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

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

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

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

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

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

Some Initial testing Investigated the following models Investigated the following models Pediatric Anesthesia Pediatric Anesthesia Apache II – Risk of Cardiac Problems in patients undergoing non-cardiac surgery 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 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 Investigation restricted to spreadsheet mechanics only as we are not medically qualified But 15 pages of notes But 15 pages of notes Used HMRC SpACE methodology Used HMRC SpACE methodology

Pediatric Anesthesia “…. here are two guides to help you in your anesthesia practice. First is a Microsoft Excel spreadsheet titled ‘Pediatric Anesthesia Worksheet’. Use it to calculate medications and other parameters for pediatric patients”.

Pediatric Anesthesia

Apache II - Chronic Health

Cardiac Risks

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

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

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

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

Pediatric Anesthesia Documentation

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

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

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”.

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