This study estimates the economic outcomes of a nutrition intervention to at-risk patients compared with standard care in the prevention of pressure ulcer.
Statistical models were developed to predict ‘cases of pressure ulcer avoided’, ‘number of bed days gained’ and ‘change to economic costs’ in public hospitals in 2002–2003 in Queensland, Australia. Input parameters were specified and appropriate probability distributions fitted for: number of discharges per annum; incidence rate for pressure ulcer; independent effect of pressure ulcer on length of stay; cost of a bed day; change in risk in developing a pressure ulcer associated with nutrition support; annual cost of the provision of a nutrition support intervention for at-risk patients. A total of 1000 random re-samples were made and the results expressed as output probability distributions.
The model predicts a mean 2896 (s.d. 632) cases of pressure ulcer avoided; 12 397 (s.d. 4491) bed days released and corresponding mean economic cost saving of euros 2 869 526 (s.d. 2 078 715) with a nutrition support intervention, compared with standard care.
Nutrition intervention is predicted to be a cost-effective approach in the prevention of pressure ulcer in at-risk patients.
Pressure ulcer, while gaining increased attention from health-care decision makers, remains a large problem. Reported prevalence in the acute setting ranges between 10 and 20%,1, 2 and incidence rates between 4 and 10%.2, 3 The annual cost of treating pressure ulcer in the United Kingdom was estimated to be £1.4–2.1 billion in 2004, equivalent to approximately 4% of the total NHS budget,4 and in the United States for the same time period it was estimated to be US$2.2–3.6 billion.1 Studies show that systematic efforts at education, heightened awareness of pressure ulcer prevention and specific interventions by multidisciplinary teams can reduce the incidence of pressure ulcer.5 Despite this evidence, more action is required to prevent pressure ulcer.2
A large part of the cost attributable to pressure ulcer is the prolonged length of stay in the hospital to treat them. The economic opportunity cost of prolonged hospital stay is that beds are not available for use to other patients.6 In an Australian study, the opportunity cost of hospital beds lost to pressure ulcer in 2001–2002 was estimated to be a median of Australian dollars (AU$) 285 million.7
Previous findings indicate malnutrition is significantly associated with having pressure ulcer (odds ratio (OR)=2.6; 95% confidence interval (CI) 1.8–3.5, P<0.001)8 and the mean economic cost of pressure ulcer attributable to malnutrition in Queensland (Australia) public hospitals in 2002–2003 was AU$13 million (euros 7 million).9 Whether investing in the prevention of pressure ulcer through nutrition intervention is cost effective is an interesting question not yet addressed in literature.
Nutrition interventions have been found to reduce the incidence of pressure ulcer in patients at risk of developing pressure ulcer.10, 11, 12, 13, 14 Meta-analysis of intensive nutrition support in the prevention of pressure ulcers (5 randomized controlled trials (RCTs), n=1325 patients) revealed a significantly lower incidence of pressure ulcer development in at-risk patients compared with standard care (OR 0.74, 95% CI 0.62–0.88, 5 RCTs, n=1325).15
An economic model was developed to predict the cost of pressure ulcer attributable to malnutrition in Queensland (Australia) public hospitals in 2002–2003.9 The aim of the analysis reported here is to extend this model to estimate changes to economic outcomes arising from an intensive nutrition support intervention targeted at patients with high risk of developing pressure ulcer, compared with standard nutrition care. The outcomes estimated are changes to the number of cases of pressure ulcer arising, the number of bed days released and the change to related economic costs.
Materials and methods
The perspective of the economic analysis model was from the health-care provider in the Australian acute care setting, considering the input costs of providing an intensive nutrition support intervention to patients at risk of developing pressure ulcer; and output opportunity cost of bed days released (that is, bed days not occupied by patients with pressure ulcer) for the period of the financial year 2002–2003. A complete cost effectiveness analysis was not possible, as the model utilizes previously published studies that do not provide patient level data to determine health benefit as quality-adjusted life years. However, an economic modeling framework was used to predict potential changes to the incidence of pressure ulcers, subsequent bed days related to pressure ulcer, and related economic (opportunity) costs saved. The results will provide useful economic information to health services decision makers.
