Pressure injuries (PIs) are wounds of the skin and deeper soft tissue that usually occur over a bony prominence.1 Age-related physiologic alterations (eg, increased fragility of blood vessels and connective tissue and the loss of fat and muscle that dissipate pressure) lower the threshold for pressure-induced injury later in life, when multiple factors related to mobility, nutrition status, and skin health increase the risk of PIs among residents of nursing homes (NHs).2 Risk factors for the development of PIs include being bed- or chair-bound, dependent on repositioning, difficulty with ambulation, fecal incontinence, low body mass index (BMI), changes in weight, reduced overall food and protein intake, inability to eat independently, and skin changes.3–5 PI treatments cost the US healthcare system an estimated $11 billion annually.5,6
A recent systematic review of randomized controlled trials (RCTs) on preventing PIs noted that the heterogeneity of study populations limited the generalizability of the findings.5 In the 2013 Turning for Ulcer ReductioN (TURN) study,7 Asians comprised 10.7% (n = 101) of participants in this multisite study but developed 53% (n = 10) of all PIs (n = 19) and had significantly different BMIs (P < .001) and dietary intakes (P = .009) than non-Asian participants. Current BMI and nutrition guidelines based on Western populations may not be appropriate for Asian populations, for whom cutoffs may need to be lower.8–12 One could deduce that Asian populations are structurally smaller than white European populations and that their intake volume and requirements may differ. Whether Asian and non-Asian NH residents are at different risk of PI because of differences in intake of meals, protein, supplements, and snacks remains unexamined, as do differences in their moisture-related risk of PI from incontinence.
The TURN study was conducted to determine the efficacy of three repositioning schedules (2-, 3-, or 4-hour intervals) among at-risk NH residents in 27 NHs in the US and Canada.7 Its data are particularly promising for extending the science on differential risk of PIs among Asian and non-Asian NH residents for three reasons: (1) all participants were at moderate or high risk of PI development as defined by the Braden Scale for Predicting Pressure Sore Risk; (2) the care context provided appropriate support surfaces, moisture-wicking briefs, and consistent and adequate repositioning of residents; and (3) BMI, nutrition, modes of feeding and bathing, and frequency of wet brief changes were assessed repeatedly over the 3-week intervention.4,7,13–15
Given that (1) optimizing nutrition status is a promising intervention for PI prevention; (2) there is suboptimal RCT evaluation of nutrition-related interventions in demographic subgroups;5,14 and (3) nursing is responsible for the delivery, monitoring, and documentation of resident food intake; the purpose of this article is to use data from the TURN RCT4 to compare Asian and non-Asian Canadian NH residents (n = 505; 54% of TURN study population) with respect to nutrition and nonnutrition risk factors for PI.
The methods of the TURN study have been described elsewhere.4,7 Briefly, NH residents at risk of PI in the US (n = 20) and Canada (n = 7) were randomized by risk level (moderate vs high) to a repositioning schedule (every 2, 3, or 4 hours), repositioned, and monitored.7 Skin areas (coccyx/sacrum, trochanter, heels) were assessed at repositioning by certified nursing assistants (CNAs) and weekly by a licensed nurse assessor blinded to turning frequency. Variables related to PI development were monitored throughout the 3-week study with specific observations related to dietary adequacy.
Settings and Participants
Nursing homes with 151 to 350 beds in the greater Toronto area were identified by the Toronto Health Economics and Technology Assessment Collaborative. Inclusion criteria included stable leadership and ability to commit facility resources for the study. Facilities were classified as urban (n = 2) or suburban (n = 5) and for profit (n = 3) or nonprofit (n = 4); quality ratings and PI history were not available at the time of the study. High-density foam mattresses were provided according to specifications.
Eligible participants were 65 years or older, did not have a PI, were at moderate (Braden Scale = 13–14) or high (Braden Scale = 10–12) risk of PI development,16,17 and scored 3 or less on the Braden mobility subscale. Both short-stay (≤7 days) and long-stay (≥90 days) residents were included. On admission, residents’ nutrition needs were assessed by a registered dietitian. When facilities had Asian residents, there were bilingual NH staff to care for them so language was not a barrier.
The study was approved by the institutional review board committee at the University of Toronto and the University of Texas Health Science Center.
