Global Epidemiology of Psoriasis: A Systematic Review of Incidence and Prevalence

Psoriasis Epidemiology: The Interplay of Genes and the Environment

There is a lack of any overview of changes over time and variation in the epidemiology of psoriasis with age and between genders. To perform a systematic review of published population-based studies on variations in psoriasis incidence and prevalence with age and between genders, and to explore trends in psoriasis epidemiology over time. Eleven electronic and regional databases were searched from their inception dates to October 2019. No language restrictions were applied. Studies were eligible if they reported on changes in psoriasis incidence and/or prevalence over time and/or by age group and gender. In total 308 papers were critically appraised, from which 90 studies from 22 countries were included. Incidence data confirmed a clear bimodal age pattern in psoriasis onset, with the first and second peaks at around 30-39 and 60-69 years of age, respectively, and evidence suggesting that it presents slightly earlier in women than in men. Prevalence data showed an increasing trend with age until around 60 or 70 years, after which it decreases. Although there was lack of agreement on specific gender differences in psoriasis incidence and prevalence, a slight male predominance was reported in several studies. Studies worldwide suggested a stable or slightly decreasing trend in psoriasis incidence, while an increasing trend in psoriasis prevalence has been consistently reported. One particular challenge faced was the vastly different methodologies used in the included studies, which contributed to some of the heterogeneity of the results. Studies on changes over time in the occurrence of psoriasis have contributed to a greater appreciation of the increasing burden of the disease. However, further research is required to determine the reasons driving the increase in psoriasis prevalence over time.

To estimate the prevalence and incidence of psoriasis and psoriatic arthritis (PsA) over time in Ontario, Canada. We performed a population-based study of Ontario health administrative data, using validated case definitions for psoriasis and PsA. We computed the crude and age- and sex-standardized cumulative prevalence and incidence of psoriasis from 2000 to 2015. Among the 10,774,802 individuals ages ≥20 years residing in Ontario in 2015, we identified 273,238 patients with psoriasis and 18,655 patients with PsA, equating to cumulative prevalence estimates of 2.54% and 0.17%, respectively. Correcting the prevalence estimates for imperfect sensitivity and specificity resulted in similar estimates. The male:female ratio was approximately 1.0 for both conditions. For psoriasis, the age- and sex-standardized cumulative prevalence increased from 1.74% in 2000 to 2.32% in 2015. For PsA, the age- and sex-standardized cumulative prevalence increased from 0.09% in 2008 to 0.15% in 2015. Between 2008 and 2015, annual incidence rates for psoriasis decreased, whereas those for PsA remained relatively stable. The prevalence and incidence of psoriasis and PsA in Ontario are similar to those observed in Europe and the US. The steady increase in the prevalence of psoriasis and PsA over the past decade may be due to a combination of population aging, population growth, and increasing life expectancy.

The article presents the results of a study on assessment the differences of psoriasis incidence in adults in regions of the Russian Federation. The indicators of general and primary incidence of psoriasis were used as the material for a study according to the data from Central Research Institute of Health Organization and Informatics of the Ministry of Public Health of the Russian Federation for the period 2009-2013. The comparative results of psoriasis prevalence among adults population in various regions in Russia were presented. Higher incidence rate was detected in the northern and northeastern regions of the North-Western, Volga, Ural, and Far Eastern regions. The results of classification for the regions of the Russian Federation according to the data of primary and general morbidity were presented. In order to establish the peculiarities of pathology formation and assess the quality of information in the regions of the Russian Federation, a multidimensional classification of the incidence of psoriasis was carried out using the cluster analysis method, using the comparison of prevalence (general morbidity) with primary incidence data for the period 2009-2011. As a result of the cluster analysis, four classes of the country regions are distinguished, the differences between which are statistically significant for all classification characteristics. The average indices of both primary incidence and prevalence of psoriasis are registered in regions of Class 1 (27 subjects of the Russian Federation). The minimum indices of primary and general incidence of psoriasis were noted in class 2 (24 subjects of the Russian Federation), which comprised regions predominantly of the Central, Southern, Siberian FD. The highest rates of primary incidence and prevalence of psoriasis were found in the group of regions that made up Class 4 (14 subjects of the Russian Federation), in a third of the regions of this class - Orel and Sverdlovsk regions, Udmurt Republic, Komi Republic and Sakha (Yakutia), data, unsatisfactory dispensary observation of patients with psoriasis. A certain decrease in the availability of specialized dermatological care can be expected in Class 3 regions, where the primary incidence is low, and the prevalence is above the average (18 subjects of the Russian Federation).

