Table I.

Parameters, their distribution, assumptions, evaluations of assumptions and data source as used in the decision analytic model.

Parameter	Distribution	2.5th and 97.5th percentile	Underlying assumptions	Assumptions checked by	Source (see also Supplementary Data File S1)
Costs for clomiphene citrate (CC)	$\mathrm{Gamma}(\sqrt{3.60},\frac{1}{\sqrt{3.60}})$	0.40–10.20	Costs for 4 IUI-OS cycles	Probabilistic sensitivity analysis	Dutch Formulary for Medication
Costs for Letrozole	$\mathrm{Gamma}(\sqrt{4.00},\frac{1}{\sqrt{4.00}})$	0.48–11.14	Costs for 4 IUI-OS cycles	Probabilistic sensitivity analysis	Dutch Formulary for Medication
Costs for gonadotrophins	N (1048,60)	930–1166	Costs for 4 IUI-OS cycles	Probabilistic sensitivity analysis	Dutch Formulary for Medication
Costs for multiple delivery	N (14 357, 250)	13 867–14 847	Costs known and increases by general price index inflation	Probabilistic sensitivity analysis	Dutch medical centre cost data
Relative risk of Letrozole versus CC (all trials)	Lognormal(ln(1.09) 0.1862)	0.76–1.57	Known relative effect that relies on the baseline rate	Probabilistic sensitivity analysis, scenario analysis	Network meta-analysis Wang et al. (2020)
Relative risk of gonadotrophins versus CC (trials up to four cycles with strict cancellation criteria)	Lognormal(ln(1.20) 0.1172)	0.95–1.51	Known relative effect that relies on the baseline rate	Probabilistic sensitivity analysis, scenario analysis	Network meta-analysis Wang et al. (2020)
Relative risk of gonadotrophins versus CC (all trials)	Lognormal(ln(1.39) 0.1204)	1.09–1.76	Known relative effect that relies on the baseline rate	Scenario analysis	Network meta-analysis Wang et al. (2020)
Probability of multiple pregnancy after CC	Beta(18.5, 721.5)	1.5–3.7%	Multiple pregnancy rates in trials in applicable to population	Probabilistic sensitivity analysis, scenario analysis	Network meta-analysis Wang et al. (2020)
Probability of multiple pregnancy after Letrozole	Beta(8.97, 290)	1.4–5.2%	Multiple pregnancy rates in trials in applicable to population	Probabilistic sensitivity analysis, scenario analysis	Network meta-analysis Wang et al. (2020)
Probability of multiple pregnancy after gonadotrophins	Beta(51.3, 916.7)	4.0–6.8%	Multiple pregnancy rates in trials in applicable to population	Probabilistic sensitivity analysis, scenario analysis	Network meta-analysis Wang et al. (2020)
Live birth rate, per cycle	Beta(140, 1536)	7.1–9.7%	Rate can be accurately extrapolated to 4 full cycles	Probabilistic sensitivity analysis, scenario analysis	Network meta-analysis Wang et al. (2020)
Live birth rate in trials up to four cycles who adhered to strict cancellation criteria	N (0.246,0.0158)	21.5–27.7%	Protocol for these trials is representative of today’s IUI-OS population for unexplained	Probabilistic sensitivity analysis, scenario analysis	Network meta-analysis Wang et al. (2020)