Developing a Screening Tool for Primary Immunodeficiency Disease (PID) in Pakistan

Case-control diagnostic accuracy study with 130 potential pediatric PID+ (primary immunodeficiency) patients, and 100 age-matched, healthy controls (PID-). The potential PID+ participants will be recruited prospectively through 9 hospitals in Sindh and Punjab states or contacted via the PID surveillance registry developed by AKU Hospital's Polio Excretion in PID study to identify children with primary antibody deficiency (PAD+: a type of PID+); healthy, age-matched PID-participants will be recruited by snowball sampling. At the point of care, health care workers (HCWs) will collect capillary blood samples (0.1mL) to run the PID rapid screening test and reader on potential PID+ participants (identified by exhibiting >2 of the Jeffrey Modell warning signs) and healthy, age-matched controls. All pediatric study participants will be sent to the hospital lab to have a confirmatory immunology panel (see 4.4.1 Diagnosing PID for the battery of tests) run on a serum/plasma sample to confirm their PID diagnosis (PID+/PAD-, PID+/PAD+, PID-); a 1.5uL aliquot of serum/plasma will simultaneously be used to run a PID rapid screening test by a laboratory technician (LT). HCWs and LTs will be blinded to true PID status. Blood and serum PID rapid screening test results will be compared to the confirmatory immunology panel to determine diagnostic accuracy. All clinical management of study participants will follow the standard of care for PID in Pakistan and will be based upon the immunology panel result. The HCWs and LTs administering the tests will be trained prior to the diagnostic accuracy test (see Objectives below) and will provide feedback on the tool post-training and post-use to assess usability, acceptability, and feasibility of integrating the test and digital reader into tertiary hospitals for the purpose of improved national PID surveillance, improved PID patient care, and polio eradication in Pakistan.