Psoriasis is common, chronic, and disabling skin disease which affects about 1 million Canadians.¹ The typical age of onset is between 30-39 years and 50-69 years, but can occur at any age.² It affects quality of life and causes significant functional impairments for patients. Over 50% of patients with psoriasis have difficulty with daily activities including physical exercise and sleep.³ Almost 60% have difficulty engaging in social activities and have problems with personal and social relationships as a result of skin involvement.³

While historically psoriasis was considered a skin-limited disease, recent research shows that it is better characterized as a multisystem chronic inflammatory disorder with multiple associated conditions, which will be discussed here. 

Inflammatory Conditions

Psoriatic Arthritis (PsA)

Psoriatic arthritis (PsA) is an inflammatory arthritis (joint disease) affecting about 5-30% of patients with skin psoriasis.⁴ In the majority of patients, the skin manifestations occur before the onset of joint disease.⁵ PsA is characterized by pain and swelling in the joints and/or the surrounding ligaments and tendons. Various subtypes exist ranging from mild joint involvement to rapidly progressive and destructive joint disease. It is usually accompanied by morning stiffness which can last 30 minutes to one hour. Generally, more extensive skin involvement, nail psoriasis, and longer disease duration are associated with a higher risk of joint involvement.⁶ Studies show that up to 15% of patients with psoriasis have undiagnosed PsA and hence it is important to bring up any new joint symptoms to your healthcare provider to allow appropriate evaluation.⁵ This will be discussed in greater detail in other sections of the website. 

Autoimmune Diseases

Having one immune mediated disease generally increases the risk of having another due to the underlying genetic predisposition. A recent study found there was an increased risk of alopecia areata (hair loss), celiac disease, systemic sclerosis, inflammatory bowel disease (especially Crohn’s disease), autoimmune blistering diseases, and vitiligo.^7,8 However, these associated conditions remain rare and your healthcare provider will evaluate whether any investigation is required based on your symptoms. 

Cardiometabolic Conditions

Cardiometabolic conditions include high blood pressure, type 2 diabetes, heart disease, obesity, high cholesterol (dyslipidemia), fatty liver, and sleep apnea. These are common among patients with psoriasis and is correlated to more severe skin disease. Psoriasis may serve as an independent risk factor for development of diabetes and major adverse cardiovascular events (such as a stroke or a heart attack) with the second being more likely with more severe psoriasis. 

Cardiovascular Disease

Major cardiovascular events include myocardial infarction (heart attack), stroke, and sudden death due to cardiovascular disease.⁶ The prevalence of cardiovascular disease has been shown to be higher in patients with psoriasis. While part of this may be related to co-occurring risk factors for both conditions such as smoking, alcohol use, increased weight, elevated blood pressure, and diabetes, newer studies have shown that the presence of psoriasis is also an independent risk factor for the development of cardiovascular disease, likely due to the chronic inflammatory state.⁹ The risk of cardiovascular disease appears to be correlated to the severity and duration of the underlying psoriasis. 

Obesity

Obesity has also been found to be an independent risk factor and leads to at least a two-fold increased risk of psoriasis development.^6,10 Psoriasis risk and severity were directly proportional to the Body Mass Index (BMI), which is a ratio of weight and height.^11,12 The adipose tissue is an active metabolic organ and contributes to the overall inflammatory state of psoriasis. Additionally, the rate of obesity was higher in patients with severe psoriasis compared to mild.¹⁰

High blood pressure 

Studies have shown that high blood pressure is more common in patients with psoriasis compared to those without.¹³ The odds of having high blood pressure increased with greater psoriasis severity.¹⁴ In addition, there is more severe and poorly controlled blood pressure in patients with psoriasis compared to those without⁶. Please be aware that rarely, some blood pressure lowering medications are associated with psoriasis such as beta-blockers, hence it is important to discuss the risk and benefits with your healthcare provider.

Diabetes

There is an elevated rate of diabetes observed in patients with psoriasis.¹⁵ Specifically, psoriasis is an independent risk factor for diabetes development.⁶ The risk of diabetes and resulting complications appear to increase with increasing severity of psoriasis.^6,15

As psoriasis appears to be an independent risk factor for development of these metabolic conditions, it is important to maintain a healthy lifestyle with regular exercise and good nutrition to minimize the other risk factors for development of these metabolic conditions. We encourage you to have a discussion with your healthcare provider about appropriate options for you. 

Cancer

A recent meta-analysis, which is an extensive review of the literature, revealed an increased cancer risk overall, skin cancer, lymphoma, lung cancer and bladder cancer.^6,16 Although there is a lot of variation in the findings of the studies, lymphomas and skin cancers were more common in patients with psoriasis than in patients without. It is not known why the rate of these cancers is elevated but for skin cancers, including basal cell carcinoma and squamous cell carcinoma it may be due to increased exposure to sunlight (as patients often find it improves their psoriasis), immunosuppressive therapies, as well as improved detection as these patients often have close follow up with a dermatologist and healthcare providers. Additionally, psoriasis is associated with certain habits such as increasing smoking and alcohol consumption, which alone might be risk factors for cancer development. For this reason, psoriasis patients need to bring any non-healing sore or newly appearing or changing spot on the body to a doctors attention.   Additionally, it is important to do all the age-appropriate cancer screening in a timely manner as well as any other investigations your healthcare provider suggests. 

