Mapping opportunities for the earlier diagnosis of psoriasis in primary care settings in the UK: results from two matched case–control studies

BACKGROUND: The diagnosis of psoriasis may be missed or delayed in primary care settings. AIM: To examine trends in healthcare events before a diagnosis of psoriasis. DESIGN AND SETTING: Two matched case–control studies using electronic healthcare records delineated from the Clinical Practice Research Datalink (CPRD GOLD and Aurum) in the UK. METHOD: Individuals aged ≥18 years with an incident diagnosis of psoriasis (case group) between 1 January 2010 and 29 December 2017 were identified and matched by age, sex, and general practice with six individuals without psoriasis (control group). Healthcare activities were examined and annual incidence rates and incidence rate ratios (IRRs) with 95% confidence intervals (CIs) for 10 years before the index date were compared between case and control groups. RESULTS: There were 17 320 people with psoriasis and 99 320 controls included from CPRD GOLD, and 11 442 people with psoriasis and 65 840 controls extracted from CPRD Aurum. Data from CPRD GOLD showed that people with psoriasis were up to eight times more likely to be diagnosed with pityriasis rosea at 6 months (IRR 7.82, 95% CI = 4.09 to 14.95) before the index date than the control group. The case group were twice as likely to be diagnosed with eczema (IRR 1.90, 95% CI = 1.76 to 2.05) or tinea corporis (IRR 1.99, 95% CI = 1.74 to 2.27) 1 year before the index date. The case group were more likely to report dry skin, rash, skin texture changes, and itching than the control group up to 5 years before the index date. The most frequently reported clinical feature was rash with an IRR of 2.71 (95% CI = 2.53 to 2.92) at 1 year before the index date. The case group were prescribed topical corticosteroids (IRR 1.97, 95% CI = 1.88 to 2.07) or topical antifungals (IRR 1.92, 95% CI = 1.78 to 2.07) in the year before the index date twice as often as those in the control group. CONCLUSION: Findings suggest that the diagnosis of psoriasis may be missed or delayed in a UK primary care setting for up to 5 years for some individuals, hence leading to a potentially detrimental delay in establishing an appropriate treatment regimen.