Multiple observational studies have demonstrated associations of psoriasis with metabolic syndrome including obesity, diabetes, hypertension, dyslipidemia, and osteoporosis. However there is paucity of Indian studies on dyslipidemia in psoriasis. The aim of this study was to assess the serum lipids in psoriasis and to investigate the association of lipids with disease severity and its duration. 100 cases of psoriasis (75/M, 25/F), between 15 and 72 years, were recruited with age and sex matched 73 controls. Using Psoriasis Area Severity Index (PASI) cases were graded into mild, moderate, and severe psoriasis. Serum total cholesterol and triglycerides were analyzed using enzymatic method. Using independent
Psoriasis is a chronic immunologically based inflammatory disease of skin. It has been estimated to affect around 2% of the population [
Cases included psoriasis patients older than 15 years who came to the Outpatient Department of JSS Medical College and Hospital from October, 2007, to July, 2009. A total of 100 consecutive cases who met the inclusion criteria were enrolled. Measurement of skin disease severity was performed using Psoriasis Area Severity Index (PASI). A PASI score below 3 was defined as “mild,” between 3 and 10 was defined as “moderate,” and above 10 was defined as “severe” disease (according to British Association of Dermatologists Guidelines) [
Study was approved by Ethics Committee of JSS Hospital. A written consent was obtained from patients/guardians.
Controls were selected by taking age and sex into consideration. Controls with past or ongoing medications that may affect lipid metabolism were excluded. 73 age and sex matched controls were recruited. Controls were thoroughly examined for any clinical evidence of psoriasis.
Detailed history was obtained from cases and controls with regard to family history, prior treatment history, physical activity, and other lifestyle factors including tobacco and alcohol exposure. Data also included weight, height, body mass index (BMI), blood pressure, duration of psoriasis, type and severity of psoriasis, and presence of psoriatic arthropathy. BMI was calculated as weight (kg)/[height (mt)]2.
Venous blood was obtained after 12 hours of fasting. Blood was drawn into sterile vacutainers and centrifuged and serum was obtained.
Serum total cholesterol was measured by enzymatic end point cholesterol oxidase method. Serum total triglycerides (TGs) were estimated using enzymatic method—glycerol phosphate oxidase: peroxidase (GPO:PAP) method. High density lipoprotein (HDL) was measured using direct method. Very low density lipoprotein- (VLDL-) cholesterol was estimated using formula: VLDL-cholesterol = TGs/5. Serum low density lipoprotein (LDL) was estimated using Friedwald’s formula [
All the statistical methods were carried out through SPSS for Windows (version 16.0).
The prevalence of psoriasis according to age and sex was calculated and compared with the controls using cross-tabulation procedure. The statistical significance was calculated by one-way analysis of variance (ANOVA) and significance level used was at 95% confidence level.
The mean values of serum lipids in cases and controls were compared using independent samples
In this case control study of 100 cases and 73 controls the age range of the cases was 15–72 years. The descriptive characteristics of study population are given in Table
Demographic characteristics of cases and controls.
Cases | Controls |
|
|
---|---|---|---|
Males- |
75 | 55 | |
Females- |
25 | 18 | |
Age range | 15–72 yrs | 18–73 yrs | |
Mean age | 40.72 ± 13.4 | 41.67 ± 11 | 0.620 |
Cases had mild to severe psoriasis with PASI ranging from 0.8 to 50.8 with a median 6.9. 19% of the cases had PASI < 3, 45% had PASI between 3 and 10, and 36% had PASI > 10.
The most common clinical type of psoriasis was chronic plaque variety accounting for 79% of cases. Out of 79 cases, 48 had associated scalp involvement. Another 5% of cases showed localized scalp psoriasis. Thus scalp involvement was seen in 53% of the patients. Palmoplantar psoriasis was seen in 10% of cases. 3 out of 100 cases showed flexural involvement also known as “inverse psoriasis.” Psoriatic arthropathy was seen in 3 cases.
The serum total cholesterol was significantly elevated in cases when compared to controls. The mean serum total cholesterol was 189.31 ± 37.84 mg/dL in cases, whereas in controls it was 170.79 ± 36.25 mg/dL (
Serum triglyceride levels were analyzed. In cases, the mean was 219.69 ± 105.46 mg/dL which was significantly higher than controls. Elevation of VLDL in cases was noted (mean 42.99 ± 20.52). The mean in controls was 28.0 ± 11.47 mg/dL. The difference was significant at
Comparison of concentration of serum lipids in cases and controls. The mean of serum cholesterol, high density lipoprotein, very low density lipoprotein, and triglycerides in cases was significantly elevated. Results are expressed as mean ± S.D.
