The global burden of diseases report tells us which diseases are contributing the most to human suffering. Which is interesting, but is that what we really need to know? Following from Ian Roberts’ talk at the LSHTM in April, I am more and more convinced that it misses the mark.
Diseases are manifestations of suffering, they are the effects that result from the causes of ill health. The DALY (disability adjusted life year) goes some way to make this interchangeability a quantitative science: all health matters, all diseases are just categorizations of suffering. So what does that global ranking tell us then? Sometimes the manifestations of suffering tell us about the underlying causes, and this is epidemiologically interesting. For example, the transitions from communicable disease manifestations of suffering to non-communicable diseases tells us something about development, food security, and society. But what really matters is what we can do about suffering in all its many manifestations. For that, we need to shift our focus from disease burden to the cost-effectiveness of averting a DALY of suffering, and not particularly worry about the proportions.
By focusing on cost effectiveness for DALY reduction we will change how we look at disease control. The ‘control arm’ in a trial for a DALY reducing intervention should be the ‘next cheapest method of DALY reduction’, rather than the usual care for the particular disease that is being targeted. Healthcare spending would be more rational, and save lives that are currently being lost in the ‘opportunity cost’ (rather mild way of putting it) of inefficient healthcare spending. And by looking outside of the disease silos we might find that multi-modal interventions such as girls education are more cost effective than they had appeared when only looking at single outcomes.
That said, a focus on cost-effectiveness should not be a shift to another narrow view. A few issues are outstanding:
- Disease burden is important for research agenda setting: the total positive effect of a new cost effective intervention (i.e. one that warrants funding in this super-efficient future) for a disease will be the individual effect multiplied by the current burden. If we developed a very cost effective method to treat a rare disease then it should be used, but the total effect of the intervention will be lower than had we developed something for higher burden diseases/risks.
- The cost effectiveness may be a function of the burden. If a disease is common then national control programmes can find efficiency in scale, and often harvest low hanging fruit.
- Evidence for effectiveness will favour single-disease targeted interventions. The statistical methods that we use, combined with the protocol and reporting standards that have been set to prevent fishing in the data for results, have made it difficult to show evidence of multi-modal effects.
While this is not a new idea at all, I am still hearing and seeing ranking of disease burden used a lot to motivate healthcare spending.