Demographic and diagnostic factors were assessed at baseline using an investigator-developed tool. Variables included age, gender, race, and chronic disease diagnoses. The investigator-developed Framework for Nutritional Risk Evaluation and Care Planning for PI Prevention guided the assessment of nutrition risk.4
Overall nutrition risk was measured in two ways. First, the nutrition subscale of the Braden Scale18 was used to assess usual food intake patterns with respect to protein, fluids, and supplements on four levels (very poor to excellent) and has been found to approximate estimated dietary intake when used as an initial screen for overall nutrition risk.4,19 Second, changes in BMI were used as outcome indicators of overall dietary adequacy. Weight was typically measured by CNAs upon admission and weekly thereafter. Measures were extracted to the TURN data collection document, calculated as BMI, and categorized as a 5% to 10% gain/loss or a 10% or more gain/loss in the past 30 days.
The 3-week dietary intake measures in the TURN study have been reported previously.4 Dietary intake was operationalized as five variables: percent of meals consumed, number of servings, types of protein consumed, liquid supplements consumed, and snacks consumed, all of which were assessed at each meal by CNAs. The percentage of meals consumed was estimated in five increments from 1%–25% to 100%; there were also designations for meals refused, NPO, or tube feeding. The numbers of servings of nine types of protein, for example, 1 egg, 1 cup dairy/milk, 3 oz fish/meat, and so on, were summed, averaged over 3 weeks, divided by 21, and reported as average daily servings. A summary measure of milk-based protein combined estimated servings of milk, cheese, protein powder, and liquid supplement per meal. Consumption of liquid supplements or snacks and the total of each that was consumed (range, 1%–25% to 100%) were assessed each day and averaged as both the percentage of days during the 3 weeks that supplements/snacks were consumed and also as the percentage consumed daily.
Nonnutrition risk was assessed with five Braden subscales and two additional measures of moisture. The Braden Scale addresses the interplay between two primary etiologic factors of PI development: (1) intensity and duration of pressure and (2) tissue tolerance for pressure. Licensed nurses with specific Braden Scale training provided full screenings for all residents on admission and weekly. The five Braden subscales (excluding nutrition) assessed sensory perception, activity, mobility, friction/shear, and moisture, each rated on a 4-point scale (except friction/shear, which was on a 3-point scale, and mobility related to eligibility, which was based on scores between 1–3). When summed with the nutrition subscale, these served as a measure of total risk of PI ranging from 6 (highly impaired) to 23 (no impairment).
To augment the Braden subscale measure of moisture, CNAs recorded each resident’s frequency and mode of bathing (tub, shower, or bed bath) per week and their frequency of wet briefs per day over the 3-week study, the latter being a measure of moisture/incontinence.
Data management and analysis of all variables have been reported elsewhere.4 All dietary intake variables presented as daily averages were assessed at breakfast, lunch, and dinner; summed and divided by 3, for that day’s average; and then summed across the study and divided by 21 days for the overall daily average. Four risk groups were created by Asian race (yes/no) and PI incidence (yes/no).
Descriptive statistics are reported as frequencies and percentages for categorical variables and as means for continuous variables. Tests of differences across groups included χ2 tests for categorical variables and analyses of variance (ANOVAs) with Duncan post hoc multiple-range tests for differences in means of continuous variables. The multiple-range test protects against type 1 error by requiring larger differences among a collection of means to reject the null hypothesis and was applied when the initial ANOVA was significant (P < .05).
Table 1 presents demographic and diagnostic characteristics across the four risk groups by race and PI incidence. Groups were similar in sex and age. Significant racial differences are reflected in the comparisons across risk groups: As previously reported, Asian residents were more likely to develop PIs.4 Asian residents were also less likely to have been diagnosed with dementia, but other diagnostic differences were nonsignificant across groups. Mean BMI appeared to be lower among Asian residents, but pairwise tests of differences between Asian residents and non-Asian residents with and without incident PIs were nonsignificant. Within race, affected and unaffected residents did not exhibit significantly different BMIs.
