NATALI-a model for National Computer Databases in ...

JOURNAL OF THE ROYAL SOCIETY OF MEDICINE

Volume 88

September 1995

NATALI-a model for National Computer Databases in the investigation of new therapeutic techniques B D Braithwaite MA FRCS A W S Ritchie MD FRCSEd J J Earnshaw DM FRCS J R Soc Med 1995;88:511-515

Keywords: database; thrombolysis; audit

SUMMARY New medical treatments are often introduced without the benefit of randomized trials. We describe how a national computerized database was produced, by the Thrombolysis Study Group, for monitoring one such new treatment: peripheral arterial thrombolysis. A novel method for transferring angiograms to computer generated arterial maps that can help in the classification and analysis of the outcome of thrombolysis is also described. Data provided by prospective collection from 14 hospitals within the UK was entered onto the database (Auditbase for Windows), to give contributing members a continual audit of their own results and complications that can be compared with that of the group as a whole. This system may be an appropriate model for other forms of multi-centre audit and the monitoring of new treatments.

INTRODUCTION

New medical treatment methods are often thought so beneficial that they should be introduced without randomized trials, e.g. laparoscopic surgery and endovascular surgical techniquesl'2. If randomized studies are not performed, methods of assessment need to be developed. One way is to collect prospectively, information from many centres, entering data onto a computer database. This method would be especially useful if the observed technique was so infrequent that results from a single centre were insufficient for adequate information. The structure of a database investigating any new technique involves three phases: (1) construction of the database itself; (2) setting up a network of data providers; and (3) evaluation of results. This article describes the construction of a database for the analysis of process and outcome of a new treatment for acute limb ischaemia: intraarterial thrombolysis (IAT). Many small, non-randomized, trials on IAT exist but few are large or detailed enough to give good data. The Thrombolysis Study Group (TSG), a UK based group of surgeons and radiologists interested in defining the indications and methods for intra-arterial thrombolysis, have therefore sponsored the development of a computerized database. It is designed to address the problems of data collection on peripheral thrombolysis and this article describes the experiences to date.

METHOD

AuditBase (Clinical Audit Systems Ltd) is a WindowsTM (Microsoft Corporation) database specifically designed for clinical audit3'4. This has been modified and extended to facilitate the TSG project. An IBM compatible personal computer with a 486 processor, 4 MB of RAM and 540 MB hard drive with tape stream back-up facilities has been used for running the program. The program is called NATALI (National Audit of Thrombolysis and Acute Limb Ischaemia). File definition At a series of consensus meetings, the TSG had specified the

data required for investigation and audit of thrombolysis: Data collected included patient identification, clinical history and the treatment details. Techniques of administration, e.g. low dose infusion or pulse spray, dose of thrombolytic agent, duration of infusions, time of initial lysis and a classification for immediate success were incorporated. Four categories of initial outcome after thrombolysis have been devised by the TSG that take into account both angiographic and clinical criteria, obviating the need for estimation of thrombus volume cleared5: 1 2

Gloucester Royal Hospital, Great Westem Road, Gloucester, GL1 3NN, England, UK

Correspondence to: Mr J J Eamshaw

Complete lysis was defined as clearance of the occluded vessel with restoration of flow to run off and restoration of peripheral pulses. Clinically useful lysis was defined as partial clearance of thrombus relieving rest pain or improving ankle-brachial pressure index (ABPI) by 0.2; or partial clearance enabling a smaller operation to be undertaken than was

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September 1995

possible before thrombolysis; or partial clearance of thrombus enabling a procedure to be performed when prior to therapy none was possible. 3 Lysis but no run off or flow was defined as lysis of the acute thrombus without establishing run off flow into major distal vessels. 4 Failed lysis was defined as no improvement or deterioration in the state of limb perfusion

