Measuring the economic cost of traumatic brain injury (TBI) in New Zealand: a cost-of-illness study
AIM: To estimate 1) the incidence, prevalence and disability adjusted life years (DALY) for traumatic brain injury (TBI) in New Zealand (NZ) in 2010 projected to 2020. 2) from a societal perspective the direct and indirect cost of traumatic brain injuries (TBIs) in New Zealand (NZ) in 2010 projected to 2020. METHODS:A multi-state life table model was constructed using inputs for first-ever in a lifetime TBI incidence and severity distribution from the Brain Injury Outcomes New Zealand in the Community (BIONIC) study, TBI mortality data from the NZ Ministry of Health’s Mortality Collection, and population data from Statistics New Zealand. The modelled estimate of prevalence was combined with the disability weights for TBI (by stage, and severity level) from the Global Burden of Disease 2010 study to obtain estimates of health loss (DALYs) for TBI. TBI incidence and prevalence were then projected to 2020. An incidence-based, cost-of-illness model was developed using data from the BIONIC study. Details of TBI-related resource use during the first 12 months after injury were obtained for 725 cases using resource utilisation information from participant surveys and medical records. Total costs are presented in NZ dollars (NZ$) year 2010 value. Multivariate probabilistic uncertainty analyses were undertaken to provide information on the strength of the results. FINDINGS:Approximately 11,300 first-ever incident traumatic brain injuries occurred in NZ in 2010, with 527,000 New Zealanders estimated to have ever experienced a TBI (prevalent cases). The estimated 20,300 DALYs attributable to TBI accounted for 27% of total injury-related health loss and 2.4% of DALYs from all causes. Of the total TBI attributable DALYs 71% resulted from fatal injuries. However, nonfatal outcomes still accounted for a substantial share of the burden (29%) with mild TBI making the greater contribution of non-fatal outcomes (56%). Total first-year cost of all new TBI cases were estimated to be NZ$71 million with total prevalence costs of NZ$151 million. The average cost per new TBI case over a lifetime was NZ$8,824 (95% Cl NZ$7,118-NZ$11,709), varying from NZ$6,908 (95% CI NZ$5,597-NZ$8,286) for mild cases to NZ$54,605 (95% CI NZ$24,359-NZ$97,371) for moderate/severe cases. Due to the unexpectedly large number of mild TBI (95% of all TBI cases) the total cost of treating these cases was nearly three times that of moderate/severe. The total lifetime cost of all TBI survivors in 2010 was NZ$218 million and is expected to increase to NZ$263.9 million in 2020. CONCLUSION: The burden of TBI in NZ is substantial and mild TBI contribute to major part of nonfatal outcomes. The results suggest that while the cost of treating TBI varies greatly with most severe TBI attracting maximal costs; the cost of all mild TBI cases accounts for a large proportion of the overall impact due to the increased incidence. There is an urgent need to develop effective interventions to reduce the incidence of lower cost mild injuries.