Research Article

Florbetaben PET in the Early Diagnosis of Alzheimer's Disease: A Discrete Event Simulation to Explore Its Potential Value and Key Data Gaps

Table 2

Equations for prediction of time to events and disease progression.

EquationCoefficient and predictorSD/shapeDistribution

Time to confirmation of a diagnosis
 AD or mixed AD 4.571 + 0.327 Male + 0.252 MixedAD − 0.353 CKD0.965Lognormal
 VaD4.529 + 0.158 Diabetes + 0.203 Hypertension + 0.385 Stroke1.005Lognormal
 Other non-AD dementia6.558 − 0.029 Age + 1.554 Stroke + 0.654 LBD + 0.400 FTD0.896Lognormal
 Predementia3.981 + 0.009 Age − 0.243 CKD − 0.179 CVD0.994Lognormal
Time to treatment initiation if not started at diagnosis
 Dementia7.149 − 0.022 Age + 1.056 VaD + 2.091 Other non-AD + 0.004 (time, in days, to confirmed diagnosis)1.517Lognormal
 Predementia18.781 − 0.150 Age3.996Lognormal
Time to treatment discontinuation
 Dementia7.487 − 0.0008 (time to confirmed diagnosis)0.922Weibull
 Predementia7.122 + 0.443 (conversion to dementia) 1.131Weibull
Time to conversion to dementiaScale = 0.02120.952Weibull
Rate of change in MMSEa5.4663 − 0.4200 PM1 − 0.0042 PM2 + 0.1415 PM3 − 0.079 PrevRate + 0.07474 Age + N/AN/A
Rate of change in NPIb(5.74 − 0.64 Treatment + 0.03 Weeks − 0.59 NPIbase − 0.59 NPI Weeks + 0.24 NPIrecent − 1.74 White − 3.82 Black + 2.34 PsyMed + 0.12 MMSEbase − 0.22 MMSErecent + ) * 1.44N/AN/A
Rate of change in ADL1.35 − 0.81 Treatment + 0.06 Weeks − 0.79 ADLbase + 0.71 IADLprevious + 0.12 MMSEbase + 0.09 Age + 0.81 PsyMed − 3.05 Black − 0.49 MMSErecent + N/AN/A
Rate of change in IADL 1.27 + 0.63 Treatment + 0.17 Weeks − 0.06 Treatment * Weeks − 0.84 IADLbase − 0.002 IADLbase * Weeks + 0.84 IADLprevious − 0.67 Male + 0.20 MMSEbase − 0.28 MMSErecent − 0.16 ADLbase + 0.18 ADLrecent + N/AN/A
Time to institutional care
 Dementia9.883 − 0.02 Age + 0.295 VaD + 1.154 Other non-AD − 0.001 Time to confirmed diagnosis + 1.079 Dementia treatment0.933Weibull
 Predementia11.469 − 0.028 Age 1.373Weibull
Time to death
 MaleScale = −9.6970.087Gompertz
 FemaleScale = −10.7870.097Gompertz
Patient utility0.408 + 0.010 MMSE − 0.004 NPI − 0.159 Institutionalized + 0.051 Living with CaregiverN/AN/A
Caregiver utility 0.90 − 0.003 AgeCG + 0.03 MaleCG + 0.001 Male − 0.001 NPI − 0.001 ADL − 0.0004 IADL − 0.01 PsyMedN/AN/A

SD: standard deviation; AD: Alzheimer’s disease; VaD: vascular dementia; LBD: Lewy body dementia; LTD: frontotemporal dementia; CKD: chronic kidney disease; CVD: cerebrovascular disease; MMSE: mini-mental state examination; NPI: neuropsychiatric inventory; ADL: activities of daily living; IADL: instrumental activities of daily living, CG: caregiver.
aPM represents patients’ previous MMSE measurement, partitioned over the scale of MMSE. PrevRate is the patients’ last known rate of decline. Age represents patients’ age at baseline. represents a random intercept parameter.
bTreatment is dementia medication, Weeks represents weeks of followup in the simulation, NPIbase is the patient’s baseline NPI, and NPIrecent is the patient’s last NPI. White and Black are dummy variables for race, PsyMed is a dummy variable for patients on psychiatric medications at baseline, MMSEbase represents the patient’s MMSE at baseline, and MMSErecent represents the patient’s current MMSE.