Psoriasis and increased prevalence of hypertension and diabetes mellitus.

BACKGROUND: Psoriasis is an autoimmune skin disease and associated with other diseases such as cardiovascular, hypertension, and diabetes mellitus. AIM: Our aim was to explore the prevalence of diabetes mellitus and hypertension in psoriatic patients.
MATERIALS AND METHODS: Between April 2008 and May 2010, a total of 304 psoriatic and 300 nonpsoriatic patients were enrolled in this cross sectional study. Data were obtained on age, sex, weight, heights, etc; documented medical history of diabetes mellitus and hypertension; family history of diabetes mellitus and hypertension in first relatives, history of smoking.
RESULTS: There was no significant difference in age and gender distribution between two groups. There was also no difference in body mass index between two groups. Within psoriatic group, 79.3% of patients present with plaque type of the disease and 20.7% present with other types. The results showed that within psoriatic patients, the prevalence of diabetes in women is significantly higher than in men (OR=1.93, CI95%: 1.1-3.6, P=0.004) but this difference is not present in nonpsoriatic patients. The results also showed that the prevalence of diabetes in psoriatic patients is significantly higher than nonpsoriatic patients (OR=1.76, CI95%: 1.11-2.8, P=0.015). The data showed that psoriatic patients were more likely to develop hypertension compared with nonpsoriatic patients (OR=2.2, CI95%: 1.2-4.6, P=0.003). According to results, although smoking rate within psoriatic patients is higher than the other group but the difference was not significant.
CONCLUSION: Psoriatic patients have an increased risk of developing metabolic syndrome and hypertension in comparison to nonpsoriatic patients.

Introduction

Psoriasis is an autoimmune skin disease and its genetic and environmental factors play a significant role in its manifestations.[1] Though psoriasis mostly affects the skin in its clinical presentations, due to the role of autoimmune mechanisms in its pathogenesis and the presence of other co-morbidities in its clinical process, it is regarded as a systemic disease. Scalp, elbows, knees, umbilicus, genitalia, sacrum, and shins are the most common places involved and usually presents with pruritus, inflammation, scaling and plaques in a wide size range.[2] Disease activity fluctuates spontaneously over a variable timescale of months or years but is usually associated with multiple organ involvements and co-morbidities. The association between psoriasis and cardiovascular co-morbidities, metabolic syndrome, skeletal diseases such as psoriatic arthritis and malignancies is found in some studies.[34]

The metabolic syndrome defined as abdominal obesity, increased insulin resistance/elevated fasting glucose level, decreased high-density lipoprotein cholesterol, hypertriglyceridemia, and hypertension is one of the cardiovascular co-morbidities that has been proposed to be associated with psoriasis. It is shown that patients with psoriasis have an increased risk of developing cardiovascular diseases and metabolic syndrome in comparison to nonpsoriatic patients.[5-7] On the other hand, hypertension, dyslipidemia, insulin resistance/diabetes mellitus, and obesity are independently related to psoriasis other than as components of the metabolic syndrome.[8-12]

In addition to cardiovascular co-morbidities, it is shown that psoriatic patients are at increased risk of developing some cardiovascular disease such as chronic inflammation and atherosclerosis, myocardial infarction, and stroke.[13]

The association between psoriasis and these co-morbidities has been reviewed in several studies, but still it remains one of the most interesting field of study in psoriasis, because of the controversial results obtained from different studies and also due to the importance of performing screening tests in these patients. This study was performed to explore the prevalence of diabetes mellitus and hypertension–the two major criteria of the metabolic syndrome in psoriatic patients.

Materials and Methods

Between April 2008 and May 2010, a total of 304 psoriatic and 300 nonpsoriatic patients were enrolled in this cross-sectional study. Informed written consent was obtained from all patients in accordance with the ethical guidelines of the 1975 Declaration of Helsinki and the local ethics committees approved the study.

All the patients were examined by one dermatologist at The Razi hospital of dermatology – a referral hospital of dermatology in Tehran, Iran. Written informed consent was obtained from all patients. Data were obtained on age, sex, weight, heights, etc; documented medical history of diabetes mellitus and hypertension; family history of diabetes mellitus; and hypertension in first relatives, history of smoking.

