ADAMO revisited: An interpretative review of a data management system

IntJBiomedComput, 23(1988)21-32 Elsevier Scientific Publishers Ireland Ltd.

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ADAM0 REVISITED: AN INTERPRETATIVE REVIEW OF A DATA MANAGEMENT SYSTEM

A. HASMAN’, R.M.J. SILKENS’, P. ZINKEN’, A.B.M.F. RARIMb and R.F. WESTERMAN’ *Department of Medical Informatics and Statistics, University of Limburg, Maastricht, Vkpartment of Radiotherapy and 9epartment of Medicine, Free University, Amsterdam (The Netherlanck) (Received January 29th, 1988) (Accepted February 1lth, 1988)

In this paper the use for research purposes of an existing data management system, ADAM0 (A Database Management system for Oncology), is described. The ahn of this paper is to discuss the experiences, obtained with this ‘home-made’ system and to describe some of the extensions that were recently made. Reasons are presented why the system is still extensively used by clinicians although a number of commercial database management systems is now available on personal computers. These database systems are more flexible than the system described here. It is concluded that it is precisely this flexibiity of current systems that prevents an optimal use by busy clinicians. Clinicians need a research system that contains just the functions that they need. These functions have to be available via simple commands, so that no additional programming - even at the high level of a query language - is necessary. Keywords: File management system; Clinical research; Query language; Data definition language; Data entry

Introduction Database management systems are available for mainframes, minicomputers and microcomputers nowadays. Any physician, having a microcomputer can choose between a number of database management systems and use such a system for clinical research. At the time A Database Management system for Oncology (ADAMO) was developed (in the period between 1975 and 1978) these database management systems were not available. Also existing hospital information systems were not suitable for supporting physicians in their clinical research activities. In the mean time things have changed. Hospital information systems have obtained more functions, usually also including the possibility of entry and storage of clinical data. Unfortunately not always a query language is available, so additional programs have to be written to answer specific questions. Although microcomputer systems become more abundant in clinical departments, commercially available database management systems also have disadvantages for clinicians. These systems are usually equipped with a rather extensive command language. This language, although giving the user flexibility, takes quite a time to learn. Usually clinicians cannot afford this time. In the ten years of its existence ADAMO, however, has shown to fulfill the requirements of clinicians. As will be explained later on, this may be due to the fact that it uses a simple command language that is easy to learn. 0 Elsevier Scientific Publishers Ireland Ltd. 002&7101/88/~3.50 Printed and Published in Ireland

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ADAM0 consists of a data definition language together with a data entry module and a command language consisting of a relatively small set of keywords. Because of this relatively simple command language clinicians remember the commands and ask the questions themselves. These advantages have also led to the use of the system for educational purposes. In this paper ADAMO, as it is now, will be described and examples of its use will be presented. The user is referred to earlier publications [l-3] for additional information about the system. History

The development of ADAM0 started in 1975 at the department of Medical Informatics of the Free University in Amsterdam, The Netherlands. At that time several clinicians were performing clinical research that was supported by computer processing. The data were gathered on punch forms and punched. The questions of the physicians were translated into computer programs that analysed and processed the data. Since in those days the analysis was performed on a mainframe the turnaround time was in the order of a day. The situation changed when the department obtained its own minicomputer, a PDP 1l/70. At that time it was already apparent that the number of functionally different research questions that were asked by clinicians, was rather limited. The differences between the applications was caused by the different data items that were used in each application. Therefore, it was decided to develop a data management system with a query language, that would enable the clinician to define the data items for each application without the necessity of changing the programs. In this way the system eventually consisted of: (i) a facility to define the items (a data definition language); (ii) a data entry and verification program; (iii) a query language. A data definition language (DDL) was developed with which the items could be defined. The definition included the data type (currently the types integer, real, alphanumeric and calendar date are supported), the length of the field, the range of allowed values (if appropriate) and the symbolic descriptions of codes (where appropriate). These data are interpreted by the DDL and translated into tables that are used among others by the data entry and verification program and the query language. A generally applicable data entry and verification program was developed, enabling one to interactively enter data. Since the allowed value ranges and the data types are known to the program, checks on the data type and the value can be performed. The program allows the correction of currently entered data but also of data entered in an earlier session. The query language was based on the idea that only a limited number of functions were required by the clinician. It was important to be able to make displays of item values, to obtain histograms and cross-tables, to be able to create subgroups of patients and to pass information from one database to the other. It was decided to offer these functions in the form of commands. The LANG-PAR system, developed by Heindel and Roberto [4] proved to be suitable for designing our query language. With the help of this system the syntax of the query language could be defined and tested. The resulting syntax table and the parser from the LANG-PAR system were embedded in the query language program

