Patent Publication Number: US-8983951-B2

Title: Techniques for relating data in healthcare databases

Description:
RELATED APPLICATION 
     The present application claims the benefit of priority as a continuation of U.S. application Ser. No. 11/029,840, filed Jan. 4, 2005, issued as U.S. Pat. No. 7,580,922, which is entitled “METHODS FOR RELATING DATA IN HEALTHCARE DATABASES,” the disclosure of which is hereby incorporated herein by reference as if set forth in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to database management in general and, more particularly, to organization of and access to data stored in databases. 
     BACKGROUND OF THE INVENTION 
     As the field of healthcare continues to become more specialized, the provision of services by many healthcare workers and/or providers to many patients may increase. In order to accomplish this, healthcare delivery has been organized into specialized departments or healthcare sources such as, for example, nursing, laboratory, pharmacy, and radiology departments. Each department has the responsibility for accomplishing its particular, often specialized, subset of tasks. Sometimes the departments are associated with different healthcare enterprises or offices having different geographic locations. Unfortunately, this has resulted in sub-optimal healthcare operations because patient information related to a single patient that is stored at various departments may not be easily accessible from a single place. 
     This patient information, or medical data, may be stored in a database environment configured to store large volumes of data. Furthermore, the medical data stored in the database environment may be processed by, for example, searching the stored medical data. Details with respect to conventional methods for storing and/or accessing medical data in and/or from databases is discussed in, for example, United States Patent Publication Nos. US 2003/0088438 and US 2003/0177132. 
     However, as the amount of available medical data expands, it may become increasingly difficult to store and/or access the medical data, especially for research and comparison purposes. For example, use of the medical data for purposes of diagnosing various medical conditions and/or researching medical areas may be very difficult. Accordingly, there is a need to improve storage of and access to medical data. 
     SUMMARY OF THE INVENTION 
     Some embodiments of the present invention provide systems and computer program products for relating facts stored in healthcare databases. At least two fact tables stored in a healthcare database including data meeting a criteria of interest are located. An identification key is assigned to the at least two fact tables including the located data meeting the criteria of interest. The identification key provides access to a dimension table including a list of subjects associated with the at least two fact tables including the located data meeting the criteria of interest so as to allow future identification of the subjects meeting the criteria of interest. 
     In further embodiments of the present invention, at least two fact tables stored in the healthcare database including data meeting a second criteria of interest may be located. A second identification key may be assigned to the at least two fact tables including the located data meeting the second criteria of interest. The second identification key may provide access to a second dimension table including a list of subjects associated with the at least two fact tables including the second criteria of interest so as to allow future identification of the subjects meeting the second criteria of interest. A third identification key may be assigned to subjects meeting the first and second criterion of interest. The third identification key may provide access to a third dimension table including a list of subjects meeting both the first and second criterion of interest so as to allow future identification of the subjects meeting the first and second criterion of interest. In certain embodiments of the present invention, the third identification key may be automatically assigned. 
     In still further embodiments of the present invention, the located data may be associated with a medical study. The data associated with the medical study may be normalized so as to allow direct comparison of the data. 
     In some embodiments of the present invention, a database may be generated including a plurality of fact tables and a plurality of associated dimension tables. The plurality of fact tables may be divided into a plurality of groups of fact tables and each of the plurality of groups may be associated with an entity. Authorization codes may be provided to each entity, which provide access to at least one of the groups of fact tables. The plurality of fact tables may include at least one identification key which identifies an associated dimension table. The associated dimension table may include information that further describes facts provided in the fact table. The plurality of fact tables may be related through the plurality of dimension tables. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating data processing systems according to some embodiments of the present invention. 
         FIG. 2  is a block diagram illustrating an exemplary network environment for operations and devices according to some embodiments of the present invention. 
         FIG. 3  is a schematic illustration of fact tables and dimension tables creating a star schema according to some embodiments of the present invention. 
         FIG. 4  is flowchart illustrating operations according to some embodiments of the present invention. 
         FIG. 5  is flowchart illustrating operations according to further embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the scope of the present invention. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     As will be appreciated by one of skill in the art, the invention may be embodied as a method, data processing system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Furthermore, the present invention may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embodied in the medium Any suitable computer readable medium may be utilized including hard disks, CD-ROMs, optical storage devices, a transmission media such as those supporting the Internet or an intranet, or magnetic storage devices. 
