Analysis of ordinal data in clinical and experimental studies.
11 Nov 2020-Jornal Vascular Brasileiro (Sociedade Brasileira de Angiologia e de Cirurgia Vascular (SBACV))-Vol. 19
About: This article is published in Jornal Vascular Brasileiro.The article was published on 2020-11-11 and is currently open access. It has received 11 citations till now. The article focuses on the topics: Ordinal data & MEDLINE.
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TL;DR: In this paper, the authors compared the efficacy and tolerability of topical 0.2% Thiamidol vs. 4% hydroquinone for facial melasma, and found that the effectiveness of topical ThiamIDol did not differ from that of 4% Hydroquinone cream.
Abstract: BACKGROUND Melasma can be refractory to treatment, and relapses are frequent. Thiamidol is a new potent tyrosinase inhibitor that has been found effective as a cosmeceutical for the depigmenting of melasma. OBJECTIVE This study compared the efficacy and tolerability of topical 0.2% Thiamidol vs. 4% hydroquinone for facial melasma. METHODS Fifty women with facial melasma participated in a randomized, evaluator-blinded, controlled study from September through November 2020. Patients were randomly assigned to apply a double layer of 0.2% Thiamidol twice a day or 4% hydroquinone cream at bedtime, for 90 days. Both groups received tinted sunscreen (sun protection factor 60, PPD 20). The primary outcome was the change from the baseline Modified Melasma Area Seve:rity Index (mMASI) score. Secondary outcomes were improvements in the patients' quality of life [Melasma Quality of Life Index (MELASQoL)], colourimetry, and Global Aesthetic Improvement Scale (GAIS) evaluation. RESULTS One participant, from the hydroquinone group, did not complete the study (unrelated to adverse effects). The mean (SD) age of the participants was 43 (6) years, and 86% were phototypes III-IV. Both groups exhibited a reduction in mMASI, MELASQoL, and colour contrast scores (P < 0.01). The mean [95% confidence interval (CI 95%)] reductions of the mMASI scores were 43% (35-50%) for Thiamidol and 33% (23-42%) for hydroquinone. There was no difference between the groups in the reductions in mMASI, MELASQoL, colourimetric contrast and GAIS scores (P ≥ 0.09). The GAIS analysis resulted in an improvement of 84% (CI: 95% 67-97%) for participants in the Thiamidol group and 74% (CI: 95% 61-93%) for those in the hydroquinone group. There were only mild adverse effects in the Thiamidol group, but allergic contact dermatitis was evidenced in two (8%) participants. CONCLUSION The melasma improvement achieved using 0.2% Thiamidol did not differ from that of 4% hydroquinone cream. Thiamidol can be considered a suitable option for melasma patients with poor tolerability or treatment failure with hydroquinone.
17 citations
TL;DR: The One21 technique yielded better results than the standard 5-point treatment in reducing glabellar dynamic lines with Incobotulinumtoxin A, especially for asymmetric lines of the glabella or the involvement of muscle groups other than the procerus and corrugator.
Abstract: Purpose Botulinum toxin type A is an effective treatment for glabellar dynamic wrinkles. As the muscular group involved in the contraction of the glabella varies among people, individualized treatment can achieve optimal results. This study evaluates a customized assessment for the treatment of glabellar lines with Incobotulinumtoxin-A, leading to an individualized points distribution and dosage. Patients and Methods A single-center, evaluator-blinded, therapeutic cohort study enrolled 130 women with moderate or severe glabellar wrinkles. They underwent Incobotulinumtoxin-A injection following the standard 5-point injection at the glabellar muscles (n = 65) or an individualized assessment and scheme treatment based on anatomical references of contraction, the One21 technique (n = 65). All the patients were photographed under maximum contraction before treatment (T0) and after 4 weeks (T28). The photos were randomly assessed by two blinded, experienced raters to consensually grade the severity according to the Merz Aesthetics Scales (MAS). The primary clinical efficacy was defined as a 2-point reduction in the MAS score, on Day 28. Results The groups were homogeneous regarding age, phototype, and baseline MAS scores. On Day 28 (T28), 64 (98.5%) patients from the One21 group and 52 (80%) from the 5-point group reduced the MAS score by at least two points (p < 0.01). When adjusted by age and phototype, both groups reduced the MAS score at T28 (p < 0.01); nevertheless, patients from the One21 group significantly performed better (p < 0.01), with a much higher rate response rate at T28, in comparison to the 5-point group. Of patients enrolled in the 5-point group, 83.1% utilized muscle groups other than the procerus and corrugator in glabellar wrinkle formation, and 17 (24.6%) presented asymmetrical contraction. Patients from the 5-point group with glabellar asymmetry and those who utilized the frontalis and orbicularis presented inferior performance (p < 0.05), reinforcing the importance of an individualized assessment and treatment plan. Conclusion The One21 technique yielded better results than the standard 5-point treatment in reducing glabellar dynamic lines with Incobotulinumtoxin-A, especially for asymmetric lines of the glabella or the involvement of muscle groups other than the procerus and corrugator.