ADAM0

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module. Additions to the language can easily be made without the necessity to change existing programs. Each command causes the execution of a procedure that performs the function specified by the command. So the addition of new commands involves two steps: (a) modification of the syntax table and (b) the addition of a relevant procedure to the query language program module. In this way it was possible to quickly develop a core query language, already possessing a number of basic functions, so that the clinician could directly perform some work with the system and then to gradually extend the system with additional functions. In 1978 the system possessed most of the functions of the present version, although at that time ADAM0 was a single user system. In 1984 the system became also available on VAX computers. It now supports multiple users. An interactive version of the DDL was designed for the use by students. Moreover the results of the DDL can be used to generate a SPSS or BMDP system file. The Query Language Each query has the following form: CLAUSE>




CLAUSE>




Each keyword has a separate function. In table I a number of available keywords together with their function are presented. < LIST> usually is a list of item names or the name of a subgroup (this notion will be explained later). With the FOR clause the user can indicate particular records, of (for example) a certain patient, that have to be processed. With the help of the FOR clause it is also possible to identify a time interval within which one or more records must occur. For example the instruction: DISPLAY BLOODPRESSURE PERIOD OF 2 MONTHS

FOR RECORD = 1 AFTER 6 MONTHS IN A

means that the clinician is interested in the first bloodpressure measurement taken after six months of the first visit. Also the clinician indicates that the relevant measurement has to be performed not more than two months after the earlier mentioned period of six months. In this way the clinician for example can compare the distribution of the bloodpressure on entry with the distribution of the bloodpressure after six months. Relevant patients can be identified via the WHERE clause. If one is interested in patients of a certain age, the age range can be specified in the WHERE clause. An example of such a WHERE clause is the following DISPLAY AGE, SEX, T-CLASS WHERE AGE > 60 OR SEX = ‘MALE’ As can be seen, the WHERE clause allows ANDs and ORs and also parentheses are possible. Since the above explained structure is used consistently the query language is easy to learn.

A. Hasman et al.

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TABLE I AN OVERVIEW OF SOME OF THE MOST FREQUENTLY USED COMMANDS IN ADAM0 TOGETHER WITH A SHORT DESCRIPTION OF THEIR FUNCTION Command

Function

BYE COUNT CRFILE

Logout Count the number of cases Create a file with patient identification (used to identify the records of these patients in other databases) Present a description of the items Display item values Edit item values Execute an external program via ADAM0 Display names of items Construct a histogram Define a new item, usually in the form of an expression containing only database items as operands Load (connect) a particular database Construct a profile, containing information about the percentage of records in which data about indicated items have been entered Execute a file containing ADAM0 commands Construct a subgroup Read the file constructed via the CRFILE command and tag the records of the patients listed in this file Construct a plot of item values as a function of time Disconnect the current database Present all the data of a specific patient Construct a scatter plot

