Table 1.
Model input parameters and probabilistic sensitivity analysis distributions.
| Parameter | Value (95% CI)a | Distribution (parameters) | Source |
|---|---|---|---|
| Yearly discount rate | 3 (2.4, 3.6) | Not varied in PSA | Assumption |
| Number of theoretical patients | 10,000 | Not varied in DSA or PSA | Assumption |
| Percent female | 51 (41.1, 60.9) | Beta (α = 49, β = 47) | Optum 2007–2017 |
| Initial SCD severities, females | |||
| Percent mild | 50.8 | Optum 2007–2017 | |
| Percent moderate | 22.1 | Dirichlet (α1 = 227, α2 = 99, α3 = 121)b | Optum 2007–2017 |
| Percent severe | 27.1 | Optum 2007–2017 | |
| Initial SCD severities, males | |||
| Percent mild | 48.3 | Optum 2007–2017 | |
| Percent moderate | 23.1 | Dirichlet (α1 = 224, α2 = 107, α3 = 133)b | Optum 2007–2017 |
| Percent severe | 28.7 | Optum 2007–2017 | |
| QALY weights, females | |||
| Control QALY weight, ages 1–44 | 0.89 (0.87, 0.91) | Beta (α = 870.42, β = 107.58) | 24,25 |
| Control QALY weight, ages 45–54 | 0.87 (0.85, 0.89) | Beta (α = 983.1, β = 146.9) | 24,25 |
| Control QALY weight, ages 55–64 | 0.84 (0.82, 0.86) | Beta (α = 1128.12, β = 214.88) | 24,25 |
| Control QALY weight, ages 65–74 | 0.84 (0.82, 0.86) | Beta (α = 1128.12, β = 214.88) | 24,25 |
| Control QALY weight, ages 75+ | 0.82 (0.8, 0.84) | Beta (α = 1209.5, β = 265.5) | 24,25 |
| QALY weights, males | |||
| Control QALY weight, ages 1–44 | 0.89 (0.87, 0.91) | Beta (α = 870.42, β = 107.58) | 24,25 |
| Control QALY weight, ages 45–54 | 0.88 (0.86, 0.9) | Beta (α = 928.4, β = 126.6) | 24,25 |
| Control QALY weight, ages 55–64 | 0.86 (0.84, 0.88) | Beta (α = 1034.58, β = 168.42) | 24,25 |
| Control QALY weight, ages 65–74 | 0.87 (0.85, 0.89) | Beta (α = 983.1, β = 146.9) | 24,25 |
| Control QALY weight, ages 75+ | 0.85 (0.83, 0.87) | Beta (α = 1082.9, β = 191.1) | 24,25 |
| QALY weights, gender invariant | |||
| SCD QALY weight, ages 1–18 | 0.69 (0.57, 0.80) | Normal (μ = 0.688, σ = 0.058)c | 25,26 |
| SCD QALY weight, ages 19+ | 0.68 (0.67, 0.69) | Normal (μ = 0.682, σ = 0.005)c | 25,26 |
| Transition probabilities, both genders | |||
| Ordered logit transition probability regression coefficients, females | |||
| Moderate SCD (α1) | 1.07 (0.64, 1.51) | Normal (μ = 1.074, σ = 0.223) | Optum 2007–2017 |
| Severe SCD (α2) | 2.63 (2.19, 3.06) | Normal (μ = 2.625, σ = 0.22) | Optum 2007–2017 |
| Age (α3) | − 0.03 (− 0.03, − 0.02) | Normal (μ = − 0.026, σ = 0.004) | Optum 2007–2017 |
| Moderate SCD * age (α4) | 0.01 (0, 0.02) | Normal (μ = 0.007, σ = 0.006) | Optum 2007–2017 |
| Severe SCD * age (α5) | 0.02 (0.01, 0.03) | Normal (μ = 0.021, σ = 0.005) | Optum 2007–2017 |
| Cut point 1 (κ1) | 1.04 (0.76, 1.32) | Normal (μ = 1.04, σ = 0.141) | Optum 2007–2017 |
