A few years ago I was surprised by an ourworldindata.org graph on diarrheal disease deaths by age, and a conversation today prompted me to look deeper into it. The data show that more over-70s die of diarrhoea than under-5s worldwide, and the trend has only got stronger with the new GBD 2023 data. On the OWID visualiser you can play with the data by country, etc., which shows that in countries with higher mortality the majority is still in children. E.g. in Mozambique 57% of diarrhoeal mortality was in children under-5, but that still shows that 43% was in older age groups. Obviously morbidity is an important part of the picture which is not shown here.
This has consequences for economic evaluations of WASH interventions, where avoided mortality has generally contributed the largest % of economics benefits, and most studies have focused on under-5s only. In our Ethiopia benefit-cost analysis of CLTS we included all ages, and this should become the norm when evaluating WASH interventions, to ensure a complete picture of benefits. Analysts should also giving adequate consideration to indirect cost of illness, e.g. productivity loss when people are sick (whether sick adults, or caregivers of sick children).
But why are more older people dying of diarrhoea than under-5s? There are a few papers on this. It’s not so much that diarrhoea in older people is getting worse, rather that (i) under-5 diarrhoeal mortality is only 18% of what it was in 1990; (ii) aging populations, e.g. that orange bar in the graph below, for over-70s, is essentially the same width as in 1980, when there were far fewer over-70s around. Nonetheless, both chronic and acute diarrhoea are an important topic for future study in older people, and affects quality of life as well as bringing mortality risk. Furthermore there are far fewer age-disaggregated or elderly-focused diarrhoeal studies in lower/middle-income countries, which most studies are focused on under-5s. So the invisible error bars on the GBD data for over-70s are probably far wider than for under-5s.
WASHeconomics.com 