
3.6.6.1 Abom

As discussed previously, we assumed the annual number of deaths due to ABOM to be zero. Therefore, the VSLbased mortality costs were assumed to be null.


3.6.6.2 Absssi

Total Number of Cases that Result in Death
We estimated the number of deaths attributable to ABSSSI to be 1,868 in 2008, or 0.61 per 100,000 population. Applying this rate to 2011 population estimates yields a total of 1,923 deaths attributed to ABSSSI in 2011.
QALYs Lost
To calculate lost QALYs for patients who die from skin infections, we used the Compressed Mortality File. Using the mortality rate and age breakdowns for 2008 from the Compressed Mortality File, we estimated the total number of deaths by age group for the year 2011. Life expectancies by age were available from the National Vital Statistics Report (NVSR). To illustrate the calculation, there were an estimated 497 deaths caused by an ABSSSI among Americans aged 7584 in 2011. The life expectancy for an 80yearold is 8.8 years; thus, each person who died from an ABSSSI at that age was assumed to have lost 8.8 years of life. After matching the Compressed Mortality File age cohorts to an appropriate age in the NVSR data (usually the age in the middle of the cohort), we calculated total QALYs lost by the 7584 age cohort as 4,374 (8.8 × 483). Summing lost QALYs across all ages yielded a total of 26,167 QALYs lost due to ABSSSI deaths in 2011.
Mortality Cost
To calculate VSLbased mortality costs, we multiplied the number of deaths in each age group by the VSL for those age groups. For ABSSSI, this resulted in $10.8 billion in mortality costs. The average perpatient VSL, weighted by the number of deaths by age, is $5.62 million.


3.6.6.3 Cabp

Total Number of Cases that Result in Death
According to mortality data obtained from the NVSR, there were 50,774 deaths attributed to pneumonia in 2009; this is equal to a mortality rate of 16.5 per 100,000 population, which is equivalent to 51,683 deaths in 2011 (U.S. National Center for Health Statistics, 2010).
QALYs Lost
Similar to ABSSSI, we used the Compressed Mortality File and data on life expectancies by age available from the National Vital Statistics Report (NVSR). The 2009 deaths were broken down by age group in the NVSR, and we applied the same proportion of deaths by age group to the expected number of deaths in 2011. To illustrate the calculation, there were estimated to be 13,971 deaths caused by pneumonia among Americans aged 7584 in 2011. The life expectancy for an 80yearold is 8.8 years; therefore, total QALYs lost by the 7584 age cohort is 122,945 (8.8 × 13,971). Summing lost QALYs across all ages yielded a total of 572,741 QALYs lost due to CABP deaths in 2011.
Mortality Cost
To calculate VSLbased mortality costs, we multiplied the number of deaths in each age group by the VSL for those age groups. For CABP, this resulted in $274 billion in mortality costs. The average perpatient VSL, weighted by the number of deaths by age, is $5.3 million.


3.6.6.4 Ciai

Total Number of Cases that Result in Death
Using the Compressed Mortality File, we estimated the number of deaths attributable to CIAI to be 14,136 in 2008, or 4.65 per 100,000 population. Applying this rate to 2011 population estimates yields a total of 14,554 deaths attributed to CIAI in 2011.
QALYs Lost
Using data available in the Compressed Mortality File and NSVR, we estimated the total number of deaths by age group for the year 2011. To illustrate the calculation, there were an estimated 3,982 deaths caused by a CIAI among Americans aged 7584 in 2011. The life expectancy for an 80 year old is 8.8 years; therefore, total QALYs lost by the 7584 age cohort is 35,042 (8.8 × 3,982). Summing lost QALYs across all ages yielded a total of 243,987 QALYs lost due to CIAI deaths in 2011.
Mortality Cost
To calculate VSLbased mortality costs, we multiplied the number of deaths in each age group by the VSL for that age group. For CIAI, this resulted in $31.6 billion in mortality costs. The average perpatient VSL, weighted by the number of deaths by age, is $5.59 million.


