Early diagnosis and treatment of psoriatic arthritis leads to better long-term outcomes. Despite this, most patients have significant diagnostic delays.
More than half of patients with psoriatic arthritis (PsA) had a diagnostic delay of more than 2 years and data showed no significant improvement in diagnostic time between 2000 and 2017, according to a study published in The Journal of Rheumatology.1 Those most likely to have diagnostic delay were patients who developed PsA at a younger age, had higher body mass index (BMI), or enthesitis. Patients with sebopsoriasis were among the least likely to experience delay.
“There is increasing evidence that early diagnosis and treatment of PsA leads to improved long-term outcomes for patients in terms of disease severity and radiographic damage. Delays in diagnosis of even 6–12 months have been shown to be associated with joint damage and poor functional outcomes,” investigators stated. “Despite this, the majority of patients have significant delays in the diagnosis of PsA; up to 40% have not been previously identified in screening studies.”
This retrospective, population-based study utilized medical records from Olmsted County, Minnesota to analyze diagnostic delay in patients 18 years or older with PsA between January 1, 2000, and December 31, 2017. PsA was determined using the ClASification of Psoriatic Arthritis (CASPAR) criteria. Symptom onset was defined by the first PsA-related musculoskeletal symptom, such as those related to joints or enthesis.
Demographics, radiographic features, clinical characteristics, and laboratory data were collected. Psoriasis was confirmed by medical records and severity was determined using factors including body surface area involvement and distribution of involved areas.
The primary outcome was the delay in symptom onset to diagnosis of more than 2 years. The secondary outcomes analyzed delays in diagnosis at the 6-month and 1-year marks.
Investigators analyzed 162 incident PsA cases that had a clinician diagnosis. The mean age at symptom onset was 41.5 (12.6) years and 46% of patients were female. All patients met CASPAR criteria and displayed distal interphalangeal erosions on radiographs. The median time to diagnosis was 2.5 years (IQR 0.5–7.3). After symptom onset, only 23% (n = 38) patients were diagnosed with PsA, 35% (n = 56) by 1 year, and 45% (n = 73) by 2 years. Investigators did not observe any trends in symptom onset to diagnosis over the course of the 17 years (P = 0.84).
While there were no significant differences between patients with and without diagnostic delay regarding sex, psoriasis severity, family history, education level, smoking status, or alcohol intake, a few trends emerged. It appeared that younger patients (OR per 10-year decrease = 1.34, 95% CI 1.04–1.74), those with a higher BMI (OR per 10 kg/m2 increase = 1.89, 95% CI 1.15–3.10), and those with enthesitis (OR 2.20, 95% CI 1.08–4.46) were linked to a greater chance of diagnostic delay of more than 2 years. Conversely, those with sebopsoriasis had a lower likelihood of delay (OR 0.19, 95% CI 0.04–0.97).
Near-complete ascertainment of PsA cases using CASPAR criteria strengthened the study. However, its retrospective nature brings forth limitations regarding the completeness of medical record documentation. As only symptoms that were recorded could be analyzed, it is possible that the exactness of symptom onset is inaccurate. Additionally, as the population was 90% White, the results may not be generalizable to other racial or ethnic populations.
“More than half of the PsA patients in our study had a diagnostic delay of > 2 years,” investigators concluded. “A better understanding of factors associated with diagnostic delay may help in earlier diagnosis and management to improve outcomes in high-risk PsA patients. As not all patients have severe or progressive disease, identifying high-risk patient subgroups will be important to stratify those who will benefit from early, aggressive treatment.”
Karmacharya P, Wright K, Achenbach SJ, et al. Diagnostic Delay in Psoriatic Arthritis: A Population-based Study. J Rheumatol. 2021;48(9):1410-1416. doi:10.3899/jrheum.201199