The WHO has highlighted the necessity of gaining a deeper understanding of the global burden of psoriasis. In response to this need, the Global Psoriasis Atlas was established to conduct comprehensive research into the global prevalence and incidence of psoriasis. We aimed to systematically review and present up-to-date data on the incidence of psoriasis, as well as to quantify its prevalence at global, regional, and country-specific levels. Literature searches were updated from 2019 to January 2024, resulting in 48 new studies. Among these, 13 studies reported incidence data, 7 reported only incidence, 6 reported both prevalence and incidence, and the remaining 35 studies reported only prevalence. In total, our updated prevalence analysis included 170 population-based epidemiological studies. A Bayesian hierarchical linear mixed model was employed to estimate the global, regional, and country-specific prevalence of psoriasis. Countries were mapped according to the global burden of disease (GBD) classification, considering geography and income. The data were fitted to a statistical model using Bayesian inference, sampling from a posterior distribution through a Hamiltonian Markov chain Monte Carlo method implemented in the RStanArm package in R (version 4.4.0). The updated review incorporated data from eight new countries and expanded to cover two additional GBD global regions. We observed a global increase in the prevalence of psoriasis, with some variations attributed to the significant expansion with the update of certain very sparse datasets. The crude lifetime prevalence for adults in high-income countries increased from 1.12% [95% confidence interval (CI): 0.39, 2.79] to 1.40% (95% CI: 0.52, 3.25). In the Latin America and Caribbean super-region, prevalence rates appear to have slightly decreased, but this finding is based on a very low evidence base, with no studies on psoriasis prevalence included from Caribbean countries. Most of the newly added studies were from high-income countries, with 70% originating from Western Europe, North America, and high-income Asian countries. The incidence of psoriasis varied from 23.14 per 100 000 person years in Taiwan to 321.0 per 100 000 person years in Italy. The incidence of psoriasis was higher in adults than in children. Seventy-six per cent of countries worldwide lack data on the epidemiology of psoriasis. The prevalence of psoriasis is higher in adults compared with children. Additionally, the distribution of psoriasis varies geographically, with higher frequency observed in high-income countries and regions with older populations. These estimates can assist countries and the international community in making informed public health decisions regarding the appropriate management of psoriasis and in monitoring changes over time.

Surveys of skin disorders have previously provided information about the prevalence and incidence of psoriasis in sub-Saharan Africa; however, the geographic and ethnic trends which may be drawn from these surveys have not been fully described in previous studies, which considered only a fraction of the available data. A critical review of clinic-based surveys of psoriasis incidence and population-based studies of psoriasis prevalence is presented. The incidence of psoriasis is adjusted, wherever possible, to factor out the widely variable incidence of infectious skin conditions seen in African skin clinics. To distinguish between genetic and environmental factors that may be responsible for the variability of psoriasis incidence, attention is drawn to climate, human leukocyte antigen (HLA) frequencies, and language groups across the regions surveyed in sub-Saharan Africa. Higher psoriasis incidence rates are consistently observed in eastern Africa than in western Africa, consistent with more limited data on the prevalence of psoriasis in western Africa. Neither rainfall/humidity levels nor HLA frequencies can simply account for these differences; however, the ethnicities of sub-Saharan African peoples may be observed to parallel roughly the trend in psoriasis incidence. Western African countries, such as Nigeria, Mali, Senegal, and Sierra Leone, where lower rates of psoriasis incidence have been reported (less than 1.0% of skin disorders), are populated mainly by non-Bantu-speaking ethnic groups. Bantu-speaking peoples constitute a majority in the populations of most countries in eastern and southern sub-Saharan Africa, where the incidence of psoriasis varies widely. African Americans, whose largely non-Bantu-speaking African ancestry is shared with modern western Africans, also have relatively low psoriasis incidence rates by comparison with North American Caucasians. Ethnic correlations both within Africa and between North America and Africa suggest that unidentified genetic factors, which differ between eastern and western sub-Saharan Africans, may govern the differential incidence of psoriasis.

ObjectiveTo systematically review and provide information on the incidence of psoriasis and quantify global, regional, and country specific estimates of its prevalence.DesignSystematic review and meta-analysis.Data sourcesMedline, Embase, Web of Science,...