11 citations
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Abstract: Background and objective There is no validated instrument to assess the clinical severity of striae distensae. Here, we aimed to develop a striae distensae severity scale. Material and methods After a Delphi-based consensus, 15 items related to striae severity were assessed in 110 areas (breasts, abdomen, and buttocks) from 45 participants. The items were analyzed through a partial least squares model to select the most important variables. To assess the reliability of the scale, 43 areas were retested. Results Of the 110 areas evaluated, 34 were breasts, 24 abdomens, and 52 buttocks. Striae were considered mild in 30% of the evaluations, moderate in 33%, severe in 21%, and extremely severe in 16%. The final model was composed by: width of the widest striae, width of the striae with the most frequent pattern, atrophy, number of affected quadrants, distribution (multiple or isolated), hypo or hyperchromia and topography. The scores of the scale demonstrated a high correlation with the clinical classification (rho = 0.77). There was a high agreement in the scores from the reassessed areas (intraclass correlation coefficient = 0.90). Conclusion An objective and reliable scale to assess the clinical severity of striae distensae on the breasts, abdomen, and buttocks was developed.
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References
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TL;DR: The impact of converting continuous data to two groups (dichotomising) is considered, as this is the most common approach in clinical research.
Abstract: Measurements of continuous variables are made in all branches of medicine, aiding in the diagnosis and treatment of patients. In clinical practice it is helpful to label individuals as having or not having an attribute, such as being “hypertensive” or “obese” or having “high cholesterol,” depending on the value of a continuous variable.
Categorisation of continuous variables is also common in clinical research, but here such simplicity is gained at some cost. Though grouping may help data presentation, notably in tables, categorisation is unnecessary for statistical analysis and it has some serious drawbacks. Here we consider the impact of converting continuous data to two groups (dichotomising), as this is the most common approach in clinical research.1
What are the perceived advantages of forcing all individuals into two groups? A common argument is that it greatly simplifies the statistical analysis and leads to easy interpretation and presentation of results. A …
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TL;DR: It is suggested that investigators who are unfamiliar with Wilcoxon-Mann-Whitney methods should seek the assistance of a professional statistician when they must deal with ordered categories of this kind.
Abstract: Clinical investigations often involve data in the form of ordered categories — e.g., "worse," "unchanged," "improved," "much improved." Comparison of two groups when the data are of this kind should not be done by the chi-square test, which wastes information and is insensitive in this context. The Wilcoxon-Mann-Whitney test provides a proper analysis. Alternatively, scores may be assigned to the categories in order, and the t-test applied. We demonstrate both approaches here. Sometimes data in ordered categories are reduced to a two-by-two table by the collapsing of the high categories into one category and the low categories into another. This practice is inefficient; moreover, it entails avoidable subjectivity in the choice of the cutting point that defines the two super-categories. The Wilcoxon-Mann-Whitney procedure (or the t-test with use of ordered scores) is preferable. A survey of research articles in Volume 306 of the New England Journal of Medicine shows many instances of ordered-categ...
310 citations
TL;DR: The application of the proposed models to data from a study of chest x-rays of workers exposed to mineral fibers confirmed that they are easy to use and interpret, but gave results quite similar to those obtained using simple logistic regression after dichotomizing outcome in the conventional way.
Abstract: Health status is often measured in epidemiologic studies on an ordinal scale, but data of this type are generally reduced for analysis to a single dichotomy. Several statistical models have been developed to make full use of information in ordinal response data, but have not been much used in analyzing epidemiologic studies. The authors discuss two of these statistical models--the cumulative odds model and the continuation ratio model. They may be interpreted in terms of odds ratios, can account for confounding variables, have clear and testable assumptions, and have parameters that may be estimated and hypotheses that may be tested using available statistical packages. However, calculations of asymptotic relative efficiency and results of simulations showed that simple logistic regression applied to dichotomized responses can in some realistic situations have more than 75% of the efficiency of ordinal regression models, but only if the ordinal scale is collapsed into a dichotomy close to the optimal point. The application of the proposed models to data from a study of chest x-rays of workers exposed to mineral fibers confirmed that they are easy to use and interpret, but gave results quite similar to those obtained using simple logistic regression after dichotomizing outcome in the conventional way.
301 citations
TL;DR: In a pedantic but playful way, some common errors in the use of statistical analysis that are regularly observed in professional plastic surgical literature are discussed.
Abstract: In a pedantic but playful way, we discuss some common errors in the use of 'statistical analysis' that are regularly observed in our professional plastic surgical literature. The seven errors we discuss are (1) the use of parametric analysis of ordinal data; (2) the inappropriate use of parametric analysis in general; (3) the failure to consider the possibility of committing type II statistical error; (4) the use of unmodified t-tests for multiple comparisons; (5) the failure to employ analysis of covariance, multivariate regression, nonlinear regression, and logistical regression when indicated; (6) the habit of reporting standard error instead of standard deviation; and (7) the underuse or overuse of statistical consultation. Confidence and common sense are advocated as a means to balance statistical significance with clinical importance.
248 citations