Age of Onset Determines Whether Psoriasis or Arthritis Develops First, Study Finds

Genetics plays a strong role in the the trajectory of the how psoriatic arthritis manifests in joint arthritis compared with skin disease.

When a person develops psoriasitic arthritis (PsA), which develops first, the telltale skin rash or the painful arthritis? Research presented last week at the American College of Rheumatology shows that the age at which psoriasis appears in the key factor in which condition presents first.

PsA occurs in patients who have skin psoriasis, but it can develop in patients who have not yet developed the skin condition associated with the disease. Genetics plays a strong role in the the trajectory of the how PsA manifests in joint vs skin disease, and researchers from Hacettepe University in Turkey sought to study the patterns to better understand the timing of each condition.

To do so, the research team used PsART International, a web-based registry of PsA patients receiving care in Turkey, Italy, and Canada; the registry keeps detailed disease history about the type and onset of skin and joint disease.

“The PsART-International cohort focuses on PsA patients in whom musculoskeletal symptoms start before skin lesions, which is approximately five to 10 percent of all PsA patients. We need more patients to determine related factors,” Umut Kalyoncu, MD, professor, Internal Medicine and Rheumatology, at Hacettepe University in Turkey, and the study’s lead author, said in a statement.

“PsA is a heterogeneous disease for clinical presentation and treatment response. If patients with arthritis first are really a different subgroup, it means that treatment response and prognosis could be different from others. Indeed, in our cohort, achieving minimal disease activity is statistically less frequent in patients with arthritis first.”

To conduct their study, the research team pulled data that included demographics, family history, and history of psoriatic disease whether it was skin psoriasis or arthritis, including the location on the skin where the disease first appeared. Patient data was placed in 3 groups: (1) arthritis first, (2) skin psoriasis first, (3) synchronous, or onset of both within 12 months.

The study’s primary outcome was how much time elapsed in months between the onset of skin disease to arthritis; the reverse onset was expressed in negative values.

The study of 1631 patients included 71 who had developed arthritis first and 1251 who had skin psoriasis first; 309 patients had synchronous onset. The analysis found a 65-month delay of the onset of arthritis after psoriasis when other independent variables are set to baseline values, according to a statement from the researchers.

Kalyoncu said the analysis showed that psoriasis has distinct subtypes:

  • starting age of disease
  • extensity of skin involvement
  • psoriasis skin type (plaque or pustular)
  • nail involvement
  • musculoskeletal involvement

Starting age of psoriasis is particularly important, because it depends on the genetic background,” Kalyoncu said in the statement. “Early-onset psoriasis is strongly associated with HLA-Cw6. However, late-onset psoriasis is not associated with it. In our study, arthritis first is highly related with late-onset psoriasis. This means arthritis-first patients may be a different subgroup of PsA, and treatment response could be worse in these patients as well. If these results are confirmed in other, well-defined PsA cohorts, we may have determined a subgroup of this highly heterogeneous disease.”


Tascilar K, Aydin SZ, Akar S, et al. Delay between the onset of psoriasis and arthritis in PsA patients from the PsART International Cohort. Presented at the American College of Rheumatology; Atlanta, Georgia; November 7-10, 2019. Abstract no. 2854.

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