|ORIGINAL RESEARCH REPORT
|Year : 2016 | Volume
| Issue : 3 | Page : 137-142
Clinical pattern of psoriasis in patients seen at a tertiary hospital in Nigeria
Olusola Ayanlowo, Ayesha Akinkugbe
Department of Medicine, Faculty of Clinical Sciences, College of Medicine, University of Lagos, Lagos, Nigeria
|Date of Web Publication||4-Jul-2016|
Department of Medicine, Faculty of Clinical Sciences, College of Medicine, University of Lagos, Lagos
Source of Support: None, Conflict of Interest: None
Background and Objectives: Psoriasis is a chronic, papulosquamous disorder of the skin with variable morphology, characterized by periods of remission and reactivity. Psoriasis is less common in the tropics and in dark-skinned persons. Prevalence in West Africans has been noted to be similar to that of the African-Americans suggesting a similarity in genetic ancestry. This study aimed to describe the clinical characteristics of psoriasis and precipitating factors in Nigerian patients. Materials and Methods: This is a retrospective study of all dermatology patients with features of psoriasis who attended the dermatology outpatient clinic of the hospital between January 2007 and May 2012. Data were obtained from the patients' clinic notes and protocol for psoriasis, which documented patients' demographic data, clinical presentations, and precipitating factors. Results: Psoriasis was found in 1.13% (124/11,015) of the study population. There was a male preponderance with a male to female ratio of 1.34:1. The majority of patients seen were in the fourth decade of life. Stress, alcohol, and drugs were the most reported predisposing factors to psoriasis. All types of psoriasis were found, and plaque psoriasis was the most common. Conclusion: This study confirms the increasing frequency of psoriasis among dermatology patients in Nigeria, which may either be due to an increased proficiency in diagnosing the condition by physicians or increase prevalence of environmental factors. The current trend in the management of psoriasis is focused on treating the inflammatory process as well as managing the modifiable environmental triggers.
Keywords: Environmental triggers, plaque psoriasis, psoriasis, recurrences, remissions
|How to cite this article:|
Ayanlowo O, Akinkugbe A. Clinical pattern of psoriasis in patients seen at a tertiary hospital in Nigeria. J Clin Sci 2016;13:137-42
| Introduction|| |
Psoriasis is a chronic, papulosquamous disorder of the skin with variable morphology, characterized by periods of remission and reactivity.  Psoriasis, like many chronic disorders such as atopic dermatitis, affects the quality of life of the patient significantly.  Psoriasis has been estimated to affect 1-3% of the world's population but is noted to be rare in the Africans and North American Indians.  An early survey of dermatology patients in Nigeria revealed a prevalence rate of <0.1-0.5%. , However, recent studies show increasing frequency of psoriasis (0.6-1.5%) among individuals attending dermatology outpatients in different parts of Nigeria. ,,
Psoriasis prevalence in African-Americans is 1.3% compared with 2.5% in Caucasians.  The prevalence of psoriasis was noted to be higher in East Africa than West Africa.  The prevalence in West Africa is similar to that found among the African-Americans. This was thought to be due to the similarity in genetic ancestry.  It is more common in women and has two peaks of onset: In adolescents and young adults (16-22 years); and in older persons (57-60 years). 
Africans have been postulated to either lack the psoriasis susceptibility gene or have genetic factors that promote resistance to psoriasis.  Dietary factors have also been thought to partly contribute to the low prevalence of psoriasis in Africans.  The African staple diet particularly corn, is rich in linolenic acid, a precursor of prostaglandin E2 (PGE2); and low in polyunsaturated fatty acids; encouraging overproduction of PGE2; suppressing cellular immunity underlying psoriasis; and directly block T-cell signaling and interleukin-2 (IL-2); ultimately reducing T-cell proliferation. 
Psoriasis is currently thought to result from genetically determined immune dysregulation (innate and adaptive immunity) resulting in production of large amount of cytokines such as tumor necrosis factor-α, interferon-α, IL-12 and recently implicated IL-17 and IL-23. , Subsequently, there is resultant epidermal proliferation with loss of differentiation; dilatation and proliferation of the dermal blood vessels; and accumulation of inflammatory cells such as neutrophils and T-lymphocytes. ,, The immune dysregulation is thought to be stimulated by an undetermined antigen, provoked by environmental factors such as trauma, infections, stress, drugs, sunlight, and metabolic derangement. ,, Several genes have been associated with psoriasis; however, only PSORS1 is well-characterized and confirmed in 30-50% of patients. ,
Clinical features of psoriasis vary in morphology, extent of disease, duration, periodicity of flares, and response to therapy. , The most common morphology is inflamed, edematous skin plaques, and coalescing papules covered with silvery white scales. The characteristic redness and edema of inflammation are more obvious in white skinned persons, whereas in blacks, it is less conspicuous or absent.  The clinical types include plaque psoriasis, guttate psoriasis, pustular psoriasis, erythrodermic psoriasis, scalp psoriasis, nail psoriasis, and psoriatic arthritis.
Almost all aspects of psoriasis have been studied extensively in western countries, whereas there is still a lot that needs to be done to determine the specific characteristics of psoriasis in Africans.
