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Diagnostic Delay in Psoriatic Arthritis: What are the Consequences?

Nov 06, 2020 4:24 pm

Despite increased awareness and better diagnostic modalities at hand, early diagnosis of psoriatic arthritis (PsA) still remains a huge unmet need. Broad spectrum of PsA manifestations, often gradual and subtle symptom development, along with lack of specific serological testing contributes to the challenge. 

Abstract 0307 outlines longitudinal analysis of the patient pathway to PsA diagnosis based on the retrospective cohort study of administrative claims data from January 2006 to April 2019. In this study authors examined sequences of health events preceding diagnosis of PsA over the 6 year period. Among13,661 patients who met diagnostic criteria for PsA eventually, diagnostic codes for arthritis prevailed, except those were frequently miscoded as osteoarthritis ( 48% vs 22% control), rheumatoid arthritis (RA 18% vs 2%) and inflammatory polyarthritis (IA 18% vs 1%). Diagnostic code for Psoriasis was recorded in 60% of the patients as opposed to 2% in control group. Not surprisingly PsA patients without a prior diagnosis of psoriasis had a higher level of coding for other forms of arthritis (osteoarthritis and RA being most common). 

Authors noted that coding for OA and IA declined over time, at the same time codes for enthesitis, psoriasis and axial symptoms were higher as it got closer to the actual PsA diagnosis. 

This article also highlights how diagnostic codes differed by the type of provider. It had been noted that general practitioners tended to generalize codes by musculoskeletal symptoms or presence of axial symptoms while rheumatologists had fairly even distribution across different types of arthritides (with RA and osteoarthritis leading the list). Amongst all specialists, dermatologists were least likely to code for arthritis.  On the other hand, rheumatologists were guilty of omitting the psoriasis code.  This study highlights differences in diagnosis by the evaluating provider in early stages of PsA and points out diagnostic challenges which often lead to misdiagnosis and delayed diagnosis in psoriatic arthritis.

Abstract 0309 echoes the above message on diagnostic delay, although time from initial presentation to diagnosis seems to be much shorter here. As per authors of this retrospective cohort study median lag from symptom onset to diagnosis calculated to be 2.5 years on average. Interestingly enough, younger age, higher body mass index (BMI), and enthesitis before diagnosis were associated with at least 1-2 years of delay in diagnosis. Presence of sebopsoriasis associated with decreased likelihood in delay as one would naturally expect. In this study authors raise the concern about higher risk of radiographic progression associated with delay in diagnosis, although this association did not reach statistical significance.

Another retrospective study (abstract 0308) evaluates the effect of psoriasis (PSO) and PsA concurrence on delay in diagnosis. Half of the patients in this study were diagnosed with both conditions concomitantly while another half experienced skin symptoms way before development of arthritis. Median lag time from PSO onset to first PsA manifestation was 263 days in the latter group. Patient’s family history of psoriasis and personal history of severe psoriasis were associated with delay in transition from skin disease to PsA. It is unclear if phenotypic difference of the patients or provider’s approach to diagnosis contributes to the delay.

In summary, the above studies do not answer many questions about the effect of diagnostic delay on long term outcomes in PsA but certainly brings attention to the phenomenon of diagnostic delay per se, calling for more studies in this regard. Development of specific and objective diagnostic modalities and education of referring and treating physicians remains an unmet need for PsA patients. Addressing these issues could potentially lead to shorter time to diagnosis and improved outcomes.

 

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