I agree with your conclusion, but disagree with how you get there. That is, I agree "that childhood nutritional interventions that reduce the prevalence of stunting may be substantially more cost-effective than previously believed." However, what I would take from this is that using only the DALY for stunting as a way to measuring the impact of nutritional interventions provides only a lower bound on the good done (and therefore an conservative bound on the cost effectiveness).
To me it looks like what you are trying to do is backfit the DALY to do something it wasn't designed to do. To me this is an argument that the CEA for nutritional interventions needs to be reworked, not the DALY number for stunting.
I believe that what you're proposing would create a double counting issue with how the GBD uses DALYs. My understanding of the DALY was that disability weights correspond to discrete symptom-states, not life-course trajectories. GBD distinguishes causes from risk factors to prevent double counting. To avoid this double counting issue, a constraint was introduced where cause-specific estimates had to sum to real population totals. This constraint is consistent with why the DALY for stunting does not include the things you are proposing.
Concretely, we see the double counting issue because your YLD estimate is built by borrowing the disability weights for moderate anemia (an independently tallied GBD cause) and the health-state weight GBD uses for cognitive impairment (which is already counted under specific causes like intellectual disability). This matters because the cognitive and physiological harms captured in those two disability weights are the same harms that already accrue to a stunted child's own anemia and cognitive-impairment burden elsewhere in GBD's accounting. You're supposed to be able to sum DALYs averted. But if you do it your way, a CEA can't count both DALYs averted from reduced stunting and separately DALYs averted from reduced anemia or cognitive impairment.
Disclaimer: I'm not a global health wonk.
I agree with your conclusion, but disagree with how you get there. That is, I agree "that childhood nutritional interventions that reduce the prevalence of stunting may be substantially more cost-effective than previously believed." However, what I would take from this is that using only the DALY for stunting as a way to measuring the impact of nutritional interventions provides only a lower bound on the good done (and therefore an conservative bound on the cost effectiveness).
To me it looks like what you are trying to do is backfit the DALY to do something it wasn't designed to do. To me this is an argument that the CEA for nutritional interventions needs to be reworked, not the DALY number for stunting.
I believe that what you're proposing would create a double counting issue with how the GBD uses DALYs. My understanding of the DALY was that disability weights correspond to discrete symptom-states, not life-course trajectories. GBD distinguishes causes from risk factors to prevent double counting. To avoid this double counting issue, a constraint was introduced where cause-specific estimates had to sum to real population totals. This constraint is consistent with why the DALY for stunting does not include the things you are proposing.
Concretely, we see the double counting issue because your YLD estimate is built by borrowing the disability weights for moderate anemia (an independently tallied GBD cause) and the health-state weight GBD uses for cognitive impairment (which is already counted under specific causes like intellectual disability). This matters because the cognitive and physiological harms captured in those two disability weights are the same harms that already accrue to a stunted child's own anemia and cognitive-impairment burden elsewhere in GBD's accounting. You're supposed to be able to sum DALYs averted. But if you do it your way, a CEA can't count both DALYs averted from reduced stunting and separately DALYs averted from reduced anemia or cognitive impairment.