Marc P. Frey

A Note on Sample Size and Solution Propriety for Confirmatory Factor Analytic Models

Determining an appropriate sample size for use in latent variable modeling techniques has presented ongoing challenges to researchers. In particular, small sample sizes are known to present concerns over sampling error for the variances and covariances on which model estimation is based, as well as for fit indexes and convergence failures. The literature on the topic has focused on conducting power analyses as well as identifying rules of thumb for deciding an appropriate sample size. Often the advice involves an assumption that sample size requirement is moderated by aspects of the model in question. In this study, an effort was undertaken to extend the findings of Gagné and Hancock (2006) on measurement model quality and solution propriety to a broader set of confirmatory factor analysis models. As well, we examined whether Herzog, Boomsma, and Reineckes (2007) findings for the Swain correction to the χ2 statistic for large models would generalize to models in our study. Our findings suggest that Gagné and Hancocks approach extends to large models with surprisingly little increase in sample size requirements and that the Swain correction to χ2 performs fairly well. We argue that likely rejection or model fit should be taken into account when determining sample size requirements and therefore, provide an updated table of minimum sample size that incorporates Gagné and Hancocks method and model fit.

The Relationship Between Dermatologist- and Patient-Reported Acne Severity Measures and Treatment Recommendations

Background: Acne treatment recommendations for individual patients may be derived from multiple factors including dermatologist- and patient-reported constructs. Objectives: To evaluate the effects of dermatologist- and patient-reported measures on acne treatment recommendations by dermatologists. Methods: An observational cross-sectional survey of acne patients was conducted with patient-reported quality of life and dermatologist-reported measures of primary and secondary (scar) acne severity using 3 assessment approaches: maximal regional grade, total grade, and facial grade. Results: The most highly associated factors with acne treatment recommendations were patient emotions, maximal regional acne severity, and total acne scar grade. Better acne-specific quality of life was negatively related to acne treatment recommendation intensity, while all 3 grading approaches were positively related to acne treatment recommendations. Conclusions: For dermatologists, overall acne severity is most highly associated with maximal regional acne grade, total scar grade, and patient’s emotional response to acne.

Assessing the Need for a Comprehensive Acne Quality-of-Life Scale for Face and Torso Acne

Purpose: While acne, a common condition, largely involves the face, chest, and back, current acne quality-of-life measures focus primarily on facial acne. The purpose of this study was to assess the need for a comprehensive quality-of-life measure intended for use with patients who have facial and/or torso acne. Methods: We evaluated the need for a comprehensive quality-of-life scale for facial and torso acne based on data from an epidemiological survey (N = 690) in which participants were grouped according to the location of their acne (face, torso, or both) and where quality of life was assessed. Results: Analysis of variance results revealed that participants with acne on their torso reported the highest levels of quality of life while participants with acne on their face reported the lowest levels. Conclusions: There is a need for a quality-of-life instrument that assesses the impact of acne on the face and torso separately. This unmet need can be addressed with a comprehensive acne quality-of-life measure that is inclusive of torso acne.

Development of a Comprehensive Quality-of-Life Measure for Facial and Torso Acne:

Background Acne is a chronic skin disorder which generally presents in adolescence but continues into adulthood, and negatively affects both physical and psychosocial well-being. Presently, there are no validated acne-specific quality-of-life (QoL) measures that include dimensions for both facial and torso acne. Objective: The objective of this study was to develop a QoL instrument for both facial and torso acne (CompAQ) in accordance with recommended standards. Methods: A literature review and Delphi survey of patients and clinicians were used to develop the conceptual framework for outcomes perceived important to acne patients. An initial version of the measure was developed, CompAQ-v1, and pilot tested with patients via cognitive interviews. Results: The Delphi survey generated 4 domains (physical, psychological, sociological, and treatment) and 54 items. These, along with a literature review and input from clinical experts, informed the development of the CompAQ-v1. Eleven cognitive interviews were conducted, resulting in the second version of the measure, CompAQ-v2. Psychometric validation resulted in the final 20-item CompAQ measure comprising 5 domains. An abbreviated 5-item measure was also developed (CompAQ-SF). Conclusion: CompAQ and CompAQ-SF are instruments intended to evaluate QoL in patients with acne on their face or torso. The former is a 21-item QoL intended for research, while the latter is intended for clinical practice.

The Utility of Assessing Neck Acne.

Background: Acne grading is an essential component in establishing treatment options, but little is known on how neck acne should be incorporated into grading scales. Objective: Our objective was to explore the prevalence of neck acne and determine if its own severity category on an acne global grading scale was warranted. Methods: Acne severity was assessed in 6 categories: face, chest, back, anterior upper (AUN), anterior lower neck (ALN), and posterior neck (PN). Results: The overall prevalence of neck acne was 49%. Of these, 44% had AUN acne, 18.5% had ALN acne, and 19.8% had PN acne. AUN and facial acne had a significant correlation (r = 0.37, P < .05). No correlation was seen amongst other areas. Males presented with a significantly higher severity of AUN (mean [SD], 1.37 [1.09]) than females (mean [SD], 0.52 [0.91]), on average. Conclusions: While neck acne has proven to be common amongst those with acne on other areas of the body, facial acne can be used as a proxy for classification, as neck severity is usually milder.