What are the risk factors for psoriasis?

Risk Factors for Psoriasis

Smoking, obesity, family history, and alcohol consumption are the strongest modifiable and non-modifiable risk factors for developing psoriasis, with behavioral factors like stress and environmental tobacco smoke exposure also playing significant roles.

Non-Modifiable Risk Factors

Genetic Predisposition

• Family history of psoriasis is the single strongest risk factor, with an odds ratio of 33.96 (95% CI = 14.14-81.57), indicating individuals with affected family members have a 34-fold increased risk 1
• The genetic effect is stronger in men (OR = 30.39) than women (OR = 16.99) 1
• Strong linkage to HLA-Cw6 and DR7 exists in early-onset disease, though concordance in monozygotic twins is only 67%, emphasizing the critical role of environmental triggers 2

Modifiable Behavioral Risk Factors

Smoking

• Both active smoking and environmental tobacco smoke exposure significantly increase psoriasis risk 3
• In the Utah Psoriasis Initiative database of over 800 subjects, 37% of psoriatics smoke versus 13% in the general population (p<0.001) 3
• Critically, 78% of psoriasis patients started smoking before disease onset versus only 22% after, suggesting smoking is a true risk factor rather than a consequence 3
• Past and current smoking is associated with psoriasis development in women according to the Nurses Health Study II 3
• Smoking is strongly associated with pustular psoriasis specifically 3
• Environmental tobacco smoke exposure at home increases risk (OR = 2.29; 95% CI = 1.12-4.67), with the effect particularly pronounced in women (OR = 2.44) 1

Obesity and Weight

• Obesity (BMI ≥30) is both a risk factor for developing psoriasis and associated with more severe disease 3
• In the Nurses Health Study II, increased adiposity and weight gain were strong risk factors for psoriasis development in women 3
• Psoriasis patients have significantly higher BMI compared to controls, with severe psoriasis associated with higher BMI than mild psoriasis 3
• The mean weight of patients entering psoriasis clinical trials frequently exceeds 90 kg 3
• Weight loss from gastric bypass surgery has resulted in psoriasis remission in case studies, suggesting the relationship may be reversible 3

Alcohol Consumption

• Alcohol use is an independent risk factor for psoriasis with an odds ratio of 2.55 (95% CI = 1.26-5.17) 1
• A positive dose-response relationship exists between alcohol intake and psoriasis severity, particularly in women 3
• Higher pretreatment daily alcohol consumption is associated with less treatment-induced improvement in men 3
• Higher mortality from alcohol-related disease is seen in patients hospitalized for moderate to severe psoriasis 3

Psychosocial Stress

• Stressful life events, particularly changes in work conditions, significantly increase psoriasis risk (OR = 8.34; 95% CI = 1.86-37.43) 1
• Emotional stress is consistently reported as a trigger for psoriasis exacerbations 2, 4
• Divorce status is associated with increased risk (OR = 5.69; 95% CI = 2.26-14.34), likely reflecting chronic stress 1

Physical Activity

• Sedentary lifestyle contributes to psoriasis risk 5, 4
• The National Psoriasis Foundation recommends exercising 3 times weekly for 30 minutes or more as a protective measure 3, 6

Environmental and Infectious Triggers

Infections

• Upper respiratory infections are reported triggers for psoriasis, particularly guttate psoriasis 2
• Streptococcal infections classically precipitate guttate psoriasis in genetically predisposed individuals 7

Trauma

• Physical skin trauma (Koebner phenomenon) can trigger psoriasis lesions in predisposed individuals 7, 2

Geographic and Social Factors

• Urban dwelling increases risk (OR = 3.61; 95% CI = 0.99-13.18) compared to rural living 1

Drug-Induced Psoriasis Risk Factors

High-Risk Medications

• Beta-blockers have strong evidence for causing or exacerbating psoriasis 8
• Lithium is strongly associated with psoriasis induction and exacerbation 8
• Synthetic antimalarial drugs (chloroquine, hydroxychloroquine) can trigger psoriasis 8
• NSAIDs and tetracyclines are occasionally reported to aggravate psoriasis 8

Associated Comorbidities as Risk Indicators

Metabolic and Cardiovascular

• Metabolic syndrome is independently associated with psoriasis regardless of disease severity 3
• Psoriasis patients have higher frequencies of hyperlipidemia, hypertension, insulin resistance, diabetes mellitus, and homocysteinemia 3
• The chronic inflammatory nature of psoriasis itself may be an independent risk factor for cardiovascular disease and myocardial infarction 3

Depression

• Depression prevalence in psoriasis patients is approximately 24%, which may compound cardiovascular risk 3
• Lack of self-esteem and mood disorders are more prevalent in psoriasis patients 3

Critical Clinical Pitfalls

• Do not assume smoking or obesity developed after psoriasis onset—the majority of behavioral risk factors precede disease development and represent true causal relationships 3
• Screen for family history carefully, as it represents the strongest single risk factor and should guide counseling about disease likelihood in relatives 1
• Review medication lists systematically for beta-blockers, lithium, and antimalarials in patients with new-onset or worsening psoriasis 8
• Recognize that cardiovascular risk factors cluster in psoriasis patients, requiring comprehensive screening starting at age 20 with intensified monitoring by age 40 3