Saudi Gastroenterology Association · Open course
Short calculators for the core calculations in this course. Move the sliders and watch the result change. Default numbers are illustrative.
Incremental cost per QALY gained, compared with a willingness-to-pay threshold.
ICER = (Cost_new − Cost_comp) ÷ (QALY_new − QALY_comp)
Linked module: Economic evaluation: costs, QALYs and the ICER
Incremental cost
SAR 90,000
Incremental QALYs
0.45
ICER per QALY
SAR 200,000
Above the threshold
The ICER is a model output. Check the horizon, perspective, discount rate and the certainty of the effect estimate before using it.
A decision rule that never divides by a small number. Positive means the technology is worth its price at this threshold.
INMB = (ΔQALY × λ) − ΔCost INHB = ΔQALY − (ΔCost ÷ λ)
Linked module: Economic evaluation: costs, QALYs and the ICER
Net monetary benefit
SAR -22,500
Net health benefit (QALYs)
-0.150
At this threshold the extra cost buys less health than the same money would elsewhere.
The maximum total cost per patient at which the ICER equals your threshold, and the discount that implies.
Max total cost = Cost_comp + (ΔQALY × λ)
Linked module: Economic evaluation: costs, QALYs and the ICER
Maximum acceptable total cost
SAR 117,500
Proposed total cost
SAR 140,000
Discount needed
16.1%
Any discount smaller than this leaves the ICER above the threshold.
Eligible patients × uptake × net incremental cost per patient-year, year by year.
BI_t = Population × Uptake_t × (Cost_new − Cost_comp − Offsets)
Linked module: Budget impact and affordability
Net cost per treated patient-year
SAR 8,000
Year 1
SAR 4,000,000
Year 2
SAR 8,000,000
Year 3
SAR 12,000,000
Three-year total
SAR 24,000,000
Budget impact is not discounted and covers only the payer’s own budget. Savings that fall outside the horizon or the budget do not count.
Annual savings from moving patients to a lower-priced biosimilar, and how many more patients that could fund.
Savings = Patients × Switch rate × Originator cost × Discount
Linked module: Budget impact and affordability
Annual savings
SAR 14,112,000
Biosimilar annual cost
SAR 31,200
Additional patients fundable
452
Savings are real only if tenders deliver the lower price and the switch actually happens.
A cost or QALY in the future is worth less than the same amount now. Use the same rate for costs and health unless the guideline says otherwise.
PV = FV ÷ (1 + r)^t
Linked module: Economic evaluation: costs, QALYs and the ICER
Present value
7,441
Value lost to discounting
2,559
Quality-adjusted life years from a utility improvement over a number of years, with optional discounting.
QALY gain = (u_with − u_without) × Σ years (discounted)
Linked module: Economic evaluation: costs, QALYs and the ICER
Undiscounted QALY gain
0.60
Discounted QALY gain
0.57
Utility 1 is full health and 0 is death. Utilities should come from a source that matches your patients.
Turns a difference in response rates into an effect size a budget-holder can use.
NNT = 1 ÷ (response_new − response_comp); cost per extra responder = NNT × cost per patient-course
Linked module: Clinical evidence: synthesis, indirect comparison and certainty
Absolute difference
14.0%
NNT
7.1
Cost per extra responder
SAR 214,286
Compare this figure with what the system would pay for one more patient in remission, but remember that response is a surrogate for QALYs.
What a detection-improving tool costs for each extra procedure that finds a lesion.
Cost per extra detection = Annual cost ÷ (Procedures × (rate_with − rate_without))
Linked module: Devices, diagnostics and AI
Extra procedures with a detection
240
Cost per extra detection
SAR 833
This is a process measure. Value depends on whether the extra detections prevent cancer and what extra surveillance they trigger.