     Computer program code for carrying out operations of the present invention may be written in an object oriented programming language such as Java®, Smalltalk or C++. However, the computer program code for carrying out operations of the present invention may also be written in conventional procedural programming languages, such as the “C” programming language or in a visually oriented programming environment, such as VisualBasic. 
     The program code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user&#39;s computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). 
     The invention is described in part below with reference to flowchart illustrations and/or block diagrams of methods, systems, computer program products and data structures according to embodiments of the invention. It will be understood that each block of the illustrations, and combinations of blocks, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the block or blocks. 
     These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function/act specified in the block or blocks. 
     The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the block or blocks. 
     Embodiments of the present invention will now be discussed with respect to  FIGS. 1 through 5 .  FIG. 1  illustrates an exemplary data processing system  100  or database environment that may be included in devices operating in accordance with some embodiments of the present invention. As illustrated, the data processing system  100  includes a processor  138 , a memory  136  and input/output circuits  146 . The data processing system  100  may be incorporated in, for example, a personal computer, server, router or the like. The processor  138  communicates with the memory  136  via an address/data bus  148  and communicates with the input/output circuits  146  via an address/data bus  149 . The input/output circuits  146  can be used to transfer information between the memory  136  and another computer system or a network using, for example, an Internet Protocol (IP) connection. These components may be conventional components such as those used in many conventional data processing systems, which may be configured to operate as described herein. 
     In particular, the processor  138  can be any commercially available or custom microprocessor, microcontroller, digital signal processor or the like. The memory  136  may include any memory devices containing the software and data used to implement the functionality circuits or modules used in accordance with embodiments of the present invention. The memory  136  can include, but is not limited to, the following types of devices: cache, ROM, PROM, EPROM, EEPROM, flash memory, SRAM, DRAM and magnetic disk. In some embodiments of the present invention, the memory  136  may be a content addressable memory (CAM). 
     As further illustrated in  FIG. 1 , the memory  136  may include several categories of software and data used in the data processing system  100 : an operating system  152 ; application programs  154 ; input/output device drivers  158 ; and data  156 . As will be appreciated by those of skill in the art, the operating system  152  may be any operating system suitable for use with a data processing system, such as OS/2, AIX or zOS from International Business Machines Corporation, Armonk, N.Y., Windows95, Windows98, Windows2000 or WindowsXP from Microsoft Corporation, Redmond, Wash., Unix or Linux. The input/output device drivers  158  typically include software routines accessed through the operating system  152  by the application programs  154  to communicate with devices such as the input/output circuits  146  and certain memory  136  components. The application programs  154  are illustrative of the programs that implement the various features of the circuits and modules according to some embodiments of the present invention. Finally, the data  156  represents the static and dynamic data used by the application programs  154 , the operating system  152 , the input/output device drivers  158 , and other software programs that may reside in the memory  136 . As illustrated in  FIG. 1 , the data  156  may include fact tables  128  and dimension tables  110  for use by the circuits and modules of the application programs  154  according to some embodiments of the present invention as discussed further herein. 
     As used herein, “fact tables”  128  refer to tables that include or store a value corresponding to an observed value. For example, the fact table may include a test result, a patient&#39;s blood pressure, a date of a lab test, and the like. The fact tables also include one or more identification keys. The identification keys may be a symbol, a series of numbers or letters or any combination thereof. The identification keys identify dimension tables  130  associated with the facts table in which they are identified. The dimension tables provide additional information about the observation stored in the fact table  128 . For example, a “dimension table”  130  accessed using the associated identification key stored in the fact table may include information about the test performed that provided the result stored in the fact table, information about the patient, information about the provider, information about the person who requested the test or authorized the test, the date and/or time of the test, international standards and the like. The dimension tables  130  may allow drilling in and out of the data stored in the dimension tables  130 . For example, if the dimension table  130  associated with the date is accessed using the associated identification key, the date of the test may be drilled out to the week of the test, the month of the test, the year of the test etc. as will be discussed further herein. 
     Medical data according to embodiments of the present invention may be stored in databases using the Ralph Kimball approach. The Ralph Kimball approach is known to those having skill in the art and, therefore, will not be discussed in detail herein. The Ralph Kimball approach is discussed at rkimball.com. As discussed above, facts or atomic data are stored in fact tables  128  including one or more identification keys which are associated with corresponding dimension tables  130 . A single fact table  128  and the associated dimension table(s)  130  form a star schema, the fact table  128  being the center of the star and the dimension tables  130  being the arms. Two or more star schemas form a constellation schema. The facts stored in the fact tables  128  may be associated with each other through the dimension tables  130 . For example, if a patient has three tests performed, each test and test result may be stored in a corresponding fact table  128 . However, each of these fact tables  128  may have an identification key for the patient, which accesses the patients dimension table  130 . Thus, the tests and test results may all be associated through the patient dimension table as discussed further herein. 
