For constructing our EPV model, we compiled information from a variety of sources, including:
- Systematic reviews of published literature;
- Interviews with experts, including individuals who previously worked for drug companies and now advise companies on drug development, U.S. Food and Drug Administration (FDA) personnel, drug company representatives, clinicians, and hospital pharmacists;
- IMS Health data on drug expenditures; and
- Databases available through the CDC National Center for Health Statistics;
- National Ambulatory Medical Care Survey (NAMCS)
- National Hospital Ambulatory Medical Care Survey (NHAMCS)
- Compressed Mortality File
- Healthcare Cost and Utilization Project National Inpatient Sample (HCUP NIS)
- National Hospital Discharge Survey (NHDS)
- National Vital Statistics Report (NVSR)
- National Nosocomial Infections Surveillance (NNIS)
Our literature search targeted several categories of literature: peer-reviewed articles in scientific journals, unpublished papers and presentations, white papers, gray literature,1 and news stories and occasional pieces appearing in newspapers and magazines or other print media outlets. Our search methodology featured systematic inquiries of the following databases:
- PubMed for peer-reviewed healthcare and biomedical journals;
- Lexis/Nexis academic for mass media and other periodical publications; and
- PAIS, Scopus, Web of Knowledge, and Embase for gray literature.
The search strategies differed for each category of literature and related database, but each query employed search terms in various combinations using logic strings.
Some of the information needed for modeling the private and social EPV came from semi-structured discussions with independent experts, FDA personnel, drug sponsors, clinical researcher, clinicians, and hospital pharmacists. In accordance with Office of Management and Budget (OMB) guidelines, we limited the number of interviews involving the same set of questions to fewer than 10. From these interviews, we collected information about how drug sponsors make the decision to move forward with the development of a novel antibacterial drug, vaccine, or diagnostic, magnitudes of various cost components (e.g., clinical trial costs, non-clinical expenditures, post-approval pediatric study commitments, etc.), timelines for getting a new product to market, and health practitioner adoption rates and considerations.
We used IMS Health data on drug expenditures to estimate the total market size for each of the indications. Through FDA’s Third Party Agreement with IMS Health, we obtained 5 years (2007 – 2011) of U.S. sales data on a total of 43 and 31 antibacterial drugs in intravenous (IV) and solid oral dosage form, respectively. The data provided included information on:
- Extended Units (EU) – These are the number of individual tablets, capsules, etc. for solids; number of grams or milliliters for other forms.
- Total Dollars (DOL/TOT) – This measure reports the amount of money pharmacies, non-federal hospitals, federal facilities, long-term care facilities, clinics, and HMOs spent on a product acquired from manufacturers and drug wholesalers.
- Units – This corresponds to the total amount of packages sold of a particular drug to the dispensing outlet/chain/hospital.
- There are a number of databases that are available through CDC’s National Center for Health Statistics (NCHS). We used these databases, as appropriate, to estimate disease duration and number of patients per annum in the U.S. for the different indications covered in the study. Details on how each of these databases was utilized are provided in the sections related to each of these indications below.
1 Gray literature encompasses those publications that fall outside of the realm of normal publishing outputs, such as journals and books. Examples of gray literature include technical reports written for a specific audience, dissertations and theses, article pre-prints, white papers, and conference proceedings.