Cost per episode of diarrhea and respiratory syncytial virus (RSV) in 128 low- and middle-income countries: how well do disease-specific and WHO-CHOICE estimates align?

Objective: Non-disease-specific WHO-CHOICE unit costs are often used in cost and cost-effectiveness studies in the absence of country-specific data. This study aims to compare reported country-specific disease costs and the corresponding WHO-CHOICE estimates. We use generically defined "diarrhea" (including rotavirus diarrhea) and pathogen-specific "respiratory syncytial virus (RSV)" disease as examples. Methods: We updated systematic reviews for both diseases in low-income (LICs), lower-middle-income (LMICs) and upper-middle-income (UMICs) countries. Diarrheal (including a sub-analysis of rotavirus-specific) and RSV-specific outpatient and inpatient costs per episode were extracted and compared with WHO-CHOICE estimates in the same countries. If a consistent pattern of under- or over-estimation was identified, we quantified the magnitude of the discrepancy. All costs were updated to 2022 international dollar values. Results: Out of 1975 new records identified, 23 new cost studies were included. Including previous reviews, we retained 31 diarrhea and 16 RSV studies for comparison. WHO-CHOICE based direct medical costs were similar for diarrheal disease including rotavirus diarrhea, but lower for RSV-related disease. We estimated the cost per episode of diarrhea and RSV in 128 countries. RSV outpatient cost were adjusted by multiplying WHO-CHOICE costs by 6.89 (95% uncertainty interval: 5.58-8.58) in LICs and LMICs and 5.87 (4.95-6.96) in UMICs; RSV inpatient costs were multiplied by 1.43 (1.01-2.01) and 1.36 (0.82-2.27), respectively. Conclusion: WHO-CHOICE based costs should be used cautiously. They aligned well with studies for diarrheal disease, but underestimate costs of RSV-related disease. More country- and disease-specific cost data are needed, especially for RSV in LICs.