DESCRIBE DISPLAY EDIT EXECUTE FIND FREQUENCY LET LOAD PROFIL REPEAT SUBGROUP SUBFILE TPLOT UNLOAD VIEW VPLOT

The functions used most often are the DISPLAY, COUNT, FREQUENCY, SUBGROUP and TABLE command. With the DISPLAY command the user obtains the values of one to six items. The order in which the values are displayed is determined by the first mentioned item. The values of this item are sorted. The COUNT command enables the user to count the number of relevant records. With the FREQUENCY command histograms can be obtained and with the TABLE command cross-tables are produced. There is only a slight difference in command between the ordering of output on the screen and ordering output on the printer. If the clinician wants a hardcopy he merely has to type a ‘*’ before the relevant command. It is important that the user can define subgroups of patients. This is done with the help of the SUBGROUP command. In ADAM0 subgroups can be ANDed or ORed or the complement of the subgroup can be obtained. In this way the clinician is able to define almost any subgroup. the system also allows scatterplots and time plots to be generated. New variables can be calculated from existing ones with the help of the LET command. Records can be tagged in a number of ways. The system assumes that the primary key, making each record unique, consists of a patient identifier and a calendar date item.

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Data of patients residing in different databases can be correlated. It is possible for example to study the fate of patients with larynx carcinoma classified as Tl (according to the TNM classification), the static data of which are stored in a database containing information about the treatment, using the data from another database, containing the follow-up data of these patients. With the command CRFILE a file with patient identifiers is constructed of patients in the treatment database, being classified as Tl, that can be used to tag the records of these patients in the follow-up database using the SUBFILE command. With the commands described here clinical research can be easily performed. As will be clear, the data management system does not provide statistical functions. For this purpose statistical analysis systems have to be used. From the DDL tables the description of the variables is transferred to a SPSS system file. Another program is available, with which a BMDP set-up can be constructed. Use of the System The system was originally designed to support clinical research in oncology. Because of the fact that all application dependent data are stored in tables outside the programs ADAM0 can be used for all kinds of studies. The system is implemented in several places inside and outside The Netherlands. In Amsterdam, where the system was initially developed, at the moment the data of more than 7000 patients participating in several research projects are stored. In this section a number of applications will be discussed that will provide a better insight to the present possibilities of ADAMO. (1) Applications in radiotherapy The first application of ADAM0 concerned the study of the outcome of radiotherapy treatment on larynx carcinoma patients. Some of the patient data are already stored in the database for about ten years. Since in these types of studies survival curves are essential a program was written to calculate and print these survival curves. Since this program would probably not be used by the majority of applications, it was decided to make this function not available via a general keyword. Instead a keyword was added, EXECUTE, allowing the user to execute any program outside ADAMO. The program can obtain its data directly from ADAMO, when a standard interface subroutine is included into this program. When commanding ADAM0 to execute the program the user can indicate via the FOR and WHERE clauses which records are needed in the program. Only the relevant item values stored in these records are communicated to the called program. In this way several external programs were developed that, although being rather application dependent, could be executed via ADAM0 taking advantage of the selection features of ADAMO. Another problem met in radiotherapy studies was the identification of matched pairs in order to compare the survival data of a certain class of patients with a control group of other patients matching the former group in a number of respects. Also for this purpose a program was developed. Initially, for each type of cancer two separate databases were defined, one con-

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mining stationary data concerning the therapy history and one containing follow-up data of patients suffering from that specific type of cancer. This was due to the fact, that the system initially could only identify patients by for example their patient number since the primary key was formed from the value of only one item. Records in a follow-up study were made unique by using the value of the follow-up date. In later versions of ADAM0 the primary key can be constructed from the values of a number of items. At this moment the total length of the primary key may be up to 15 characters in length and can be constructed from the values of at most fifteen items. This change in the definition of the primary key resulted in the possibility of using a single checklist for a number of research studies concerning different cancer types. The identification is now made via a primary key, consisting of a patient identification, the ICD code for the tumor and an indication concerning the side (e.g. left or right) of the tumor. For follow-up purposes a calendar date item is added, forming the so-called secondary key. With this identification each tumor and each patient visit can be uniquely identified. The radiotherapy database is constantly updated. Regularly articles are published concerning results of research projects based upon this database (see for example Refs. 5-7). (2) Hypertension management ALMMO is also used to support hypertension management. The data of patients from different locations in the surroundings of Amsterdam were stored in the system. The information is sent to a hospital specialist by several general practitioners. These data are entered into the computer in the hospital and transmitted to the PDP 11170 of the department of Medical Informatics via a telephone connection (see Fig. 1). As explained above ADAM0 already possessed the features needed for research purposes. In this case it was investigated which additions would be needed, so that the system would also be suitable for management purposes.

