The Effect of Repositioning Frequency Determined According to Body Mass Index on Pressure Ulcer Development Time: Randomized Controlled Trial
Phase: NA
Conditions: Pressure Ulcer
Sponsor: Aydin Adnan Menderes University

 
 
 
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THE EFFECT OF REPOSITIONING FREQUENCY DETERMINED ACCORDING 
TO BODY MASS INDEX ON PRESSURE ULCER DEVELOPMENT TIME: 
RANDOMIZED CONTROLLED TRIAL 
ClinicalTrials.gov ID: NCT05504980 
Document Date: June 30, 2023 
Setting/Participants 
This study was conducted in the intensive care and palliative care units of a university 
hospital between 01.07.2022 - 29.01.2023. The sampling volume that should be included in 
the sample of the study was calculated using power analysis; considering the margin of error 
(α= 0.05), effect size (f= 0.347) and power 80% (1-β= 0.80) values and research design, the 
sample calculation was made for the Chi-Square test and a total of 66 people were 
determined. Considering the losses, the number of patients included in the sample was 
planned to be 86 patients (43 intervention group, 43 control group), 30% above the calculated 
value, and the study was completed with 71 patients. According to body mass index, weight 
status was stratified into four groups as underweight (≤18.49 kg/m2), normal weight (18.5 
kg/m2-24.9 kg/m2), overweight (25kg/m2-29.9kg/m2) and obese (≥30kg/m2). 
Body Mass Index 
Intervention Group 
Control Group 
Underweight 
1 
1 
Normal Weight 
8 
12 
Overweight 
17 
14 
Obese 
11 
7 
Total 
37 
34 
General Total 
71 
 
Statistical Analysis 
Statistical analysis of the research data was performed in the "Statistical Package for the 
Social Sciences (SPSS) 25.0" statistical package program (PASW Inc., Chicago. IL.USA) 
under the supervision of a statistical expert. In descriptive statistics; number and percentage 
distributions were shown and mean (mean) ± standard deviation (SD) values were given. 
Demographic quantitative data were compared between the groups by Mann Whitney U test. 
The distribution of qualitative characteristics of the patients in the groups was analyzed using 
Pearson Chi-square test or Fisher's exact probability test. "Kaplan Meier - Survival Time" 
analyses were performed for the duration of pressure ulcer development. General Linear 
model analysis was performed for effect size. For repeated measures, changes in groups were 

 
 
 
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analyzed using the nonparametric Brunner Langer (F1 LD F1 model) method. Since only one 
patient in the intervention group developed pressure ulcers, intra-group statistical analysis 
could not be performed. The results were evaluated at 95% confidence interval and p<0.05 
significance level. 
Results 
Socio-demographic characteristics, data on health status, pressure injury development risk 
assessment scale score, averages of some laboratory findings, and interface pressure values 
measured from pressure points of patients in the intervention and control groups in intensive 
care clinics are homogeneously distributed. Pressure injuries developed in 2.70% of the 
patients in the intervention group and 14.70% of the patients in the control group, the 
difference between them wasn’t statistically significant (p=0.098). The effect size is 0.216 
and has a low/medium effect size. Injury development time was 16 days in the intervention 
group and 6.00±2.0 days in the control group (earliest 3rd day, latest 8th day), the difference 
between them was not statistically significant (p=0.137). Pressure injury developed in one 
underweight, one normal weight, and three obese patient in the control group and one obese 
patient in the intervention group, the difference between them was statistically significant 
(p=0.006). 
In the control group, one patient with underweight, one patient with normal weight and three 
patients with overweight developed pressure injuries and the difference between them was 
statistically significant (p=0.003). Since only one of the obese patients in the intervention 
group developed pressure injuries, the development of pressure injuries according to body 
mass index could not be evaluated. The risk of pressure injury development is higher in 
underweight and obese patients, and less in overweight patients. 
Pressure injuries developed in the gluteal area and sacrum in the patient in the intervention 
group, and in the sacrum in 8.8% of the patients in the control group, there was no statistically 
significant difference between them (p=0.143). 
Conclusion 
It was concluded that the frequency of position changes should be done with a personalized 
program for each patient, not at routine two-hour intervals, and the risk of pressure injury 
development is higher in low-weight and obese patients, while it is less in overweight 
patients.