There are no publicly available estimates of how long each of the different types of illnesses last in patients who do not respond to existing commonly used antibacterial drugs. Thus, for analysis purposes, we assume that those patients who do not respond to existing drugs have an average duration of illness 50 percent longer than those who do respond. For sensitivity analysis purposes, we further assume that the parameter follows a uniform distribution with a lower bound of 25 percent and an upper bound of 100 percent.
In the analysis, we further assume that 1) all those not responding to existing commonly used antibacterial drugs respond to the new drug and 2) their duration of illness is reduced to the average of those responding to existing drugs.13 Combining these assumptions, we then calculate that a new antibacterial will reduce the total social burden of illness by about 9 percent. This estimate is highly uncertain, as we do not know the actual improvement in patient response to a hypothetical new antibacterial drug. It should also be noted that this does not imply that the new antibacterial drug will avert 9 percent of deaths attributable to the different types of indications studied here. Given data limitations, our analysis cannot distinguish between avoided mortality and morbidity cases due to the new antibacterial drug. We only are able to compute overall reductions in the total social burden of illness due to these new drugs in monetary terms.
Table 16: Reported Estimates of Antimicrobial Resistance
|Source||% of Patients Resistant to Commonly Used Antibacterial Drugs|
|Evans, et al., 2007 [a]||23.0%|
|Roberts, et al., 2009 [b]||13.5%|
|ECDC/EMEA Joint Technical Report, 2009 [c]|
|Methicillin-resistant S. aureus (MRSA)||25.0%|
|Vancomycin-resistant Enterococcus faecium||8.0%|
|Penicillin-resistant S. pneumonia||4.0%|
|Third-generation cephalosporin-resistant E. coli||9.0%|
|Third-generation cephalosporin-resistant K. pneumoniae||20.0%|
|Carbapenem-resistant P. aeruginosa||19.0%|
|Outpatient||10.0% - 15.0%|
|Expert 2||20.0% - 25.0%|
[a] Based on a sample of 604 surgical admissions treated for at least one Gram-negative rod (GNR) infection [b] Based on a sample of 1,391 patients in a Chicago area hospital
[c] Based on European Antimicrobial Resistance Surveillance System (EARSS) for EU Member States, Iceland
and Norway for each year during the period 2002–2007
13 This is a simplifying assumption that likely leads to an overestimation of social benefits. In reality, there will be time lost for the patient due to being on the wrong drug initially.