The accuracy of clinical diagnosis of onychomycosis in Dutch general practice: a diagnostic accuracy study

Abstract

Background:Onychomycosis,the most common cause of nail dystrophy is generally diagnosed by clinical examination. Current guidelines for Dutch general practice advise confirmatory testing onlyin case of doubt or insufficient response to treatment. However, making a correct diagnosis can be challenging given the wide variety of clinical features and differential diagnosis.Aim:To establish accuracy of clinical diagnosis of onychomycosis by general practitioners (GPs).Design and Setting:A diagnostic accuracy study based on GPs clinical diagnosis of primary care patients suspected of onychomycosis.Methods:Using 137 complete data sets from the Onycho Trial, diagnostic accuracy of clinical diagnosis as index test was compared with confirmatory testing as reference test.A sensitivity analysis was performed to determine diagnostic values for different combinations of index and reference test. Logistical regression was usedto assess whichclinical characteristics were associated with the positive predictive value (PPV) of the index test.Results:Clinical accuracy i.e. the PPV of the index testwas 74.5%. Sensitivity analysisshowed no significant difference in diagnostic values. Male gender and a history of any previous treatmentsignificantly increased clinical accuracy with an OR of 3.873 (95% C.I. 1.230 – 12.195) and 4.022 (95% C.I. 1.075 – 15.040), respectively.Conclusion:Our study demonstratesthat theGPs clinical diagnosis of onychomycosis is insufficiently accurate to initiate treatment without confirmatory testing.Further research is needed to investigate how to increase clinical accuracy and reduce potentially unnecessary exposure to treatment.

Inter‐observer reliability of the Onychomycosis Severity Index depending on clinical experience: A review of 50 cases

“…In the current study, we observed a significant level of concordance Various studies, including those conducted by Watjer et al 4 Elewski et al 7 and Gupta et al 12 have conducted pre-and posttreatment assessments using the OSI scale. However, none of these studies specify the number of professionals who administered the OSI scale.…”

“…

The most characteristic clinical signs include nail thickening, subungual hyperkeratosis, nail plate discolouration and onycholysis. [1][2][3][4]6,7 Traditionally, ONM is typically classified based on these clinical signs through visual assessment. However, it is worth noting that there are numerical classifications available, though not all of them are validated.

…”

Clinical Diagnosis and Laboratory Testing of Abnormal Appearing Toenails: A Retrospective Assessment of Confirmatory Testing for Onychomycosis in the United States, 2022–2023

“…By contrast, performing only a histopathologic examination is not able to provide genus-or species-level identification, and thus does not allow for more targeted treatment approaches. Amidst the current high risk of misdiagnosis and mistreatment of onychomycosis [13,15,16], a greater advocacy for laboratory testing is warranted to address these pressing challenges.…”

“…Consequentially, more than half of onychomycosis patients reported to have self-diagnosed and self-treated their condition, which likely contributed to a high treatment failure rate of 24.0% [15]. The current healthcare burden is further compounded by a high rate of misdiagnosis (25.5%) among general practitioners [16] and a growing number of patients seeking care from specialists rather than primary care providers [17].…”