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Table 3 List of inputs and sources used in cost-effectiveness model, Vietnam

From: The cost-effectiveness of government actions to reduce sodium intake through salt substitutes in Vietnam

Variable name Input Source/Description
Clinical events and epidemiology
    Blood pressure See Supplementary Table 1 Supplementary Material Calculated based on Ha 2011 baseline blood pressure. Reduction in SBP for each intervention was calculated from the reduction of sodium intake with a linear regression using the Law 1991 SBP with no sodium in the diet as reference [13]
    Stroke incidence See Supplementary Table 2 Supplementary Material Ha 2011 [13]
    Relative risk of stroke with change in SBP See Supplementary Table 3 Supplementary Material Cobiac 2012 and intervention specific change in blood pressure from baseline. Each 1% decrease in SBP equals a 6.3% risk reduction for stroke [17]
    IHD incidence See Supplementary Table 2 Supplementary Material Ha 2011 [13]
    Relative risk of IHD with change in SBP See Supplementary Table 4 Supplementary Material Cobiac 2012 and intervention specific change in blood pressure from baseline. Each 1% decrease in SBP equals a 3.4% risk reduction for IHD [17]
    Mortality Vietnam life tables World Health Organisation and Global Health Observatory; age and gender specific [35]
    Mortality following stroke event 37% Tirschwell 2012 [36]
    Long term stroke mortality risk Year 1: 3.33Year 2: 2.85Year 3: 3.44Year 4: 2.84Year 5+: 1.56 Kiyohara 2003 [37]. Relative risk of patients with history of stroke compared to healthy controls. Model assumes patients have elevated risk of mortality (1.56x higher) compared to “healthy” population
    Mortality of IHD event Age specific mortality risk Southeast Asian NCD impact module dataset through the WHO-CHOICE OneHealth tool
    Long term IHD mortality Year 1: 18.7%Year 2: 25.0%Year 3: 39.2%Year 4+: Revert back to regular population mortality Tang 2007 [38]. Model assumes that after Year 3 patients have same mortality risk as rest of “healthy” population
Resource use and programme costs reported in ₫ (USD)
    Cost of lowering sodium content by potassium-enriched salt substitutes per capita 1791 ₫ (US$ 0.08) Calculated as the cost of a sodium reduction Government subsidy included in the subsidised scenario. Based on:- 534,798 t of salt produced each year [39]- 70% of salt is in cooking salt, fish sauce and bot canh of which 50% of sodium varieties [24]- US$0.04 to develop 1 kg of low sodium salt [40]
    Personnel Costs for policy implementation and management Project coordinator, manager, chief accountant, technical specialist etc.: 511,526,874 ₫ (US$ 22,039) per yearProject administrative assistant/secretary, accountant, interpreter, translator: 295,489,873 ₫ (US$ 12,730.88) per yearClerk, Driver, Auxiliary Staff, Messenger, Cleaner: 155,828,979 ₫ (US$ 6714) per yearPer diem daily subsistence allowance: 4,015,413 ₫ (US$ 173.00) UN-EU 2015 human resource costs inflated to 2019 US$ and converted to ₫ [41].Per diem costs from the International Civil Service Commission [42]
    Human resource requirements for policy implementation and management Webb 2017 eTable2 Webb 2017 [26]
Healthcare costs
    Percent of healthcare costs paid by the Government 54% Local expert opinion; WHO 2018 [43]
    Cost of stroke event to Government 13,325,677 ₫ (US$ 574.12) Khiaocharoen 2012 (one off event cost) [44]
    Long term cost of stroke to Government 0 Nguyen 2016 identifies stroke patients are cared for at home by family members [45]
    Cost of IHD event to Government 17,297,679 ₫ (US$ 745.25) Nguyen 2016 (one off event cost) [45]
    Long term cost of IHD to Government 368,835 ₫ (US$ 15.89) Nguyen 2016 recurring yearly cost for the lifetime of the patient [45]
Quality of life
    Healthy utility (SBP < 130) Male: 0.734Female: 0.712 Nguyen 2015 [46]
    Stage 1 hypertension utility (SBP > 130 and < 140) Male 0.726Female: 0.705 Nguyen 2015 [46]
    Stroke event disutility − 0.312 GBD 2010 [47]
Long term post-stroke utility Year 1: 0.66Year 2+: 0.68 Luengo-Fernandez 2013 [48]
    IHD event disutility − 0.186 GBD 2010 [47]
    Long term post-IHD utility OR = − 0.004 Nguyen 2015 odds ratio of patients who had a history of experiencing a cerebrovascular event compared to those without event. Applied to life of patient [46]
  1. Abbreviations: IHD ischaemic heart disease, GBD Global Burden of Disease study, SBP systolic blood pressure