Fig. 1. Overview of the method of communication between GPs, the hospital specialist and the computer system in the department of Medical Informatics.

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ADAM0 revisited THIS DATE1

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Fig. 2. A histogram of the diastolic blood pressure for a group of patients at the time they entered the therapy program.

The influence of medication on the bloodpressure is one of the items that is important in the management of hypertension. This information is easily obtained with ADA&IO. With the help of the system for example the first record of all patients can be identified. From the data in these records histograms of the initial diastolic and systolic bloodpressure can be constructed. These histograms can be compared with the corresponding histograms obtained after the patient is under medication for a certain period of time (Figs. 2 and 3). From the difference in distributions the effect of the therapy can be inferred. For hypertension management other functions are also necessary. For each patient it should be possible to construct a time plot of the diastolic and systolic pressures. In these plots the type of drugs prescribed and the date when they were described had to be indicated. When these functions were made available the time plots proved not only to be useful for the GP but also for the patient. The patient

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A. Hasman et al. THIS DATE:

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Fig. 3. A histogram of the diastolic bloodpressure of the patients after 6 months.

could be kept informed about the results of the therapy thus enhancing his compliance. The time plots have to be printed for those patients that will visit the GP the next day. Since also in this case this application is very user specific it was developed as a stand alone program that can be executed via the earlier mentioned EXECUTE keyword. It not only became possible to print these time plots, also a printout could be obtained of the data of the last visit of these patients. This function is available in ADAM0 by using the keyword VIEW. For patient management it is important to identify those patients who did not show up for follow-up. These patients have to be sent a reminder. A program was developed that printed reminder letters for those patients that were not seen in the last three months. For the GP it is important that the system can provide a surveillance function. With the help of the REPEAT command, the commands stored earlier in a separate file, can be executed at a later date by ADAMO. The repeat file can be modified when necessary since the file is constructed with the help of the system editor. In the repeat file the user may specify a number of conditions that need further attention or corrective action. For example, a warning can be issued for patients on diuretics notifying the physician of the need to determine the serum potassium level in the blood, since diuretics may decrease the potassium level to an unacceptable value.

