CHI Report – Innovation in Hepatitis C Treatment – Page – 9
Center for Disease Analysis Hepatitis C Model
The Center for Disease Analysis (CDA) is a research firm focused on providing independent research and analyses for poorly understood diseases. It uses a multi-discipline approach that combines epidemiology research, expert interviews, advanced modeling, forecasting, and decision science to provide predictive analyses. The organization has studied and modeled Hepatitis C for the last six years and published numerous papers in the peer reviewed journals on the subject.
The CDA Hepatitis C Model is a disease progression model that simulates the US hep C epidemic. The model tracks chronic HCV disease progression by five-year age and gender cohort and liver disease stage from 1950 through 2100. New infections enter the model at any year, progress through the disease stages using published transition probabilities, and exit upon spontaneous clearance of HCV, cure (through drug treatment), or mortality (all-cause or liver-related). Appendix Exhibit 1 shows the different stages of the disease (boxes) and the possible movements of a patient through the model (arrows).
The full description of the CDA model, as well as results of its application to six countries, were published in the Journal of Viral Hepatitis earlier this year. xxiii The US model that was used for the production of this publication has not yet been published in a peer-reviewed journal but was created by CDA in close collaboration with academic experts in the field of hepatitis.
To model different treatment scenarios in the US, CDA primed the model with current US population data (including incidence, prevalence, and distribution of patients across age-groups and stages of the disease).This dynamic model included an algorithm for patient aging and new Hepatitis C incidence. Data sources included the US CDC, academic publications, as well as interviews with leading Hepatitis C researchers. A full description of such sources will be made available in the coming months, when CDA publishes the US model results.
Different treatment scenarios were applied to the US population starting in 2013. Our assumptions on the SVRs of different treatment regimens and the risk of discontinuation are shown in Appendix Exhibit 2. To calculate the number of people progressing to decompensated cirrhosis, we summed the incident cases of diuretic sensitive ascites, variceal hemorrhage, and hepatic encephalopathy from 2013 to 2030. Lastly, to calculate liver-related deaths, we summed the annual liver-related mortality from 2013 to 2030.
In Exhibit 5, diagnosis rates were held constant at approximately 50 percent of total hep C patients. Treatment rates were held constant at 59,000 patients per year regardless of treatment regimen. Treatment was allocated randomly to patients across medically eligible stages of the disease. For interferon-based treatments, patients with decompensated cirrhosis, liver transplants, and liver cancer were considered non-eligible based on clinical studies demonstrating that interferon can exacerbate cirrhosis. xxiv In addition, patients younger than 15 years and older than 65 years were considered ineligible for interferon-based treatments based on expert interviews with physicians, who noted that the side effects of interferon therapy are likely too severe for these patients. No stage restrictions were placed on interferon-free regimens, while patients as old as 74 years were considered eligible for the treatment, based on a significantly more favorable side-effect profile.
In Exhibit 6, treatment rates were scaled up annually at 1, 5, or 10 percent annually using the same medical eligibility criteria discussed above. For the 10 percent annual scale-up scenario, all medically eligible patients had been treated (or had died) by 2029 and, hence, no further scale-up was applied.