Analytical approach:
The analysis was based on a validated Markov model with a lifetime horizon. The authors stated that the perspective of a single health care payer was adopted.
Effectiveness data:
Clinical inputs for the model were derived from multiple sources. Specifically, data on the direct effect (the key clinical input of the analysis) of the preventative strategies were based on published randomised controlled trials (RCTs): pressure redistribution mattresses (five RCTs), oral nutritional supplements (four RCTs), skin emollients (one RCT), and foam cleansing (one RCT). Additional data on patient characteristics and some transition probabilities came from the Resident Assessment Instrument - Minimum Data Set (RAI-MDS), which included 89 Canadian facilities and 18,325 residents. Some estimates were from a telephone survey of current prevention practice, administrative databases, and literature reviews.
Monetary benefit and utility valuations:
Utility valuations were estimated from the RAI-MDS database using the health utility index score.
Measure of benefit:
Quality-adjusted life-years (QALYs) were used as the summary benefit measure, discounted at an annual rate of 3%.
Cost data:
Three main sets of costs were included: costs of the preventative strategies under examination; long-term costs associated with routine care (nursing, personal care, food, basic accommodation, and other costs); and costs of managing pressure ulcers, whose severity determined the cost per patient. Most costs were derived from official Ontario sources, including the Ontario Ministry of Health and Long-term Care, the Practice Survey, and the Canadian Institute for Health Information - Discharge Abstract Database. Resource use was taken from the RAI-MDS database and other published sources. Prices of devices and supplies were from manufacturers. Costs were in Canadian dollars (CAD). The price year was 2009. A 3% annual discount rate was applied.
Analysis of uncertainty:
Alternative strategies were analysed by varying the following inputs: excess mortality risk estimate, long-term care perspective, and supply costs only for oral nutritional supplements, skin emollients, and foam cleansing. A probabilistic sensitivity analysis was carried out using conventional probability distributions for model inputs.