Table 2 presents the mean and range of the total Braden Scale and its six subscales, mean BMI, and change in BMI by risk group. According to ANOVA on the total Braden Scale and subscales, there were no significant differences in overall PI risk or specific risk by pressure or tissue tolerance between the risk groups. Nor did the mean nutrition subscale screening scores differ significantly by group. Pairwise tests of differences suggested that Asian residents with or without incident PIs differed significantly only in comparison with non-Asian residents with incident PIs and not the larger group of unaffected non-Asians. Within race, affected and unaffected residents did not exhibit significantly different BMIs. Weight loss/gain over 21 days was minimal among participants and did not vary by race or PI incidence.
Table 3 presents patients' average dietary intake and exposure to moisture. Over 21 days, the mean percentage of meals consumed by residents did not differ significantly across risk groups. However, Asian participants were significantly less likely to consume 100% of meals overall. The mean number of total protein servings or milk-based protein consumed each day did not differ across groups.
That said, when examined by subtype of protein, the pattern of protein consumption across the risk groups was somewhat more complex; PI incidence alone was not associated conclusively with a particular protein consumption profile among either Asian or non-Asian residents, nor did Asian residents consume any specific type of protein exclusively when compared with non-Asian residents. However, ANOVA suggested the following noteworthy trends that should be considered with caution, as they may be subject to type I error. Asian residents consumed more meat and somewhat less cheese, nuts, and protein powder than non-Asian residents who developed PI. Asian residents were less likely than non-Asian residents to consume liquid supplements at all. However, if they did accept liquid supplements, they did so somewhat more frequently than non-Asian residents. All groups consumed similar mean percentages of their daily liquid supplement, but Asian residents consumed a lower mean percentage of their snacks.
All residents were bathed at a similar frequency overall, but Asian residents, particularly those with PIs, bathed in a tub more often than non-Asians; whereas showers and/or bed baths predominated among non-Asian residents. Among the 10 residents who developed PIs, Asian residents had significantly more wet briefs per day than did non-Asian residents.
This study extends previous work among non-Asian NH residents by providing new evidence of the differential short-term risk of PI related to both nutrition and nonnutrition factors. Among those at similarly moderate/high overall and immobility risk of PI, Asian residents consumed significantly smaller meals, were less likely to consume liquid supplement, and took more frequent tub baths. Asian residents also had marginally lower BMIs. Although Asian residents who developed PIs did not differ significantly on type of protein consumed compared with all other residents, they tended to group with unaffected Asian residents in their dietary consumption patterns.
Overall Nutrition Status
Malnutrition is a well-known contributor to PI development for those admitted to both hospitals and NHs.20–22 However, newly admitted NH residents may not be assessed as malnourished because the typical focus is on determining the potential for unintentional weight loss. Sustainability of body weight is a common outcome measure of dietary adequacy, employing both a balanced diet and nutrition supplementation to avoid malnutrition and low body weight, which together increase the risk of PI development.23–25 The findings of the current study suggest that weight was generally sustained among all residents, at least during the 3 weeks of observation, which contrasts favorably with the 9.9% prevalence for 30-day weight loss reported from the Minimum Data Set quality ratings.26
In general, a higher BMI is protective against PI development among hospitalized older adults, and underweight individuals are at higher risk of PI development in most anatomical regions than those who are normal-weight and obese.27 Asian populations demonstrate different relationships among BMI, body fat distribution, and health risks than populations of European descent.12 Specifically, the World Health Organization criteria classify BMIs 18.5 to 23 kg/m2—the range reported for Asian participants in the current sample—as representative of an “increasing but acceptable” level of undernutrition for Asian populations.12 Given other risk factors for PI in NH populations, the risk may be higher for Asians in NHs if their BMI is either not properly evaluated or lower than reported.
The nutrition subscale, total score on the Braden Scale, and weight change during the study did not differentiate risk of PI between Asian and non-Asian NH residents. This extends recent secondary analyses of the TURN study nutrition status of other racial subpopulations, which showed nonsignificantly different risk between African American, Caucasian, and Hispanic residents of US and Canadian NHs.4
Intake of well-planned meals is imperative for PI prevention because calories, protein, fluids, vitamins, and minerals are necessary to maintain tissue integrity and prevent tissue breakdown.3 A significant majority of NH residents in the current study consumed at least 75% of their daily meals, although Asian residents ate slightly less of their meals. Commercial supplements and snacks are also common adjuncts to well-planned meals in NHs, although intake may be inadequate.4 Consumption of snacks and frequency of supplement use were lower among Asian residents in the current study.
