Epidemiological Patterns of Skin Disease in Saudi Arabia: A Systematic Review and Meta-Analysis

Background Large epidemiological studies on patterns of skin diseases in Saudi Arabia are scarce. Therefore, this systematic review and meta-analysis was conducted to gather available epidemiologic data describing the pattern of skin diseases in different geographical areas in Saudi Arabia. Methods A comprehensive literature search of articles was conducted in PubMed, SCOPUS, and Web of Science through October 2019. We included all published cross-sectional studies that provided data on relevant incidence or prevalence of skin disease in Saudi Arabia. The risk of bias within the included cross-sectional studies was assessed using the Hoy tool for the prevalence studies. All statistical analysis was performed using the Comprehensive Meta-analysis software. Results The present meta-analysis included 14 studies that reported the frequency of the skin disease patterns in different regions in Saudi Arabia with a total sample size of 30436 patients with an overall low risk of bias. The diseases of skin appendages and dermatitis were the most commonly reported skin diseases in Saudi Arabia (24.8% (95% CI, 24.3–25.3) and 24% (95% CI, 23.6%–24.6%), respectively). Skin infection represented about 18.5% (95% CI, 18.1%–19%), while the papulosquamous disorders represented 5.3% (95% CI, 5%–5.6%) of the skin diseases in Saudi Arabia. Skin cancers were pooled from only two studies. Basal cell carcinoma and squamous cell carcinoma were the most common malignant neoplasm in Saudi Arabia (51.4% and 22.5% of the malignant neoplasm, respectively), while malignant melanoma represents only 3.8% of the malignant skin cancer. Conclusion Adnexal disorders and dermatitis are the most common skin disease in Saudi Arabia, followed by skin infection and pigmentary disorders. While skin cancer is more frequent than other countries, awareness campaigns should be initiated to increase knowledge about the harmful effect of long-term sun exposure.


Introduction
Skin, similar to other human organs, can be affected by all types of pathological changes, including hereditary, inflammatory, neoplastic, endocrinal, traumatic, and degenerative affection [1]. Epidemiological studies are important for understanding the implications of human disease. Identifying the incidence and prevalence of specific diseases is indispensable to decision making regarding the distribution of resources for clinical care and research [2]. For example, the management of skin disorders requires an appropriate diagnosis. Nondermatologists, as in the case of general practitioners, usually perform diagnoses and treatment of skin disorders in underserved areas, which highlights the importance of providing a comprehensive review of the skin disease patterns in each specific region; in addition to further focus on educating nondermatologists regarding some common skin conditions they might encounter [3][4][5]. e incidence and prevalence of skin disorders are mainly related to the ethnic and the genetic constitution of the community. In addition, hygiene, dietary style, social background, and weather conditions are important contributing factors.
Population-based epidemiological studies of skin disease are relatively inadequate. Because these epidemiologic studies have been published through many decades in different journals, many dermatologists are not aware of these data [2].
In Saudi Arabia, the large epidemiological studies on patterns of skin diseases are scanty. Previous epidemiological studies in Saudi Arabia investigated the pattern of skin and skin-related diseases in different regions of Saudi Arabia such as Madinah, Al-Khobar, Jeddah, Al-Baha, Hail, Abha, Qassim, and Najran [6][7][8][9][10][11][12][13][14][15], which reflect the pattern of skin and skinrelated diseases in Saudi Arabia. erefore, this systematic review and meta-analysis was conducted to gather available epidemiological data describing the pattern of skin diseases and investigate the current evidence of frequency, type, and distribution of skin disorders in different geographical areas in Saudi Arabia.

Methods
All steps of this systematic review were performed in strict compliance with the Cochrane handbook of systematic reviews and meta-analysis [16] in addition to following the preferred reporting items for systematic reviews and metaanalyses (PRISMA statement guidelines) during the drafting process of this manuscript [17].

Literature Search Strategy.
e following medical electronic databases were searched: PubMed, SCOPUS, and Web of Science through October 2019 using the following query: [

Eligibility Criteria and Study
Selection. All published cross-sectional studies that provided data on relevant incidence or prevalence of skin disease in Saudi Arabia were included. Excluded articles included all studies with a small sample size (less than 100 patients), reviews, case reports, conference abstracts, or case series, studies with self-reported data unless diagnoses were validated by a trained physician, studies on specific ethnic or social groups, non-English articles, and duplicate references.
Eligibility screening was conducted in two steps, each by two independent reviewers (MA and MA) as follows: (a) title and abstract screening for matching the inclusion criteria and (b) full-text screening for eligibility to meta-analysis. Disagreements were resolved upon the opinion of a third reviewer (HA).

Data Extraction.
Two independent reviewers (MA and MA) extracted the data that included the following: (a) general characteristics of each study including study setting, study design, sample size; (b) patients' baseline characteristics of each study including age, gender, and nationality; (c) types and proportion of the reported skin diseases; (d) risk of bias criteria.

Risk of Bias Assessment.
To assess the risk of bias within the included cross-sectional studies, two independent reviewers (MA and MA) used the risk of bias assessment tool developed by Hoy et al. [18] for the prevalence studies. e domains of risk of bias assessment were presented in Supplementary file 1.

Results of the Literature Search.
Our search yielded a total of 1701 studies. Following screening and excluding duplicates, we remained with 95 studies that entered full-text screening. Finally, 14 studies were included in this systematic review as reported in the PRISMA flow diagram ( Figure 1).

