Objective To study the impact of obesity and smoking on psoriasis.
Design Cross-sectional study.
Setting University of Utah Department of Dermatology clinics.
Patients A case series of patients with psoriasis enrolled in the prospective Utah Psoriasis Initiative (UPI) (which carefully performs phenotyping of patients with psoriasis) was compared with 3 population databases: the Behavioral Risk Factor Surveillance System of the Utah population, the 1998 patient-member survey from the National Psoriasis Foundation, and 500 adult patients who attend our clinics and do not have psoriasis (nonpsoriatic population).
Results The prevalence of obesity in patients within the UPI population was higher than that in the general Utah population (34% vs 18%; P<.001) and higher than that in the nonpsoriatic population attending our clinics. Assessment of body image perception with a standardized diagram in the UPI group resulted in the median body image score of normal weight at 18 years of age and the onset of psoriasis, but it transitioned to overweight at the time of enrollment in the UPI. Thus, obesity appears to be the consequence of psoriasis and not a risk factor for onset of disease. We did not observe an increased risk for psoriatic arthritis in patients with obesity; furthermore, obesity did not positively or negatively affect the response or the adverse effects of topical corticosteroids, light-based treatments, and systemic medications. The prevalence of smoking in the UPI population was higher than in the general Utah population (37% vs 13%; P<.001) and higher than in the nonpsoriatic population (37% vs 25%; P<.001). We found a higher prevalence of smokers in the obese population within the UPI than in the obese population within the Utah population (25% vs 9%; P<.001).
Conclusions Patients with psoriasis attending the University of Utah Dermatology Clinics were more likely to be obese and to smoke compared with nonpsoriatic patients and more likely to be obese compared with other large cohorts with psoriasis. Smoking appears to have a role in the onset of psoriasis, but obesity does not. The high prevalence of obesity and smoking in a psoriasis cohort has not been previously noted; if confirmed, it supports the prediction that a significant portion of patients with psoriasis will have the comorbid conditions and public health issues of those with obesity and smoke.
Objective To evaluate the association between different components of smoking history and the clinical severity of psoriasis.
Design A hospital-based cross-sectional study.
Setting Inpatient wards of a hospital for skin diseases in Rome, Italy.
Patients A total of 818 adults with psoriasis.
Main Outcome Measure The Psoriasis Area and Severity Index was used to assess the clinical severity of psoriasis between February 21, 2000, and February 19, 2002.
Results After adjustment for potential confounders (sex, age, body mass index, psychological distress, family history of psoriasis, duration of psoriasis disease, and alcohol consumption), high intensity of smoking (>20 cigarettes daily) vs a lower level of consumption (≤10 cigarettes daily) was associated with a more than 2-fold increased risk of clinically more severe psoriasis (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.2-4.1). Cigarette-years, measured as the product of the intensity and duration (years) of smoking, significantly increased the risk of clinically more severe psoriasis after adjustment for confounding factors (OR, 1.3; 95% CI, 1.0-1.6, for a 600-U increase in cigarette-years). Separate analyses for men and women showed that the effect of cigarette-years was stronger for women (OR, 1.8; 95% CI, 1.2-2.6, for a 400-U increase in cigarette-years) than for men (OR, 1.2; 95% CI, 0.9-1.6, for a 700-U increase in cigarette-years).
Conclusions Smoking is associated with the clinical severity of psoriasis and highlights the importance of smoking cessation in patients with psoriasis.
Psoriasis is a common disease, affecting approximately 2% of the population.1 That psoriasis might serve as a marker of cardiovascular risk, even if indirectly, would be important information for physicians. Three articles2- 4 published in the December issue of the Archives of Dermatology suggest that patients with psoriasis vulgaris are frequently overweight or obese and smoke tobacco more frequently than patients with other skin diseases or in patients from the general population. The implications for caring for these patients go well beyond the dermatologic considerations.
The association between obesity and psoriasis has been suspected by clinicians for many years. The report by Herron et al2 confirms the association between obesity and psoriasis and answers a number of important questions about that association. The prevalence of obesity in psoriasis patients at the University of Utah's dermatology clinic was nearly double that of the general population in Utah and also greater than the prevalence of obesity in the dermatology clinic population without psoriasis.2 A report by McGowan et al3 noted a higher frequency of overweight and obesity in nationally representative data sets of psoriasis patients compared with the nonpsoriatic population, although the study was not sufficiently powered to detect statistical significance.