This study aimed to document the clinical characteristics, precipitating factors and associated features of psoriasis in patients seen at the dermatology outpatients' clinic of the hospital between January 2007 and May 2012.
| Materials and methods|| |
This is a retrospective survey of all dermatology patients with features of psoriasis who attended the dermatology outpatient clinic of the hospital (be specific about the name of the hospital) between January 2007 and May 2012. Lagos is the former capital of the Federal Republic of Nigeria and the heart of the economic activities in Nigeria. It harbors people from different ethnic and geographical zones in Nigeria. The dermatology outpatient clinic attends to walk-in patients and receives referrals from public hospitals, private hospitals and company clinics in Lagos and others states, with an average of 200 new patients per month.
Data were obtained from the patients' clinic notes and the clinic protocol for all psoriasis patients seen during the study period. This protocol was developed in 2006 to ensure proper documentation of psoriasis patients and contains demographic data, clinical presentations, precipitating factors and associated findings in individuals with features of psoriasis. Data included were those of Nigerians patients (predominantly Fitzpatrick skin prototype five and six); and those in which the clinical diagnosis was confirmed by histopathology of skin biopsies. Data of patient with inconclusive clinical features and histology were excluded).
Documentation of disease severity was introduced in 2010 using the body surface area (BSA) affected; hence, only a fraction of the patients have this documented. Disease affecting <2% of the BSA was classified as mild; 2-10% as moderate; and >10% as severe. Psoriasis area and severity index (PASI) were not used because of the difficulty in the perception of erythema in dark-skinned Africans.
Data were entered on the excel spreadsheet and analyses were performed with IBM SPSS statistics version 16 (New York, US) using descriptive statistics. Results were expressed in tables and bar charts. Statistical significance was determined using Chi-square; P values <0.05 was considered statistically significant.
This was a hospital-based study hence it might not reflect the exact situation in the community. It, however, provides an insight into the magnitude of the problems and can be used to develop strategies in the management of the disease condition.
| Results|| |
The diagnosis of psoriasis was made in 124 (1.13%) of the 11,015 patients seen during the study period. There was a slight male preponderance; 71 patients were male (57.3%), while 53 patients (42.7%), giving a male to female ratio of 1.34:1.
Psoriasis was seen in all age groups and the highest frequency of patients presented in the fifth decade of life [Table 1]. The mean age of presentation was 36.2 ± 18.8 years. The youngest patient was a 10-week-old baby who presented with a 9 weeks history of plaque and scalp psoriasis. Auspitz sign was documented in the plaque psoriasis. The oldest patient was 82 years old and presented with pruritic guttate, plaque and scalp psoriasis. The peak age of presentation was in the first and fourth decades of life [Table 2]. The age of onset varied between 2 weeks and 82 years with the mean age of onset being 30.64 ± 18.5 years. A positive family history of psoriasis (first-degree relatives) was documented in 10 patients (8.1%). The duration of symptoms is shown in [Table 3].
Pruritus was the most common presenting symptom found in 91 patients (73.4%), followed by pain in 33 (26.6%), fever in 25 (20.2%), arthralgia in 23 (18.5%) of patients, chills in 11 patients (8.9%), and dehydration in 4 patients (3.2%). Half of the patients, 50% (62) presented for the first time, whereas the other 50% (62 patients) have had recurrences. The common predisposing factors to psoriasis were alcohol ingestion, physical and emotional stress, exposure to chemicals, cold weather, trauma, drugs, and herbs [Table 4]. Drugs noted to predispose patients to psoriasis were antimalarials (5), beta-blockers (3), aspirin (3), steroids (1) and antiretroviral drugs (1). Chemicals predisposing to psoriasis were soaps, detergents, antiseptic liquids, and hair relaxers.
Plaque psoriasis was the most common presentation found in 82 patients (66.1%), followed by scalp psoriasis in 63 patients (50.8%), nail psoriasis in 36 patients (29.0%), guttate psoriasis in 34 patients (27.4%) and erythrodermic psoriasis in 25 patients (20.2%). Other types found included pustular, inverse and psoriatic arthritis [Table 5] and [Figure 1]. No patient presented with generalized pustular psoriasis. All patients with psoriasis were managed as outpatients and none of the patients with erythrodermic psoriasis had features or complications that warranted emergency management. Koebner's phenomenon was noted in 38 patients (30.6%) and the Auspitz sign was elicited in 80 patients (64.5%). [Figure 2] shows bilateral palmar psoriasis whereas [Figure 3] shows plaque psoriasis in elbows and dorsum of both hands.
|Figure 3: Chronic plaque psoriasis affecting both knees and the dorsum of the hands|
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Nail findings in individuals with nail psoriasis were pitting in 30 patients (24.2%), onycholysis in 20 patients (16.1%), subungual hyperkeratosis in 18 patients (14.5%), dystrophy in 8 patients (6.5%), salmon patch (oil drop sign) in 5 patients (4.0%), and longitudinal ridging in 5 patients (4.0%). Other nail findings were half and half nails, trachyonychia, leukonychia, melanonychia, and acrodermatitis continua of Hallopeau. Acrodermatitis continua of Hallopeau was documented in a 7-year-old girl with localized palmoplantar pustular psoriasis. The severity of psoriasis was documented using the BSA in only 68 patients: 10 (14.7%) of these had mild disease, 28 (41.2%) had moderate psoriasis whereas 30 (44.1) had severe psoriasis.