Patients with documented medical history of diabetes or fasting blood glucose ≥126 were mentioned as diabetes and patients with documented medical history of hypertension or blood pressure ≥140/90 mmHg were mentioned as hypertensive patients. Body mass index (BMI) was calculated and obesity was defined as BMI ≥30. Patients were considered as smoker even if they smoked one cigarette a day.

The exclusion criteria were BMI ≥35 or age fewer than 10 or over 80 years.

Statistical analysis

The results are expressed as mean ± SEM. Statistical analysis was performed using SPSS version 16.0.1 (SPSS Inc., Chicago, IL, U.S.A.). The statistical differences between proportions were determined by chi-square analysis. Numerical data were evaluated using analysis of variance, followed by Tukey's post-hoc test. The P value <0.05 was considered as significant.

Results

The study included 304 psoriatic and 300 nonpsoriatic patients. There was no significant difference in age and gender distribution between two groups. There was also no difference in BMI between two groups [Table 1].

Table 1

Demographic data of patients

Within the psoriatic group, 79.3% of patients present with plaque type of the disease and 20.7% present with other types. The results showed that within psoriatic patients, the prevalence of diabetes in women is significantly higher than men (P=0.004), the prevalence of diabetes in women is 1.93 times higher than men (OR=1.93, CI95%: 1.1 to 3.6) but this difference is not present in nonpsoriatic patients. The results also showed that the prevalence of diabetes in psoriatic patients is significantly higher than nonpsoriatic patients (P=0.015). According to the results, the risk of diabetes in psoriatic patients is 1.76 times higher than the other group (OR=1.76, CI95%: 1.11 to 2.8).

Prevalence of hypertension within groups was not different between males and females but the psoriatic patients had higher prevalence of hypertension in comparison to nonpsoriatic patients, where the difference was statistically significant [Table 2]. The data showed that psoriatic patients are at 2.2 times higher risk for developing hypertension than nonpsoriatic patients (OR=2.2, CI95%: 1.2 to 4.6, P=0.003). Indeed, according to the results there was no difference in family history of patients of two groups in diabetes or hypertension.

Table 2

Differences of diabetes and hypertension prevalence between patients of groups

Among 304 psoriatic patients, 62 of them were smokers but just 17 of 300 nonpsoriatic patients were smokers. Although smoking rate within psoriatic patients was higher than the other group the difference was not significant.

Discussion

Genetic and environmental factors play a significant role in the clinical manifestations of psoriasis that is known as an autoimmune skin disease.[14] A higher risk of diabetes mellitus, insulin resistance, hypertension, metabolic syndrome, and myocardial infarction especially in young patients with severe psoriasis has been reported.[15-20] Major factors that may contribute to this increased cardiovascular and metabolic risk include cigarette smoking, dyslipidaemia, obesity, physical inactivity, hyperhomocysteinaemia, and psychological stress, all of which have a higher occurrence among patients with psoriasis.[21-25]

In the current study, the association between psoriasis and cardiovascular disease and diabetes mellitus was explored and the data demonstrated that psoriasis is associated with hypertension and diabetes mellitus and showed that the prevalence of diabetes mellitus and hypertension in psoriasis patients is higher than in nonpsoriatic patients. Our results were in accordance with previous studies.

Previous studies showed that psoriasis is a risk factor for cardiovascular disease and diabetes mellitus.[7916-20] It is possible that psoriasis and diabetes mellitus share a same mechanism that is inflammation.[12] It is shown that inflammation and inflammatory responses are risk factors for developing diabetes mellitus, atherosclerosis, cardiovascular disease, and some other diseases. This evidence is also confirmed by some genetic studies.[12] We also found that prevalence of DM in women is higher than men among psoriatic patients. Thus it may be be concluded that psoriasis is a risk or for fact DM especially in women, the results were also found in other studies.[9]

In contrast, there are some studies that are in conflict. For example, Neimann et al., failed to find a relation between psoriasis and hypertension.[16] The same result was also shown in the Mallbris et al. study that no association was found between psoriasis and hypertension.[3] Taken together, these observations further support the opinion that there is an association between hypertension and DM with psoriasis.[3] The diversity in results reflects the need for more studies to find the real impact of psoriasis on hypertension, diabetes and other related diseases.

Conclusion

Psoriatic patients have an increased risk of the developing metabolic syndrome and hypertension in comparison to nonpsoriatic patients. Although metabolic syndrome leads to cardiovascular disease, psoriasis might be an independent risk factor for hypertension and cardiovascular disease even after correction for metabolic syndrome components.