| Cut point 2 (κ2) | 1.86 (1.57, 2.15) | Normal (μ = 1.858, σ = 0.147) | Optum 2007–2017 |
| Ordered logit transition probability regression coefficients, males | |||
| Moderate SCD (α1) | 0.7 (0.23, 1.17) | Normal (μ = 0.701, σ = 0.24) | Optum 2007–2017 |
| Severe SCD (α2) | 1.98 (1.53, 2.42) | Normal (μ = 1.976, σ = 0.225) | Optum 2007–2017 |
| Age (α3) | − 0.03 (− 0.04, − 0.02) | Normal (μ = − 0.03, σ = 0.004) | Optum 2007–2017 |
| Moderate SCD * age (α4) | 0.01 (0, 0.03) | Normal (μ = 0.012, σ = 0.007) | Optum 2007–2017 |
| Severe SCD * age (α5) | 0.03 (0.02, 0.05) | Normal (μ = 0.034, σ = 0.007) | Optum 2007–2017 |
| Cut point 1 (κ1) | 0.79 (0.49, 1.08) | Normal (μ = 0.787, σ = 0.151) | Optum 2007–2017 |
| Cut point 2 (κ2) | 1.6 (1.3, 1.91) | Normal (μ = 1.605, σ = 0.158) | Optum 2007–2017 |
| Cost parameters | |||
| Cost of single administration durable therapy | 2.1 M (1.68 M, 2.52 M) | Uniform (a = 1,680,000, b = 2,520,000) | Assumption |
| GLM gamma log-link cost regression coefficients, females | |||
| Intercept (β0) | 8.05 (7.88, 8.22) | Normal (μ = 8.051, σ = 0.085) | Optum 2007–2017 |
| Mild SCD (β1) | 1.58 (1.3, 1.85) | Normal (μ = 1.575, σ = 0.139) | Optum 2007–2017 |
| Moderate SCD (β2) | 1.78 (1.48, 2.09) | Normal (μ = 1.785, σ = 0.154) | Optum 2007–2017 |
| Severe SCD (β3) | 3.16 (2.88, 3.45) | Normal (μ = 3.165, σ = 0.147) | Optum 2007–2017 |
| Age (β4) | 0.03 (0.03, 0.04) | Normal (μ = 0.032, σ = 0.002) | Optum 2007–2017 |
| Mild SCD * age (β5) | − 0.01 (− 0.02, − 0.01) | Normal (μ = − 0.01, σ = 0.003) | Optum 2007–2017 |
| Moderate SCD * age (β6) | − 0.01 (− 0.02, − 0.01) | Normal (μ = − 0.014, σ = 0.003) | Optum 2007–2017 |
| Severe SCD * age (β7) | − 0.02 (− 0.03, − 0.02) | Normal (μ = − 0.023, σ = 0.003) | Optum 2007–2017 |
| GLM gamma log-link cost regression coefficients, males | |||
| Intercept (β0) | 8.39 (7.51, 9.28) | Normal (μ = 8.395, σ = 0.452) | Optum 2007–2017 |
| Mild SCD (β1) | 2.13 (1.16, 3.09) | Normal (μ = 2.126, σ = 0.494) | Optum 2007–2017 |
| Moderate SCD (β2) | 1.14 (0.21, 2.07) | Normal (μ = 1.14, σ = 0.475) | Optum 2007–2017 |
| Severe SCD (β3) | 2.36 (1.46, 3.27) | Normal (μ = 2.364, σ = 0.46) | Optum 2007–2017 |
| Age (β4) | 0.02 (0.01, 0.04) | Normal (μ = 0.024, σ = 0.009) | Optum 2007–2017 |
| Mild SCD * age (β5) | − 0.02 (− 0.03, 0) | Normal (μ = − 0.016, σ = 0.009) | Optum 2007–2017 |
| Moderate SCD * age (β6) | 0.01 (− 0.02, 0.03) | Normal (μ = 0.006, σ = 0.011) | Optum 2007–2017 |
| Severe SCD * age (β7) | − 0.01 (− 0.02, 0.01) | Normal (μ = − 0.005, σ = 0.009) | Optum 2007–2017 |
PSA probabilistic sensitivity analysis, DSA deterministic sensitivity analysis, GLM generalized linear model.
aConfidence intervals omitted for variables drawn from multivariate distributions.
bNot varied in DSA.
cTruncated normal distribution on [0,1].