     Referring again to  FIG. 1 , according to some embodiments of the present invention the application programs  154  include a database circuit  118 , a location circuit  120 , an identification circuit  122 , a normalization circuit  124  and an authorization circuit  126 . The database circuit  118  may be configured to generate a database including a one or more fact tables  128  and one or more associated dimension tables  130  as discussed above. The location circuit  120  may be configured to receive a criteria of interest, such as a type of medical condition, for example, diabetes. As used herein, a “criteria of interest” may include any information or statistic that may provide useful information for medical research purposes. For example, a criteria of interest may be a test result, a medical condition, the presence or absence of a gene, the presence or absence of a protein, a medical procedure and the like. The location circuit  120  is further configured to locate the criteria of interest in one or more fact tables  128  stored in the database being searched. Once located, the identification circuit  122  may be configured to assign the subjects or patients associated with each of the located fact tables  128  an identification key. This may be referred to as “premarking” the subjects associated with the fact tables  128  including the criteria of interest. Premarking these subjects may enable future access to the subjects satisfying the criteria of interest without having to search the entire database again for the criteria of interest. The assigned identification key may be used to access a dimension table  130  that lists the subjects who satisfy the criteria of interest. 
     It will be understood that in some embodiments of the present invention, the patients having a criteria of interest, for example, a patient afflicted with diabetes, may be premarked as the information is entered into the database. For example, once the database circuit  118  has generated a database according to embodiments of the present invention, the “new” entries to the database may be premarked upon entry. 
     In some embodiments of the present invention, the location circuit  120  may be further configured to locate a second criteria of interest, for example, coronary artery disease (CAD), in one or more fact tables  128 . Once located, the identification circuit  122  may be configured to assign the subjects associated with the fact tables including the second criteria of interest a second identification key, i.e., premark a second number of subjects. In certain embodiments of the present invention, the subjects associated with the first identification key and the subjects associated with the second identification key may be compared and the identification circuit may be configured to assign the subjects satisfying both criterion of interest, i.e., diabetes and CAD, a third identification key. The third identification key may allow access to an associated third dimension table, or compound index, which may list the subjects satisfying both criterion of interest. 
     In some embodiments of the present invention, the criteria of interest may be a patient&#39;s participation in a medical study, for example, the use of an experimental drug for curing cancer. As discussed above, the location circuit  120  may be configured to locate the patient&#39;s participating in the study and the identification circuit  122  may be configured to assign an identification key to the located patients so as to allow future access to this list of patients. If, for example, the results of the drug treatments for each of the patients participating in the study were to be compared, the outcome of the comparison may not provide useful information as each of the patients may be at different stages in the study. Some patients may have just received their first dose of the experimental drug, while others may have had twenty or more doses. Accordingly, the normalization circuit  124  may be configured to normalize the first doses of each of the patients such that the results of the comparison compare a first dose result of a first patient to a first dose result of a second patient, regardless of how many doses the patients have actually received at the present time. 
     The cost of developing the type of database discussed herein may be large, thus, in some embodiments of the present invention groups of entities, such as pharmaceutical companies, having a single goal, such as, researching a new drug for curing cancer, may pool their resources and generate a single database for use by all of the groups of entities. The group of entities may be termed a “club” and embodiments of the present invention including the club may be termed the “club model.” In embodiments of the present invention using this “club model”, the entities may not want to share results of their research, just the database resource. Thus, the authorization circuit  126  may be configured to provide an additional identification key assigned by the identification circuit  122  in the fact tables  128  of this database. The additional identification key may provide information as to which groups, entities, individuals etc. are allowed access to the facts in the fact table. Thus, access to the facts in the fact table may only be provided to those groups, entities, individuals etc. that are authorized to view them. Which groups, entities and individuals have access to what information can be changed at any time. 
     It will be understood that generation of databases according to embodiments of the present invention including application programs  154  may be performed in multiple fashions. For example, medical data may be physically instantiated, i.e., all medical data may be brought into a single database, federated, i.e., the medical data may be stored in remote database and links may be provided to those databases to provide access thereto, or a combination of the two without departing from the scope of the present invention. 
