Spreadsheets In Clinical Medicine

1. Spreadsheets In Clinical Medicine  Grenville J. Croll & Raymond J. Butler EuSpRIG 2006, Cambridge, UK

2. What We Know about Spreadsheets Spreadsheets are error-prone Spreadsheets are not tested Errors are difficult to find Users are overconfident Users are inconsistent Users interpret information differently Backup and Archiving are overlooked Spreadsheets are pervasive

3. What We Know about Medicine Medical error is a major killer 98,000 deaths per year in US 30,000 in UK 7th largest cause of death Rate of non-fatal injuries is not known Spreadsheets are used in Clinical Medicine

4. Spreadsheets in Clinical Medicine Initial Google Searches Spreadsheet + Oncology, Anesthesia, Cardiac etc very many hits Search of PubMed Database >800 references, many clinical Discovered www.medal.org - Institute of Algorithmic Medicine - 8,000 spreadsheets Numerous specialist sites

5. Spreadsheets in Clinical Medicine Widely used for decision support Applied in diagnosis, dosage, prescription, case management, classification, statistical planning & analysis Home-grown by practitioners Used by medical device manufacturers Described in books & papers for re-keying Many downloadable, modifiable templates

6. Controls on Software Development Drug development & trials Onerous FDA software development requirements Medical Devices Medical Device Regulations Apply to Medical Devices intended for sale Clinical Medicine No regulation found Medics free to develop & deploy for own use

7. Some Initial testing Investigated the following models Pediatric Anesthesia Apache II � Risk of Cardiac Problems in patients undergoing non-cardiac surgery Brodaty � to support a decision to assess an elderly patient for masked depression Investigation restricted to spreadsheet mechanics only as we are not medically qualified But 15 pages of notes Used HMRC SpACE methodology

8. Pediatric Anesthesia

9. Pediatric Anesthesia

10. Pediatric Anesthesia

11. Apache II - Chronic Health

12. Apache II - Chronic Health

13. Cardiac Risks

14. Problems Found Constants in formulas Complex nested IF�s Formulas with no dependents Poor or no embedded documentation Little/No data validation Some Mixed units Weak cell protection

15. Embedded constants Same risk as in finance/tax etc domains What happens if medical practice changes? What happens if manufacturers reformulate drugs to require different dosages? Table Lookups preferable

16. Nested IF�s e.g. Atropine dose calculation (L7): =IF(E19*0.02>0.6,0.6,IF(E19*0.02<0.1,0.1,E19*0.02)) E19 is �Bodyweight� The rest are embedded constants for drug dosage Hard to follow Hard to update Table Lookup preferable

17. Other Issues Documentation None/almost none embedded Data Validation None or inadequate Forms tools, data validation essential Units Milligrams / Micrograms appear in same column NB Medication errors cause 7,000 annual deaths in US

18. Pediatric Anesthesia Documentation

19. Inherent Risks Distribution channels Large scale web enabled distribution via Global Medical Literature Secondary �viral distribution� Inability to recall source Spurious �stamp of approval� Spreadsheet may be changed somewhere in the chain

20. Conclusions Initial indications are that same risks exist No specific clinical good practice for spreadsheet development & deployment No evidence that this well studied problem is known in the clinical domain Opportunity for dialogue and advancement Obvious reasons for increased caution when one is involved in medical procedures!

21. Disclaimers �The authors have exerted every effort to ensure that the drug dosages set forth are in accordance with current recommendations at the time of publication. The user is urged to check the drug's package insert for any changes in indications and dosages as well as for warnings and precautions. The responsibility is ultimately that of the prescribing clinician�.

22. �Delegation of responsibility is no barrier to the repeated perpetration of grave errors� G.J.Croll & R.J. Butler, July 2006