Adjunctive procedures after thrombolysis, complications and outcome on the thirtieth day after treatment were also recorded. These details now serve as the basic information for audit and the prospective trials that the group is running, although additional information can be added if necessary. In order to build a bespoke computerized database, programs were written to record the information in an easy to use format. File definitions followed conventional database rules with incorporation of many novel features. File formats and screen design ensure that the sequence of all data entry possesses maximum 'user-friendliness', which in combination with both mouse and keyboard entry makes NATALI an easy program to use. 'Yes' or 'No' answers to questions use check boxes while multiple, but limited answer questions use single letters in single letter boxes (Figure 1). These fields can be programmed to ensure each data field is completed before progressing to another screen of information. In the early period of use of any database program, there will be information added that the initial design had not expected. NATALI contains extendible lists to which information can be added as required, e.g. drugs given during thrombolysis (Figure 1). Extendible lists lenghen, in a parabolic fashion, as more data are collected so, with time, fewer new entries will be required. Future editions of the program will have fixed lists, ensuring compatibility of entered information __AudWase 3.N aC

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Figure 1 Computer screen image showing the details related to the procedure of thrombolysis. The right-hand box is a 'pop-up' extendible list of additional drugs used during thrombolysis with tissue plasminogen activator

Figure 2 Screen image of the computerized arterial map before thrombolysis. This patient has an occluded suprageniculate femoro-popliteal bypass graft in addition to occlusions in the tibio-peroneal trunk, peroneal, proximal anterior tibial and proximal posterior tibial arteries. The superficial femoral artery occlusion is chronic. A total of seven arterial segments are occluded

when the software has been distributed to several hospitals. Pull down, fixed list menus are used where all the options are known. Numeric data can be entered as integers or decimal entry. Long pieces of text, e.g. comments, are entered using a text editor. This free text cannot be searched for data retrieval but is available for review and/or editing when searches have been based on validated fields. Arterial maps The most challenging part of the development of the software was the invention of a graphical form of angiographic data entry. NATALI provides a new system for the recording and computer analysis of angiograms. Conventional databases do not allow for structured pictorial records so a separate module was developed using Visual BasicTM (Microsoft). A schematic distal arterial tree of major vessels from the distal aorta to the ankle has been superimposed on anatomical land marks. The vessels are divided into arterial segments (Figure 2). Any one segment can be marked as occluded, patent, stenotic or aneurysmal. The arterial segmentation is rigid, forcing data entry towards one of the available options for each segment, e.g. an occlusion in part of the proximal superficial femoral artery (SFA) is recorded as occupying the whole of the proximal SFA while one in the mid SFA occupies both proximal and distal SFA on the computer record. Although it was possible to record data in Visual Basic, there was some difficulty in enabling AuditBase to analyse this information. The problem was solved by storing information in dbase III formatTM (Borland) which is compatible with both Visual Basic and Auditbase. Linking Visual Basic to Auditbase was performed using Dynamic

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Data Exchange (DDE), a process in which any two Windows programs can communicate directly. Entering angiographic information is made in two stages. NATALI constructs an arterial map with patent segments

Table 1 Report form summarizing 2 years of data collection from the Thrombolysis Study Group. All centres from 1 January 1993 to 1 January 1995: Printed 16 January 1995

Total number of patients Total number of events Limb salvage Amputation Death Duration of ischaemia Highest Lowest Mean Fontaine grades No clinical symptoms Ila Chronic claudication llb Sudden onset claudication IlIl Rest pain IV Ulcer gangrene Age at date of radiology Highest Lowest Mean Initial lysis results Complete lysis Clinically useful lysis Lysis but no run off No lysis Total number of grafts Agents Streptokinase (IU) Number Highest dose Lowest dose Mean dose t-pa (mg) Number Highest dose Lowest dose Mean dose Urokinase (IU) Number Highest dose Lowest dose Mean dose

246 289* 215 (77%) 35 (13%) 29 (10%) 365 days 0 h 1h 14 days 3 9 50 195 32

92 48 68 134 (46%) 85 (30%) 35 (12%) 35 (12%) 123

16 290000 50000 122066 267 185 24

6 20000 10000 11 670

*Ten events had not reached the 30 day outcome date and were excluded from limb

salvage analysis

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September 1995

and relevant bypass grafts. Using a combination of mouse and keyboard entry, arterial segments can be changed to reflect vessel state by 'clicking' on the appropriate area of the map and selecting one of the four available options: Patent, occluded, stenosis, aneurysm. For the latter two a facility is available to record dimensions. On completion, the pre-lysis map is stored and internally analysed by NATALI. When the post-lysis arterial map is 'opened' NATALI generates a copy of the pre-lysis screen which can then be changed in a similar fashion. When this screen is closed NATALI calculates the number of vessels cleared, the patency of run-off vessels in continuity with the distal popliteal artery, and the patency of the foot arch as well as recording the proximal limit of the original occlusion. Reports NATALI produces reports summarizing the events recorded on the database (Table 1). A summary report for each patient can also be generated for inclusion in the patients'

