(RxWiki News) Knowing how common a certain condition is can help prepare health care systems to treat patients. But the estimates for one disease may be way off.
A new study found that US estimates on rates of hepatitis C virus (HCV) infection may be much lower than the actual case counts.
"Accurate and current estimates of the incidence of HCV infection at the local, state, and national levels are critical for quantifying disease burden, guiding public health agency initiatives, and tracking the outcomes of preventive interventions," wrote lead study author Arthur Y. Kim, MD, of Massachusetts General Hospital in Boston, and colleagues.
According to Dr. Kim and team, there is no single test used for HCV infection. Because of this, data depends on different policies and tests — which sometimes come from multiple doctors and labs for each patient. This allows for possible errors in HCV case estimates.
Hepatitis C is an infectious disease that mostly affects the liver. HCV is spread mostly through blood-to-blood contact associated with intravenous drug use, poorly sterilized medical equipment and blood transfusions.
According to the Centers for Disease Control and Prevention (CDC), many patients with HCV infections have no symptoms. Over time, chronic HCV infection may lead to liver failure or liver cancer.
HCV cases confirmed by the CDC require a number of factors, including the presence of certain symptoms and specific test results.
The CDC's latest data (released in 2010) estimated that there were 17,000 HCV cases in the US. These estimates were based on 850 acute HCV cases that met requirements and on other cases reported to the CDC.
To study possible errors in these estimates, Dr. Kim and team looked at 183 patients with acute HCV infection between 2001 and 2011.
Dr. Kim and team found that 81.4 percent of these cases were reported to the Massachusetts Department of Public Health (MDPH). The MDPH then investigated 43 of these cases — based on CDC requirements — as potential acute HCV infections.
In the end, only one of these cases met the national requirements and was included in the CDC's statistics. This means that less than 1 percent of HCV cases in Massachusetts were reported to the CDC.
According to Dr. Kim and team, these findings suggest that data on HCV rates may be greatly underestimated.
This study was published online June 29 in the journal Annals of Internal Medicine.
The National Institutes of Health and the CDC funded this research.
Several study authors disclosed financial ties to pharmaceutical companies, such as AbbVie Pharmaceuticals, Bristol-Myers Squibb and Gilead Sciences.