The data from a meta-analysis of intensive nutrition support in the prevention of pressure ulcers15 was applied to the Queensland public hospital population in 2002–2003 to determine if an intensive nutrition support intervention provided to patients at risk of developing pressure ulcer, would have been a cost-effective approach to reduce the incidence of pressure ulcer, compared with the standard nutrition care.
If an intensive nutrition support intervention had been implemented in Queensland public hospitals in 2002–2003, the annual economic cost of pressure ulcer becomes a function of the cost of providing the intervention to all patients at risk of developing pressure ulcer for the year, less the opportunity cost savings for a reduction in bed days related to a reduction in the incidence of pressure ulcer for the year. A diagrammatic representation of the input parameters and model to determine the economic outcomes of reducing the incidence of pressure ulcer with an intensive nutrition support intervention is shown in Figure 1.
A probabilistic sensitivity analysis was undertaken whereby probability distributions rather than fixed values are used to describe each input parameter. Samples are drawn at random from these distributions to generate an empirical distribution of the results. The advantage is that uncertainty arising from a large number of variables is simultaneously included and propagated forward to the results. This indicates the degree of confidence that can be attached to decisions made from the results.16
Input parameter data and sources
The methods used and values determined for several input parameters have been described previously9 and are summarized in Table 1. These include: the number of relevant discharges (parameter A); the incidence rate for pressure ulcer (parameter B); the independent effect of pressure ulcer on length of stay (parameter C); and the cost of a bed day (parameter D). The methods used and values determined for the other input parameters are described next. These include: change in risk in developing pressure ulcer associated with nutrition support (parameter E) and the annual cost of providing an intensive nutrition support intervention to patients at risk of pressure ulcer (parameter F).
Parameter E. The input parameters for determining the change in risk of developing a pressure ulcer with intensive nutrition support was determined from the OR of 0.74 and corresponding 95% CIs (0.62–0.88) determined in the meta-analysis by Stratton et al.15 of intensive nutrition support in the prevention of pressure ulcers. The s.e. of the OR was calculated backwards from the 95% CI, where 95% CI=OR±1.96 × s.e. Rearranged, s.e.=95% CI−OR/1.96. The s.e. value was calculated to be 0.066.
Parameter F. The input parameters for the annual cost of provision of intensive nutrition support to at-risk patients was determined to include: (i) the annual cost of extra staffing resources to ensure at-risk patients receive and consume the required nutrition, and (ii) the annual cost of additional food and/or commercial nutritional supplements. Details of how these input parameters were determined are provided in Supplementary Appendix 1, available in Supplementary Information.
Costs were estimated based on the following: the proportion of malnourished patients represented patients at risk of developing pressure ulcer requiring intensive nutrition support with a subset of malnourished patients already receiving nutrition support; additional nutrition support was considered to be additional food or commercial nutritional products provided over and above standard hospital food, however, where patients may have required total enteral tube nutrition support this would replace similar food costs and so does not need to be considered; malnourished patients require extra staffing resources for encouragement, assistance and monitoring to ensure the receipt and consumption of the required nutrition support.
The lowest and highest costs per annum based on a combination of the lowest and highest staff numbers were calculated and are presented in Table 2.
The addition of a high and low value for each of the parameters of extra staffing and extra food/nutrition was determined to provide an overall high and low value for the annual cost of providing an intensive nutrition support intervention (see Table 2).
Method of evaluation
A total of 1000 samples were drawn at random from each distribution, using Microsoft Excel and Visual Basic Programming language, to generate an empirical distribution of the outputs. Probability distributions for specified input parameters were assigned according to standardized methodology for statistical modeling.16 The values and distributions for the parameters A, B, C and D were used as described previously.9 Information on values and distributions for parameters E and F can be found in Supplementary Appendix 2 available in Supplementary Information.
Cost values were determined in Australian dollars (AU$) and then converted to euros as at 1 January 2003. The exchange rate on this date was AU$1=0.534 euros (www.oanda.com).
