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Correlation between psoriasis' severity and waist-to-height ratio* * Work performed at Universidade Federal da Bahia (UFBA) - Salvador (BA), Brazil.

Abstract

In the absence of ideal biomarkers, the research for clinical markers correlated to the severity of psoriasis and/or its comorbidities becomes crucial. Recently, studies have shown positive correlation between body mass index and prevalence and severity of psoriasis. Abdominal circumference showed stronger correlation with disease severity than body mass index. We evaluated the waist-to-height ratio in a sample of 297 adult patients with psoriasis and observed that it has a significant correlation with body mass index and PASI, and together with body mass index allows the identification of central obesity, reducing its subdiagnosis.

Anthropometry; Comorbidity; Obesity; Psoriasis


We have previously demonstrated that the severity of psoriasis measured by PASI (Psoriasis Area Severity Index) in a Brazilian population presents a significant correlation with anthropometric measurements, such as Body Mass Index (BMI), Waist-to-Hip Ratio (WHR) and Waist Circumference (WC), especially the last two.1Duarte GV, Oliveira Mde F, Cardoso TM, Follador I, Silva TS, Cavalheiro CM, et al. Association between obesity measured by different parameters and severity of psoriasis. Int J Dermatol. 2013;52:177-81.

Recent studies show that Waist-to-height Ratio (WhtR) has a stronger correlation with cardiovascular diseases than WC.2Wakabayashi I. Necessity of Both Waist Circumference and Waist-to Height Ratio for Better Evaluation of Central Obesity. Metab Syndr Relat Disord. 2013;11:189-94.,3Xu Z, Qi X, Dahl AK, Xu W. Waist-to-height ratio is the best indicator for undiagnosed Type 2 diabetes. Diabet Med. 2013;30:e201-7. Paller and cols. (2013) demonstrated that children with psoriasis have greater averages of WhtR than non-affected children. As it is not adequate for different ethnicities/ages, muscle mass levels, bone structure and not measuring central adiposity, BMI does not seem to be the best method for follow-up of patients with psoriasis even though it is still the most recommended by all guidelines.5Sterry W, Strober BE, Menter A; International Psoriasis Council. Obesity in psoriasis: the metabolic, clinical and therapeutic implications. Report of an interdisciplinary conference and review. Br J Dermatol. 2007;157:649-55.,6Kimball AB, Gladman D, Gelfand JM, Gordon K, Horn EJ, Korman NJ, et al. National Psoriasis Foundation clinical consensus on psoriasis comorbidities and recommendations for screening. J Am Acad Dermatol. 2008;58:1031-42.,7Duarte GV, Follador I, Cavalheiro CM, Silva TS, Oliveira Mde F. Psoriasis and obesity: literature review and recommendations for management. An Bras Dermatol. 2010;85:355-60. We performed a cross-sectional study in which minimum sampling size (292) was calculated based on obesity prevalence in Bahia, around 5%, according to data from IBGE 2002 - 2005 Pesquisa de Orçamentos Familiares (Family Budgets Survey). A prevalence variation of 5% was considered, and then the formula N = z.p.q/d2 was used, where Z=1.96, P=prevalence, Q=(1-P) and d=error margin (±2.5%). New and subsequent patients were enrolled, totaling 296 patients in the period from October/2008 to August/2010. We evaluated WhtR in a sample of 297 adult patients with psoriasis, 289 of which had complete anthropometric measurements.

A structured questionnaire was used for data collection. The results of the obesity prevalence study were previously published1Duarte GV, Oliveira Mde F, Cardoso TM, Follador I, Silva TS, Cavalheiro CM, et al. Association between obesity measured by different parameters and severity of psoriasis. Int J Dermatol. 2013;52:177-81.. Descriptive statistics were done with the help of SPSS version 20.0 for Windows, the continuous variables described through means (± standard deviation) as well as medians and interquartiles, while categorical variables were described as proportions. The quantitative variables studied were submitted to the normality test of Kolmogorov-Smirnov. The significance level adopted was of 5%.

The mean ± standard deviation (SD) of PASI for the sample was of 8.1 ± 7.8 (median 5.3; p25=2.7 and p75=10.9). WhtR varied from 0.38-0.92 with mean ± SD of 0.57 ± 0.08 and median of 0.56.

