What’s so scary about ICD-10? That’s shorthand for the International Classification of Diseases, tenth edition, an updated coding system that hospitals and doctors offices were supposed to start using to submit medical bills to health insurers on Oct. 1, 2014. However, amid concerns that adopting the new codes would lead to chaos and lost revenue, President Obama in April signed into law a bill delaying implementation until at least Oct. 1, 2015. While the United States has been using ICD-9 for more than 30 years, most other countries long ago upgraded to ICD-10 (though outside this country the updated codes are used primarily for administrative purposes, not billing). The U.S. Department of Health and Human Services’ decision to adopt the new standard has both fans and critics.