Psoriatic Arthritis, Tonsillitis Among Most Common Comorbidities Linked to Generalized Pustular Psoriasis


This retrospective study from Japan highlighted several key elements linked to a generalized pustular psoriasis diagnosis among individuals with psoriasis vulgaris.

Koremasa Hayama MD, PhD

Credit: ResearchGate

Koremasa Hayama MD, PhD

Credit: ResearchGate

Patient comorbidities such as psoriatic arthritis (PsA), tonsillitis, and sinusitis are some of the most likely comorbidities linked to diagnosis of generalized pustular psoriasis (GPP) for those with psoriasis vulgaris (PsV), according to new findings, as are treatments such as systemic corticosteroids and phototherapy.1

These findings resulted from a retrospective cohort study which was conducted through data drawn from health insurance claims in Japan and sought to highlight the elements found to be associated with a diagnosis of GPP in those with PsV.

The study’s investigators pointed out that while it is clear that comorbidities or symptoms are often present in GPP patients, it remained less obvious whether their presence in those with PsV was linked to an increased risk of developing GPP.2 To address this question, the new research was conducted and led by Koremasa Hayama, MD, PhD, from the Nihon University School of Medicine in Tokyo, Japan.

“PsV is dominated by the adaptive immune response (the Th17 pathway), whereas GPP is dominated by the innate immune response (the interleukin [IL]-36 pathway); therefore, it remains unknown why some patients with PsV proceed to receive a GPP diagnosis,” Hayama and colleagues wrote.

Background and Findings

The investigators used a retrospective cohort study design, with patient claims data having been drawn from the Japanese Medical Data Center (JMDC). The JMDC is known to cover more than 4 million individuals known to be employed in Japan.

The team’s research ended up spanning from July 2005 to January 2019, and it was made up of 2 distinct cohorts: the first was made up of individuals with diagnoses of PsV only—known as PsV only group—and the second was made up of individuals with PsV that was later followed by diagnosis of GPP—the PsV with GPP group.

The ‘PsV only’ group included those that had 2 PsV diagnoses which had been confirmed at the time of the study period, and the ‘PsV with GPP’ group involved those with 2 confirmed diagnoses of PsV in addition to a single confirmed GPP diagnosis in the same timeframe as the PsV only group.

Patients that had been included in both the study’s groups maintained continuous insurance enrollment following the end of the second PsV claim, and the investigators determined the index date to be the second PsV diagnosis code’s date.

The research team’s follow-up period would end at the earliest point of the following occurrences: for the PsV with GPP group, the ending of continuous enrollment or the maximum follow-up time; for the PsV with GPP group, the period was completed at the time of the initial confirmed diagnosis of patients’ GPP.

Overall, the investigators found that the most significant factor associated with a diagnosis of GPP was shown to be PsA (OR 20.2, 95% CI 17.06–23.92, P < 0.0001). They added that PsA had a median time from event to diagnosis of 119 days.

The team also found that other comorbidities like tonsillitis, other types of psoriasis, and sinusitis were also shown to be linked to GPP. As far as related treatments, systemic corticosteroids (OR 2.19, 95% CI 1.98–2.43, P < 0.0001) were found to have been linked with GPP, and the team noted a median time of 180 days from treatment initiation to diagnosis of GPP.

Conversely however, other treatments which included interleukin (IL)-17 or IL-23 inhibitors, immunosuppressants, and phototherapy were reported by the research to have a delay of ≥1 year from the time of treatment initiation to diagnosis of patients’ GPP. They also found that symptoms such as headaches, back pain, and fever were shown to be indicators of a possible future GPP diagnosis.

Overall, individuals with PsV that also required systemic therapies were identified by the investigators as more likely to be given a GPP diagnosis versus individuals not in need of systemic treatment, allowing for helpful insights for clinicians in identification of high-risk PsV patients and supporting early diagnosis of patients’ GPP.

“By raising awareness of GPP among physicians who are treating patients with moderate-to-severe PsV, these findings may support physicians in recognizing patients who are potentially at high risk of GPP and facilitate early diagnosis,” they wrote. “Further research is required to establish the clinical course and pathobiology leading to a GPP diagnosis in patients with PsV.”


  1. Hayama, K, Iwasaki, R, Tian, Y, Fujita, H. Factors associated with generalized pustular psoriasis progression among patients with psoriasis vulgaris in Japan: Results from a claims database study. J Dermatol. 2023; 00: 1–8.
  2. Ohata C, Tsuruta N, Yonekura K, Higashi Y, Saito K, Katayama E, et al. Clinical characteristics of Japanese pustular psoriasis: a multicenter observational study. J Dermatol. 2022; 49: 142–150.
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