Year: 2023
Type: reference-entry
Abstract: We calculated the annual expected cost of an acute hepatitis B infection to be $1,481. This expected annual cost is the weighted average cost of outpatient care for acute symptomatic infection, the cost of hospitalization for those with acute fulminant hepatitis B infection, and the cost of hospitalization for non-fulminant cases, as calculated below: where Cdenotes costs, and pdenotes the probabilities of each event. Specifically,CAcuterepresents the annual cost per capita of an acute infection, CAdenotes the cost of an asymptomatic infection (assumed to be zero), COis the outpatient costs for symptomatic patients, CFrepresents the annual hospitalization cost for fulminant cases, and CHdenotes the annual hospitalization cost for non-fulminant cases. Similarly, pAis the proportion of asymptomatic cases among individuals with an acute infection, pHis the hospitalization risk among symptomatic patients, and pFdenotes the proportion of hospitalized patients that are fulminant cases. Substituting the values of each parameter into the equation, we calculate the health-related quality of life (HRQoL) weight for acute infections as: The HRQoL utility weight associated with the Infected state is calculated in a similar fashion as costs: where Cdenotes costs, and pdenotes the probabilities of each event, as defined above. Specifically, CAcuterepresents the annual cost per capita of an acute infection,COis the outpatient costs for symptomatic patients, CFrepresents the annual hospitalization cost for fulminant cases, and CHdenotes the annual hospitalization cost for non-fulminant cases. Substituting the values of each parameter into the equation, we calculate the HRQoL weight for acute infections as: The derivation of the annual expected cost and HRQoL utility weights associated with a chronic infection from the data in Hoerger, Young, and Walker (2013) requires a slightly more complex analysis. The mathematical derivation of these expected costs goes beyond the scope of this handbook. But it is enough for the reader to know that these costs are calculated by accumulating the expected lifetime medical costs of an individual with a chronic hepatitis B infection, as they cycle through various stages of chronic hepatitis B disease progression, including chronic hepatitis, inactive carrier, compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma, liver transplantation, and death (see Figure 1.b in the Supplementary Data of Hoerger et al. (2013)). From that model, we estimated the expected annual cost of chronic hepatitis B infection to be approximately $4,688; the expected HRQoL utility weight for chronic hepatitis B is approximately 0.939. With these annual estimates, we are nearly ready to calculate the expected cost of spending a year in the Infected state. But we need one more parameter, the prevalence of chronic (or acute) hepatitis B infection in the population, so that we can calculate the proportions of the Infected population who have acute and chronic hepatitis B infections. Fortunately, data from the epidemiological literature allow us to calculate such a parameter. Data from 1999 to 2010 from the National Health and Nutrition Examination Survey reported that the relative risk of chronic hepatitis B infection for diabetes patients in the US was 60% higher than the risk for individuals without diabetes, with odds ratios (OR) of 1.7 (95% confidence interval (CI) 1.3–2.2) for persons aged 18 through 59 years, and 1.3 (95% CI 1.0–1.6) for persons aged 60 years and older. The reported prevalence of chronic hepatitis B infection among diabetics in the sample was 8.2% (95% CI 6.8–9.8) (Schillie, Xing, Murphy, & Hu, 2012). We will use this prevalence estimate in our model. Applying this prevalence and its complement as weights to the annual costs and HRQoL utility weights of acute and chronic hepatitis B infection, we estimate an expected cost and HRQoL utility weight of $1,744 (i.e., 0.082 × $4,688 + (1 − 0.082) × $1,481) and 0.992 (i.e., 0.082 × 0.939 + (1 − 0.082) × 0.997), respectively, for spending a year in the Infected state. These are the cost and HRQoL utility weight estimates that we use in the simplified Markov model that was introduced in Chapter 4.1.
Authors: David Bishai, Logan Brenzel, William V. Padula
Language: English
Subfield: Economics and Econometrics
Domain: Social Sciences
Open Access status: gold
OpenAlex ID: W4366581780