Rasch analysis of the Patient and Observer Scar Assessment Scale (POSAS) in burn scars

The Patient and Observer Scar Assessment Scale (POSAS) is a questionnaire that was developed to assess scar quality. It consists of two separate six-item scales (Observer Scale and Patient Scale), both of which are scored on a 10-point rating scale. After many years of experience with this scale in burn scar assessment, it is appropriate to examine its psychometric properties using Rasch analysis. Cross-sectional data collection from seven clinical trials resulted in a data set of 1,629 observer scores and 1,427 patient scores of burn scars. We examined the person-item map, item fit statistics, reliability, response category ordering, and dimensionality of the POSAS. The POSAS showed an adequate fit to the Rasch model, except for the item surface area. Person reliability of the Observer Scale and Patient Scale was 0.82 and 0.77, respectively. Dimensionality analysis revealed that the unexplained variance by the first contrast of both scales was 1.7 units. Spearman correlation between the Observer Scale Rasch measure and the overall opinion of the clinician was 0.75. The Rasch model demonstrated that the POSAS is a reliable and valid scale that measures the single-construct scar qualit

Objective Scar Assessment Tools: A Clinimetric Appraisal

Background: Scars may lead to an array of cosmetic, psychological, and functional problems. Different scar features can be distinguished (i.e., color, thickness, relief, pliability, and surface area) that are clinically relevant and contribute to the quality and judgment of a scar. Today, objective evaluation of these scar features is indispensable for practicing evidence-based medicine (e.g., to evaluate the outcome of clinical trials). In this review, an overview and update are given on the most relevant noninvasive objective measurement tools for scar evaluation. Methods: A PubMed literature search was performed. Articles evaluating the clinimetric properties of noninvasive scar assessment tools were included. The selected objective measurement tools were then critically reviewed with respect to the clinimetric properties of reliability, validity, and feasibility. Results: In total, 75 articles were selected and 23 different noninvasive measurement methods were evaluated. Conclusion: Based on the scar features color, thickness, relief, pliability, and surface area, the best measurement tools that are currently available were recommended. (Plast. Reconstr. Surg. 127: 1561, 2011.

Intra- and Interobserver Variability of Aortic Aneurysm Volume Measurement With Fast CTA Postprocessing Software

Purpose: To study inter- and intraobserver variability of volume measurements with anew, fast semi-automatic method and compare the results to a previously validated standard manual method for volume measurement. Methods: Twenty abdominal computed tomographic angiography (CTA) datasets of patients with abdominal aortic aneurysms undergoing endovascular aneurysm repair (EVAR) were randomly selected from a clinical database (10 pre and 10 post EVAR). Aneurysm sac volume was measured by 2 independent observers using both the standard and semi-automatic methods. Intra- and interobserver variabilities and variability between the 2 methods were studied. Differences of each pair of measurements were plotted against their mean, and the repeatability coefficient (RC) was calculated according to Bland and Altman. Results: For the standard method, the intraobserver mean difference was 0.9 mL (0.4% of the first measurement), with an FIC of 8.4 mL (4.2%); the interobserver mean difference was 0.0 mL (0.0%), with a RIC of 11.8 mL (5.9%). For the semi-automatic method, the intraobserver mean difference was 1.4 mL (0.7%), with an RIC of 7.8 mL (4.1%); the interobserver mean difference was -1.8 mL (-1.0%), with an RIC of 10.8 mL (5.7%). The mean difference between the methods was 8.3 mL (4.2%), with an RIC of 25.1 mL (12.6%) for observer 1, and a mean difference of 6.4 mL (3.2%) and an IRC of 21.3 mL (10.7%) for observer 2. Conclusion:The semi-automatic method showed good intra- and interobserver variability for volume measurements of aortic aneurysms before and after EVAR. Volume measurements with the semi-automatic method correspond to measurements with the standard method. Sophisticated and fast postprocessing software may facilitate acceptance and clinical application of volume measurements in daily practice. The cutoff of 5% for relevant volume changes during follow-up, as advised in the reporting standards for EVAR, is sustained

Intra- and Interobserver Variability of Aortic Aneurysm Volume Measurement With Fast CTA Postprocessing Software

