Encinosa William E, Bernard Didem, Dor Avi
Center for Delivery, Organization, and Markets, Rockville, MD, USA.
Adv Health Econ Health Serv Res. 2010;22:151-73. doi: 10.1108/s0731-2199(2010)0000022010.
To estimate the impact of diabetic drug adherence on hospitalizations, emergency room (ER) visits, and hospital costs.
It is often difficult to measure the impact of drug adherence on hospitalizations since both adherence and hospitalizations may be correlated with unobservable patient severity. We control for such unobservables using propensity score methods and instrumental variables for adherence such as drug coinsurance levels and direct-to-consumer advertising.
We find a significant bias due to unobservable severity in that patients with more severe health are more apt to comply with medications. Thus, the relationship between adherence and hospitalization will be underestimated if one does not control for unobservable severity. Overall, we find that increasing diabetic drug adherence from 50% to 100% reduces the hospitalization rate by 23.3% from 15% to 11.5%. ER visits reduce by 46.2% from 17.3% to 9.3%. Although such an increase in adherence increases diabetic drug spending by $776 a year per diabetic, the cost savings for averted hospitalizations and ER visits are $886 per diabetic, a cost offset of $1.14 per $1.00 spent on diabetic drugs.
Most of the drug cost-offset literature focuses only on the impact of cost-sharing and drug spending on cost-offsets, making it impossible to back-out the empirical impact of actual drug adherence on cost-offsets. In this chapter, we estimate the direct impact of adherence on hospitalizations and costs.
评估糖尿病药物依从性对住院治疗、急诊就诊及住院费用的影响。
由于依从性和住院治疗可能都与无法观察到的患者严重程度相关，因此通常难以衡量药物依从性对住院治疗的影响。我们使用倾向评分方法以及药物共付水平和直接面向消费者的广告等依从性的工具变量来控制这些无法观察到的因素。
我们发现由于无法观察到的严重程度存在显著偏差，即健康状况较差的患者更倾向于遵医嘱服药。因此，如果不控制无法观察到的严重程度，依从性与住院治疗之间的关系将被低估。总体而言，我们发现将糖尿病药物依从性从50%提高到100%可使住院率从15%降至11.5%，降低23.3%。急诊就诊率从17.3%降至9.3%，降低46.2%。尽管依从性的这种提高使每位糖尿病患者每年的糖尿病药物支出增加776美元，但避免住院和急诊就诊节省的费用为每位糖尿病患者886美元，即每花费1.00美元用于糖尿病药物，成本抵消为1.14美元。
大多数药物成本抵消文献仅关注成本分担和药物支出对成本抵消的影响，因此无法得出实际药物依从性对成本抵消的实证影响。在本章中，我们估计了依从性对住院治疗和成本的直接影响。