Out of 100 cases, 7 patients had hypertension. (Systolic BP > 140 mmHg, diastolic > 90 mmHg.) The group statistics are described in Table
Comparison of serum lipid levels in controls and nonhypertensive and hypertensive cases with psoriasis.
Controls ( |
No hypertension ( |
Hypertension ( |
|
|
---|---|---|---|---|
Total cholesterol | 170.79 ± 36.25 | 187.03 ± 35.94 | 219.57 ± 51.7 |
|
HDL | 37.47 ± 12.18 | 43.11 ± 8.17 | 41.71 ± 4.53 | 0.657 |
LDL | 104.41 ± 26.51 | 100.83 ± 26.41 | 114.14 ± 27.47 | 0.203 |
VLDL | 28.00 ± 11.47 | 41.45 ± 18.64 | 63.42 ± 33.15 |
|
TGs | 141.31 ± 57.90 | 212.29 ± 96.86 | 318.0 ± 165.91 |
|
Variations in serum lipids were observed with disease severity. No specific trend was noticed except in HDL-cholesterol. The levels decreased with increasing severity, but the difference was not statistically significant (
Variations of mean serum lipoproteins in psoriasis patients based on disease severity. Results are expressed as mean + S.D.
Lipid levels were assessed taking disease duration into consideration. The comparison of total cholesterol, LDL, HDL, and TGs and their variation with disease duration is depicted in Figure
Variations of mean serum lipoproteins in psoriasis patients with duration of disease. Results are expressed as mean + S.D.
No significant variations in lipid levels were observed in different types of psoriasis. 3 cases that had inverse psoriasis did not show any significant change. 23 cases were chronic smokers and 10 cases were alcoholics. Through multivariate logistic regression, the effect of various confounding factors like smoking, alcoholism, and obesity was found to be nonsignificant through chi-square test.
Half a century ago Lea Jr. et al. [
Various studies done in Caucasians have reported increased [
Thus various studies reported contradictory results. In our study significant elevation of serum total cholesterol, TGs, VLDL, and HDL was observed, whereas LDL levels were comparable in cases and controls. Thus we report elevation of protective HDL and normal levels of most atherogenic lipid LDL which is not consistent with the above mentioned reports.
PASI score was used to grade the cases into mild, moderate, and severe. This score is considered as outstanding when severe cases are involved. It also provides the advantage of a large base of studies in which it has been used for comparison [
In our study, there was an increase in the serum total cholesterol levels and LDL, VLDL, and triglyceride levels but a fall in the levels of HDL in patients with long term psoriasis (more than 5 years). Though the changes in HDL based on disease severity and duration were not significant, they form an interesting observation. HDL levels, which are protective against cardiovascular risk, show changes different from other lipids. This could signify increased risk and systemic damage with disease severity and duration.
Till date all accumulated knowledge is derived from studying psoriasis patients without considering disease duration. Mallbris et al. [
In the study conducted by Mallbris et al. [
Patients with hypertension had significant elevation of lipid abnormalities than others. However the number of patients with hypertension in our study was less (7%). Hypertension along with dyslipidemia adds to the comorbidities of psoriasis. These together cause increase in the systemic inflammatory burden. There was a definite increase in serum lipids in hypertensive psoriatic patients when compared to nonhypertensive cases and controls in our study which might suggest an accelerated “psoriatic march” causing an early development of insulin resistance [
Various external and internal factors may possibly work together leading to lipid aberrations in psoriasis. The chronic nature of the disease influences lifestyle of the patient setting up a vicious cycle. Smoking, increased alcohol intake, and stress increase the oxidative damage in the body [
Psoriasis is a T helper cell 1 response, leading to increased levels of TNF-
The lipids present in the scales of psoriasis have shown increased levels of cholesterol and low free fatty acids [
We are well aware of the following limitations in our study. First diabetes in the patients was ruled out based on history and no diagnostic test could be performed. Second, no detailed history regarding smoking and alcohol intake could be obtained from the controls. Third, we could not perform followup lipid analysis in these patients. The numbers of hypertensive psoriatic cases were few.
We could establish that the occurrence of dyslipidemia in psoriasis is not just coincidental but there is a definite association. Our study shows no significant correlation of lipids with disease severity and duration. This strengthens the fact that psoriasis is a systemic disease. We can conclude that severe psoriasis cases should be screened for lipid abnormalities which can help in early detection of lipid dysfunction and cardiovascular comorbidity.
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors thank Professor Suresh, Vice Chancellor of JSS University, Mysore, for his encouragement. They thank the Principal of JSS Medical College for his support. The authors also thank the staff of Department of Dermatology, JSS Hospital, for their help and support.