Date Published: July 18, 2017
Publisher: Public Library of Science
Author(s): Sanminder Singh, Paulina Young, April W. Armstrong, Shahrad Taheri.
The relationship between psoriasis and metabolic syndrome is not well understood. Though multiple epidemiologic studies have suggested a link between psoriasis and metabolic syndrome, there is a lack of a comprehensive meta-analysis synthesizing the results of all available observational studies to date. In this meta-analysis, we examined global data on the relationship between psoriasis and odds of metabolic syndrome by searching for studies published between 1946–2016. Specifically, we analyzed the results from 35 observational studies from 20 countries with 1,450,188 total participants, of which 46,714 were psoriasis patients. The pooled odds ratio based on random effects analysis was 2.14 (95% CI 1.84–2.48). Publication bias was present, as evidenced by an Egger test and graphical visualization through a funnel plot (p = 0.001). Based on this comprehensive meta-analysis, psoriasis patients have higher odds of having metabolic syndrome when compared with the general population.
Psoriasis is a chronic, inflammatory skin condition that affects between 2–4% of the general population, with recent estimates suggesting over 125 million patients worldwide [1, 2]. It is associated with a number of comorbidities as well as a high socioeconomic burden [3, 4]. Psoriasis patients also experience a decreased quality of life as a result of this disease . The pathogenesis of psoriasis is currently under active investigation, with studies aiming to identify genetic susceptibility loci for psoriasis in order to detect novel targets for systemic therapy [6–9]. While the exact pathogenesis of psoriasis is not fully understood, basic and translational investigations have led to a renewed understanding of Th-17 and Th-1 pathways involved in the development of psoriasis . Notably, the Th-1 pathway involving dysregulation and activation of Th-1 inflammatory cells is thought to contribute to obesity and insulin resistance, which can increase the risk for cardiovascular disease [11–13].
To examine the association between metabolic syndrome and psoriasis, we followed PRISMA guidelines to perform a meta-analysis of observational studies identified through our two prior systematic reviews [27, 28] combined with additional studies from a new literature search. The PRISMA checklist is attached (S1 File). For the prior systematic reviews, we used the search terms “Psoriasis” [MeSH] and “Metabolic Syndrome X” [MeSH] to search literature from January 1, 1946 to June 30, 2016. To search for any additional studies published after June 30, 2016, we repeated the search using the same search terms and applied a time restriction for studies published from July 1, 2016 to Jan 1, 2017.
This meta-analysis analyzed data from 35 studies with a total of 1,450,188 participants, among which 46,714 were patients with psoriasis. We searched over 70 years of literature, spanning from January 1, 1946 to Jan 1, 2017, using the Medline, Embase, Cochrane Central register, and Scopus databases [27, 28]. Out of the 35 articles, ten provided adjusted odds ratios after multivariate adjustment for factors such as age, sex, smoking, alcohol consumption, physical activity, and education [31, 34–42]. Among the remaining articles, 16 provided unadjusted odds ratios [30, 43–58], seven provided percent values for metabolic syndrome prevalence [59–65], and two provided specific numbers of patients affected without percent values or odds ratios. For the nine articles that did not provide any odds ratios, we calculated unadjusted odds that were then included in the meta-analysis (Table 1).
This is a meta-analysis based on primary studies published between 1946–2017 that were identified through a comprehensive systematic review. The meta-analysis examines the relationship between psoriasis and metabolic syndrome, incorporating 35 articles from 20 countries with a total of 1,450,188 participants, including 46,714 psoriasis patients. To our knowledge, this is the most comprehensive meta-analysis on psoriasis and metabolic syndrome to date. Our pooled OR of 2.14 indicates a higher prevalence of metabolic syndrome in psoriasis patients in comparison to the general population. With the added impact of new and previously unexamined primary studies, our study maintains and strengthens the positive correlation between psoriasis and metabolic syndrome found in our 2013 meta-analysis, which had demonstrated a pooled odds ratio of 2.26 from 12 studies [27, 28].