MADRID (FRONTLINE MEDICAL NEWS) – Comorbidities are relatively common in psoriatic arthritis patients, and they are more prevalent in patients with a worse disease course while on initial treatment with a tumor necrosis factor inhibitor, based on data from more than 1,700 Danish patients.

The presence of comorbidities in psoriatic arthritis (PsA) patients on initial tumor necrosis factor inhibitor (TNFi) treatment “was associated with higher disease activity, shorter adherence to the first TNFi, and reduced clinical response,” Lars Erik Kristensen, MD , said at the European Congress of Rheumatology.

“We need to put more focus on comorbidities” in PsA patients, Dr. Kristensen added during a press conference. PsA has traditionally been considered similar to rheumatoid arthritis, but the comorbidity profile of many PsA patients sets the two rheumatic disorders apart. “Comorbidities play a more central role in PsA than they do in rheumatoid arthritis,” said Dr. Kristensen, a rheumatologist and chief scientific officer of the Parker Institute in Copenhagen. “PsA is not like rheumatoid arthritis.”

To better understand the possible impact of comorbidities on PsA, he and his associates reviewed 1,750 Danish patients with PsA enrolled in a national registry at the time they began treatment with a TNFi. At the time they started treatment, 1,066 (61%) had no comorbidities, 493 (28%) had one comorbidity, and 191 (11%) had two or more comorbidities.

A comparison of the subgroups with no comorbidities and those with two or more showed several important and statistically significant differences in their baseline characteristics. Patients with at least two comorbidities had longer disease duration, and they had more active disease as measured by parameters including the Disease Activity Score 28 and the Health Assessment Questionnaire. Patients with two or more comorbidities also were older and had a higher average body mass index.

Further analyses showed that patients with two or more comorbidities were 72% more like to discontinue their TNFi treatment, compared with patients with no comorbidities – a statistically significant difference, Dr. Kristensen reported .

After 6 months of TNFi treatment, patients with two or more comorbidities had lower rates of achieving the American College of Rheumatology 20%, 50%, or 70% improvement criteria compared with patients with no comorbidities. For example, an ACR20 response occurred in 40% of patients with no comorbidities and in 31% of patients with two or more comorbidities after 6 months in an adjusted analysis.

Dr. Kristensen has been a consultant to or a speaker for several drug companies.

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