Overdiagnosis of scabies and overprescribing of scabies treatment in a scabies‐endemic region

Objective To assess the objective evidence upon which diagnosis of scabies and subsequent prescription of permethrin cream or oral ivermectin is based at a tertiary referral hospital in the Northern Territory. Design, setting and participants A retrospective cohort study of inpatients who were prescribed permethrin or ivermectin between July and September 2017 at a single tertiary referral hospital. Eighty-eight inpatient admissions, belonging to 77 unique patients, were included. This list was generated with the hospital's electronic prescribing software. Main outcome measures Age, ethnicity, skin diagnosis on admission, which anti-scabies medications were prescribed, which concurrent medications were prescribed to treat a rash or pruritus, which differential or concurrent skin diagnoses were made, whether the dermatology department had seen the patient during their admission, and what evidence was documented as reason for diagnosis of scabies. Results In the cases in which scabies treatment was prescribed, less than one quarter had positive skin scrapings for scabies, and few had documentation of burrows, and documentation of a contact history combined with clinical lesions. Most cases met none of these diagnostic criteria. Very few were reviewed by the dermatology department as an inpatient. Conclusions There were likely high rates of diagnostic uncertainty among the cases in which scabies treatment was prescribed. It is possible that anti-scabies medications are being prescribed empirically in this hospital.