Since 2000, the number of overdose deaths from drugs in the U.S. has risen more than 137%. Deaths from opioids - which include painkillers and heroin - make up a large portion of these deaths; 91 Americans die every day from an opioid overdose. Federal numbers like these reveal a dire situation. But a new study finds that many opioid-related deaths are underreported, and that the full picture of the epidemic may be worse than even those numbers show. In the report, Christopher Ruhm, a professor of public policy & economics at the University of Virginia ... found that nationwide, the death rate from opioids is 24% higher than what has been estimated previously. Deaths related to heroin, which is cheaper than prescription painkillers, are 22% higher, he says. When hospitals enter the cause of death on a person's death certificate, the drugs that contributed might not be specified, or multiple drugs will be listed as present. Between 20%-25% of the overdose death certificates Ruhm studied did not have any drug specified, suggesting that statewide estimates of deaths linked to opioids could be significantly off. Ruhm found that the overall death rates from opioids were substantially underreported across the U.S. - by more than half in Pennsylvania, for example. The growth in death rates from 2008 to 2014 - the time period Ruhm studied - was also substantially underestimated in many states.