Spreadsheets In Clinical Medicine

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Spreadsheets In Clinical Medicine

• Grenville J. Croll Raymond J. Butler
• EuSpRIG 2006, Cambridge, UK

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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

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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

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Spreadsheets in Clinical Medicine

• Initial Google Searches
• Spreadsheet Oncology, Anesthesia, Cardiac etc
• very many hits
• Search of PubMed Database
• gt800 references, many clinical
• Discovered www.medal.org - Institute of
  Algorithmic Medicine - 8,000 spreadsheets
• Numerous specialist sites

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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

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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

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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

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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. 
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Pediatric Anesthesia
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Pediatric Anesthesia
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Apache II - Chronic Health
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Apache II - Chronic Health
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Cardiac Risks
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Problems Found

• Constants in formulas
• Complex nested IFs
• Formulas with no dependents
• Poor or no embedded documentation
• Little/No data validation
• Some Mixed units
• Weak cell protection

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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

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Nested IFs

• e.g. Atropine dose calculation (L7)
• IF(E190.02gt0.6,0.6,IF(E190.02lt0.1,0.1,E190.02)
  )
• E19 is Bodyweight
• The rest are embedded constants for drug dosage
• Hard to follow
• Hard to update
• Table Lookup preferable

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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

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Pediatric Anesthesia Documentation
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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

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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!

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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.

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