Protein intake may be a more important predictor of PI than anthropometric measures.4 Dietary intake of protein was also the most significant nutrition-related risk predictor for PI development in a comprehensive study of dietary intake, anthropometric measures, and biomarkers in an early study among NH residents.28
Milk-based protein supplemental drinks are commonly used for treatment of malnutrition in NH residents.23 Similarly, diets high in protein are considered important for decreasing the risk of incident PI as well as healing.24,26,29 The average number of protein servings in the current sample was less than two servings per day across all risk groups, although most residents consumed liquid supplements.
Unfortunately, a high-protein diet may also have negative effects on skin integrity because of acidic by-products. In Canada, where this study was located, those of Asian descent are more likely to be lactose intolerant than their Caucasian counterparts: 99% versus 32%, respectively.30 The inability to digest a lactose sugar found in milk causes multiple gastrointestinal symptoms,30 such as abdominal distension and loose stools. These symptoms occur because lactose is neither digested nor absorbed and reaches the colon intact, where bacteria feed on it and produce chemicals that cause diarrhea and gas and result in acidic stool. Also, lactose intolerance results in decreased absorption of nutrients and deprives the individual of nutrition benefits.31 Although racial differences did not survive the most rigorous statistical tests, Asian residents in this study appeared to avoid milk-based protein sources in favor of meat when compared with non-Asian residents. Data collection measures did not account for whether fecal matter was present in wet briefs.
The typical North American diet consumed in the Canadian region where this study was conducted may further compromise skin integrity because it generates large amounts of acid, mainly as phosphates and sulfates from the high volume of protein and relatively lower volume of fruits and vegetables. The resulting acid generated by this diet is excreted in the urine.32 An increased urine acidity and frequency of loose stools in the population studied would be likely to lead to an increased frequency of bathing.
In the current study, there was a statistically significant difference in the number of tub baths for Asian versus non-Asian residents with a PI, as well as a trend toward more wet briefs per day among Asian residents with a PI. Tub baths may lead to more moisture absorption, which can compromise skin integrity.
Finally, other research suggests that nursing staff may lack confidence in their skin assessments for PI because of the skin coloration of residents. However, skin assessments were not likely to have affected the outcome assessment for residents with Asian ancestry in this study because the PIs were stage 2.33
The primary limitation of this secondary data analysis was the small sample size of participants with PIs, as well as the short study period. A longer follow-up period might have provided more cases and therefore a more robust statistical comparison of differences between risk groups. Although PI can develop within a matter of hours, observation over days or weeks of follow-up (as in this study) may be adequate only for conclusions relative to healthy patients and not for NH residents with protracted immobility, where PI risk increases for up to 2 years.5
A second limitation was lack of specificity regarding Asian heritage in the TURN study, because research by the World Health Organization suggests that there is significant variability in nutrition status and risk of health problems among persons in differing Asian subgroups.12
A final limitation was the lack of data on fecal contents of wet briefs, which might have allowed for a more nuanced examination of protein-related risk.
Recommendations for Future Study
Both BMI and undernutrition are areas of research specifically recommended for further longitudinal study of Asian subpopulations around the world.12 One strength of the current study is the ability to compare a sizable group of Asian and non-Asian residents.
In addition, the findings of this study highlight the importance of protein intake in relation to PI prevention. However, further study is indicated for how to encourage and maintain dietary intake of protein, such as through feeding assistance, as part of PI prevention protocols.
Whether specific snacks and/or the taste of supplements satisfy taste preferences among cultures or more frequent/smaller quantities of foods and snacks would appeal more to persons of smaller stature would be two areas of important focus, with the goal of improving dietary intake.
The findings of this secondary analysis of a short-term RCT are preliminary but consistent with previous research that suggests differences between Asian and non-Asian NH residents in BMI and the patterns of amount and type of dietary intake and their sequelae. These differences may be relevant for PI risk but not captured by PI screening tools such as the Braden Scale if considered alone. Targeted research is needed to refine the parameters of nutrition risk that inform best clinical practices to protect skin integrity across racial subpopulations of NH residents.
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