Current issues of ACP Journal Club are published in Annals of Internal Medicine


A pressure-decreasing mattress helped prevent pressure sores

ACP J Club. 1994 July-Aug;121:13. doi:10.7326/ACPJC-1994-121-1-013

Source Citation

Hofman A, Geelkerken RH, Wille J, et al. Pressure sores and pressure-decreasing mattresses: controlled clinical trial. Lancet. 1994 Mar 5;343:568-71.



To assess the effectiveness of a pressure-decreasing mattress in preventing pressure sores in elderly patients hospitalized with a femoral neck fracture.


2-week randomized controlled trial.


A teaching hospital in the Netherlands.


46 patients (mean age 84 y, 83% women) who were admitted to the hospital with a femoral neck fracture and a pressure sore risk of ≥ 8 points on a 10-point risk index were eligible for inclusion. Patients with pressure sores of ≥ 2 on a 5-point pressure sore grading were excluded from the study. 82% of correctly randomized patients were available for evaluation after 2 weeks.


Consecutively admitted eligible patients were randomly assigned in blocks of 6 to receive care on the Comfortex DeCube mattress (n = 23) or the standard hospital mattress (n = 23). Patients were examined 1 and 2 weeks after surgery by 2 physicians who graded pressure sores independently. The trial was stopped early because interim analysis showed that the distributions of the maximum pressure sore gradings differed significantly.

Main outcome measure

Pressure sore grading measured by a 5-point pressure sore index (0 = normal skin and 4 = deep subcutaneous necrosis).

Main results

At the ends of both weeks 1 and 2, the median maximum pressure sore grading was higher for patients nursed on the standard mattress compared with patients nursed on the DeCube mattress (P = 0.004 and P = 0.007, respectively). Fewer patients nursed on the DeCube mattress had pressure sores of ≥ grade 2 compared with those nursed on the standard mattress at week 1 (P = 0.013) and week 2 (P = 0.008) (Table).


The Comfortex DeCube mattress reduced the occurrence and severity of pressure sores in patients with a femoral neck fracture who were at risk for developing pressure sores.

Source of funding: Not stated.

For article reprint: Dr. R.H. Geelkerken, University Hospital Leiden, Department of Surgery, Postbus 9600, 2300 RC Leiden, the Netherlands. FAX 31-71-526-6750.

Table. Comfortex DeCube mattress vs standard hospital mattress in elderly patients hospitalized with femoral neck fractures*

Outcomes Comfortex DeCube mattress Standard hospital mattress RRR (95% CI) NNT (CI)
Pressure sore grade ≥ 2 at 1 wk 25% 64% 61% (17 to 83) 3 (2 to 12)
Pressure sore grade ≥ 2 at 2 wk 24% 68% 66% (23 to 87) 3 (2 to 9)

*Abbreviations defined in Glossary; RRR, NNT, and CI calculated from data in article.


This is the first randomized trial comparing the effectiveness of a foam mattress with a regular hospital bed in preventing pressure sores. From earlier work, 2-inch convoluted foam overlays did not reduce interface pressures compared with standard hospital mattresses. 4-inch convoluted foam reduced interface pressure over the sacrum but not the trochanter (1). The Comfortex DeCube mattress has been described as a 6.5-inch foam mattress with 3 columns and 5 rows of foam cubes with the feature of being able to remove small cubes in the area of the buttocks and the heels (2). Thus, either the added thickness or the cube design contributes to the effectiveness.

The potential for cointervention is raised because the providers and observers were not blinded and additional care provided to either group was not documented (3). The groups appear reasonably balanced, however, and the results were dramatic and consistent with expectations of the pressure-relieving device. The study suggests that further research is needed to compare the effectiveness of 6.5-inch foam mattresses with low-air-loss beds in the prevention of pressure sores. No difference was shown in a previous study, but the patients were not randomized (2).

Two messages for clinical practice are derived from this study. First, we should be alerted to the exceptionally high incidence of pressure sores that develop in patients with hip fractures, and preventive measures should be implemented as quickly as possible. Second, a 6.5-inch foam mattress should be seriously considered as part of the preventive intervention protocol in high-risk patients.

David M. Smith, MD
Regenstrief Health CenterIndianapolis, Indiana, USA


1. Krouskop TA, Williams R, Krebs M, Herszkowicz I, Garner S. Effectiveness of mattress overlays in reducing interface pressures during recumbency. J Rehabil Res Dev. 1985;22:7-10.

2. Warner DJ. A clinical comparison of two pressure-reducing surfaces in the management of pressure ulcers. Decubitus. 1992;5(3):52-64.

3. Fernie GR, Dornan J. The problems of clinical trials with new systems for preventing or healing decubiti. In: Kenedi RM, Cowden JM, Scales JT, eds. Bed Sore Biomechanics: Proceedings of a Seminar on Tissue Viability and Clinical Applications. London: Macmillan;1976:315-20.