Effects of a price cut reform on the cost and utilization of antidiabetic drugs in Korea: a national health insurance database study

Table 3 Segmented regression coefficients for antidiabetics in outpatients by the price cut

Outcome variable		Policy group	Model	Coefficient								DW
				Baseline		Outpatient Prescription Incentive Program (OPIP)		Price cut (SPS)		February	AR(1)
				ß ₀	ß ₁	ß ₂	ß ₃	ß ₄	ß ₅	ß ₆	AR(1)
Costs (billion KRW)		Overall	AR	29.982^§	0.295^§	−0.984^#	− 0.136^†	− 4.384^§	0.192^†	−2.643^§	0.282^#	1.98
		Reduced	AR	23.738^§	0.065^†	1.357^§	−0.185^§	−4.809^§	− 0.023	− 1.858^§	0.277^#	2.06
		Constant	AR	6.240^§	0.229^§	−2.264^§	0.049	0.384	0.211^§	−0.856^§	− 0.080	1.80
Utiliz-ation	DDDs (million)	Overall	AR	79.447^§	0.463^§	−0.556	− 0.023	−1.058	− 0.114	−6.344^§	0.338^*	2.12
		Reduced	AR	70.638^§	0.161^†	1.321	−0.119	−1.442	− 0.340^†	−5.002^§	0.333^*	2.14
		Constant	OLS	8.794^§	0.301^§	−1.792^§	0.094^*	0.426	0.220^§	−1.370^§	–	1.99
	Number of patients	Overall	OLS	1,408,058^§	11,758^§	− 47643^*	1698	17,535	− 2504	−89,533^§	–	1.95
		Reduced	OLS	1,129,486^§	4909^§	− 6604	532	7296	−7523^§	−64,306^§	–	2.07
		Constant	AR	278,489^§	6820^§	−39,690^§	1207	8751	4989^§	−26,186^§	−0.168	1.79
Costs per patient (KRW)		Overall	OLS	43,492^§	160^§	− 2149^§	− 163^§	−3380^§	107^*	− 1063^§	–	1.86
		Reduced	OLS	20,992^§	−30^†	1123^§	−145^§	−3670^§	81^§	− 550^§	–	1.96
		Constant	AR	22,455^§	183^§	− 2800^§	−27	233	43	− 499^†	−0.485^†	2.12
DDDs per patient		Overall	AR	94.160^§	0.095^#	0.317	−0.083	−1.564	− 0.010	−2.610^*	0.224	2.12
		Reduced	AR	62.535^§	−0.120^§	1.330^†	−0.090^*	−1.416^†	0.056	−1.384^§	0.135	2.04
		Constant	OLS	31.594^§	0.215^§	−0.934	−0.0004	0.005	−0.068	−1.123^#	–	2.08

ß₀ = coefficients for the baseline levels of the outcome variables; ß₁ = coefficients for the changes in the outcome variables before the OPIP, i.e. the baseline trends; ß₂ = coefficients for the level changes in the outcome variables after the OPIP; ß₃ = coefficients for the changes in the trend of the outcome variables after the OPIP; ß₄ = coefficients for the level changes in the outcome variables after the SPS; ß₅ = coefficients for the changes in the trend of the outcome variables after the SPS; and ß₆ = coefficients for Feb variables
OLS ordinary least squares estimates, AR 1st order Autocorrelation Maximum likelihood estimates, DW Durbin-Watson d statistic, KRW Korean won (1000 KRW ≒ 1 US$ in January 2015), DDD defined daily dose
^# p < 0.1; ^* p < 0.05; ^† p < 0.01; ^§ p < 0.001

ISSN: 1472-6963