Economic Evaluation of Letrozole for Early Breast Cancer in a Health Resource-Limited Setting

Table 1

Model inputs.

Parameters	Base-case Value	Range Tested	Reference
Clinical data
Exponential distribution of distant recurrence in Tamoxifen strategy	λ=0.001524	0.001423 - 0.001625	[5]
Exponential distribution of local recurrence in Tamoxifen strategy	λ=0.000292	0.00029 - 0.000294	[5]
Weibull distribution of contralateral recurrence in Tamoxifen strategy	λ=0.000017; γ=1.6165	λ=0.000013 - 0.000021	[5]
RR for recurrence (AI 5-years versus Tamoxifen strategy)
Distant recurrence	0.830	0.74 - 0.93	[5]
Local recurrence	0.7200	0.57 - 0.92	[5]
Contralateral recurrence	0.6500	0.52 - 0.81	[5]
RR for recurrence (AI switch versus Tamoxifen strategy)
Distant recurrence	0.90	0.8 - 1.01	[5]
Local recurrence	0.84	0.68 - 1.03	[5]
Contralateral recurrence	0.63	0.51 - 0.8	[5]
Probability of death for distant recurrence	0.0290	0.023 - 0.041	[21]
Weibull distribution of PFS after local recurrence	λ=0.0458; γ=0.782	λ=0.004498 - 0.023713	[20]
Weibull distribution of PFS after contralateral recurrence	λ=0.0487; γ=0.742	λ=0.044114 - 0.053286	[20]
Probability of endometrial cancer in Tamoxifen strategy	0.00010	0.000084 - 0.000117	[5]
Probability of fracture in Tamoxifen strategy	0.00047	0.000375 - 0.000551	[5]
RR for endometrial cancer in AI treatment	0.33	0.21 - 0.51	[5]
RR for fracture cancer in AI treatment	1.42	1.28 - 1.57	[5]
Probability of death for endometrial cancer	0.0098	0.0091 - 0.0105	[22]
Preference weights (Utility)
DFS without any event	0.94	0.92 - 0.97	[28, 29]
Endocrine therapy	0.01	0.01 - 0.01	[28, 29]
Fracture	0.70	0.64 - 0.96	[30]
Regional recurrence	0.78	0.77 - 0.79	[28, 29]
Distant recurrence	0.53	0.42 - 0.64	[28, 29]
Endometrial cancer	0.83	0.68 - 0.95	[31]
Resource utilization and cost data (CNY ¥)
Tamoxifen generic treatment per day	1.4	0.98 - 1.67	Local charge
Generic letrozole treatment per day	11.9	11.08 - 12.9	Local charge
Treatment for local and contralateral recurrence in the first month	75421	44364 - 106478
Treatment for local and contralateral recurrence in subsequent months	865	509 - 1221	[25]
Treatment for distant recurrence in the first month	83008	34876 - 131140	[25]
Treatment for distant recurrence in subsequent months	888	373 - 1403	[25]
Treatment for endometrial cancer per patient	17138	14499 - 19776	[27]
Treatment for fracture per event	25552	21440 - 30622	[26]

The RRs were recalibrated based on the reported data [5] using network meta-analysis.
AI: aromatase inhibitor; RR: risk ratio.