How Health Economists Use iPhone Notes for Model Documentation

Health economic modeling is decision science. The assumptions embedded in a cost-effectiveness model — transition probabilities, utility values, discount rates, comparator selection — directly influence payer coverage decisions that affect millions of patients. Health economists who document their modeling decisions create defensible models; those who rely on memory create models that fall apart under scrutiny.

Why Health Economists Need Systematic Notes

A health technology assessment (HTA) submission to NICE, ICER, or a US payer can take 18 to 24 months to develop. During that time, a health economist will review hundreds of clinical publications, make thousands of modeling decisions, and respond to dozens of reviewer queries. Without notes, the rationale for early decisions becomes invisible by submission time.

Model Architecture Notes

Every economic model requires documented architecture decisions:

• Model type — decision tree, Markov cohort, partitioned survival, individual patient simulation
• Time horizon — 5-year, lifetime, and the justification
• Perspective — payer, societal, healthcare system
• Discount rates — costs and effects, per country/agency guidelines
• Health states — defined states, their clinical basis, transitions allowed
• Cycle length — rationale for weekly, monthly, or annual cycles

Architecture decisions made at model initialization shape every subsequent calculation. Documenting them prevents inconsistent methodological drift across modeling rounds.

Data Source Notes

Every parameter in the model needs a documented source:

• Clinical efficacy data — trial name, publication, specific table or figure
• Baseline risk data — epidemiological source, population applicability
• Utility values — source study, elicitation method (EQ-5D, TTO, SG), population
• Resource use — how unit costs were estimated, source country, year
• Unit costs — published tariffs, expert elicitation, or costing databases
• Adverse event rates — trial source, grading criteria used

When NICE or ICER asks "how did you derive the utility for progressive disease state?", your notes contain the answer. Without them, you're reverse-engineering from a model you built 18 months ago.

Literature Review Notes

Systematic literature review underlies good health economics:

• Search strings used — PubMed, Embase, Cochrane queries
• Inclusion/exclusion criteria — what studies were included and why
• Quality assessment — for key studies, how they were evaluated
• Data extraction — key outcomes, follow-up duration, population characteristics
• Indirect comparison decisions — network meta-analysis methodology

Notes from literature reviews are often needed for PRISMA flow diagrams and methods sections of HTA submissions.

Sensitivity Analysis Notes

Sensitivity analyses test model robustness:

• Parameters varied — which inputs were included in one-way and PSA
• Ranges used — and their justification (95% CI, published ranges, expert opinion)
• Tornado diagram interpretation — which parameters drive uncertainty most
• Scenario analyses — alternative modeling assumptions tested
• Conclusions for decision-makers — what the sensitivity analysis means for coverage decisions

Sensitivity analysis notes prevent the panic of rebuilding the analysis when a reviewer asks "what happens if you use the lower CI bound for the hazard ratio?"

Payer Meeting Notes

Interactions with NICE, ICER, CMS, or commercial payers are high-stakes:

• Meeting date, attendees, agency/payer
• Questions raised — specific concerns about model structure or inputs
• Responses provided — what you committed to clarifying
• Guidance received — methodological direction from the committee
• Follow-up commitments — analyses promised for the next round

Payer engagement notes are often the difference between a positive coverage recommendation and a rejection with requests for additional analysis.

FAQ

Q: How do I document changes to the base case model? A: Keep a model change log note — version number, date, what changed, who requested the change, and why. Model version control through notes prevents confusion in multi-analyst teams.

Q: What about notes from health technology assessments in other countries? A: International HTA decisions are public and inform global strategy. Note NICE decisions, SMC submissions, and PBAC rulings relevant to your therapy area — they shape comparator selection and ICER benchmarks.

Q: How do I note assumptions I'm uncertain about? A: Flag uncertain assumptions explicitly: "Assumed 15% treatment discontinuation rate — clinical expert opinion only, no published data. High uncertainty." These become priority sensitivity analyses.

Q: Should I note expert panel discussions? A: Expert advisory board input is often the primary data source for parameters with no published evidence. Note the expert, their affiliation, the question asked, and the response.

Q: How do I track budget impact model updates for launch? A: A version-controlled BIM note with each update cycle, the trigger (new epidemiology data, label change, new comparator), and the impact on model outputs.

Q: How do I note competitive HTA decisions? A: A competitor intelligence note per therapy area — approved treatments, their cost-effectiveness evidence, ICER assessments, and pricing. This shapes your value story positioning.

Related Reading

• How health economists use notes during payer negotiations
• How clinical research coordinators document study data
• How medical writers organize regulatory documents
• How researchers use iPhone notes for systematic reviews

Sources

• NICE Decision Support Unit (DSU) technical support documents
• ICER value assessment framework and methods guides
• International Society for Pharmacoeconomics and Outcomes Research (ISPOR) good practices