Table 3 shows the mean, variance and ranges for the number of cases of pressure ulcer avoided, bed days released and associated economic costs if an intensive nutrition support intervention had been implemented for at-risk patients in Queensland public hospitals in 2002–2003.
The mean number of bed days released was 12 397 (s.d. 4491), which was 0.52% of patient bed days in Queensland Health in 2002–2003.
Scatter plots of the ‘cases of pressure ulcer avoided versus economic cost’ and associated ‘bed days released from cases of pressure ulcer avoided versus economic cost’ are illustrated in Figures 2 and 3, respectively. These scatter plots represent cost effectiveness planes, where the desired outcomes (number of pressure ulcers avoided (Figure 2) and number of bed days released (Figure 3)) are represented on the x-axes and economic costs on the y-axes. Each data point represents a possible output from the model, and the overall distribution demonstrates the likelihood of the output result.
Overall there were 951 of the 1000 samples where the economic cost is a negative value, indicating a 95.1% chance that implementing an intensive nutrition support intervention is overall cost saving, while reducing the cases of pressure ulcer and related hospital bed days. The model predicts mean economic opportunity for cost savings of AU$5 373 645 (s.d. $3 892 727) (euros 2 869 526 s.d. 2 078 715) if an intensive nutrition support intervention had been implemented in Queensland public hospitals in 2002–2003.
The economic modeling undertaken for this study predicts that a substantial number of cases of pressure ulcer could have been avoided, had an intensive nutrition support intervention been provided to all at-risk patients in Queensland Health in 2002–2003. This corresponds to a substantial number of patient bed days that could have been used for purposes other than patients staying in hospital for an extended period of time with pressure ulcers. Importantly, there were no predicted additional cases of pressure ulcer or bed days lost to pressure ulcer from this model, with the minimum number of cases and bed days saved being 1082 and 3807, respectively (see Table 2 and related Figures 2 and 3).
The economic cost of implementing an intensive nutrition support intervention for at-risk patients was predicted to be overall cost saving with a mean value of approximately—AU$5.4 million (euros 2.9 million), despite input costs of between approximately AU$3.8–5.5 million (euros 2–2.9 million).
Importantly, the model chosen predicted a 95.1% chance of being economically cost saving, while reducing the incidence of pressure ulcers and releasing valuable bed days for use by other patients. Of course, evaluation of the implementation of such an intervention is required to test whether the economic outcomes predicted are accurate. This research can be considered to be hypothesis generating while also providing useful information for decision making.
No published studies were located investigating the economic outcomes of nutrition intervention for comparative purposes. A few studies have investigated the cost effectiveness of alternative types of pressure-relieving surfaces18, 19, 20 and although a comparison of economic outcomes cannot be made due to different methodological approaches, they appear to indicate that the prevention of pressure ulcers is overall associated with significant positive economic outcomes. Graves et al.7 discussed the need for more studies that estimate the changes in cost and health benefits that would arise from competing strategies to reduce the risk of pressure ulcers.
Economic cost savings in this study do not represent actual monetary savings, rather the opportunity costs of patient bed days not available for alternative use. Potential cost savings of treatment and care or broader patient burden issues associated with pressure ulcers have also not been considered. The value to the public health system of increased throughput is considered the most relevant factor here, but the additional costs saved from avoided cases of pressure ulcer with respect to treatment would also be substantial. Other potential benefits of an intensive nutrition intervention in this patient population have also not been considered, such as potential reduction in other complications and improvement in recovery.
The cost of the modeled intensive nutrition intervention was between AU$3.8 million and AU$5.5 million (euros 2–2.9 million) (2002–2003 prices), representing a substantial investment in nutritional care in the Queensland public hospital system at this time. The nutrition support intervention was chosen to provide additional food or commercial supplements to patients who were at nutritional risk and unlikely to be receiving additional nutrition supplements. It also included additional nutrition/nursing support staffing to encourage and assist patients to consume the required nutrition, although this task could possibly be achieved within existing resources with a change in care models and emphasis on importance of patients achieving nutritional intakes. This model of staffing was chosen based on the results of a study where the intensive nutrition intervention resulted in significantly improved intake (62% achieved ⩾75% of requirements) compared with patients receiving standard nutrition care (36% achieved ⩾75% of requirements).21 However the most effective way of spending funds to ensure optimal nutrition care is not clear at this stage and requires further investigation.
