Table 4.

Analysis of uncertainty

References	Scenarios & Sensitivity analyses applied	Sensitivity analysis
		Parameters to which results were most sensitive	Results
Gottlob et al. [12]	Three best–worst-case scenarios: (1) utility value range from athlete (best-case) to non-athlete (worst-case); (2) results from best surgical and worst non-operative vs results from worst surgical and best non-operative; (3) most favorable utilities (athlete) and outcome vs least favorable utilities (non-athlete) and outcome	Cost, utilities, and outcome	early ACLR preferred strategy over CTa for all scenarios, ICER early ACLR for athletes and non-athletes, range $7,805 to $10,974/QALY
Farshad et al. [10]	Monte Carlo simulation using 10,000 samples	Sequelae of ACL injury: meniscus injury, osteoarthritis	early ACLR preferred strategy over delayed ACLR
Mather et al. [18]	Monte Carlo simulation using 10,000 samples 1-way sensitivity analysis	Rate of instability after initial conservative treatment (if ICER as outcome) Age (if cost only as outcome)	In 93% of cases, early ACLR preferred at WTP threshold of $50,000/QALY (short-to-medium-term) In 59% of cases, early ACLR preferred at WTP threshold of $50,000/QALY (long term)
Mather et al. [17]	Monte Carlo simulation used 10,000 samples 1-2-and 3-way sensitivity analysis	Rate of instability after initial conservative treatment (if ICER as outcome) Rehabilitation visit ratio, no. patients choosing delayed reconstruction, cost of early ACLR (if cost only as outcome)	In 78% of cases, early ACLR preferred at WTP threshold of $50,000/QALY
Kiadaliri et al. [15]	1-way and multi-way sensitivity analysis Bootstrapping technique used 10,000 samples	Cost of secondary procedure, productivity losses, second ACL reconstruction, operation not related to the knee, and outliers cost and QALY	In 66% of cases, early ACLR preferred at WTP threshold of SEK500,000/QALY
Stewart et al. [38]	Monte Carlo simulation used 10,000 samples 1 and 2-way sensitivity analysis	QoL of returning or not returning to play, cost, and duration of follow-up (if ICER as outcome)	In 80% of cases, early ACLR preferred at WTP threshold of $50,000/QALY
Eggerding et al. [8]	Bootstrapping technique used 5000 samples	NA	In 35% of cases, early ACLR preferred at WTP threshold of €50,000/QALY (using societal perspective) In 54% of cases, early ACLR preferred at WTP threshold of €50,000/QALY (using healthcare perspective)

ICER incremental cost-effectiveness ratio, QALY quality-adjusted life-year, early ACLR early anterior cruciate ligament reconstruction, CTa conservative treatment alone, delayed ACLR conservative treatment with optional delayed anterior cruciate ligament reconstruction, QoL quality of life, WTP willingness to pay, NA not applicable