Psoriatic arthritis patients have increased morbidity already at the time of diagnosis: a case-control study

To evaluate the prevalence of comorbidities preceding the diagnosis of psoriatic arthritis (PsA) compared with the general population. We identified all adult patients granted a special reimbursement (SR) for disease-modifying anti-rheumatic drugs for PsA between 2002 and 2014 from the Finnish Social Insurance Institution register (N = 6077). Three general population controls were matched to each case. Visits to specialized medical care (Classification of Disease 10th revision coded), and prescription drug purchases categorized by Anatomical Therapeutic Chemical codes were collected for cases and controls between 2000 and 2014. We evaluated the period from 24 months before to 3 months after the index date (ID), defined as the date when the SR was granted. SRs granted for other chronic diseases prior to the ID were additionally collected. PsA patients had three times more visits to specialized medical care and increased overall drug use compared with controls. Based on SRs valid at the time of PsA diagnosis, new-onset PsA patients had significantly higher prevalence of diabetes mellitus (women: 11% vs. 7%; men: 14% vs. 10%; all p < 0.001), cardiovascular diseases (women: 19% vs. 14%; men: 23% vs. 18%; all p < 0.001), and obstructive lung diseases (women: 12% vs. 7%; men: 8% vs. 6%; all p < 0.001) compared with controls. PsA patients demonstrate increased morbidity already at the time of PsA diagnosis. Screening for comorbidities should therefore be considered when joint disease is clinically apparent.