This study found little evidence of an association between the use of PRSSs and a lower rate of IPUs in a large cohort of older adults with hip fracture, a population at particularly high risk of pressure ulcer development because of the common experience of long periods of immobility.29,34,44–46
In the full cohort, no evidence was found of an association between use of powered or nonpowered PRSSs at a given study visit and rate of IPU at the following visit, compared to no PRSS use, although for bedbound participants in the acute setting, the use of nonpowered PRSSs was significantly associated with a lower rate of IPUs. Frequent manual repositioning or pressure ulcer risk factors did not appear to explain this association, because results of analyses adjusting for these covariates did not differ from the unadjusted results. If confirmed in future studies, these results suggest that the effect of PRSSs may be limited to patients who are at particularly high risk because of immobility and that powered PRSSs are not effective at pressure ulcer prevention.
Although prior studies have found that high-density foam mattresses are effective in preventing pressure ulcers,18,20,47
this finding was not replicated in the current study. The reason for this disagreement is unclear, because there was not a good measure for use of high-density foam mattresses in the current study, which limits interpretation of this finding or there may have been a misclassification of mattress type, because the definition of foam mattresses provided to the research nurses was ambiguous.
Findings of this study in a high-risk population suggest that there is little or no preventive effect of PRSS use in nonbedbound patients at risk of pressure ulcers, indicating that the resources used to provide PRSSs to these individuals may be better allocated to other methods of pressure ulcer prevention. Although guidelines for pressure ulcer prevention recommend the use of PRSSs for all at-risk patients,13–17
there is little evidence that all patients would benefit equally. The heterogeneity of effects seen in this study suggests that future studies should examine the effect of PRSSs in various subgroups of patients, particularly those at risk of pressure ulcers because of immobility and those at risk because of other factors, to inform the guidelines about the appropriate use of these devices.
This study found no significant differences in pressure ulcer prevention according to whether powered or non-powered PRSSs were in use. This finding is particularly important given the considerable variation in burden associated with different PRSSs. As previously described, powered PRSSs generally cost much more and have higher burdens for patients and healthcare providers than non-powered PRSSs. Given these considerations, it is important to determine the clinical outcomes of using different PRSS types in order to choose PRSSs that will maximize the cost-effectiveness of pressure ulcer prevention. Current guidelines are unable to provide much guidance on this issue because of the heterogeneity of previous studies. Thus, the finding of no significant difference in pressure ulcer incidence rate between powered and nonpowered PRSSs suggests that the additional expense and burden of powered PRSSs may be unwarranted for pressure ulcer prevention.
These findings may have additional implications for use by Medicare beneficiaries, because the categorization of PRSS into powered and nonpowered is closely related to the policy for Medicare Part B reimbursement. Nonpowered PRSSs are categorized as Group 1 support surfaces, intended primarily for prevention of pressure ulcers, whereas powered PRSSs are categorized as Group 2 and 3 support surfaces, intended for both treatment and prevention of pressure ulcers. Thus, powered PRSSs may be better reserved for treatment of pressure ulcers in Medicare beneficiaries rather than for use in prevention.
The observational design of this study limits the ability to assess the effectiveness of PRSSs, in part because indications for the use of PRSSs (e.g., pressure ulcer risk factors) may be predictive of pressure ulcer incidence, resulting in confounding by indication. To address this, a number of clinically important pressure ulcer risk factors were adjusted for, and WEE was used to mitigate the problem of selection bias due to missing data. Nevertheless, as in any observational study, residual bias due to unmeasured confounders is a possibility. Also, potential misclassification of support surface use, which is likely to be nondifferential, may have been present and would tend to bias the association between PRSS use and incident rate of pressure ulcers toward the null. A possible source of misclassification is due to the inclusion of data from the 276 visits (4% of the study sample) at which nurses were unable to identify the PRSS in use, although results were similar in secondary analyses in which these visits were excluded (data not shown). Misclassification of support surface use may also have occurred if the participant was changed to a different type of support surface between the study visit at which it was observed and the development of an IPU within the following 2 days. Finally, although this study was larger than many previous studies of PRSS effectiveness, the sample size was limited. The number of participants observed on each type of PRSS was small, limiting the ability to estimate the association between specific types of PRSSs and the incidence rate of pressure ulcers. Also, only a small number of bedbound participants were observed, so this study was limited in its ability to estimate the association between PRSS use and the incidence rate of pressure ulcers in these participants.
In summary, the rate of incident pressure ulcers in older adults with hip fracture was not lower for participants using powered or nonpowered PRSSs than for those not using a PRSS, although in bedbound participants, the use of non-powered, but not powered, PRSSs was associated with a significantly lower rate of IPUs than for those not using PRSS. Thus, future studies should account for the bedbound status of study participants; clinical guidelines may need to be revised to account for the more-limited effect of PRSS use. The fact that powered PRSSs were not found to be effective at preventing pressure ulcers suggests that the higher expense and patient and healthcare provider burden associated with their use may not be warranted for pressure ulcer prevention.