Increased incidence and prevalence of psoriasis in multiple sclerosis

Latitude and psoriasis prevalence

The Canadian province of Newfoundland and Labrador (NL) is recognized as a founder population of English and Irish descent, with an approximate population of 525 000 people. The incidence and prevalence of psoriasis in the NL population have not been formally studied, although provincial dermatologists acknowledge an increased burden of psoriasis, compared with other regions in Canada. Our objective was to examine the incidence and prevalence of psoriasis in NL and the variation by age, gender, geographic region, and time. Digital Health, Newfoundland and Labrador Health Services provided Provincial Electronic Health Records that were used to identify patients with psoriasis using International Classification of Diseases 9th revision (ICD-9) code 696 from 2001 to 2020. The prevalence of psoriasis was 6830 per 100 000 people (3801 women, 3029 men), and incidence was 365.4 per 100 000 person-years [95% confidence interval (CI), 298.0–432.9]; 395.9 (329.5–462.2) per 100 000 person-years for women and 334.2 (263.5–404.9) per 100 000 person-years for men. The peak age group for incident cases was 55–59 years, suggesting that the late onset of psoriasis is higher than in most Western European and North American populations. There was significant geographic variation in the prevalence of psoriasis, as 20 of the 234 communities with a population over 200 people had a psoriasis prevalence between 0 and 3% and nine communities with psoriasis prevalence over 30%. It is likely that regional founder effects most likely account for the high prevalence of psoriasis in selected communities, although environmental influences cannot be discounted. The NL populations had a high incidence and prevalence of psoriasis, with significant regional variations in prevalence.

There are no population-based epidemiological data on psoriasis in Southeast Asia, including Malaysia. To determine the incidence and prevalence of psoriasis over 11 years in multiethnic Johor Bahru, Malaysia. A population-based cohort study was made using the Teleprimary Care database between January 2010 and December 2020. Cases of psoriasis, identified by ICD-10 diagnostic codes, were validated by dermatologists. Annual prevalence and incidence were estimated and stratified by age, sex and ethnicity. We identified 3932 people with dermatologist-confirmed psoriasis, including 1830 incident cases, among 1 164 724 Malaysians, yielding an 11-year prevalence of 0·34% [95% confidence interval (CI) 0·33-0·35] and incidence of 34·2 per 100 000 person-years (95% CI 32·6-35·8). Rates were higher in Indian patients; the prevalences were 0·54% (0·50-0·58) in Indian, 0·38% (0·36-0·40) in Chinese and 0·29% (0·28-0·30) in Malay patients, and the respective incidences per 100 000 person-years were 52·5 (47·3-57·7), 38·0 (34·1-41·8) and 30·0 (28·2-31·8). Rates were higher in males; the prevalence was 0·39% (0·37-0·41) in males and 0·29% (0·27-0·30) in females, and the respective incidences per 100 000 person-years were 40·7 (38·2-43·2) and 28·3 (26·4-30·3). Between 2010 and 2020, annual psoriasis prevalence and incidence increased steadily from 0·27% to 0·51% and from 27·8 to 60·9 per 100 000 person-years, respectively. Annual rates were consistently higher in male and Indian patients. Overall, psoriasis was significantly more common in males than females [odds ratio (OR) 1·37, 95% CI 1·29-1·46] and in Indian and Chinese patients vs. Malay (OR 1·85, 1·71-2·01 and OR 1·30, 1·20-1·41, respectively). Prevalence increased with age, with the highest rates in the groups aged 50-59 and 60-69 years at 0·67% and 0·66%, respectively. A modest bimodal trend in age of psoriasis onset was observed, with first and second peaks at 20-29 and 50-59 years. Disease onset was significantly earlier in females than males [mean (SD) 36·8 (17·3) vs. 42·0 (17·2) years, P < 0·001] and in Malay vs. Indian and Chinese patients [mean (SD): Malay 36·4 (17·5), Indian 40·8 (15·2), Chinese 47·4 (16·9) years, P < 0·001]. We found that psoriasis incidence and prevalence are increasing and varied by age, sex and ethnicity. Our findings should help inform healthcare planning and management for patients with psoriasis in Malaysia. What is already known about this topic? The incidence and prevalence of psoriasis are generally lower in Asian populations and children. There is a lack of agreement on sex-specific differences in psoriasis incidence and prevalence. There has been no population-based study on the incidence and prevalence of psoriasis in Southeast Asia, including Malaysia. There is no information on differences in psoriasis prevalence and incidence by sex, age and ethnicity in Malaysia. What does this study add? Psoriasis incidence and prevalence are increasing in the multiethnic population of Johor Bahru, Malaysia. Incidence and prevalence rates were higher in male than female patients and were consistently highest among Indian patients, followed by Chinese and Malay. A modest bimodality in the age of psoriasis onset was observed among the groups aged 20-29 and 50-59 years. Psoriasis onset was significantly later in male than female patients and in Chinese vs. Indian and Malay patients.

