Quantifying Asymmetry and Scar Quality of Children With Repaired Cleft Lip and Palate Using Symnose 2

Defining the Aesthetic Range of Normal Symmetry for Lip and Nose Features in 5-Year-Old Children Using the Computer-Based Program SymNose

Objective:

To provide a normal comparison group against which to judge symmetry results after cleft surgery and to introduce the thin lip correction (TLC) feature in SymNose. A lip–aspect ratio algorithm has been added to the latest version of SymNose to compensate for the higher degree of overlap in thicker lips when compared to thin lips.

Design:

Retrospective analysis of symmetry in healthy participants, using the computer-based program SymNose on both anteroposterior (AP) and base view images. Photographs of 91 noncleft children were traced twice by 3 independent investigators experienced with SymNose.

Participants:

Five-year-old healthy participants from a local state school in Tavistock (West Devon, United Kingdom).

Main Outcome Measure:

Asymmetry expressed as the perimeter mismatch percentage for nose and lip features on AP view images and for nose features on base view images.

Results:

The perimeter mismatch reference range for the nose (AP view) was 2.65% to 30.91%, for the lip 2.13% to 15.44%, for the nose (base view) 1.69% to 14.84%, for the nostrils 4.68% to 26.6%, and for the width–height ratio 1.15% to 1.80%. The perimeter mismatch percentage for the lip without TLC was significantly higher compared to the perimeter mismatch percentage with TLC (P < .001).

Conclusion:

This article provides a noncleft reference range for all perimeters drawn from SymNose against which to compare results after cleft surgery at 5 years of age. Furthermore, it shows the importance of correcting for variance in lip volume per child.

Spearman-Brown prophecy formula and Cronbach's alpha: different faces of reliability and opportunities for new applications

OBJECTIVES

There are similarities between the different forms of reliability, such as internal consistency (internal reliability) and interrater and intrarater reliability. Reliability coefficients that are based on classical test theory can be expressed as intraclass correlation coefficients (ICCs), such as Cronbach's alpha. The Spearman-Brown prophecy formula (SB formula) is used to calculate the reliability when the number of items in a questionnaire is changed. This paper aims to increase insight into reliability studies by pointing to the assumptions of reliability coefficients, similarities between various coefficients, and the subsequent new applications of reliability coefficients.

DESIGN, SETTINGS AND RESULTS

The origin and assumptions of Cronbach's alpha and the SB formula are discussed. Cronbach's alpha is written as an ICC formula, using the well-known property that taking the average value of a number of ratings increases the reliability of a measurement. We illustrate with an example that the ICC formulas for average measurements of multiple raters and the SB formula give similar results. This implies that the SB formula can be used to decide on the number of measurements to be averaged and thus on the number of raters required, for obtaining measurements with acceptable reliability, even if the variance components of the ICC formula are not known. Using the same example, we illustrate the principle of "Cronbach's alpha if item deleted" to decide on the poorest performing raters in a set of raters.

CONCLUSION

These applications have different assumptions: the principle of "Cronbach's alpha if item deleted" is based on the assumption of a fixed set of items/raters and the SB formula is based on the assumption of random raters. The example also emphasizes the need for more raters in the design of the reliability study to obtain a robust estimation of reliability.

The use and reliability of SymNose for quantitative measurement of the nose and lip in unilateral cleft lip and palate patients

INTRODUCTION

It is essential to have a reliable assessment method in order to compare the results of cleft lip and palate surgery. In this study the computer-based program SymNose, a method for quantitative assessment of the nose and lip, will be assessed on usability and reliability.

METHODS

The symmetry of the nose and lip was measured twice in 50 six-year-old complete and incomplete unilateral cleft lip and palate patients by four observers. For the frontal view the asymmetry level of the nose and upper lip were evaluated and for the basal view the asymmetry level of the nose and nostrils were evaluated.

RESULTS

A mean inter-observer reliability when tracing each image once or twice was 0.70 and 0.75, respectively. Tracing the photographs with 2 observers and 4 observers gave a mean inter-observer score of 0.86 and 0.92, respectively. The mean intra-observer reliability varied between 0.80 and 0.84.

CONCLUSIONS

SymNose is a practical and reliable tool for the retrospective assessment of large caseloads of 2D photographs of cleft patients for research purposes. Moderate to high single inter-observer reliability was found. For future research with SymNose reliable outcomes can be achieved by using the average outcomes of single tracings of two observers.