Elsevier

Injury

Volume 47, Issue 6, June 2016, Pages 1258-1263
Injury

Reliability of tristimulus colourimetry in the assessment of cutaneous bruise colour

https://doi.org/10.1016/j.injury.2016.01.032Get rights and content

Abstract

Background

Bruising is one of the most common types of injury clinicians observe among victims of violence and other trauma patients. However, research has shown commonly used qualitative description of cutaneous bruise colour via the naked eye is subjective and unreliable. No published work has formally evaluated the reliability of tristimulus colourimetry as an alternative for assessing bruise colour, despite its clinical and research applications in accurately assessing skin colour. The purpose of this study was to systematically evaluate the test–retest and inter-observer reliability of tristimulus colourimetry in the assessment of cutaneous bruise colour.

Methods

Two researchers obtained repeated tristimulus colourimetry measures of cutaneous bruises with participants of diverse skin colour. Measures were obtained using the Minolta CR-400 Chomameter. Commission Internationale d’Eclairage (CIE) L*a*b* colour space was used. Data was analysed using intraclass correlation coefficients (ICC), Cronbach's alpha, and minimal detectable change (MDC) on all three L*a*b* values.

Results

The colorimeter demonstrated excellent test–retest or intra-rater reliability (L* ICC = 0.999; a* ICC = 0.973; b* ICC = 0.892) and inter-rater reliability (L* ICC = 0.997; a* ICC = 0.976; b* ICC = 0.982).

Conclusions

With consistent placement, the tristimulus colourimetry is reliable for the objective assessment and documentation of cutaneous bruise colour for purposes of clinical practice and research. Recommendations for use in practice/research are provided.

Introduction

Bruising is one of the most common types of soft tissue injury from accidental and non-accidental blunt or squeezing force mechanisms of injury [1]. Bruising from non-accidental blunt or squeezing force trauma is a common sequelae to being a victim of interpersonal violence, including intimate partner violence, sexual assault, child abuse, and vulnerable adult abuse [1], [2], [3], [4]. The prevalence of this type of injury ranges from 50% among injured victims of sexual assault to 89% of injured victims of child abuse [2], [3]. Overall, the identification and documentation of violence-related injuries, such as bruises, are associated with more successful prosecution [5]. Therefore, it is vital these types of injuries are properly assessed and documented in a consistent and reliable manner.

Visual inspection of colour is a complex, psychophysical process of both colour perception and qualitative operationalisation [6]. Thus, research has shown describing the subtle colour changes of bruising via the naked eye is a subjective and unreliable practice with poor inter- and intra-observer reliability [7], [8]. This visual practice has often led to a disparity in the recognition of bruises on various skin types, in particular dark skinned individuals [9].

The use of tristimulus colourimetry as an accurate and objective measure of colour is well established in the field of dermatology, including the pigmentation of skin and scars [10]. However, the reliability of this technology applied to measuring bruise coloration has not been formally evaluated, despite its potential clinical and research applications [11], [12], [13], [14]. The purpose of our study was to examine the test–retest (intra-rater) and inter-rater reliability of using tristimulus colourimetry in the assessment of cutaneous bruise colour on a diverse group of healthy, adult subjects. In addition, we evaluated whether it is necessary to lift the head of the instrument from the skin's surface between measures in order to prevent venous congestion.

Section snippets

Participants

This research was performed as part of a larger, longitudinal study on bruise colour change [15]. Participants were a convenience sample of 27 healthy adult men and women who had 31 bruise examinations conducted for the test–retest evaluation portion of this study (Phase 1). To examine inter-rater reliability (Phase 2), 22 bruise examinations were performed on 10 adult subjects. The participants were primarily young (mean age = 27 years), female (69%), but with diverse skin colour (Table 1). Skin

Phase 1

The overall mean L*a*b* values for Measures 1 and 2 are presented in Table 2. The median (range) overall colour difference (ΔEab) was 0.34 (0.01–1.28). Only two of the 31 sets of measurements demonstrated an overall colour difference of ΔEab  1 (Fig. 2). However, paired t-tests demonstrated no statistically significant difference between Measures 1 and 2 for all three L*a*b* values (Table 2).

The ICCs for test–retest reliability of the CR-400 for bruise colour demonstrated excellent single and

Discussion

To our knowledge, our study is the first to thoroughly evaluate both the intra- and inter-observer reliability of a tristimulus colorimeter on bruises. The Minolta Chromameter® CR-400 demonstrated excellent reproducibility and precision on bruises for all three colour parameters, L*, a*, and b*. During repeated testing, the colour difference between average measures was not statistically (p < 0.05) nor clinically (ΔEab < 1.0), significant. Our findings are consistent with the work of Hughes et al.

Practice application

Experts at the U.S. Food and Drug Administration have long recommended using colourimetry for measuring subtle colour changes in skin [26]. Current trauma-relevant applications of this technology noted in the literature include assessing erythema [27], documenting bruise healing [15], and evaluating scar vascularity [28]. In addition, research has demonstrated the use of this technology for detecting early stage pressure ulcers [29] and granulation tissue [30]. The interest in accurate

Limitations

There are a few limitations to this study. First, the observers were not blinded to the colorimeter readings. However, no systematic bias was evident when evaluating the mean difference between observers. Since some subjects participated more than once, one could argue there may be bias with the high correlation between subjects’ repeated participation. Each set of scans was treated as independent because time trend was not the focus of this study. However, if the sample was viewed as more

Conclusion

Using a colorimeter to accurately assess bruise colour greatly decreases, if not eliminates, subjectivity in the interpretation and description of bruise appearance. The Minolta Chromameter® CR-400 demonstrated excellent test–retest and inter-observer reliability on the assessment of bruise colour. During repeated measurements, the colorimeter's application should be consistent in location while limiting contact pressure. When obtaining an average of multiple scans, it is not necessary to lift

Conflict of interest

The authors of this manuscript (Reliability of tristimulus colourimetry in the assessment of cutaneous bruise colour) have no conflicts of interest to declare. No funding was received for this study. Study equipment was on loan from Konica Minolta®.

Acknowledgements

Jacquelyn Campbell, PhD, RN, FAAN, Valerie DeLeon, PhD, MA, JD, Elizabeth Jordan, DNSc, RN, and Sharon Olsen, PhD, RN, AOCN are acknowledged for their critical review of the study proposal. Jane Fall-Dickson, PhD, RN is also recognised for her assistance in the preparation of this manuscript.

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