Summary of the Included Studies.
e fourteen Saudi studies reported the frequency of the skin disease patterns in different regions in Saudi Arabia with a total sample size of 30436 patients. Only two studies reported the pattern of skin cancers only in southeastern and western regions in Saudi Arabia, with a total sample size of 395 patients with skin cancer [6,10]. Baseline characteristics and summary of the included studies are reported in Table 1.
Overall low risk of bias was observed in accordance with the Hoy et al. [18] assessment tool for the prevalence studies. Summary of risk of bias assessment is reported in Table 2.

Discussion
is systematic review presented a summary of populationbased data describing the pattern of skin disease in Saudi Arabia. Previous studies investigated the pattern of skin and skin-related diseases in different regions of Saudi Arabia such as Madinah, Al-Khobar, Jeddah, Al-Baha, Hail, Abha, Qassim, and Najran through population-based cross-sectional studies, which reflect the true pattern of skin diseases in Saudi Arabia [6][7][8][9][10][11][12][13][14][15]. Although these included data did not cover every part of Saudi Arabia, the results are generalizable to other populations and reflect the current evidence of the frequency, type, and distribution of skin diseases in different geographical areas in Saudi Arabia. e different patterns of skin disorders in different cities in Saudi Arabia might be justified by overcrowding and/or poor living conditions in some cities. Other ecological and environmental considerations should be considered.
Fourteen Saudi studies with a total sample size of 30436 were included in this systematic review and meta-analysis reporting the frequency of the skin disease patterns in different regions in Saudi Arabia. e average sample size of the individual studies is 2000 patients, which is small to determine the true pattern of skin disease in a large country as Saudi Arabia.
e high prevalence of dermatitis may contribute to climatical variability in different parts of Saudi Arabia.
Skin infections and infestations prevalence have been reported with an overall pooled proportion of 18.5% derived from 12 studies with an overall sample size of 29244 patients.
Cutaneous leishmaniasis was the most common parasitic skin diseases, while the warts were the most common viral  Dermatology Research and Practice infection followed by chickenpox. In addition, bacterial skin diseases represented 3.3% of the total prevalence of skin disease in Saudi Arabia. Similar to the results of this study, a review of populationbased studies from the Rochester epidemiology project showed that skin-related infections and infestations have a high prevalence rate. e incidence of herpes zoster has repeatedly been found to be very high (590 Per 100,000 person-years). e incidence of lower extremity cellulitis is also very common (213 Per 100,000 person-years) [2].
A recent study reported that 10.9% of the population had a fungal infection in Jeddah, Saudi Arabia [21], which is almost equal to that in Al-Khobar (9.6%) [21]. is high prevalence of fungal infection is probably attributed to the    [24], and this finding was similarly reported in other developing countries where poor hygiene, low educational level, and poverty play important roles [25][26][27][28]. Interestingly, similar  Dermatology Research and Practice data showed a high prevalence of fungal infection in high socioeconomic countries in the same region such as Abu Dhabi (8.5%) and Qatar (11.4%) [21]. e present study reported that the most common fungal infections were dermatophytosis and onychomycosis.
Regarding skin appendages disorders, the mean prevalence was 24.8% in Saudi Arabia. Acne served the highest proportion of them. Saudi studies reported that acne is the second most common skin disease in Jeddah, Saudi Arabia [21]. is result was also reported in Al-Khobar [8], Najran [23], Hail [12], and Al-Qunfudah [20], while acne was the third most common in Asir [15]. In Cairo, Egypt, acne represented the second most common skin disease (6.11%), after scabies (9.26%), contact dermatitis (7.92%), and pityriasis versicolor (7.7%) [24]. Diseases of skin appendages in Iran [25] and Tunisia [28] represented the second most common skin disease with significant female predominance over men among all diseases of skin appendages.
In Cairo, Egypt, the most common skin disease was infections (45.4%) followed by hypersensitivity diseases (22.08%) and adnexal disorders (16.17%). Papulosquamous disorders represented about 4.69% of the total prevalence of skin diseases. Lastly, pigmentary disorders represented only 4.24% and skin neoplasm 1.29%.
In this meta-analysis of Saudi studies, the overall mean proportion of pigmentary disorders as reported by 11 studies was 16.1% from a total sample size of 16658 patients. Melanocytic nevi and vitiligo were the most common pigmentary disorders in Saudi Arabia.
Lastly, the overall prevalence of benign skin neoplasms as reported by two studies was 21.2%, while malignant neoplasms were 5%. Basal cell carcinoma and squamous cell carcinoma were the most common malignant cancer in Saudi Arabia. Malignant melanoma represents 3.8% of malignant skin cancer. ese figures are believed to be not representable as skin cancer is barely seen in Saudi Arabia. e many strength points of this meta-analysis are the large numbers of included studies with a large sample size that covers most of the Saudi regions. Besides, we reported the first class of evidence form studies with low risk of bias according to the Hoy et al. [18] assessment tool for the prevalence studies.
For future researches, we recommend a comprehensive nationwide population-based study to identify the prevalence of skin diseases in Saudi Arabia.
In conclusion, Adnexal disorders and dermatitis are the most common skin disease in Saudi Arabia followed by skin infection and pigmentary disorders. Dermatological educational programs for primary healthcare physicians should be implemented to provide rapid detection of cases at early stagesbib19.