Sometimes there is ambiguity in the cause of death: besides the illness leading directly to death, the medical data on the death certificate should also contain a causal chain linked to the suffering of the deceased. Other substantial health conditions may be indicated, which did not have a link to the illness leading directly to death, but may have unfavourably affected the course of a disease and thus contributed to the fatal outcome. Indeed, there is sometimes criticism that the coding of only one illness as a cause of death appears more and more unrealistic in view of the increasing life expectancy and associated changes in morbidity. For the majority of the deceased of 65 years and over the selection of just one out of a number of possible causes of death may be somewhat misleading. For this reason, some of the EU Member States have started to consider multiple-cause coding. Eurostat has supported Member States in their efforts to develop a joint automated coding system called IRIS for the improvement and better comparability of causes of death data in Europe.
In the consecutive 2014 and 2015 seasons, tragedies that each killed more than a dozen people caused no one to ascend the mountain in those years. On April 18, 2014, 16 Sherpas were killed in an avalanche that struck Base Camp.    Just over a year later, on April 25, 2015, 19 people were killed in an avalanche at Base Camp following a powerful earthquake , which killed at least 9,000 people and injured at least 23,000. [ where? ]    This is the worst single-day death toll ever in the history of Mount Everest, in modern incidents with accurate counts. [ clarification needed ]