Aims: Patients with Turner syndrome (TS) may have a higher risk of psoriasis as suggested by some reports. Data on this association are still limited. We investigated the association between TS and the risk of prevalent and incident psoriasis by combining results from available studies using systematic reviews and meta-analysis techniques. Methods: Potentially eligible studies were identified from Medline and EMBASE databases from inception to December 2023 using a search strategy that comprised of terms for “Turner syndrome” and “psoriasis”. An eligible cohort study must comprise of two groups of participants—those with and without TS. It must report our outcome of interest—incidence and/or prevalence of psoriasis in each group. The pooled effect estimates were generated using the generic inverse variance method, which assigns weight to each study in reversal to its variance. Meta-analyses of the prevalent and incident psoriasis were conducted separately. Results: A total of 4919 articles were retrieved. After two rounds of independent review by two investigators, five cohort studies (two incident studies and three prevalent studies) met the eligibility criteria and were included in the meta-analyses. The meta-analyses found a significantly elevated risk of both incident and prevalent psoriasis in patients with TS compared to individuals without TS, with the pooled risk ratio of 5.58 (95% CI, 3.73–8.35; I2 0%) and 5.66 (95% CI, 1.52–21.03; I2 19%), respectively. Conclusions: An increased risk of both incident and prevalent psoriasis among patients with TS was demonstrated in this study.

In this systematic literature review and meta-analysis, we aimed to investigate the impact of cigarette smoking on the prevalence and incidence of psoriasis and psoriatic arthritis (PsA). We performed a systematic literature review using the MEDLINE, EMBASE and Cochrane Central Register databases. The literature included publications from January 1980 to July 2019. The studies that provided clear information on the number of patients with ever smoking data were included in the meta-analysis. The systematic literature review identified 52 and 24 articles for the prevalence of smoking in psoriasis and PsA, respectively. Of these, 16 articles on psoriasis and three and four (general population and psoriasis, respectively) articles on PsA met the criteria and were included in the meta-analysis. The prevalence of ever smoking was increased in psoriasis compared with the general population (OR: 1.84; 95% CI: 1.4, 2.3). For PsA the prevalence of ever smoking was reduced in psoriasis patients (OR: 0.70; 95% CI: 0.60, 0.81), but not changed compared with the general population (OR: 1.10; 95% CI: 0.92, 1.32). This meta-analysis showed that ever smoking increases the risk of psoriasis in the general population, but may reduce the risk of PsA in psoriasis patients. The latter may be also due to the collider effect. Whether smoking cessation neutralizes the risk of developing psoriasis requires a well-defined smoking data collection for the past history and this is currently unavailable in the literature.

British Journal of DermatologyVolume 184, Issue 2 p. e34-e34 Plain Language SummaryFree Access Epidemiology of psoriasis over time and by age and gender First published: 05 February 2021 https://doi.org/10.1111/bjd.19725AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Psoriasis is a long-lasting disease involving inflammation of the skin. The extent to which the occurrence of psoriasis varies over time, as well as by gender and with age, has not been systematically explored. Therefore, we – a group of researchers based in Manchester, UK – aimed to perform a systematic review of published studies on variations in psoriasis incidence (the number of new individuals affected by psoriasis during a particular period of time) and prevalence (all individuals affected with the disease at a particular time) over time, as well as by gender and with age. We systematically searched 11 large electronic databases and identified 90 studies from 22 countries. We observed two peaks in age bands in psoriasis onset, with the first and second peak at around 30–39 and 60–69 years of age, respectively. Evidence suggested psoriasis presents slightly earlier in women than men. There was no agreement on specific differences between genders in psoriasis incidence and prevalence. However, a slight male predominance was reported in several studies. The prevalence of psoriasis has been consistently reported to be increasing over time, while the incidence of psoriasis has been reported to be stable or slightly decreasing over time. Our conclusion is that studies on changes over time in the occurrence of psoriasis have contributed to a greater appreciation of the increasing burden of the disease. However, further research is required to determine the reason driving the increase in psoriasis prevalence over time. Linked Article: Iskandar et al. Br J Dermatol 2021; 184:243–258. Volume184, Issue2February 2021Pages e34-e34 RelatedInformation

Psoriasis is a common chronic inflammatory skin disease associated with a heavy burden of morbidity, disability and cost. The occurrence of the disease in Israel has not been previously investigated. To provide standardized estimates of trends in psoriasis incidence, prevalence and mortality among patients in Israel between 2011 and 2017. Using electronic health records from Clalit Health Services, the largest nationwide public health provider in Israel, we conducted a population-based study investigating trends in the annual incidence and prevalence of psoriasis between the years 2011 and 2017. We report age- and sex-adjusted rates, using the standard European population as a reference. We identified 71094 incident psoriasis cases. The mean (SD) age of onset was 42.4 (21.0)years with a bimodal distribution, peaking in the early '30s and early '60s. Late-onset psoriasis, occurring after 40years of age, accounted for 51.1% of incident cases. The annual psoriasis incidence rate was constant throughout the study period (280/100000 person-years). Psoriasis prevalence rose from 2.5% in 2011 to 3.8% in 2017. Psoriasis prevalence is increasing in Israel, although its incidence is stable. Clinicians and policymakers should plan to address the growing demands in the clinical, economic and societal burden of psoriasis.