     While the present invention is illustrated with reference to the database circuit  118 , the location circuit  120 , the identification circuit  122 , the normalization circuit  124  and the authorization circuit  126  being application programs in  FIG. 1 , as will be appreciated by those of skill in the art, other configurations fall within the scope of the present invention. For example, rather than being application programs  154 , these circuits may also be incorporated into the operating system  152  or other such logical division of the data processing system  100 . Furthermore, while the database circuit  118 , the location circuit  120 , the identification circuit  122 , the normalization circuit  124  and the authorization circuit  126  are illustrated in a single data processing system, as will be appreciated by those of skill in the art, such functionality may be distributed across one or more data processing systems. Thus, the present invention should not be construed as limited to the configuration illustrated in  FIG. 1 , but may be provided by other arrangements and/or divisions of functions between data processing systems. For example, although  FIG. 1  is illustrated as having various circuits, one or more of these circuits may be combined without departing from the scope of the present invention. 
       FIG. 2  illustrates an exemplary environment  200  for operations and devices according to some embodiments of the present invention. As illustrated in  FIG. 2 , the environment  200  may include a communications device  210 , a network  220 , a first server  240  and a second server  245 . It will be understood that the communications device  210  illustrated in  FIG. 2  may include the data processing system  100  discussed above with respect to  FIG. 1 . For example, the application programs  154  discussed with respect to  FIG. 1  could be included as part of the local database  217  of the communications device  210 . The communications device  210  may be, for example, a laptop computer, a desktop computer, a personal data assistant (PDA), a web capable mobile terminal or any device capable of communicating with the network  220 . The communications device  210  may include a user interface  244 , which may be used to enter queries for criterion of interest, a web browser  215  that may be accessed through the user interface  244 , and a local database  217  according to embodiments of the present invention. The local database  217  may include, for example, medical data which has been instantiated from other sources. The first server  240  may include a standards database  230  including international standards as discussed further below. The second server  245  may include a remote database  235 , which may include medical data which may be accessed by the local database  217  according to embodiments of the present invention. In other words, the remote database  235  may be federated. The communications device  210  may communicate over the network  220 , for example, the internet, through a telephone line, a digital subscriber link (DSL), a broadband cable link, a wireless link or the like. The first and second servers  240  and  245  may also communicate over the network  220 . Thus, the network  220  may convey data between the communications device  210  and the first and second servers  240  and  245 . 
     Exemplary operations of methods and devices according to some embodiments of the present invention will now be discussed with respect to  FIG. 2 . A researcher may be researching a cause of diabetes. The researcher may have access to a communications device  210  including a database  217  according to some embodiments of the present invention. The research may enter “blood test positive for diabetes” as the criteria of interest using the user interface  244  of the communications device  210 . For example, the user interface  244  may be a graphical interface that receives a query, for example, the criteria of interest. Devices and methods according to embodiments of the present invention may be configured to located one or more fact tables in the local database  217  or the federated database  235  including the criteria of interest. It will be understood that although the local database  217  is illustrated as being stored at the communications device  210 , the local database  217  may be stored at a remote server associated with the communications device  210  without departing from the scope of the present invention. 
     Once the fact tables including diabetes are located, the database may premark these fact tables by assigning each of the fact tables the same identification key, which may be stored in the fact table with other identification keys. The identification key may be used to access a dimension table, which may list all the patient identification keys for patients associated with the fact tables including data that matches the criteria of interest. Thus, the fact tables associated with diabetes and the patients associated therewith may be easily accessible in the future without searching the entire database  217  again. 
     A schematic illustration of an exemplary fact table and associated dimension tables is illustrated in  FIG. 3 . As illustrated therein, the fact table  328  is provided for an observation that this patient&#39;s blood tested positive for diabetes. The fact table  328  also includes identification keys  100  through  400 , which identify different dimension tables associated with the fact table  328 . It will be understood that  FIG. 3  is only an exemplary embodiment of fact tables and dimension tables according to some embodiments of the present invention and, therefore, embodiments of the present invention should not be limited to the configuration illustrated therein. For example, more or less than four dimension tables may be provided without departing from the teachings of the present invention. 
     As further illustrated in  FIG. 3 , the date key  100  provides access to the date dimension table  130 . The date dimension table may provide information about the date of the blood test was taken. As further illustrated, the information provided in the date dimension table may also be drilled out to the week, month or year in which the test was taken. Similarly, the blood test key  200  provides access to the blood test dimension table  230 . The blood test dimension table may provide information about the blood test, for example, the positive blood test was for type II diabetes in stage 3. This information may be drilled out beyond the blood test level to all blood tests for this patient, all blood tests for any patients having similar results and the like. 
