Cardiovascular Disease and Osteoporosis in Psoriatic Arthritis

Abstract

Psoriatic arthritis (PsA) is an inflammatory joint disease (IJD) associated with psoriasis. The clinical presentation is heterogeneous and may involve the peripheral joints, the axial skeleton and the entheses, as well as skin and nails. The diagnosis is based on clinical manifestations, and the ClASsification of Psoriatic ARthritis (CASPAR) criteria can be used. PsA has been associated with several comorbid conditions, such as cardiovascular (CV) disease (CVD), osteoporosis, inflammatory bowel disease and depression. This thesis focuses on two important comorbidities in rheumatic diseases, namely CVD and osteoporosis. Until now, patients with rheumatoid arthritis (RA), the most prevalent IJD, have been most extensively examined concerning both CVD and osteoporosis. However, PsA is a disease distinct from RA, clinically, radiologically and pathologically. Research findings from RA on disease course, comorbidity, treatment and outcome cannot be automatically translated to PsA patients. In three of the papers included in this thesis we used data from the Health study in Nord -Trøndelag (HUNT). The HUNT studies are population-based cohorts established in the 1980ies, HUNT1 (1984 -86), HUNT2 (1995-97) and HUNT3 (2006-08). In Paper 4 we used data from the Department of Rheumatology, Hospital of Southern Norway Trust. Increased CV burden has been documented in PsA patients, however the exact risk increase or causal relationship with inflammation is documented to a lesser degree. Paper 1 in this thesis showed that patients with PsA in the HUNT3 study had an increased burden of several CV risk factors, such as obesity, smoking, hypertension, CRP and high triglyceride levels. However, when it comes to established CVD, we observed only an increased risk of angina pectoris. Also, the estimated 10-years risk of a fatal CV event calculated with the Systematic Coronary Risk Evaluation (SCORE) was comparable to the background population. Whether CV risk factors are increased prior to diagnosis of PsA, co-existing or are a result of PsA itself has not been clarified. Longitudinal data from HUNT2 and HUNT3 in Paper 2 indicate that the unfavourable CV risk factors in PsA patients were present before the PsA diagnosis was established, which may be related to the patients already having psoriasis. Because modifiable CV risk factors are often present in PsA patients, it is important to educate doctors and patients on how to manage their CV risk factors, to decrease their risk of CVD in the future. Data from HUNT3 and the Rheumatology department of Hospital of Southern Norway Trust indicate that PsA patients did not have lower bone mineral density than the background population. The prevalence of osteoporosis according to the World Health Organization definition was low. This indicates that PsA patients may follow guidelines for osteoporosis assessment developed for the general population, in line with the current recommendations. However, extra vigilance for patients with long-standing high disease activity or on high doses of glucocorticoids is probably needed. Both osteoporosis and CVD may be silent conditions that the patients are unaware of. Therefore, to wisely target the use our health resources, it is important to know the risk of these conditions, so that we can identify the patients who need extra surveillance. Hopefully, the knowledge from this thesis may guide both doctors who care for patients with PsA, and the patients themselves, on how to manage important comorbid conditions.