Given evidence suggesting that psoriasis and obesity are linked, it is important to know whether obesity causes psoriasis or results from this skin disease. Herron et al report that most patients had a normal body mass index at age 18 years and at onset of psoriasis, but 71% became overweight or obese at some point after acquiring psoriasis. The body mass index of psoriasis patients in this study was significantly greater than that of the Utah population (after controlling for sex and age) and also was greater than the dermatology clinic population without psoriasis. Similarly, the median body image score was normal at the onset of psoriasis, but increased to indicate overweight or obesity after psoriasis developed. The authors concluded that obesity is a consequence rather than a risk factor for psoriasis.
Data reported by Herron et al2 suggest that obesity after psoriasis onset is linked to a sedentary lifestyle. Obese study participants with psoriasis were less likely to exercise than nonobese participants, and 32% of obese psoriasis participants reported that arthritis interfered with physical activity compared with 14% of nonobese participants. Those who were obese were less likely than nonobese individuals to present with mild psoriasis (defined as <2% body surface area involvement). Conversely, obese individuals were more likely than nonobese individuals to have severe disease (defined as >20% body surface area involvement).
Herron et al also report a higher prevalence of smoking in psoriasis patients compared with the nonpsoriatic population. Seventy-seven percent of patients started smoking before developing psoriasis and 22% started after disease onset, suggesting a possible contributory role. Fortes et al4 report that high-intensity smoking (>20 cigarettes daily) was associated with more than a 2-fold increased risk of severe psoriasis compared with smoking 10 or fewer cigarettes daily. Cigarette-years, which combines the intensity and duration of smoking in years, was associated with more severe psoriasis and that effect was greater for women than for men. The authors highlight the importance of smoking cessation as part of the management of psoriasis.4
Similar results were reported by Naldi et al5 in a case-control study of Italian patients that showed the risk of psoriasis was higher in former and current smokers than in never-smokers with a relative risk of 1.9 for former smokers and 1.7 for current smokers. The relative risk of developing pustular lesions, a more severe and occasionally life-threatening manifestation of psoriasis, was 5.3. This association between smoking and psoriasis, which also has been reported in Chinese patients, is likely to be present in all populations.6
The negative effects of obesity and smoking on general health are well-known. Apart from a potential impact of obesity on psoriasis, this comorbid condition can seriously complicate therapies for psoriasis and these effects may be both direct and indirect. For example, nonalcoholic steatohepatitis has been associated with obesity and psoriasis.7 Fatty liver predisposes some psoriasis patients to methotrexate-induced cirrhosis.8 McGowan et al3 point out the comorbidities of psoriasis and obesity including type 2 diabetes, dyslipidemia, hypertension, and cardiovascular disease. The presence of hypertension makes treatment with cyclosporine more difficult because the latter drug is commonly associated with the development of hypertension. Both cyclosporine and acitretin are associated with the development of hyperlipidemia, making these drugs more difficult to prescribe in a patient already predisposed to dyslipidemia. Moreover, some patients who are obese have had their treatment courses complicated by sleep apnea,9 raising concern about the use tumor necrosis factor inhibitors and the possible compromise of pulmonary function with the secondary development of congestive heart failure.
Considering the association between psoriasis and obesity and psoriasis and smoking, it should not be surprising that increased cardiovascular mortality has been reported in psoriasis inpatients.10 The contribution of alcohol to excess mortality in psoriasis patients must not be overlooked.11
Now that associations between psoriasis and obesity and psoriasis and smoking have been firmly established, clinicians should emphasize the importance of diet, exercise, and smoking cessation to patients affected by psoriasis. The adverse effects of obesity and smoking on general health combined with the potential negative impact on psoriasis vulgaris, psoriatic arthritis, and on the therapies used for the management of psoriasis must be emphasized to patients.
Corresponding Author: Jeffrey P. Callen, MD, 310 E Broadway, Louisville, KY 40202 (firstname.lastname@example.org).
Financial Disclosures: Dr Lebwohl has been a consultant for and received honoraria from Abbott, Amgen, Biogen, Centecor, Genentech, Warner Chilcott, and Novartis and has received honoraria from Astellis, Connetics, Galderma, and Pharmaderm. Dr Callen has received honoraria either directly or indirectly from Dermik, Amgen, Doak Dermatologics, Medicis, 3M, Biogen, Genentech, Intendis, Roche, and Connetics; has served as a consultant for 3M, Intendis, Amgen, Abbott Immunology, Biogen, Doak Dermatologics, Novartis, Connetics, Genentech, and Taro; and has served on safety monitoring committees for Centocor and Genmab.
Lebwohl M, Callen JP. Obesity, Smoking, and Psoriasis. JAMA. 2006;295(2):208-210. doi:10.1001/jama.295.2.208