|
Putting a lid on injury costs: the economic impact of the California motorcycle helmet law |
Max W, Stark B, Root S |
|
|
Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Implementing motorcycle helmet law (requiring all motorcycle riders to wear helmets) in the reduction of motorcycle crash injuries in a state-wide population of motorcycle riders.
Economic study type Cost-effectiveness analysis.
Setting Hospital. The economic study was carried out in California, the USA.
Dates to which data relate Effectiveness and resource use data were related to the period between 1991 and 1993. The price year was 1993.
Source of effectiveness data Effectiveness data were derived from a single study.
Link between effectiveness and cost data Costing was retrospectively performed on a state-wide sample of motorcycle crashes used in the effectiveness analysis.
Study sample Power calculations were not used to determine the sample size. The study sample consisted of al motorcyclists in California, USA. The discharge records of 11,163 initial admissions for motorcycle injuries were examined, 43 injuries being the result of a second crash for an individual during the 3-year period. Also, 699 readmission's related to the initial hospitalisation, 219 inpatient rehabilitation records, and 147 nursing home records were obtained for the purposes of the study.
Study design The study was a retrospective cohort, carried out in a state-wide scale database consisting of discharge records of 500 hospitals. The duration of follow-up was until discharge, readmission, or 3 months after the previous crash. Loss to follow-up was not reported.
Analysis of effectiveness The principle (intention to treat or treatment completers only) used in the analysis of effectiveness was not explicitly specified . The clinical outcome measures were the rate of motorcycle crash fatalities and hospitalisation (including head and spinal injuries) per 100,000 registered motorcycle riders.
Effectiveness results The rate of motorcycle crash fatalities was 80 per 100,000 registered motorcycle riders in 1991 (one year before the introduction of the helmet law) versus 56 in 1992 (first year of the introduction of the law) and 54 in 1993 (second year after the introduction of the law). A 33% reduction for the period between 1991 and 1993.
The corresponding values with respect to the total rate of hospitalisation per 100,000 registered motorcycle riders were 735 in 1991, 585 in 1992, and 548 in 1993.
The rate of head injury per 100,000 registered motorcycle riders was 230 in 1991, 129 in 1992, and 119 in 1993 (p<0.001).
The corresponding values in terms of spinal injury per 100,000 registered motorcycle riders were 15 in 1991, 10 in 1992, and 11 in 1993 (NS).
Clinical conclusions The study results showed that the implementation of the motorcycle helmet law was associated with reduction in motorcycle crash injuries and fatalities during the first 2 years of the introduction of the law.
Measure of benefits used in the economic analysis The benefit measure was years of life lost per 100,000 registered motorcycle riders.
Direct costs Direct costs were not discounted as they appear to have been incurred over a short period of time. Quantities were reported separately from the costs only in terms of the length of hospital stay due to motorcycle crash injuries. Cost items were reported separately. Cost analysis covered the costs of initial hospitalisation, rehospitalisation, professional fees, emergency department, inpatient rehabilitation, ambulatory care services, emergency medical services, and nursing home care. The perspective adopted in the cost analysis was that of the payers (including private insurance, uninsured, Medical, CMS (county medical services), and Military/other federal government programmes). Cost calculations were performed using both charge and true cost data. The sources of the resource use and cost data were the California hospital discharge data and San Diego County data. Cost-to-charge ratios were used to convert hospital charges into costs. The costs attributed to nursing home care were based on estimation rather than actual data due to unavailability. The date of the price data was 1993.
Statistical analysis of costs The differences in medical expenditures were compared using the Kruskal-Wallis test and/or the Wilcoxon signed-rank test. Poisson regressions were performed, using injury and fatality rates as a proxy for costs, to determine how much of the decrease in costs was due to the helmet law.
Indirect Costs Indirect costs were discounted. Quantities were not reported separately from the costs. Indirect cost analysis employed the human capital approach and covered the costs of productivity loss resulting from fatalities. The lifetime earnings were estimated using both labour market earnings and imputed value for housekeeping services. The perspective adopted in the indirect cost analysis was that of society. The date of the price data was 1993.
Sensitivity analysis A one-way sensitivity analysis was performed on the discount rates used in the valuation of the productivity loss due to motorcycle crashes.
Estimated benefits used in the economic analysis Total years of life lost per 100,000 registered motorcycle riders was 3,824 in 1991 (one year before the introduction of the helmet law) versus 2,591 in 1992 (first year of the introduction of the law) and 2,478 in 1993 (second year after the introduction of the law). A 35% reduction for the period between 1991 and 1993. Benefits do not appear to have been discounted.
Cost results The total direct cost was $98,111 in 1991 (one year before the introduction of the helmet law) versus $63,087 in 1992 (first year of the introduction of the law) and $63,315 in 1993 (second year after the introduction of the law). Using a 3% discount rate, the indirect cost (productivity loss) was $603,232 in 1991 versus $380,000 in 1992 and $345,266 in 1993. A 42% reduction for the period between 1991 and 1993.
Synthesis of costs and benefits Costs and benefits were not combined since the use of the helmet law was the dominant strategy.
Authors' conclusions During the first 2 years of implementation of California's helmet law, there were reduced costs for injuries and fatalities and large dollar savings to the state and other payers compared with the previous year.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator (the usual practice before the introduction of the helmet law) is clear.
Validity of estimate of measure of benefit Despite the retrospective nature of the study design, the findings of the study appear to be valid given the size of the study sample - all motorcyclists in California, USA.
Validity of estimate of costs Quantities were not fully reported separately from the costs. However, adequate details of methods of cost estimation were given. Cost results may not be generalisable to other settings or countries.
Other issues More extensive sensitivity analyses could have been performed to account for the uncertainties in the data. The authors chose not to discount benefits and to discount costs at 3%. These discount rates might not apply in other countries. The issue of generalisability to other settings or countries was not addressed. Appropriate comparisons were made with other studies.
Source of funding Funded by a grant from the California Office of Traffic Safety (MC9201).
Bibliographic details Max W, Stark B, Root S. Putting a lid on injury costs: the economic impact of the California motorcycle helmet law. Journal of Trauma 1998; 45(3): 550-556 Indexing Status Subject indexing assigned by NLM MeSH Accidents, Traffic /economics; Adult; Age Distribution; Aged; California; Craniocerebral Trauma /economics /prevention & Female; Head Protective Devices; Health Care Costs; Humans; Male; Middle Aged; Motorcycles /legislation & Public Policy; Sex Factors; control; jurisprudence AccessionNumber 21998001418 Date bibliographic record published 31/08/2000 Date abstract record published 31/08/2000 |
|
|
|