Grootendorst P V
Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
Health Econ. 1997 Jul-Aug;6(4):365-82. doi: 10.1002/(sici)1099-1050(199707)6:4<365::aid-hec279>3.0.co;2-e.
The British Columbia Ministry of Health provides enhanced prescription drug insurance coverage to residents aged 65 and older. This exogenous change in the effective price of prescription drugs is used to investigate aspects of the drug use by seniors. Three sets of issues are of interest. First, what is the effect of enhanced insurance coverage on drug use and programme costs once drugs are provided free of charge? Second, is this effect permanent, or transitory? Third, are any increases in use observed concentrated among those with lower incomes? Longitudinal administrative claims payment data on 18,000 seniors over the period 1985-92 are used. All individuals in the sample turned 65 at some point and therefore became eligible for subsidized prescription drugs. Health status information is not collected; instead, health status is treated as an individual-specific fixed endowment, subject to a common rate of decay. Estimation is complicated by censoring of real drug expenditures for those under 65, rendering 'first differencing' methods invalid. A semi-parametric fixed effects Tobit estimator is used instead. For most individuals, the extension of insurance does not permanently increase drug use. Males with lower income were the exception. Little evidence of transitory effects to insurance coverage was found. Finally, the extension of insurance has made only a minor contribution to growth in seniors' drug use, relative to secular growth in drug use over time.
不列颠哥伦比亚省卫生部为65岁及以上的居民提供强化的处方药保险。这种处方药有效价格的外部变化被用于研究老年人的用药情况。有三组问题值得关注。第一，一旦药品免费提供，强化保险覆盖对药物使用和项目成本有何影响？第二，这种影响是永久性的还是短暂的？第三，观察到的用药增加是否集中在低收入人群中？使用了1985 - 1992年期间18000名老年人的纵向行政理赔支付数据。样本中的所有人在某个时间点年满65岁，因此有资格获得补贴处方药。未收集健康状况信息；相反，健康状况被视为个体特定的固定禀赋，服从共同的衰减率。对65岁以下人群实际药品支出的审查使估计变得复杂，导致“一阶差分”方法无效。取而代之的是使用半参数固定效应托比特估计器。对于大多数人来说，保险范围的扩大并没有永久性地增加药物使用。低收入男性是个例外。几乎没有发现保险覆盖有短暂影响的确凿证据。最后，相对于药品使用随时间的长期增长，保险范围的扩大对老年人药品使用增长的贡献很小。