     Referring again to  FIG. 3 , the provider key  300  provides access to the provider dimension table  330 . The provider dimension table may provide information about the patient&#39;s healthcare provider, for example, United Healthcare (UHC). This dimension table  330  may include the provider&#39;s address, telephone number, copay, locations and the like. Finally, the patient key  400  provides access to the patient dimension table  430 , which provides information about the patient having the positive blood test. As illustrated in  FIG. 3 , the patient dimension table may include the patient&#39;s first and last name, gender, social security number, height, weight, date of birth, blood type and the like. 
     The dimension tables according to some embodiments of the present invention may be expanded to provide a broader view of the information available in the database or a narrower view of the information provided in the database (drill in and out). For example, the criteria of interest may be a adverse reaction to a particular drug. The results of this query may be quite large as the “adverse reaction” may range from a rash to death. Thus, the information may be narrowed to just those patients who experienced a rash as a result of taking the drug. The information may be further narrowed to look at each patient experiencing the rash individually or patients that are women between the ages of 20 and 40. Furthermore, the type of drug may be expanded to provide all of the drugs in the particular class of drugs. These examples of drilling in and out of the data are provided for exemplary purposes only and, therefore, embodiments of the present invention are not be limited to these examples. 
     Referring again to  FIG. 2 , the researcher may enter a second criteria of interest, for example, heart disease, using the user interface  244  of the communications device  210 . The second criteria of interest may be located in one or more fact tables in the local database  217  or the federated database  235 . Once the fact tables including heart disease are located, the database may premark the fact tables by assigning each of the fact tables the same identification key. The second identification key may be used to access a second dimension table, which may list all the patient identification keys associated with the fact tables that match the second criteria of interest. Furthermore, the fact tables and associated patient records identified by the first and second identification keys may be searched to determine if any of these patients associated with the fact tables identified satisfy both the first and second criterion of interest (diabetes and heart disease). If any of the patient associated with the fact tables identified satisfy both criterion of interest, these patients may be provided a third identification key which accesses a third dimension table listing all the patients identification keys associated with the fact tables meeting both criterion. Thus, the results of the first and second searches may be combined to provide a compound index in the third dimension table to provide even more detailed information. Premarking the first, second and third groups of patients may allow future access to this information without having to search through the entire database  217  again. 
     In some embodiments of the present invention, the database  217  may be configured to automatically premark compound indexes based on previous queries done by the researcher. In other words, some embodiments of the present invention may be extended to include automated learning to discover new types of combinations of criteria that of interest based on, for example, actual queries or text mining of medical data and/or literature. 
     The web browser  215  may be used to access other databases, for example, standards databases  230 , such as Logical Observation Identifiers Names and Codes (LOINC) and SNOMED clinical terms (SNOMED CT). These standards databases  230  may be used to translate, for example, test results, into a national format so that any researcher in any part of the world may be able to access and understand the test results. For example, the test may be a cholesterol panel. A national standard for a cholesterol panel may have five different results including HDL, LDL and so on. In a local hospital the cholesterol panel may have seven results. Thus, using LOINC the results of the local cholesterol panel having seven results may also be stored in the database  217  using the national format of five different results. Thus, when non-local researchers access the results, they will understand the information provided in the database. 
     In some embodiments of the present invention, the local database  217  may be shared among several groups of people who are all interested in the solving the same problem. For example, five pharmaceutical companies (a club) may all be interested in developing a drug to cure cancer. Each of the pharmaceutical companies may perform research on the drug and store the results of their research in the database  217 . When a new fact or research result is entered into the database  217 , an identification key may be included in the fact table that identifies a dimension table including a list of people who are authorized to view these facts. Thus, the pharmaceutical companies can share certain information with each other and retain certain information internally and still share the cost of the database  217 . 
     In some embodiments of the present invention, the database  217  may be used by an entity performing a controlled study, for example, a controlled study for an experimental drug. Individuals may enter the study at various times and, therefore, may all be at different stages of their treatment. Fact tables may be maintained for each of the patients involved for time of study, time since initial treatment, cumulative dosage, patient&#39;s weight, size, gender, age, race and the like. The database  217  may be configured to normalize the information collected about each of the patients so that a first dose reaction of a first patient may be compared to a first dose reaction of a second patient even though the first patient began the program 4 years before the second patient. Furthermore, the database  217  may be further configured to select participants having a similar size (height, weight, frame), gender, age and the like to further remove any outside factors that may effect the way a dose of the drug may effect the participant. These groups sharing similar qualities may be termed cohorts. 