notes and for comparison with the submitted record for verification of details. Report generating takes only a few seconds. A query option can analyse data for specific scenarios, e.g. the outcome of women over the age of 70 presenting with SFA or popliteal proximal occlusions. The search criteria are selected from pull-down menus. All fields, except free text, within the database can be interrogated by this query option so any combination of results can be swiftly produced. Arterial maps are analysed for each patient and converted to text format. A report for each patient or summation of all patients' results can be produced describing proximity of occlusion, vessel clearance and run off indices. Data collection The TSG have prospectively collected information about events of thrombolysis using hand written data sheets that are presently sent to a database coordinator who transfers the information to NATALI. Some data forms are returned prior to the thirtieth day after treatment, NATALI therefore prompts the coordinator when patients have reached the 30day outcome date. Respective hospitals can then be contacted and follow up information obtained. At regular intervals, the computer data is analysed and two reports are generated. The first is a confidential report for each hospital and the second is a cumulative report of the TSG's results for that period of time. These are sent out to individual hospitals for their own audit and are discussed at biannual meetings of the group. All record forms are stored as hard copies for future reference and verification of information. Currently, data entry is carried out in one of the hospitals within the TSG. In the near future, NATALI

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programs will be distributed to all centres within the TSG. Each hospital will then have the ability to enter data at the time of thrombolysis directly onto their own database system. At quarterly intervals, each centre will be asked to send its accumulated data to the central database using a 'floppy' computer disk or by modem transfer so accelerating the time for data processing. Reports can then be generated and returned in a matter of days providing a continual audit of results and complications. The Data Protection Act is an important consideration in any system involving computer records6'7. It restricts the possibility of individuals being harmed by abuse of the personal data held on computers and conforms to the Council of Europe Convention on Data Protection. All patient and hospital information is therefore coded and the main database hardware is secured in a locked office on a ward where entry is restricted. The program and data can only be used after passing through at least two password protected entry screens. The contents of the database are regularly backed-up both onto a magnetic tape and floppy disks using a file compression program. RESULTS In the first year of Data collection nearly 300 events of intraarterial thrombolysis using streptokinase, tissue plasminogen activator (t-PA) and urokinase have been recorded. These

include prospective information collected before the database became operational (see Table 1). By exporting the results of a data search of angiograms it has been possible to relate 30-day outcome to the angiographic appearances before and after thrombolysis8. This and other analysed information from the database has been used by the group for internal audit, publication9, and presentation10, while the TSG's prospective randomized studies are currently being monitored using the software. DISCUSSION

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National databases are used for prospective and retrospective analysis of data to be used for audit and publication of results11. Registration networks, especially within general practice, have also been described to build up databases12. Continuous national audit and early feedback has proved successful in the introduction of laparoscopic techniques, establishing a system of close cooperation in data collection between interested clinicians1. NATALI is the first computer database used to audit the process and outcome of peripheral thrombolysis in the UK. One of the disadvantages of any database system is the slow process of establishing the data set. For NATALI, the TSG had been collecting data for over a year before the program was written so the data set was already known. This period of establishing a paper database is probably