Economic analysis of the impact of nutrition intervention has been undertaken in a few studies indicating substantial economic benefits.22, 23 Stratton et al.6 estimated mean cost savings of between £352 and £8179 per patient if nutritional supplements were provided to patients at nutritional risk. However, a review of the economic literature related to nutrition support found many studies were inadequately designed and collected only rudimentary figures associated only with the cost of the nutrition intervention, rather than considering the wider economic benefits, such as an associated decrease in length of stay or reduction in infectious complications post-operatively.24 Most studies also failed to make even a minimal allowance for uncertainty by the use of sensitivity analysis, nor did the authors take advantage of the stochastic nature of the data to present measures of precision such as CIs. This review highlights a lack of evidence related to costs and effects of different types of nutrition intervention. On the contrary, this present study uses sound economic analysis methodology to determine the economic outcomes of nutrition intervention in a medical condition for which poor nutritional status is a risk.
Limitations of this study mainly relate to the information used for the input parameters.9 The economic estimates rely on effect estimates from a meta-analysis of five studies, limitations of which are detailed by Stratton et al.15 However, confidence in the results of the meta-analysis is supported by the results of the individual studies, all of which reported a decreased incidence of pressure ulcer with nutritional support. A lack of significance of the individual studies is most likely to be due to small sample sizes, with the increased power of the meta-analysis arising mostly from pooling of the data. Therefore, the findings of the meta-analysis despite some methodological limitations is considered robust, and given the heterogeneity of subjects and settings included, applicable to large proportions of patients considered to be at risk for pressure ulcer development. Another limitation of this study was the assumption that patients at risk of developing pressure ulcer were also considered to be at risk of, or malnourished and hence would benefit from intensive nutrition support. Stratton et al.15 determined that although the nutritional status of all subjects at risk of pressure ulcer in the studies included in the meta-analysis were not specifically assessed or done in a standardized way, data available for subjects indicated a majority would have been at risk of being, or malnourished. There are many factors associated with being at risk of malnutrition that are also factors for being at risk of pressure ulcer, such as age, functional capacity, diagnoses and severity of illness, so this assumption is considered reasonable. The assumption that the prevalence of malnutrition is equivalent to the prevalence of nutritional risk may have also underestimated the number of patients at nutritional risk and hence the number of patients who might have benefited from nutritional support. There were also a number of other assumptions made regarding developing the model for costing of the intensive nutrition support intervention, which may be considered limitations, however as discussed previously, the modeled costs represented a substantial investment in nutrition support that could be spent in alternate ways. In fact, the current predicted economic savings allow substantial scope for even more funds to be spent, if necessary, on the nutrition support intervention and it still remains cost effective.
While this study utilizes data and predicts outcomes from almost a decade ago, intensive nutrition intervention for patients at risk of pressure ulcer in the public hospital population of Queensland (Australia) is still not routine, and so although parameter inputs may have subsequently changed, including escalating costs and increasing hospital waiting lists, the overall findings of this study remain applicable.
This economic modeling study predicts that investment in intensive nutrition support to patients at risk of pressure ulcer will realize substantial opportunity cost savings for the health system with respect to the prevention of pressure ulcer, which improves patient outcomes.
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This research was supported by a grant from the Royal Brisbane & Women’s Hospital Research Foundation.
The authors declare no conflict of interest.
Supplementary Information accompanies the paper on European Journal of Clinical Nutrition website
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Banks, M., Graves, N., Bauer, J. et al. Cost effectiveness of nutrition support in the prevention of pressure ulcer in hospitals. Eur J Clin Nutr 67, 42–46 (2013). https://doi.org/10.1038/ejcn.2012.140
- pressure ulcer
- nutrition support
- cost effectiveness
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