     It will be understood that databases that are not written in a format according to embodiments of the present invention may interact with the database  217  according to some embodiments of the present invention. For example, if an entity stores patient information in an Excel spreadsheet, the Excel spreadsheet is not in the fact table/dimension table format as discussed herein. However, an identification key may be established for the Excel spreadsheet and/or the information stored therein and these identification keys may be included in fact tables according to some embodiments of the present invention. Thus, information provided in the Excel spreadsheet may be accessed through queries of the database  217 . 
     It will be understood that teachings of the present invention may be combined with any relational database management system, such as DB2 and Oracle. It will be further understood that the database  217  according to some embodiments of the present invention is customizable by the customer. 
     Operations according to some embodiments of the present invention will now be discussed with respect to  FIGS. 4 and 5 . Referring now to  FIG. 4 , operations begin at block  405  by locating data meeting a criteria of interest in at least two fact tables stored in a healthcare database. The criteria of interest may be, for example, a medical condition, such as diabetes or heart disease, a participant in a particular medical study, a reaction to a particular drug or family of drugs or the like. An identification key may be assigned to the fact tables including the located data meeting the criteria of interest so as to allow future identification of the fact tables using the identification key (block  410 ). In other words, the fact tables including the criteria of interest are provided with an additional identification key to store therein. The identification key points to a dimension table indicating the identification keys of subjects associated with the fact tables that met the criteria of interest. The dimension tables may enable additional facts and supporting dimensional information to be found. This may allow researchers to iterate through the data looking for additional interesting and relevant information. Furthermore, when accessing this information in the future, the entire database does not have to be searched. 
     Referring now to  FIG. 5 , operations begin at block  500  by generating a database having fact tables and dimension tables according to some embodiments of the present invention. As discussed above, the generated database may be customized by the user of user(s). The generated database may be physically instantiated, federated or a combination of both. A first criteria of interest may be located in at least two fact tables stored in a healthcare database (block  505 ). A first identification key may be assigned to the fact tables including the located data meeting the criteria of interest so as to allow future identification of the fact tables using the identification key (block  510 ). A second criteria of interest may be located in at least two fact tables stored in the healthcare database (block  520 ) and a second identification key may be assigned to the fact tables including the located data meeting the second criteria of interest (block  525 ). A third identification key may be assigned to ones of the fact tables having both the first and second assigned identification keys (block  530 ). Thus, a compound index or dimension table may be created including identification keys associated with patients having both diabetes and heart disease. In some embodiments of the present invention the third identification key may be automatically assigned. 
     It will be understood that in some embodiments of the present invention, the information found in the fact tables may not be revealed to the researcher unless the researcher is authorized to view the information in the fact tables. The issue of authorization typically occurs when multiple groups of entities share a single database environment, but do not wish to share all the information stored therein as discussed above. 
     In some embodiments of the present invention, the generated database ( 500 ) is generated for a medical study. Individuals may enter the study at various times and, therefore, may all be at different stages of their treatment. The generated database may be configured to normalize the information collected about each of the patients so that a first dose reaction of a first patient may be compared to a first dose reaction of a second patient even though the first patient began the program 4 years before the second patient (block  535 ). As discussed above, the normalized data may be further broken down into participants having a similar size (height, weight, frame), gender, age and the like to further remove any outside factors that may effect the way a dose of the drug may effect the participant. 
     Databases according to some embodiments of the present invention, allow a researcher to have multiple frames of reference. Once the data intersections have been made the data may then be viewed from many different perspectives, for example, patient, associated patient facts, fact values, such as lab tests results and the like, to provide answers. Furthermore, databases according to some embodiments of the present invention may be used to look for combinations of combinations. In other words, databases according to some embodiments of the present invention may be configured to look for similarities and differences between entities of interest, mark down those similarities or differences and find combinations of the similarities or differences. Then, the results may be used to research and analyze the data from many perspectives using manual observation, simple query tools, simple statistical tools or very complex statistical tools. 
     Many alterations and modifications may be made by those having ordinary skill in the art, given the benefit of present disclosure, without depa9407-rting from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of example, and that it should not be taken as limiting the invention as defined by the following claims. The following claims are, therefore, to be read to include not only the combination of elements which are literally set forth but all equivalent elements for performing substantially the same function in substantially the same way to obtain substantially the same result. The claims are thus to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and also what incorporates the essential idea of the invention.