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Onychomycosis

Jake Anderson, MD and Andrew Buelt, DO
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Onychomycosis is most commonly a dermatophytic or yeast  infection of the nails complex.  Confirmation of diagnosis by nail culture is recommended prior to treatment.  Topical treatments include ciclopirox and efinaconazole. Terbinafine is the preferred oral agent.

 

Pearls:

  • Onychomycosis is a common problem.

  • Current guidelines recommend testing prior to initiating treatment.

  • Topical efinaconazole is most effective of the topicals but is the most expensive and requires 48 weeks of treatment.

  • Oral terbinafine is more effective than itraconazole and is safe with recommended baseline AST, ALT, CBC and Cr.

  • Prevention strategies include not wearing moldy shoes, not sharing nail clippers, wearing protective footwear in public showers and treating tinea pedis immediately.

 

  • Onychomycosis: General prevalence is around 5% and fungal disease causes 50% of the nail conditions for which a patient sees a dermatologist. While not a serious condition, 51% have discomfort walking and 13% felt it limited work or physical activity.

  • Diagnosis - treat empirically or wait test nail clippings: KOH prep has 48% sensitivity while periodic acid-Schiff stain has better sensitivity at 82%. However, it is more expensive and sometimes won’t be covered if KOH is available.

    • American Academy of Dermatology (AAD) Choosing Wisely recommendation: Best to get a nail clipping for testing to make sure you aren’t treating a dystrophic nail because 50% of the time the nails won’t actually have fungus.

    • JAMA 2016 article looked at cost effectiveness of empiric treatment and found AAD recommendations were based on data from 1999 when terbinafine (common empiric treatment) was $547 as opposed to $10 today. Based on these prices, there is cost savings for treating empirically.

  • Treatment: Topical cream v. systemic pills

    • Topical: require longer treatment duration, overall poor efficacy and should be considered only when <50% of nail is affected without matrix area involvement.

      • Most recent Cochrane Review concluded there is little evidence and only small studies to support topical treatments in management of dermatophyte infections.

      • Ciclopirox: topical studied in RCT in Journal of American Academy of Dermatology that applied to all toenails and affected fingernails covering nail plate and 5mm of surrounding skin for 48 weeks (!) found 33% had negative culture and light microscopy as opposed to 10% of those treated with placebo. NNT is 5. Cost $20 per month.

        • Gupta AK, et. al. Ciclopirox nail lacquer topical solution 8% in the treatment of toenail onychomycosis. J Am Acad Dermatol. 2000 Oct;43(4 Suppl):S70-80. PMID:. PMID: 11051136.

      • Efinaconazole or Jublia: effective against distal lateral nail involvement, once daily application for 48 weeks. Two industry sponsored RCTs showed clinically significant improvement in complete cure rates (0% nail involvement) with NNT 7-11 at 4 weeks out from the complete 48 week course. Cost $500-600 per month!

      • Vicks VapoRub©: small prospective trial of 18 patients applied to toenail every night for 48 weeks and 83% had a positive effect with 28% showing clinical and mycologic cure at 48 weeks.

    • Oral: consider in distal and lateral involvement in >50% of nail, involvement of lunula, involvement of greater than 3-4 nails, non-response to topical therapies.

      • Terbinafine: standard treatment

        • Double-blind, multicenter, parallel group study over 72 weeks showed complete clear rate around 50% for terbinafine and only about 25% for itraconazole. Toenails had >70% involvement and current episode had lasted at least 10.5 years.

          • Evans EG et. al. Double blind, randomised study of continuous terbinafine compared with intermittent itraconazole in treatment of toenail onychomycosis. The LION Study Group. BMJ. 1999 Apr 17;318(7190):1031-5. PMID: 10205099.

        • Side effects include headache, fever and respiratory symptoms in roughly 7%, GI symptoms and rash in 2.5-5%. Can cause severe hepatic injury making monitoring of LFTs important. 1-3% of patients will have transiently elevated LFTs during treatment. One in 50,000 to one in 120,000 will develop clinically significant liver disease.

          • Monitoring: CBC, AST, ALT and Cr at baseline and then as clinically indicated.

      • Itraconazole: less effective, side-effects occur rarely but are similar to those of terbinafine.

    • Surgical treatment: remove the toenail, apply topical treatment BID for up to 6 months. One study showed about a 50% cure rate with this approach.

    • Treatment course: ~40% of patients will have normal nails at one year and only 33% will have normal nails at two years.

  • Prevention: All consensus and expert opinion

    • Don’t share nail clippers

    • Don’t use old moldy shoes

    • Use protective footwear in public showers

    • Treat tinea pedis immediately to prevent relapse

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The Benzos & Fungus Among Us Full episode audio for MD edition 169:10 min - 79 MB - M4AHippo Primary Care RAP March 2017 Summary 563 KB - PDF

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