Table 2.

Effects of 2002 HMO Office Visit Copayment Increase on Office Visit Utilization

	Copayment (Dollars per drug)	Utilization (Number of office visits per member per month)
Independent variable	(1)	(2)	(3)	(4)
HIPAY	$10.06** (0.05)	–0.132** (0.018)		–0.095** (0.012)
HIPAYt–4			0.016 (0.018)
HIPAYt–3			0.0002 (0.016)
HIPAYt–1			0.130** (0.016)
HIPAYt			–0.036** (0.016)
HIPAYt+1			–0.094** (0.016)
HIPAYt+2			–0.071** (0.016)
HIPAYt+3			–0 .082** (0.021)
HIPAYt+4			–0.101** (0.016)
HIPAYt+5			–0.113** (0.016)
HIPAYt+6			–0.029** (0.016)
N	128	128	128	104

Notes: Each column shows coefficients from a different regression; standard errors are reported in parentheses. The dependent variable is indicated on the column heading; the independent variable is indicated on the row label. Regressions control for plan and month fixed effects. They are estimated by GLS, allowing for plan-specific autocorrelation and plan-specific heteroskedasticity. Regressions include data from February 2001 through September 2003. Column 4 excludes data from the three months before and after the policy change, in order to eliminate the effects from any temporary shifts in the timing of care.

^**Denotes significance at the 5 percent level.