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essential to avoid the time consuming and costly reprogramming of an established computer database. The information contained within computer databases can be inaccurate because of errors at the time of entry, so invalidating analysed information as well as contravening the Data Protection Actl 3. NATALI reduces the risk of this by in-built data consistency mechanisms, prompts and warnings. Additionally, the program produces individual patient reports for comparison with the patient's notes and data sheets. Finally, because of the small numbers involved and the trials conducted by the group, contributing hospitals are visited and notes reviewed to ensure that all events of thrombolysis have been recorded correctly. The most novel feature of this project is the method for transferring angiographic details to a computer-generated map. This has not been described before and has already proved to be of use in the analysis of multiple angiograms8. The simplified process of arterial segmentation is essential in providing information that can usefully be interpreted. It is hoped that this system may lead to a method for staging acute limb ischaemia treated by thrombolysis, while the form of data entry might be useful in other radiological and endovascular procedures. The TSG's cumulative results for intra-arterial thrombolysis reflect those found in previous reports on thrombolysis (see Table 1)14. NATALI is not designed to give all the answers for prospective research but for audit and to direct an enquiring clinician to a select population from which more information can then be obtained. With this information the notes of these patients can be reviewed to test any given hypothesis. For a single hospital, acquisition of this information might take years during which time numerous patients could be exposed to potential complications. As more events of thrombolysis are entered onto the database, the TSG should be able to provide guidelines and outcome standards for the variety of techniques for peripheral thrombolysis. The development and running of this database would not be possible without the cooperation of all the surgeons and radiologists involved. With increasing sub-specialization and blurring of clinical territories in many disciplines this type of cooperative grouping is likely to become more common. Future collaborative projects are therefore likely while the introduction of new techniques should be thoroughly assessed. For infrequent but new treatments, this type of database may prove to be an appropriate model. Acknowledgments We gratefully acknowledge the programming skills of Stuart Freeman and Ian Balm. The development of NATALI and funding of Mr Braithwaite was

provided by a grant from Boehringer Ingelheim. Computer

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hardware and program funding were provided by a grant from the Department of Health. Note This research was carried out on behalf of the Thrombolysis Study Group which indudes: Dr A Al-Kutoubi, MrJ Beard, Prof P Bell, Mr D Berridge, Dr P Birch, Dr Bolia, Mr B Braithwaite, Dr T Buckenham, MrJ Chamberlain, Dr S Darby, Mr K Dawson, MrJ Earnshaw, Dr J Ferguson, Dr P Gaines, Mr R Galland, Mr A Giddings, Dr R Gregson, Mr G Hamilton, Mr B Hopkinson, Mr R Lonsdale, Dr H Loose, Mr T Loosemore, Dr G Plant, Dr A Platts, Dr K Reddy, DrJ Rose, Mr C Shearman, Mr R Taylor, Dr P Torrie, Mr P Wenham, Dr S Whittaker, MrJ Wolfe, Mr W Yusaf

A demonstration disk of NATALI is availablefrom the authors.

REFERENCES I Dunn D, Nair R, Fowler S, McCloy R. Laparoscopic cholecystectomy in England and Wales: results of an audit by the Royal College of Surgeons of England. Ann R Coll Surg Eng) 1994;76:269-75 2 Palmaz JC, Laborde JC, Rivera FJ, Encarnacion CE, Lutz JD, Moss JG. Stenting of the iliac arteries with the Palmaz stent: Experience from a multicenter trial. Cardiovasc Intervent Radiol 1992;15:291-7 3 Gilbert HW, Hartley RH, Simpson AD, Jones DJ, Ritchie AWS. Fax that discharge! Hospital Update 1994;20:217

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4 Jones G. Lose patience with lost patients. Hlthcare Mgmt

1993;November:23-4 5 Shortell CK, Ouriel K. Thrombolysis in acute peripheral arterial occlusion: Predictors of immediate success. Ann Vasc Surg 1994;8:59-65 6 HMSO. The Data Protection Act. London:HMSO, 1984 7 Pangalos GJ. Medical database security policies. Methods Inf Med 1993;32(5):349-56 8 Braithwaite BD, Petrik PV, Ritchie AWS, Earnshaw JJPComputerized Angiographic Analysis of the Outcome Of Peripheral Thrombolysis. Am J Surg 1995:(in press) 9 Braithwaite BD, Thrombolysis Study Group. Thrombolysis with tissue plasminogen activator: results with a high-dose transthrombus technique. [Letter] J Vasc Surg 1995;21:540 10 Plant G. Consensus in Thrombolysis. J. Intervent Radiol 1994;9:47-56 11 Yoong A, Das S, Carroll S, Chard T. A national survey to assess current use of computerized information systems in obstetrics. Br J Obstet Gynaecol 1993; 100(3):205-8 12 Metsemakers JF, Hoppener P, Knottnerus J, Kocken RJ, Limonard CB. Computerized health information in the Netherlands: a registration network of family practices. BrJ Gen Pract 1992;42(356): 102-6 13 Kahn MG. Clinical databases and critical care research. Crit Care Clin

1994;10(l):37-51 14 Earnshaw JJ. Thrombolysis in acute limb ischaemia. Ann R Coll Surg Engi 1994;76:219-22

(Accepted 15 March 1995)

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