The prevalence of hypoxemia among pediatric and adult patients presenting to healthcare facilities in low- and middle-income countries: protocol for a systematic review and meta-analysis.

Background: Hypoxemia is a severe condition associated with high rates of mortality, particularly in low- and middle-income countries (LMICs) with poor access to oxygen therapy. Despite its clinical significance, there have been few studies to describe the burden of hypoxemia. Thus, the primary objective of this study is to systematically describe the prevalence of hypoxemia among pediatric and adult patients in low- and middle-income countries.

Methods/design: Standard systematic review methods will be used. Bibliographic databases (MEDLINE, EMBASE, CINAHL) will be searched from 1998 onwards. The search strategy aims to identify studies that have measured peripheral blood oxygen saturation (SpO) in children and adults presenting to health facilities in LMICs. Studies will be included if oxygen saturation measurements by pulse oximetry were measured. No studies will be excluded based on study design though patients recruited from intensive care units and post-operative care will be excluded. The primary outcome is the prevalence of hypoxemia on presentation to the healthcare facility. We define hypoxemia on the basis of SpO measurements, and use a threshold of SpO less than 90% at sea level though allow for a lower threshold for studies conducted at higher altitude and where justified. Standardized tools will be used to extract data on number of patients with SpO measurements, number of patients with hypoxemia, patient population characteristics, and study characteristics. Quality of the included studies will be assessed using the "Checklist for Prevalence Studies" developed by the Joanna Briggs Institute. If there are enough studies to do so, we will conduct meta-analysis using a random effects model to estimate prevalence of hypoxemia and conduct subgroup analyses by age and disease groups.

Discussion: Hypoxemia is a critical condition and understanding the burden of hypoxemia may support decision-making in LMICs to deploy pulse oximeters and oxygen treatments more efficiently to address diseases and patient populations with the highest burden. Previous studies on hypoxemia prevalence have focused too narrowly on a few diseases or specific patient populations (e.g., pneumonia in children under five) whereas any effort to improve access to oxygen requires understanding of the potential demand for oxygen for all diseases and population groups. Governments, UN agencies, donors, and NGOs are investing strongly to improve oxygen systems in LMICs. Effective oxygen system planning requires estimation of oxygen need, informed by robust data on hypoxemia prevalence and admission patterns at all the levels of the health system. This study aims to fill that gap by providing comprehensive estimates of hypoxemia prevalence.

Systematic Review Registration: PROSPERO CRD42019136622.