| Discussion|| |
Psoriasis may not be as common in Africans as in Caucasians. However it is certainly not rare. This study confirms the increasing frequency of psoriasis among dermatology patients in Nigeria. It is not clear whether this represents a true increase in prevalence, or an increase knowledge and diagnostic acumen on the part of the dermatologists, or an increase in awareness and accessibility of the patients to dermatology care. Psoriasis as a skin disorder is known to the indigenous Yoruba tribe of South West, Nigeria as "ela alapadi" which means a very thickly scaly dermatitis (personal communication).
This study found psoriasis in 1.13% of patients attending the dermatology outpatient clinic. Survey of dermatology clinics in Nigeria suggested the possibility of a geographical variation in psoriasis epidemiology in Nigeria; frequency of patients appears to be higher in the Northern part of Nigeria than in the South. ,,, Hospital surveys in India reported the frequency of psoriasis between 0.44 and 2.8%.  Psoriasis was noted to be significantly lower in individuals of African descent than those of East Indian descent in a comparative study from Trinidad and Tobago. 
Studies from the UK, US, and other parts of the world documented a female preponderance; while this study showed a male predominance similar to findings in India and by Obasi in Northern Nigeria. ,,,, Dermatology clinic surveys in Nigeria showed a female preponderance for most skin disorders, whereas psoriasis was seen more in males. There was no statistically significant difference in frequency of all types of psoriasis in males and females in this study.
Psoriasis was seen in all age groups, with the highest number of patients presenting in the fifth decade of life, a finding similar to that in Indian population.  There were two peaks in the age of onset: First and fourth decades of life. The frequency of psoriasis was lower in the older age group, similar to documentation from the UK.  It is of note that psoriasis is quite common in the paediatric age group and adolescents. ,,, More than one-fifth of psoriasis patients seen in this study (21.8%) presented in the first two decades of life and approximately a third had the onset of disease in the first two decades. This finding is similar to previous studies which documented 25-45% of individuals with psoriasis having onset in childhood and adolescents. ,
Childhood and adolescent psoriasis are associated with more significant genetic predisposition evidenced by the higher frequency of affectation of first-degree relatives, compared with adult-onset psoriasis; and association with human leukocyte antigen - Cw6.  All types of psoriasis have been documented in children and adolescents; although, guttate and plaques types were the most common seen. Since children and adolescents take less drugs and alcohol than adults, trauma, stress, and infections particularly pharyngitis from group A streptococcal infections are the most important precipitating or triggering factors in them. ,
The itching was the most common symptom in this series accounting for about three-quarters of the symptoms (73.4%) similar to previous documentation.  While itching in psoriasis was found to be less significant than in atopic dermatitis, it correlated with severity of psoriasis as evidenced by increased PASI score; impairment of quality of life; the degree of stigmatization and depressive symptoms. ,, Pruritus in psoriasis has been associated with neurogenic inflammation with release of neuropeptides from dermal nerve endings; increased dermal vasculature and abnormal functioning of the opioid system among others. , Some of the neuropeptides found to be associated with itching in psoriasis include substance P receptor, high-affinity nerve growth factor tropomyosin receptor kinase A and calcitonin gene-related peptide receptor.  The phenotype of psoriasis is broad and this study documents all types of psoriasis apart from generalized pustular psoriasis. 
Apart from the genetic factors, a broad spectrum of environmental factors has been documented to definitely modulate features, course and severity of psoriasis.  Stress, high body mass index, smoking, infectious skin diseases, psoriasis in first degree relatives and upper respiratory tract infections are very important and well-known risk factors for psoriasis. ,,,, Individually, these factors increase the incidence and severity of psoriasis and the combined effect of multiple risk factors were found to significantly increase the population attributable risk factor for developing psoriasis.  The frequency of remissions was reported to be significantly less in smokers and individuals with high levels of stress while psoriasis was more extensive in overweight persons. 
While genetic factors are nonmodifiable, environmental factors which play an additive role in the pathogenesis of psoriasis, are usually modifiable. Knowledge of the environmental triggers and their avoidance is likely to contribute to cure or reduction of recurrences/exacerbation. , Lifestyle modification such as abstaining from smoking and alcohol; stress management; regular exercises and healthy habits are advocated to be paramount in the holistic management of psoriasis, resulting in reduction of recurrences, and ameliorating severity and clinical presentation of psoriasis. 
| Conclusion|| |
This study highlights some of the common triggers of psoriasis in our patients apart from bringing to fore the clinical characteristics and confirming the increasing frequency of psoriasis in Nigerian patients. This is important in view of the current trend in the management of psoriasis, which is focused on managing the modifiable environmental triggers along with treating the inflammatory processes. Further research into the environmental and genetic factors at play in the epidemiology of psoriasis in Nigerians will further improve the quality of care in this clime.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]