Authors (including presenting author) :
Yiu MP, Luk CW, Wu CY, Yiu YK, Luk W
Affiliation :
Kowloon West Cluster Department of Family Medicine and Primary Health Care
Introduction :
Scabies is a skin infestation by mite Sarcoptes scabiei hominis. It is a highly contagious disease. Typical features include burrow in groove of fingers and limbs. Face is spared except in children. The diagnosis can be confirmed by the presence of scabies mite in skin scraping.
However, the test has low sensitivity (46%) and low negative predictive value (77%).
In the recent fact sheets on scabies released by the HA Central Committee on Infectious Diseases and Emergency Response ( CCIDER) in Sept 2021, it is stressed that a negative scraping test in a symptomatic patient dose not exclude the diagnosis and treatment may be offered based on clinical grounds alone
Objectives :
3 cyclical reviews were conducted in KWC GOPC from 2018-2021 with clinical/suspected diagnosis of scabies and skin scraping arranged.
1. Assess the efficacy of this investigation
2. Observe prescribing patterns of scabicides
3. Suggest future improvement strategies
Methodology :
All skin scrapings for scabies performed from Jan to Aug 2018 by KWC GOPC were retrieved in CDARS. The detection rate was noted. The doctor prescription pattern and patient outcome were reviewed. Another 2 reviews of the same period were conducted in 2019 and 2021 to demonstrate any changes in practice.
Result & Outcome :
From Jan- Aug 2018, 26 skin scrapings for scabies were performed. There was no positive result. The findings were shared in different doctor meetings. Doctors were suggested to prescribe scabicides if scabies infection was suspected rather than ordering a skin scrapping and waited for the result due to low sensitivity.
Another reviews in the same period in 2019 and 2021 were conducted. A drop to 15 tests and 7 tests was noted respectively yet all results were negative.
During the 3 cycles review of 48 cases, 17 cases (35.4%) were OAHR or staff. Scabicides (BBE: 14 Premathrin: 6) were prescribed in 20 cases. The prescription rate increased from 27%(2018) to 53%(2019) and 71%(2021). For the treatment group, improvement in itchiness was 60%( 12/20). For patients without scabies prescription, itchiness improvement was 25%( 7/28).
Conclusion:
Skin scraping for Scabies is a procedure with low sensitivity and cumbersome
Several strategies are suggested:
Doctor: Treat patient directly for suspected cases. Premathrin is the 1st line treatment nowadays. Improve collaboration with nurses for the scraping sites and the sample numbers if procedure is deemed necessary
Dermatoscopy is a simple yet sensitive (83% sensitivity) alternative to skin scrapping for trained family physicians
