier comparing regular bed linens to a silk-like fabric,7 suggesting that bed linens, underpads, and patient gowns may affect the incidence of hospital-acquired pressure ulcers. Prospective, controlled, clinical studies of bed linens and patients in other high risk patient populations such neonatal and pediatric intensive care units, burn units, and long-term acute-care facilities,18 are warranted.
Limitations
Retrospective before-and-after study design limitations inherently include potential missing, incomplete, or inaccurate data.
Existing pressure ulcers at admittance could have been an indicator of further ulcer development. However, the overall levels of pressure ulcer development for homogeneous groups of patients were analyzed to produce statistically significant differences.
Patients assigned to highly specialized beds that required proprietary coverings or no coverings by bed manufacturers, rather than standard cotton-blend bed linens, were excluded from the study, which probably lowered the actual overall incidence rate in both arms of the study.
Conclusion
In this retrospective, nonrandomized, before-and-after controlled study involving 1,427 patients, the incidence of patients with facility-acquired pressure ulcers at all stages was 10.3% for the control group compared to 2.5% for the intervention group (P <0.001). The incidence of Stage I pressure ulcers was 5.6% in the control group compared to 2.3% in the intervention group (P <0.001), and 5.9% in the control and 0.8% in the intervention group for ulcers Stage II and greater (P <0.001). The total incidence of facility-acquired pressure ulcers was 11.5% in the control and 3.1% in the intervention group. Prospective, controlled clinical studies are needed to further elucidate the impact of a synthetic silk-like technology on persons at high risk for the development of pressure ulcers and skin breakdown.
Ms. Smith is Vice President of Nursing; Ms. McNichol is a Clinical Nurse Specialist/WOC Nurse; Ms. Amos is a Director, Telemetry/Urology Units; and Ms. Mueller is a Director, Intensive Care Unit, Wesley Long Community Hospital, Greensboro, NC. Ms. Griffin is Director of Supply Chain Operations and Mr. Davis is Assistant Director of Supply Chain Operations, Cone Health System, Greensboro, NC. Ms. McPhail is a Nurse Consultant and Dr. Montgomery is a Vice President, Precision Fabrics Group, Inc, Greensboro, NC. Please address correspondence to: Terry Montgomery, PhD, Precision Fabrics Group, Inc, 301 North Elm Street, Suite 600, Greensboro, NC 27401; email: terry.montgomery@precisionfabrics.com.
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