Sources of heterogeneity: LMIC particularities
| Baseline age, comorbidities and performance status |
| Age, comorbidities and previous performance status are important determinants of critical care outcome |
| Baseline health status and comorbidities have a different profile in LMICs when compared to HICs [7, 8] |
| ICU admission policies |
| Patients may be more prone to be admitted to the ICU according to bed availability or admission policies |
| Paucity of ICU beds in Latin American and other LMICs may compromise appropriate timing for ICU admission and result in higher mortality [9, 10] |
| Local practices in mechanical ventilation |
| Some units may choose to start mechanical ventilation early and/or may adopt early weaning protocols; thereby, duration of mechanical ventilation may vary |
| Ventilator settings may also be different (i.e. tidal volume) |
| Mortality of acute respiratory failure is high in LMICs and adherence to best practices may be lower [11, 12] |
| Diagnostic technique availability |
| Diagnostic techniques may vary between centres and countries |
| LMICs may have restricted access to basic and advanced diagnostic methods [10] |
| Microbiological profile |
| Causative pathogen is associated with outcome in nosocomial pneumonia |
| Gram-negative rods (including MDR pathogens) are more common in LMICs, especially Latin America [13] |
| Initial empirical antimicrobial therapy |
| Lack of adherence to early antimicrobial therapy may impact clinical outcomes |
| Sepsis awareness is lower in LMICs [14] |
| Use of prevention strategies |
| Several prevention strategies may be effective in preventing nosocomial pneumonia, especially VAP (subglottic suctioning tubes, coated tubes, etc.) |
| Limited availability of some devices in LMICs |
| Lack of availability of single rooms in some settings [15] |
| EOL preferences |
| EOL policies vary between different countries and between different cultures |
| This may result in changes in outcome estimates |
| Physicians in Latin America may be less prone to establish clear EOL policies and to discuss treatment directives with patients and relatives [16] |
HIC: high-income country; EOL: end-of-life.