ADAM0 revidted

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Also the system may present the physician with the names of the patients that have not been seen the last x months, etc. Another possibility is to store all kinds of data checks in a REPEAT file. In this way the number of errors in the datafile can be kept to a minimum. The commands in the repeat file are executed every day. Initially for a period of 2 years the data received from the GPs were entered without intervention from the clinic in order to determine the need for the surveillance procedure [8]. This feasibility study showed, that half of the patients did not reach the goal of a diastolic blood pressure below 95 mmHg after these 2 years. Moreover several patients were not seen by the GP during the last 18 months. In total 8% of the known hypertensive population was lost to follow-up in these initial 2 years. One third of these patients had a diastolic blood pressure of 100 mmHg or more at the last visit. Monitoring therapy by laboratory data was done in a few instances only. Only 7 potassium measurements were performed although over 550 times a drug with effects on potassium metabolism was prescribed. The pilot study gave satisfaction. It was established that reminders were necessary in order to obtain a better follow-up of the patients. The patients and their doctors appreciated the blood pressure graphs that were produced. Although for the reasons explained above the surveillance function was not used initially, patients who did not show up in time could be easily identified. Moreover the results of the treatment could be better evaluated and the warning messages were useful for the prevention of adverse effects. The impression is that patient compliance can be improved by supplying him with the feedback of his bloodpressure recordings. On the basis of our experiences it was decided to use the data management system for the support of more GP practices. (3) Educational applications The system is not only used for clinical research and patient management purposes. At the University of Limburg, Maastricht, The Netherlands, both medical students as well as students from the faculty of the health sciences are confronted with the use of database management systems. Since the educational system of this university is problem-oriented, a course in Medical Informatics is presented in a different format than the usual lecture method [9]. During each period of 6 weeks, called blocks, the students are confronted with one theme (e.g. ‘tumors’), integrating the contributions of the relevant disciplines. A group of staff-members compile what is called a ‘block book’ for this purpose. In this book the problems concerning the theme of the block are to be found. The students are guided by the problems in the block book. They meet for a few hours twice a week in a small-group tutorial session. Each group consists of about ten students and is put together on an arbitrary basis by the staff. Two main points are that (a) students have to solve the problems individually after discussing them during a small-group tutorial session and (b) report their results to the other members of the group. In the case reported here, the students are presented with a problem in which the use of database management systems can play a role. For medical students the problem is for example to determine which of three management types for treating a sprained ankle is optimal and under what conditions. The students have to design a questionnaire for investigating this problem. After some discussion between the students of a group the content of

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the questionnaire is decided upon. Each student has to enter the questionnaire into the computer, using an interactive version of the DDL program. Having done this he can then enter the data and observe how the data entry program checks the data type and the value entered. The student is provided with a user manual of ADAMO. On the basis of an existing database he is asked to formulate some queries and watch the results. In another task health science students make use of an existing database for policy making [lo]. Graduate medical students use the system to enter data they have collected for their research project and to ask the relevant questions using the query language. (4) Other applications In the previous paragraphs some important uses of ADAM0 have been reported. The applications in radiotherapy and hypertension management have been described in more detail because these applications give a good indication of what type of research can be performed with ADAMO. Quite a number of other research projects make use of ADAMO, however. These include research applications in dentistry, gastroenterology, microbiology, cardiology, gynecology, etc. The ideas of ADAM0 have also been adopted to design a similar system that was used for signal analysis purposes. Defining the language again via the LANG-PAK system, a program was developed with which serial EKG signals can be processed in different ways without the necessity of modifying programs each time [l 11.The query language is used to specify the relevant EKGs. Since in the database among others information is stored about the tape on which the relevant EKGs reside, the system can identify the tape and ask the user to mount it. When this is done the program, started via the EXECUTE command, will only process the signals specified by the user. Discussion In this paper some research applications were presented that use the data management system ADAMO. Even after 10 years of operation the system is still extensively used. At the Free University in Amsterdam, The Netherlands, the data of more than seven thousand patients are stored in the system and used for answering research questions. One may wonder why the system is still so intensively used. The hospital information system contains a package with which data entry of clinical research items can be supported. Also microcomputer systems are common in hospital departments. The commercial database management systems that are presently available on these microcomputers offer more flexibility than ADAM0 does. ADAM0 is not really a relational database system, although the patient data are stored in tables. Joins of (parts of) different databases are not possible for example. In our opinion the success of ADAM0 is due to the fact, that it precisely contains the functions that are really necessary for clinical research and not more. Analysis of the questions asked in research applications showed, that only a small number of functions like e.g. the construction of tables, histograms and subgroups are used rather often. This explains why a query language with a limited number of com-

