Risks of hypertension associated with cyclosporine, nonsteroidal anti-inflammatory drugs, and systemic glucocorticoids in patients with psoriasis: a nationwide population-based nested case-control study in Taiwan : Psoriasis drug use and hypertension

Observational studies constitute an important category of study designs. To address some investigative questions in plastic surgery, randomized controlled trials are not always indicated or ethical to conduct. Instead, observational studies may be the next best method of addressing these types of questions. Well-designed observational studies have been shown to provide results similar to those of randomized controlled trials, challenging the belief that observational studies are second rate. Cohort studies and case-control studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. In this review article, the authors describe these study designs and methodologic issues, and provide examples from the plastic surgery literature.

Previous studies suggest that patients hospitalized for psoriasis have an increased frequency of a variety of cardiovascular comorbidities. Limited population-based data exist on this association, and few studies have determined which factors are independently associated with psoriasis. We sought to determine whether the prevalence of the major cardiovascular risk factors was higher in mild and severe psoriasis than in patients without psoriasis. We conducted a population-based study in the United Kingdom using the General Practice Research Database. Patients were classified as having severe psoriasis if they received a code for psoriasis as well as systemic therapy. Patients were defined as having mild psoriasis if they ever received a psoriasis code but no systemic therapy. Control subjects were selected from the same practices and start dates as psoriasis patients. Patients were classified as having risk factors if they received codes for diabetes, hypertension, hyperlipidemia, obesity, or smoking. Analyses were performed by using conditional logistic regression, and adjustments were made considering age, gender, person-years, and all cardiovascular risk factors. We identified 127,706 patients with mild psoriasis and 3854 with severe psoriasis. Respective prevalence rates of risk factors in those with severe psoriasis, mild psoriasis, and in controls were as follows: diabetes (7.1%, 4.4%, 3.3%), hypertension (20%, 14.7%, 11.9%), hyperlipidemia (6%, 4.7%, 3.3%), obesity (20.7%, 15.8%, 13.2%), and smoking (30.1%, 28%, 21.3%). Patients with mild psoriasis had a higher adjusted odds of diabetes (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.08-1.18]), hypertension (OR, 1.03; 95% CI, 1.01-1.06), hyperlipidemia (OR, 1.16; 95% CI, 1.12-1.21), obesity (OR, 1.27; 95% CI, 1.24-1.31), and smoking (OR, 1.31; 95% CI, 1.29-1.34) than controls. Patients with severe psoriasis had a higher adjusted odds of diabetes (OR, 1.62; 95% CI, 1.3-2.01), obesity (OR, 1.79; 95% CI, 1.55-2.05), and smoking (OR, 1.31; 95% CI, 1.17-1.47) than controls. Additionally, diabetes (OR, 1.39; 95% CI, 1.22-1.58) and obesity (OR, 1.47; 95% CI, 1.32-1.63) were more prevalent in those with severe psoriasis than with mild psoriasis. The study was cross-sectional and therefore the directionality of the associations could not be determined. Multiple cardiovascular risk factors are associated with psoriasis. Cardiovascular risk factors that are key components of the metabolic syndrome are more strongly associated with severe psoriasis than with mild psoriasis.

In 2,147 patients suffering from psoriasis, evaluation of the age of onset revealed two peaks, one occurring at the age of 16 years (female) or 22 years (males) and a second peak at the age of 60 years (female) or 57 years (males). Human lymphocyte antigen (HLA) tissue typing in 112 randomly assigned patients showed that HLA-Cw6, known to be at disequilibrium in psoriasis, is present in 85.3% of patients with early onset. In contrast, 14.7% patients with late onset showed this marker. Parents (father or mother) were affected in approximately half of the patients with early onset and in none belonging to the group with late onset. Furthermore, psoriasis in patients with early onset follows an irregular course and shows a strong tendency to become generalized. On the basis of clearly defined criteria (e.g., age of onset, heritability, and clinical course of disease), nonpustular psoriasis shows two distinct forms, one of which is hereditary, with early onset, and the other is sporadic and occurs in older age.