TABLE 2.
Decision tree model parameters for the main analysis
| Parameter | Value | Data source |
|---|---|---|
| Number of primary care facilities, n | 32 | [18] |
| Percentage of patients with ARI who have LRTI, % | 1.1; see Table 1 for age‐stratified values | [18] |
| Percentage of patients with LRTI who have severe disease, % | 8 | [13] |
| Percentage of patients with severe LRTI correctly diagnosed without pulse oximetry, % | 60 | [20] |
| Percentage of patients with severe LRTI correctly diagnosed with pulse oximetry, % | 80 | Adapted from [13] |
| Percentage of patients with non‐severe LRTI incorrectly diagnosed with severe LRTI without pulse oximetry, % | 25 | Assumed |
| Percentage of patients with non‐severe LRTI incorrectly diagnosed with severe LRTI with pulse oximetry, % | 10 | Assumed |
| Percentage of patients with URTI treated with antibiotics without pulse oximetry, % | 36.5; see Table 1 for age‐stratified values | [18] |
| Relative reduction in antibiotic prescription with pulse oximetry and clinical guideline retraining, % | 50 | [16] |
| Percentage of patients with severe LRTI diagnosed without pulse oximetry who recover without hospital admission, % | 65 | [21] |
| Relative increase in recovery without hospital admission in patients with severe LRTI diagnosed with pulse oximetry, % | 10 | Assumed |
| Percentage of patients with severe LRTI who re‐present who go to hospital, % | 100 | Assumed |
| Percentage of patients initially diagnosed with severe LRTI who go to hospital, % | 80 | [22] |
| Percentage of patients with non‐severe LRTI incorrectly diagnosed as severe who go to hospital, % | 75 | Assumed |
| Percentage of in‐hospital deaths of patients correctly diagnosed with severe LRTI without pulse oximetry, % | 10 | [22, 23] |
| Relative reduction in in‐hospital deaths of patients correctly diagnosed with severe LRTI with pulse oximetry, % | 20 | [24, 25] |
| Percentage of in‐hospital deaths of patients with severe LRTI incorrectly diagnosed as non‐severe without pulse oximetry who re‐present, % | 10 | [22, 23] |
| Relative reduction in in‐hospital deaths of patients with severe LRTI incorrectly diagnosed as non‐severe with pulse oximetry who re‐present, % | 20 | [24, 25] |
| Median hospital LOS of patients with severe LRTI diagnosed without pulse oximetry and of re‐presentations with severe LRTI, days | 5.34 | Medical Records Department, Chiang Rai Prachanukroh Hospital (personal communication, 21 September 2021) |
| Median LOS of hospitalised patients with severe LRTI correctly diagnosed with pulse oximetry, days | 4.01 | Assumed at 75% of median LOS |
| Median LOS of hospitalised patients with non‐severe LRTI incorrectly diagnosed as severe with pulse oximetry, days | 2.67 | Assumed at 50% of median LOS |
| Purchase cost of one pulse oximeter (includes one each of universal, paediatric, and neonatal probes), US$ | 275 | [19, 26] |
| Maintenance cost of one pulse oximeter per year (includes replacement probes and batteries), US$ | 55 | [19, 27] |
| Cost of district‐wide staff training per year (initial training plus two refreshers) and monitoring at 0.2 primary health worker FTE, US$ | 1324.75 | Chiang Rai Provincial Public Health Office (personal communication, 2 August 2022) [14], |
| Cost of extra staff time per primary care unit per year at 0.05 primary health worker FTE, US$ | 331.19 | Chiang Rai Provincial Public Health Office (personal communication, 2 August 2022) |
| Cost of one course of amoxicillin, US$ | 0.61 for children <5 years, 0.91 for children 5–14 years, 1.21 for adults | [28] |
| Cost of antimicrobial resistance associated with one course of amoxicillin, US$ | 11.80 | [29] |
| Cost of one occupied bed‐day at provincial hospital, US$ | 658.46 | Finance Department, Chiang Rai Prachanukroh Hospital (personal communication, 21 September 2021) |
Note: Parameters apply to all age groups unless explicitly stated. Costs were adjusted for inflation and expressed in US dollars as at 1 August 2021.
Abbreviations: FTE, full‐time equivalent; LOS, length of stay; LRTI, lower respiratory tract infection; URTI, upper respiratory tract infection.