PASI for the 243 patients with WhtR >0.5 had a median of 5.7, significantly greater than in the 48 patients with WhtR <0.5, 3.7 (Mann Whitney; p=0.03). Correlation between WhtR and BMI was of 0.86 (Spearman, p<0.01). Correlation between WhtR and PASI was of 0.14 (Spearman, p=0.01).

Among 243 patients with alteration in anthropometric measure (BMI or WhtR), only 82 (33%) were detected by BMI (Table 1). In table 2 we observed that 110 patients whose WhtR showed obesity were classified as "overweight" instead of "obese" by BMI. When WhtR was <0.5, no obese patient was found according to BMI.

TABLE 1
Comparison of abnormal findings of WhtR and BMI based on cutoff points for obesity
TABLE 2
Distribution of WhtR frequencies and description of subgroups as per BMI cutoff points ("normal", "overweight" and "obese"). BMI in kg/m2

The importance of a clinical marker correlated to the severity of psoriasis resides in the fact that we still do not have ideal biomarkers.8Fitzgerald O and Chandran V. Update on Biomarkers in Psoriatic Arthritis: A Report from the GRAPPA 2010 Annual Meeting. J Rheumatol. 2012;39:427-30. WhtR is found to be an accessible method, with an equal cutoff point for both sexes, correlated to obesity, cardiovascular disease and diabetes mellitus.2Wakabayashi I. Necessity of Both Waist Circumference and Waist-to Height Ratio for Better Evaluation of Central Obesity. Metab Syndr Relat Disord. 2013;11:189-94.,3Xu Z, Qi X, Dahl AK, Xu W. Waist-to-height ratio is the best indicator for undiagnosed Type 2 diabetes. Diabet Med. 2013;30:e201-7. Considering that there is still no consensus about which is the best method, WhtR in this sample was quite correlated with obesity in patients with psoriasis, avoiding the problems of using BMI alone, besides presenting a positive correlation with PASI values.

  • Financial funding: None
  • How to cite this article: Duarte GV, Silva LP. Correlation between psoriasis' severity and waist-to-height ratio. An Bras Dermatol. 2014;89(5):846-7.
  • *
    Work performed at Universidade Federal da Bahia (UFBA) - Salvador (BA), Brazil.

ACKNOWLEDGEMENTS

To Pedro Dantas and Lídia Machado, dermatologists from Universidade Federal da Bahia, for the enriching critical reading of the work and collaboration on statistical analysis. To Yuri Oliveira for grammatical review.

REFERENCES

  • 1
    Duarte GV, Oliveira Mde F, Cardoso TM, Follador I, Silva TS, Cavalheiro CM, et al Association between obesity measured by different parameters and severity of psoriasis. Int J Dermatol. 2013;52:177-81.
  • 2
    Wakabayashi I. Necessity of Both Waist Circumference and Waist-to Height Ratio for Better Evaluation of Central Obesity. Metab Syndr Relat Disord. 2013;11:189-94.
  • 3
    Xu Z, Qi X, Dahl AK, Xu W. Waist-to-height ratio is the best indicator for undiagnosed Type 2 diabetes. Diabet Med. 2013;30:e201-7.
  • 4
    Paller AS, Mercy K, Kwasny MJ, Choon SE, Cordoro KM, Girolomoni G, et al Association of pediatric psoriasis severity with excess and central adiposity: an international cross-sectional study. JAMA Dermatol. 2013;149:166-76.
  • 5
    Sterry W, Strober BE, Menter A; International Psoriasis Council. Obesity in psoriasis: the metabolic, clinical and therapeutic implications. Report of an interdisciplinary conference and review. Br J Dermatol. 2007;157:649-55.
  • 6
    Kimball AB, Gladman D, Gelfand JM, Gordon K, Horn EJ, Korman NJ, et al National Psoriasis Foundation clinical consensus on psoriasis comorbidities and recommendations for screening. J Am Acad Dermatol. 2008;58:1031-42.
  • 7
    Duarte GV, Follador I, Cavalheiro CM, Silva TS, Oliveira Mde F. Psoriasis and obesity: literature review and recommendations for management. An Bras Dermatol. 2010;85:355-60.
  • 8
    Fitzgerald O and Chandran V. Update on Biomarkers in Psoriatic Arthritis: A Report from the GRAPPA 2010 Annual Meeting. J Rheumatol. 2012;39:427-30.

Publication Dates

  • Publication in this collection
    Sep-Oct 2014

History

  • Received
    09 June 2013
  • Accepted
    09 Sept 2013
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