3.6.6.5 Cuti

Total Number of Cases that Result in Death
For CUTI, estimates of both mortality and potential longterm morbidity are problematic because they are confounded by the morbidity/mortality of underlying disease and/or injury. Our best source for mortality associated with communityacquired CUTI estimated an overall mortality rate of 13.7 percent, but then concluded that “only 15 [of 43] deaths were attributed directly to bacteremic urinary tract infection according to the criteria used in this study. Of these 15 deaths, 13 occurred among patients on medical services, all but 1 of whom had alcoholic liver disease, malignancy and/or chronic neurologic disease” (Bryan & Reynolds, 1984). For our calculations, we used a mortality rate of 4.8 percent (15 deaths out of 313 cases), although even this adjusted rate might be high.
In the public health report cited above in the calculation of projected healthcareassociated cases, Klevens et al. (2007) estimate that there were 13,088 deaths associated with healthcareassociated urinary tract infections in 2002, which is equivalent to a rate of 4.55 deaths per 100,000 population. In that study, the percentage of patients with a healthcareassociated UTI whose death was determined to be caused by or associated with the UTI from NNIS data was used to estimate the number of deaths. Applied to the 2011 U.S. population, this rate produces 14,259 deaths due to healthcareassociated pneumonia in 2011. Though the 2007 report is not specific with regard to the types of infections that are included (for instance, it may not be strictly limited to complicated UTIs), we used these figures in the absence of better data.
QALYs Lost
As was done for the other indications, we relied on data from the Compressed Mortality File (from Centers for Disease Control and Prevention, National Center for Health Statistics, available online from CDC WONDER) to approximate a breakdown of deaths by age. Specifically, we utilized a 2008 age distribution of deaths for individuals where the listed cause of death was “Urinary tract infection, site not specified.” This distribution is highly skewed; 92 percent of deaths due to UTIs are among individuals 65 years of age or older. We used this distribution to estimate the number of deaths by age category for 2011. To calculate lost QALYs, we multiplied the number of deaths due to CUTI (redistributed by age group by the breakdowns in the Compressed Mortality File) in each age category by the average years of life remaining for that age group. Life expectancies by age were available from the NVSR. Multiplying the number of deaths by these average life expectancies yields a total of 196,165 QALYs lost due to communityacquired CUTI deaths and 123,748 QALYs lost due to hospitalacquired UTI in 2011 for an overall total of 319,913 QALYs lost.
Mortality Cost
To calculate VSLbased mortality costs, we multiplied the number of deaths in each age group by the VSL for those age groups. For CUTI, this results in mortality costs of $112 billion and $71 billion for communityacquired and hospitalacquired CUTI, respectively, for an overall total of $183 billion. The average perpatient VSL, weighted by the number of deaths by age, is $4.95 million.


3.6.6.6 HABP/VABP

Total Number of Cases that Result in Death
Due to the nature of HABP/VABP, estimation of mortality was quite difficult. As mentioned above, incidence estimates are relatively unrefined because HABP is not a reportable illness, and accurate diagnosis can be complicated. Estimating mortality involves even greater uncertainty due to the fact that HABP occurs in patients who are already hospitalized for other serious conditions, making it difficult to determine whether deaths are due to the underlying illness or HABP/VABP. Accordingly, the mortality rates seen in the literature on HABP/VABP vary widely. As summarized in the 2005 American Thoracic Society/Infectious Diseases Society of America guidelines on hospitalacquired, ventilatorassociated, and health careassociated pneumonia, “[t]he crude mortality rate for HAP may be as high as 30 to 70 percent, but many of these critically ill patients with HAP die of their underlying disease rather than pneumonia. The mortality related to HAP (or ‘attributable mortality’) has been estimated to be between 33 and 50 percent in several casematching studies of VAP.”
In our review of the literature, we saw mortality rates ranging from about 14 percent (Klevens, et al., 2007) to 50 percent (Warren, et al., 2003) to 50 percent and have therefore selected 30 percent as a reasonable middle point among the varying estimates and the low end of the mortality rates reported by the American Thoracic Society/Infectious Diseases Society of America guidelines. Multiplying 30 percent by our estimated number of HABP/VABP cases in 2011, 272,598, results in an estimated 81,779 deaths in 2011.
QALYs Lost
Due to the difficulties associated with measuring mortality and HABP’s status as a nonreportable illness, we were unable to find a breakdown of deaths by age group. Therefore, to calculate years of life lost, we multiplied the number of deaths due to HABP/VABP by average years of life remaining for the age group including the average age of HABP/VABP patients. We estimated average age by taking the midpoint of the average patient ages reported in two studies, 61.7 (Rello, et al., 2002) and 58.3 (Kollef, et al., 2006), to get 60. Life expectancies by age are available from the NVSR. For a 60yearold, there are estimated to be 22.6 years of life remaining; thus, each person who died from HABP/VABP is assumed to have lost 22.6 years of life. Multiplying the number of deaths (81,779) by this average life expectancy yields a total of 1,848,212 QALYs lost, due to HABP/VABP deaths in 2011.
Mortality Cost
To calculate VSLbased mortality costs, we multiplied the number of deaths in each age group by the VSL for those age groups; however, as mentioned above, the literature and available data resources did not provide a breakdown of deaths by age group for HABP/VABP. Therefore, it was necessary to use the VSL for a representative patient (based on average age, which is 60), and multiply that by the annual number of deaths. The VSL for people aged 55 to 62 is $4.77 million.

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