Purpose: To study inter- and intraobserver variability of volume measurements with anew, fast semi-automatic method and compare the results to a previously validated standard manual method for volume measurement. Methods: Twenty abdominal computed tomographic angiography (CTA) datasets of patients with abdominal aortic aneurysms undergoing endovascular aneurysm repair (EVAR) were randomly selected from a clinical database (10 pre and 10 post EVAR). Aneurysm sac volume was measured by 2 independent observers using both the standard and semi-automatic methods. Intra- and interobserver variabilities and variability between the 2 methods were studied. Differences of each pair of measurements were plotted against their mean, and the repeatability coefficient (RC) was calculated according to Bland and Altman. Results: For the standard method, the intraobserver mean difference was 0.9 mL (0.4% of the first measurement), with an FIC of 8.4 mL (4.2%); the interobserver mean difference was 0.0 mL (0.0%), with a RIC of 11.8 mL (5.9%). For the semi-automatic method, the intraobserver mean difference was 1.4 mL (0.7%), with an RIC of 7.8 mL (4.1%); the interobserver mean difference was -1.8 mL (-1.0%), with an RIC of 10.8 mL (5.7%). The mean difference between the methods was 8.3 mL (4.2%), with an RIC of 25.1 mL (12.6%) for observer 1, and a mean difference of 6.4 mL (3.2%) and an IRC of 21.3 mL (10.7%) for observer 2. Conclusion:The semi-automatic method showed good intra- and interobserver variability for volume measurements of aortic aneurysms before and after EVAR. Volume measurements with the semi-automatic method correspond to measurements with the standard method. Sophisticated and fast postprocessing software may facilitate acceptance and clinical application of volume measurements in daily practice. The cutoff of 5% for relevant volume changes during follow-up, as advised in the reporting standards for EVAR, is sustained

An objective device for measuring surface roughness of skin and scars

Scar formation remains a major clinical problem; therefore, various therapies have been developed to improve scar quality. To evaluate the effectiveness of these therapies, objective measurement tools are necessary. An appropriate, objective measuring instrument for assessment of surface roughness is not yet available in a clinical setting. The Phaseshift Rapid In Vivo Measurement of the Skin (PRIMOS) (GFMesstechnik GmbH, Teltow, Germany) could be such an instrument. This device noninvasively produces a 3-dimensional image of the skin microtopography and measures surface roughness. The aim of this study was to investigate the reliability and validity of the PRIMOS for objective and quantitative measurement of surface roughness of skin and scars. Three observers assessed skin and burn scars in 60 patients using the PRIMOS and a subjective scale, the Patient and Observer Scar Assessment Scale. Reliability was tested using the intraclass correlation of intraobserver and interobserver measurements. An intraclass correlation coefficient of 0.7 or greater was required for reliable results. To test validity, scores of the PRIMOS were compared with scores of the subjective scale (Pearson correlation). A Pearson correlation coefficient greater than 0.6 was considered a strong positive correlation. All 3 surface roughness parameters of the PRIMOS showed good intraobserver and interobserver reliability for skin and scars (intraclass correlation coefficient arithmetic mean of surface roughness > 0.85, mean of 5 highest peaks and 5 deepest valleys from entire measuring field > 0.88, peak count > 0.86). The parameter arithmetic mean of surface roughness showed a strong correlation with the subjective score (Pearson arithmetic mean of surface roughness 0.70; mean of 5 highest peaks and 5 deepest valleys from entire measuring field 0.53; peak count 0.54). The reliability and validity of the PRIMOS were only tested on skin and burn scars, not in other dermatologic diseases. The PRIMOS is a valid and reliable tool for objective noninvasive evaluation of surface roughness of both skin and burn scar

Clinical effectiveness of dermal substitution in burns by topical negative pressure:a multicenter randomized controlled trial

Previous research has shown clinical effectiveness of dermal substitution; however, in burn wounds, only limited effect has been shown. A problem in burn wounds is the reduced take of the autograft, when the substitute and graft are applied in one procedure. Recently, application of topical negative pressure (TNP) was shown to improve graft take. The aim of this study was to investigate if application of a dermal substitute in combination with TNP improves scar quality after burns. In a four-armed multicenter randomized controlled trial, a split-skin graft with or without a dermal substitute and with or without TNP was compared in patients with deep dermal or full-thickness burns requiring skin transplantation. Graft take and rate of wound epithelialization were evaluated. Three and 12 months postoperatively, scar parameters were measured. The results of 86 patients showed that graft take and epithelialization did not reveal significant differences. Significantly fewer wounds in the TNP group showed postoperative contamination, compared to other groups. Highest elasticity was measured in scars treated with the substitute and TNP, which was significantly better compared to scars treated with the substitute alone. Concluding, this randomized controlled trial shows the effectiveness of dermal substitution combined with TNP in burns, based on extensive wound and scar measurements