Q&A: Diagnostic Delay in Psoriatic Arthritis

Author(s):

The diagnosis of psoriatic arthritis (PsA) may be delayed by more than 2 years in half of patients, especially those of younger age at symptom onset, or with a higher body mass index (BMI) or enthesitis before diagnosis.

Paras Karmacharya, MD

In this Q&A, corresponding author Paras Karmacharya, MD, MBBS, instructor of medicine at the Mayo Clinic College of Medicine in Rochester, Minnesota, highlights the findings of this retrospective, population-based study.

The study examined demographic and clinical characteristics associated with diagnostic delay in PsA. Diagnostic delay was defined as the time from any patient-reported PsA-related joint symptom to a physician diagnosis of PsA.

Of the 164 incident cases of PsA from 2000 to 2017 in Olmsted County, Minnesota, 162 had a physician or rheumatologist diagnosis. The patients’ mean age was 41.5 years and 46% were female. The median time from symptom onset to physician diagnosis was 2.5 years. Of the patients, 23% received a diagnosis by 6 months, 35% by 1 year and 45% by 2 years after symptom onset. Earlier age at onset of PsA symptoms, higher BMI and enthesitis were associated with a diagnostic delay of more than 2 years, while sebopsoriasis was associated with a lower chance of diagnostic delay. No significant improvement in time to diagnosis was noted between 2000 and 2017.

Rheumatology Network: Why was the study conducted?

Paras Karmacharya, MBBS: Delays in diagnosis in general leads to poor outcomes in rheumatologic diseases. In PsA, even a delay of 6 to 12 months has been shown to be associated with joint damage and poor functional outcomes. Also, treatment response may be better in early PsA. Despite this, the majority of patients have significant delays in diagnosis of PsA; up to 40% have not been previously identified in screening studies.

Only a few studies have examined delay in diagnosis of PsA. Trends in diagnostic delay of PsA in the United States and factors associated with delay in diagnosis have not been well studied. Lack of longitudinal, population-based PsA cohorts in the United States has made this type of study difficult. We wanted to utilize the strengths of our retrospective inception cohort for PsA from the Rochester Epidemiology Project (REP) to study delay longitudinally.

RN: What were the surprises from the findings?

PK: More than half of PsA patients in our study had a diagnostic delay of more than 2 years, and no significant improvement in time to diagnosis was noted from 2000 to 2017. Younger patients, obese patients, or those with enthesitis were more likely to have a diagnostic delay of more than 2 years.

RN: How significant are the results?

PK: Our study results help to understand some of the factors associated with diagnostic delay in PsA, which could help in earlier diagnosis and management to improve outcomes in high risk PsA patients.

Furthermore, identifying high risk patient subgroups will be important to stratify those that will benefit from early, aggressive treatment.

RN: What is the current practice and how could the findings possibly change things?

PK: The majority of patients with PsA have a history of psoriasis, often years prior to developing arthritis. People who are unsure if they could have psoriasis, including those with small skin plaques on the scalp or hidden areas such as the buttock or genital region should consult a dermatologist.

Physicians should be aware that PsA diagnosis may be missed in younger patients ignoring their symptoms, and in obese patients or patients with enthesitis, where it may be challenging to differentiate inflammatory from mechanical joint pain.

Psoriasis patients with joint symptoms should seek care with a rheumatologist to figure out whether they have PsA or another musculoskeletal disorders.

RN: What are the takeaway points for clinicians who may be reading this article?

PK: Our study showed that patients with PsA often wait for more than 2 years for the right diagnosis. Despite recent advancement in diagnostics, this delay has not significantly improved in the United Sates.

In our study, patients with younger age at onset of arthritis symptoms, those who were obese, or had enthesitis were more likely to have a delayed diagnosis. Younger patients are more likely to dismiss their symptoms, not report joint symptoms, or be aware of joint inflammation. Also, enthesitis may be attributed to overuse and trauma by the patients and general practitioners, and is not a common symptom of inflammatory arthritis such as rheumatoid arthritis. Similarly, obese patients often have other joint conditions which could potentially explain their joint symptoms such as osteoarthritis or gout. Therefore, the joint symptoms might be dismissed in these cases.

If anyone with psoriasis develops joint or entheseal pain, they should seek appropriate care and PsA should be ruled out.

Reference:

Karmacharya P, Wright K, Achenbach SJ, et al. Diagnostic Delay in Psoriatic Arthritis: A Population Based Study.[published online ahead of print, 2021 Feb 15]. The Journal of Rheumatology. 2021;jrheum.201199.doi: 10.3899/jrheum.201199