Psychological Conditions

Psoriasis can have a significant effect on the physical and emotional health of a patient and may increase the risk of development of depression, anxiety, and suicidality*. Mood disorders occur more frequently (up to 1.6 times greater) in patients with psoriasis compared to the general population.¹⁷ The risk of depression is greatest in patients with more severe psoriasis. A study in Quebec found that severe psoriasis was associated with a higher risk of suicidal behavior compared to mild disease.¹⁸  Thus, psoriasis can increase the risk of psychiatric comorbidities and if you are experiencing these symptoms, it is important to approach your healthcare provider to discuss options for management. 

*If you are in crisis contact The Canada Suicide Prevention Service by calling 1.833.456.4566.  Help is available 24 hours a day! 

References

1. Levy AR, Davie AM, Brazier NC, et al. Economic burden of moderate to severe plaque psoriasis in Canada. International journal of dermatology. 2012;51(12):1432-1440.
2. Parisi R, Symmons DP, Griffiths CE, Ashcroft DM. Global epidemiology of psoriasis: a systematic review of incidence and prevalence. The Journal of investigative dermatology. 2013;133(2):377-385.
3. Associations IFoPMa. Psoriasis.https://www.ifpma.org/subtopics/psoriasis/.
4. Alinaghi F, Calov M, Kristensen LE, et al. Prevalence of psoriatic arthritis in patients with psoriasis: A systematic review and meta-analysis of observational and clinical studies. Journal of the American Academy of Dermatology. 2019;80(1):251-265.e219.
5. Villani AP, Rouzaud M, Sevrain M, et al. Prevalence of undiagnosed psoriatic arthritis among psoriasis patients: Systematic review and meta-analysis. Journal of the American Academy of Dermatology. 2015;73(2):242-248.
6. Takeshita J, Grewal S, Langan SM, et al. Psoriasis and comorbid diseases: Epidemiology. Journal of the American Academy of Dermatology. 2017;76(3):377-390.
7. Wu JJ, Nguyen TU, Poon KY, Herrinton LJ. The association of psoriasis with autoimmune diseases. Journal of the American Academy of Dermatology. 2012;67(5):924-930.
8. Kridin K, Bergman R. Association between bullous pemphigoid and psoriasis: A case-control study. Journal of the American Academy of Dermatology. 2017;77(2):370-372.
9. Gelfand JM, Neimann AL, Shin DB, Wang X, Margolis DJ, Troxel AB. Risk of Myocardial Infarction in Patients With Psoriasis. JAMA. 2006;296(14):1735-1741.
10. Armstrong AW, Harskamp CT, Armstrong EJ. The association between psoriasis and obesity: a systematic review and meta-analysis of observational studies. Nutrition & diabetes. 2012;2(12):e54.
11. Kumar S, Han J, Li T, Qureshi AA. Obesity, waist circumference, weight change and the risk of psoriasis in US women. Journal of the European Academy of Dermatology and Venereology. 2013;27(10):1293-1298.
12. Langan SM, Seminara NM, Shin DB, et al. Prevalence of metabolic syndrome in patients with psoriasis: a population-based study in the United Kingdom. The Journal of investigative dermatology. 2012;132(3 Pt 1):556-562.
13. Armstrong AW, Harskamp CT, Armstrong EJ. The association between psoriasis and hypertension: a systematic review and meta-analysis of observational studies. Journal of hypertension. 2013;31(3):433-442; discussion 442-433.
14. Alexandroff AB, Pauriah M, Camp RDR, Lang CC, Struthers AD, Armstrong DJ. More than skin deep: atherosclerosis as a systemic manifestation of psoriasis. British Journal of Dermatology. 2009;161(1):1-7.
15. Armstrong AW, Harskamp CT, Armstrong EJ. Psoriasis and the risk of diabetes mellitus: a systematic review and meta-analysis. JAMA dermatology. 2013;149(1):84-91.
16. Chiesa Fuxench ZC, Shin DB, Ogdie Beatty A, Gelfand JM. The Risk of Cancer in Patients With Psoriasis: A Population-Based Cohort Study in the Health Improvement Network. JAMA dermatology. 2016;152(3):282-290.
17. Dowlatshahi EA, Wakkee M, Arends LR, Nijsten T. The Prevalence and Odds of Depressive Symptoms and Clinical Depression in Psoriasis Patients: A Systematic Review and Meta-Analysis. Journal of Investigative Dermatology. 2014;134(6):1542-1551.
18. Laverde-Saad A, Milan R, Mohand-Saïd S, LeLorier J, Litvinov IV, Rahme E. The risk of suicidal behaviour in individuals with psoriasis: A retrospective cohort study in Quebec, Canada. Journal of the European Academy of Dermatology and Venereology : JEADV. 2020;34(12):e800-e802.