The impact of health insurance expansion on physician treatment choice: Medicare Part D and physician prescribing

Abstract

We test the effect of the introduction of Medicare Part D on physician prescribing behavior by using data on physician visits from the National Ambulatory Medical Care Survey (NAMCS) 2002-2004 and 2006-2009 for patients aged 60-69. We use regression discontinuity designs to estimate the effect of part D around the age of 65 before and after 2006 and then compare the discrete jump in outcomes at age 65 before and after Part D. We find a 32% increase in the number of prescription drugs prescribed or continued per visit and a 46% increase in the number of generic drugs prescribed or continued for the elderly after the introduction of Medicare Part D.

Keywords: Expenditure of health care; Medicare; Part D; Prescribing pattern; Prescription drug.

Figure 1:. Number of Drugs Prescribed of Continued During a Physician Visit, NAMCS 2002–2004 and 2006–2009

Note: Samples are based on data from the National Ambulatory Medical Care Survey (2002–2004 and 2005–2009). The estimated discontinuities (and standard errors) at age 65 and the fitted lines are from a regression with a cubic polynomial in age fully interacted with a dummy for age greater than or equal to 65 and a dummy for year in or after 2006. Points represent means for people in each age cell (measured in quarters).

Figure 2:. Number of Drugs with A Generic Equivalent Prescribed or Continued During a Physician Visit, NAMCS 2002–2004 and 2006–2009

Note: Samples are based on data from the National Ambulatory Medical Care Survey (2002–2004 and 2005–2009). The estimated discontinuities (and standard errors) at age 65 and the fitted lines are from a regression with a cubic polynomial in age fully interacted with a dummy for age greater than or equal to 65 and a dummy for year in or after 2006. Points represent means for people in each age cell (measured in quarters).

Figure 3:. Distribution of Patient Age at Physician Visits, NAMCS 2002–2004 and 2006–2009

Note: Samples are based on data from the National Ambulatory Medical Care Survey (2002–2004 and 2005–2009). The estimated discontinuities (and standard errors) at age 65 and the fitted lines are from a regression with a cubic polynomial in age fully interacted with a dummy for age greater than or equal to 65 and a dummy for year in or after 2006. Points represent means for people in each age cell (measured in quarters).