Field Evaluation of a Device for Automated Malaria Microscopy (Autoscope Version 2)
Condition: Malaria
MeSH terms: Malaria
Study type: Observational

Summary: 
      Microscopy remains a key indicator in drug efficacy testing performed in the context of
      clinical trials for monitoring existing antimalarials or in the context of regulatory
      clinical trials for registration of new drugs. It is one of the main diagnostic methods for
      malaria diagnosis in general, as in an ideal setting it can provide low-cost accurate
      diagnosis, determine the density of parasites in the blood, and accurately differentiate
      between different malaria parasite species, characteristics vital to the implementation of
      global plans for drug efficacy monitoring. Malaria rapid tests (RDTs), while useful for case
      management, do not provide information on the parasite density nor the species
      differentiation necessary for research and drug efficacy assessment. Microscopy therefore
      retains key advantages over a number of newer technologies, but its reliability is severely
      impeded by dependence on high technical competence of the human operators as well as
      availability of high quality equipment and reagents. Recent studies have demonstrated the
      frequent poor specificity and sensitivity associated with manual microscopy diagnostics in
      operational conditions , , . Advances in digital microscopy performance and affordability
      have now opened the door to potentially significant improvements in the performance of
      malaria diagnostic microscopy, overcoming serious deficiencies in current drug efficacy
      assessment, and more broadly in malaria diagnosis and management.

      Intellectual Ventures Laboratory (IVL), in collaboration with Global Good Fund (GG), has
      developed an initial microscope prototype to support its research into dark field imaging of
      unstained malaria slides. The system consists of low cost electromechanical components for
      scanning a standard slide, an optical train with a high numerical aperture objective, and an
      image capture system. Captured images are analyzed with custom image analysis software
      developed at GG/IVL, using algorithms that are designed for automatic malaria diagnosis,
      without user input. Additionally, image processing algorithms have been built around
      detection of Giemsa-stained malaria slides which is the current standard for malaria
      microscopy. Initial results show excellent potential for sensitivity and specificity which
      exceeds that of typical manual microscopists in the field. Based on the positive market and
      needs assessment in January, 2013, given by stakeholders in the malaria diagnostics
      community, GG/IVL are pursuing improvement and integration of this algorithm into a portable
      microscope platform with characteristics similar to the prototype microscope already
      developed at GG/IVL for dark field imaging. The prototype Autoscope was first tested in field
      settings in Thailand in Nov 2014 - Jan 2015 at clinics operated by the Shoklo Malaria
      Research Unit (SMRU). The goal of the first field evaluation was to assess the Autoscope in
      with respect to its diagnostic performance and also its suitability for harsh conditions
      typically encountered in field clinics. Further, user feedback on the design and
      functionality was sought. The Autoscope and the accompanying image analysis algorithms have
      since been further developed and a new version is now available for testing.
    

Detailed description: 
      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).
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Eighty slide-confirmed malaria cases (P. falciparum, P. vivax) will be recruited in the
        study per study site. Accordingly,

          -  At EOCRU, with an estimated malaria prevalence of 30% in febrile patients, up to 270
             patients will be recruited

          -  At SMRU, with an estimated malaria prevalence of 10% in febrile patients, up to 800
             patients will be recruited I.e., a total of 1070 subjects with up to 160 malaria
             positive cases across study sites.
      
Biospecimen description: 
      Blood collection from finger-prick (maximum 150-200 µL), which will be used to prepare
      slides.