Field Evaluation of a Device for Automated Malaria Microscopy (Autoscope Version 2) (Autoscope)

Study Design & Procedure The primary purpose of this evaluation is to quantify the diagnostic performance of the Autoscope version 2 prototype in a field setting. The performance of the Autoscope version 2 prototype will be assessed by scanning of negative and positive slides with the Autoscope version 2 and comparing the results with expert microscopy. Plasmodium genus- and species-specific PCR will also be performed as an additional confirmatory test for the detection of malaria parasites and their species if present. Testing by microscopy and Autoscope will be performed in field clinic settings on Giemsa-stained stained slides prepared from febrile patient blood collected from a finger-prick. Patient recruitment will aim to recruit up to 80 slide-confirmed malaria cases (P. falciparum, P. vivax or other species) per country (i.e., total 160 cases) have been included in the study.

Patient procedures Patients who present at the clinic will be screened to assess eligibility. A consent form in the local languages (Karen or Burmese at SMRU sites, Bahasa in South Sumatera at EOCRU site) will be administered to patients with a description of the intentions of this study in order to protect human subjects before any study specific procedures are conducted. It will be clearly stated that participation is voluntary and that the subject or guardian is free to discontinue participation or withdraw consent to participate at any time for any reason without prejudice to future care, and with no obligation to give the reason for discontinuation nor for withdrawal. The subject or guardian will be allowed as much time as needed to consider the information and the opportunity to question the authorized research member, or other independent parties to decide whether they will (or allow his/her charge to) participate in the study. Written informed consent will then be obtained by means of subject or guardian dated signature or thumb print (if unable to write), with signed and dated signature of a witness and dated signature of the person who presented and obtained the informed consent. All individual written informed consent forms will be stored securely.

Children capable of understanding the study (approximately 7 years of age or above for SMRU sites and 12 years of age or above for EOCRU sites) will be asked to sign an assent form. A copy of the signed informed consent document(s) will be given to the participants.

Once informed consent has been obtained, the subject number will be assigned and recorded on the screening and enrollment log. A few drops of blood (maximum of 150-200 µL) will be obtained from a finger-prick and study-specific laboratory procedures as described below will be performed. The patient will then receive clinical care as appropriate according to the routine procedures.

Laboratory procedures All laboratory procedures will be performed according to the applicable standard operating procedures.

At the clinics (Wang Pha, Mawker Tai, Thailand and Hanura, South Sumatera, Indonesia)

• Blood collection from finger-prick (maximum 150-200 µL), which will be used to prepare slides.
• Perform malaria RDT (part of routine practice for malaria detection), prepare 2 slides each with thick and thin blood films, store remainder of blood sample for PCR to detect and determine species of malaria parasites
• Microscopy of Giemsa-stained blood films (microscopists will remain blinded to RDT and Autoscope results), record results
• Run Autoscope detection, record results, store images captured by the device At SMRU and EOCRU
• Review of all slides by expert microscopists (microscopists will remain blinded to RDT and Autoscope results)
• PCR to detect and determine species of malaria parasites At the WWARN Laboratory, Bangkok
• Review of field data to identify discrepant readings and tie-breaker readings in case of discordance between results obtained on site and on re-checking of the slides Quality Assurance
• Quality control performed by WWARN expert microscopists on 20% randomly selected slides or 25 positive and 25 negative slides per country, whichever is greater

The funder is Intellectual Ventures Lab/ Global Good and grant reference PA No.3.

Summary of Results

The sensitivity and specificity of the Autoscope version 2 prototype were 92.2% and 89.2%, respectively. The accuracy was 90.03%. Parasite species were correctly determined in 132/158 slides (83.5%) and kappa value for species detection was 0.60(0.45-0.73). 45.6% of the parasite density estimates from the Autoscope were within 25% range of the reference results, yielding the interclass correlation coefficient (ICC) of 0.78 (95%CI: 0.70-0.83). Bland-Altman plot showed no systematic bias of the measurement. Differences between the 2 counts increased in higher parasite density (correlation coefficient (r) = 0.861, P < 0.001).