ADAM0

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mands can still be very useful. Moreover in existing databases a number of these functions cannot be executed directly because there is no single command with which one can initiate this function: the user has to develop a program for it. In ADAM0 several databases can be defined all covering different items of the same patient group. Nevertheless for most research purposes two data files will be sufficient: one datafile containing the stationary data of the patient and one datafile containing the follow-up data. Switching between these databases is easily done in ADAM0 (via the UNLOAD and LOAD command). Moreover, although the user can change from one database to another, he does not have to label each item with the corresponding relation name. In ADAM0 item values can be represented as code numbers. In the DDL the user specifies the meaning of these numbers by assigning to each code number a so-called symbolic description. For output purposes the system directly translates the code numbers into text, so that the user clinician does not have to remember the descriptions of the codes. This feature is not always directly available in commercial systems. Here the descriptions have to be stored in a separate file. Although several records may belong to the same patients, ADAM0 allows the user to choose only one of them with the help of the FOR clause. This means that for those research questions for which it is important that a patient is counted as a single occurrence, no additional programming is needed. ADAM0 handles inverted files. The user can specify which items should be indexed, when defining the database. When this has been done the user does not have to remember which items were indexed. The system keeps track of this fact. It even determines whether it is useful to use index files and which one(s) to use when a specific question containing a WHERE clause is asked. Also here ADAM0 has an advantage over some existing database management systems. Usually in those cases the user must indicate which index files are important for his questions. The clinician can manage the system himself. He does not depend on a programmer. The syntax of the command language is straightforward and the function of the keywords becomes familiar to him rather quickly. The use of the system resulted in a large number of papers and a number of theses. It can therefore safely be stated that the manpower invested in the design of the system, approximately 5 man-years, was worthwhile for the job. References 1 2 3

4 5 6

Hasman A, Chang SC, de Moe1 EJPM and Karim ABMF: A data storage and retrieval system for clinical research, Int JBiomed Comput, 10 (1979) 3-14. Hasman A and Chang SC: ADAMO, a data storage and retrieval system for clinical research, Camp BiomedRes. 15 (1982) 145-154. Karim ABMF, Kralendonk JH and Hasman A: Clinical research with ADAMO, a physician’s viewpoint. In MEDZNFO 86 (Eds: R Salamon, B Blum and M Jorgensen), Elsevier Science Publishers B.V.. Amsterdam, 1986, pp. 575-578. Heindel LE and Roberto JT: LANG-PAK - An Interactive Language Design System, American Elsevier Publishing Company, New York, 1975. Karim ABMF, Kralendonk JH, Yap LY et al.: Heterogeneity of stage II glottic carcinoma and its therapeutic implications, Znt JRadiat OncolBiol Phys, 13 (1987) 313-317. Karim ABMF, Kralendonk JH, Njo KH, Tierie AH and Hasman A: Radiation therapy for

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A. Hasman et al. advanced (T3T4NO-N3MO)laryngeal carcinoma: the need for a change of strategy: a radiotherapeutic viewpoint, Int JRadiat OncolBiolPhys, 13 (1987) 1625-1633. Karim ABMF, Yap LY, Njo KH and Hasman A: Multiple fractions versus single fraction a day in advanced laryngeal carcinoma: A matched pair prospective study. In Progress in Radio-Oncology (Eds: KH Karcher. HD Kogelnik and T Szepesi), ICRO, Vienna, 1987, pp. 65-68. Westerman RF, Hasman A, Schouten JA, Kwakman JVI, Guyt HJM, Kreuzen WE and Donker AIM: A data management system to assist hypertension treatment in primary health care, Int J Biomed Comput, 19 (1986) 137-148. Groothuis S, Ambergen AW and Hasman A: Teaching Medical Informatics at the University of Limburg. In A Computer for Each Student (Eds: R Lewis and ED Tagg), Elsevier Science Publishers B.V.. Amsterdam, 1987, pp. 113-119. Groothuis S, Ambergen AW, Hasman A: Medical Infonnatics in problem based education. In Medical Iqformatics Europe ‘87 (Eds: A Serio, R O’Moore, A Tardini and FH Roger), Rome, 1987, pp. 1425-1430. Chang SC, Hasman A and Talmon JL: Data management systems for ECGs and VCGs. In Proceedings of Computers in Cardiofoa (Eds: KL Ripley and HG Ostrow), IEEE Inc., 1980, pp. 16% 168. ;5-